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chromium / external / dynamorio / 943803169438bfb21cc82c52f9b141574bb4b249 / . / core / link.c
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/* **********************************************************
* Copyright (c) 2012-2014 Google, Inc. All rights reserved.
* Copyright (c) 2000-2010 VMware, Inc. All rights reserved.
* **********************************************************/
/*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
*
* * Redistributions of source code must retain the above copyright notice,
* this list of conditions and the following disclaimer.
*
* * Redistributions in binary form must reproduce the above copyright notice,
* this list of conditions and the following disclaimer in the documentation
* and/or other materials provided with the distribution.
*
* * Neither the name of VMware, Inc. nor the names of its contributors may be
* used to endorse or promote products derived from this software without
* specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL VMWARE, INC. OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
* SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
* CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH
* DAMAGE.
*/
/* Copyright (c) 2003-2007 Determina Corp. */
/* Copyright (c) 2001-2003 Massachusetts Institute of Technology */
/* Copyright (c) 2000-2001 Hewlett-Packard Company */
/*
* link.c - fragment linker routines
*/
#include "globals.h"
#include "link.h"
#include "fragment.h"
#include "fcache.h"
#include "emit.h"
#include "monitor.h"
#include <string.h> /* for memset */
#include "perscache.h"
#include "instr.h" /* PC_RELATIVE_TARGET */
/* fragment_t and future_fragment_t are guaranteed to have flags field at same offset,
* so we use it to find incoming_stubs offset
*/
#define FRAG_INCOMING_ADDR(f) \
((common_direct_linkstub_t **) \
(!TEST(FRAG_IS_FUTURE, f->flags) ? &f->in_xlate.incoming_stubs : \
&((future_fragment_t *)f)->incoming_stubs))
/* forward decl */
static void
coarse_stubs_init(void);
static void
coarse_stubs_free(void);
static fragment_t *
fragment_link_lookup_same_sharing(dcontext_t *dcontext, app_pc tag,
linkstub_t *last_exit, uint flags);
static void
link_new_coarse_grain_fragment(dcontext_t *dcontext, fragment_t *f);
static void
coarse_link_to_fine(dcontext_t *dcontext, cache_pc src_stub, fragment_t *src_f,
fragment_t *target_f, bool do_link/*else just add incoming*/);
static coarse_incoming_t *
prepend_new_coarse_incoming(coarse_info_t *info, cache_pc coarse, linkstub_t *fine);
static fragment_t *
fragment_coarse_link_wrapper(dcontext_t *dcontext, app_pc target_tag,
cache_pc know_coarse);
static void
set_fake_direct_linkstub(direct_linkstub_t *proxy, app_pc target, cache_pc stub);
/* Removes an incoming entry from a fine fragment to a coarse unit */
static void
coarse_remove_incoming(dcontext_t *dcontext, fragment_t *src_f, linkstub_t *src_l,
fragment_t *targetf);
/* We use temporary structs to pass targets to is_linkable().
* change_linking_lock protects use of these.
* FIXME: change is_linkable to take in field values directly?
*/
DECLARE_FREQPROT_VAR(static fragment_t temp_targetf, {0});
DECLARE_FREQPROT_VAR(static direct_linkstub_t temp_linkstub, {{{0}}});
/* This lock makes changes in a shared fragment's link state consistent --
* the flags indicating whether it is linked and the link state of each of
* its exits. Since future fragments are driven by linking, this lock
* also synchronizes creation and deletion of future fragments.
* Exported so micro routines can assert whether held.
*/
DECLARE_CXTSWPROT_VAR(recursive_lock_t change_linking_lock,
INIT_RECURSIVE_LOCK(change_linking_lock));
/* Special executable heap for separate stubs
* To avoid wasting capacity space we use a shared heap for all stubs
*/
void *stub_heap;
#ifdef X64
void *stub32_heap;
#endif
#ifdef X64
# define SEPARATE_STUB_HEAP(flags) (FRAG_IS_32(flags) ? stub32_heap : stub_heap)
#else
# define SEPARATE_STUB_HEAP(flags) stub_heap
#endif
/* We save 1 byte per stub by not aligning to 16/24 bytes, since
* infrequently executed and infrequently accessed (heap free list
* adds to start so doesn't walk list).
*/
#define SEPARATE_STUB_ALLOC_SIZE(flags) (DIRECT_EXIT_STUB_SIZE(flags)) /* 15x23 */
/* Coarse stubs must be hot-patchable, so we avoid having their last
* 4 bytes cross cache lines.
* For x64, the stub is 29 bytes long, so the last 4 bytes are fine
* for a 16-byte cache line.
*/
#define COARSE_STUB_ALLOC_SIZE(flags) \
(ALIGN_FORWARD(STUB_COARSE_DIRECT_SIZE(flags), 4)) /* 16x32 */
/* Static linkstubs to give information on special exits from the cache.
* We make them const to get them in read-only memory even if we have to cast a lot.
* Our accessor routines do NOT cast since equality tests can use const and they
* are the most common use.
* FIXME: we're accumulating a lot of these -- but we don't have room in our flags
* space to distinguish any other way nicely, so we carry on w/ a bunch of
* identical static linkstubs.
*/
/* linkstub_fragment() returns a static fragment_t for these fake linkstubs: */
static const fragment_t linkstub_empty_fragment = { NULL, FRAG_FAKE, };
#ifdef X64
static const fragment_t linkstub_empty_fragment_x86 = { NULL, FRAG_FAKE | FRAG_32_BIT, };
#endif
static const linkstub_t linkstub_starting = { LINK_FAKE, 0 };
static const linkstub_t linkstub_reset = { LINK_FAKE, 0 };
static const linkstub_t linkstub_syscall = { LINK_FAKE, 0 };
static const linkstub_t linkstub_selfmod = { LINK_FAKE, 0 };
static const linkstub_t linkstub_ibl_deleted = { LINK_FAKE, 0 };
#ifdef UNIX
static const linkstub_t linkstub_sigreturn = { LINK_FAKE, 0 };
#else /* WINDOWS */
static const linkstub_t linkstub_asynch = { LINK_FAKE, 0 };
#endif
static const linkstub_t linkstub_native_exec = { LINK_FAKE, 0 };
/* this one we give the flag LINK_NI_SYSCALL for executing a syscall in dispatch() */
static const linkstub_t linkstub_native_exec_syscall =
{ LINK_FAKE| LINK_NI_SYSCALL, 0 };
#ifdef WINDOWS
/* used for shared_syscall exits */
static const fragment_t linkstub_shared_syscall_trace_fragment =
{ NULL, FRAG_FAKE | FRAG_HAS_SYSCALL | FRAG_IS_TRACE, };
static const fragment_t linkstub_shared_syscall_bb_fragment =
{ NULL, FRAG_FAKE | FRAG_HAS_SYSCALL, };
# ifdef PROFILE_LINKCOUNT
/* For PROFILE_LINKCOUNT we need to be able to write to these from the cache
* to update their linkcounts, so we can't have them const or in .data.
* Since this is not a product config we don't care if we don't protect their
* flags (if we did we could put these on the heap).
*/
DECLARE_NEVERPROT_VAR(static linkstub_t linkstub_shared_syscall_trace,
{ LINK_FAKE| LINK_INDIRECT | LINK_JMP, 0 });
DECLARE_NEVERPROT_VAR(static linkstub_t linkstub_shared_syscall_bb,
{ LINK_FAKE| LINK_INDIRECT | LINK_JMP, 0 });
DECLARE_NEVERPROT_VAR(static linkstub_t linkstub_shared_syscall_unlinked,
{ LINK_FAKE, 0 });
# else
static const linkstub_t linkstub_shared_syscall_trace =
{ LINK_FAKE| LINK_INDIRECT | LINK_JMP, 0 };
static const linkstub_t linkstub_shared_syscall_bb =
{ LINK_FAKE| LINK_INDIRECT | LINK_JMP, 0 };
/* NOT marked as LINK_INDIRECT|LINK_JMP since we don't bother updating the ibl table
* on the unlink path */
static const linkstub_t linkstub_shared_syscall_unlinked = { LINK_FAKE, 0 };
# endif
#endif
/* A unique fragment_t for use when the details don't matter */
static const fragment_t coarse_fragment =
{ NULL, FRAG_FAKE | FRAG_COARSE_GRAIN | FRAG_SHARED |
/* We mark as linked so is_linkable() won't reject it on any side of a link */
FRAG_LINKED_OUTGOING | FRAG_LINKED_INCOMING, };
/* We don't mark as direct since not everything checks for being fake */
static const linkstub_t linkstub_coarse_exit = { LINK_FAKE, 0 };
static const linkstub_t linkstub_coarse_trace_head_exit = { LINK_FAKE, 0 };
#ifdef HOT_PATCHING_INTERFACE
/* used to change control flow in a hot patch routine */
static const linkstub_t linkstub_hot_patch = { LINK_FAKE, 0 };
#endif
#ifdef CLIENT_INTERFACE
/* used for dr_redirect_exection() call to transfer_to_dispatch() */
static const linkstub_t linkstub_client = { LINK_FAKE, 0 };
#endif
/* for !DYNAMO_OPTION(indirect_stubs)
* FIXME: these are used for shared_syscall as well, yet not marked as
* FRAG_HAS_SYSCALL, but nobody checks for that currently
*/
static const fragment_t linkstub_ibl_trace_fragment =
{ NULL, FRAG_FAKE | FRAG_IS_TRACE, };
static const fragment_t linkstub_ibl_bb_fragment =
{ NULL, FRAG_FAKE, };
# ifdef PROFILE_LINKCOUNT
DECLARE_NEVERPROT_VAR(static const linkstub_t linkstub_ibl_trace_ret,
{ LINK_FAKE | LINK_INDIRECT | LINK_RETURN, 0 });
DECLARE_NEVERPROT_VAR(static const linkstub_t linkstub_ibl_trace_jmp,
{ LINK_FAKE | LINK_INDIRECT | LINK_JMP, 0 });
DECLARE_NEVERPROT_VAR(static const linkstub_t linkstub_ibl_trace_call,
{ LINK_FAKE | LINK_INDIRECT | LINK_CALL, 0 });
DECLARE_NEVERPROT_VAR(static const linkstub_t linkstub_ibl_bb_ret,
{ LINK_FAKE | LINK_INDIRECT | LINK_RETURN, 0 });
DECLARE_NEVERPROT_VAR(static const linkstub_t linkstub_ibl_bb_jmp,
{ LINK_FAKE | LINK_INDIRECT | LINK_JMP, 0 });
DECLARE_NEVERPROT_VAR(static const linkstub_t linkstub_ibl_bb_call,
{ LINK_FAKE | LINK_INDIRECT | LINK_CALL, 0 });
/* we only need special_*_ret and *_call for client_ibl and native_plt/ret_ibl */
DECLARE_NEVERPROT_VAR(static const linkstub_t linkstub_special_ibl_bb_ret,
{ LINK_FAKE | LINK_INDIRECT | LINK_RETURN, 0 } /* client_ibl */);
DECLARE_NEVERPROT_VAR(static const linkstub_t linkstub_special_ibl_bb_call,
{ LINK_FAKE | LINK_INDIRECT | LINK_CALL, 0 } /* native_plt_ibl */);
DECLARE_NEVERPROT_VAR(static const linkstub_t linkstub_special_ibl_trace_ret,
{ LINK_FAKE | LINK_INDIRECT | LINK_RETURN, 0 } /* client_ibl */);
DECLARE_NEVERPROT_VAR(static const linkstub_t linkstub_special_ibl_trace_call,
{ LINK_FAKE | LINK_INDIRECT | LINK_CALL, 0 } /* native_plt_ibl */);
# else /* !PROFILE_LINKCOUNT */
static const linkstub_t linkstub_ibl_trace_ret =
{ LINK_FAKE | LINK_INDIRECT | LINK_RETURN, 0 };
static const linkstub_t linkstub_ibl_trace_jmp =
{ LINK_FAKE | LINK_INDIRECT | LINK_JMP, 0 };
static const linkstub_t linkstub_ibl_trace_call =
{ LINK_FAKE | LINK_INDIRECT | LINK_CALL, 0 };
static const linkstub_t linkstub_ibl_bb_ret =
{ LINK_FAKE | LINK_INDIRECT | LINK_RETURN, 0 };
static const linkstub_t linkstub_ibl_bb_jmp =
{ LINK_FAKE | LINK_INDIRECT | LINK_JMP, 0 };
static const linkstub_t linkstub_ibl_bb_call =
{ LINK_FAKE | LINK_INDIRECT | LINK_CALL, 0 };
static const linkstub_t linkstub_special_ibl_bb_ret =
{ LINK_FAKE | LINK_INDIRECT | LINK_RETURN, 0 }; /* client_ibl */
static const linkstub_t linkstub_special_ibl_bb_call =
{ LINK_FAKE | LINK_INDIRECT | LINK_CALL, 0 }; /* native_plt_ibl */
static const linkstub_t linkstub_special_ibl_trace_ret =
{ LINK_FAKE | LINK_INDIRECT | LINK_RETURN, 0 }; /* client_ibl */
static const linkstub_t linkstub_special_ibl_trace_call =
{ LINK_FAKE | LINK_INDIRECT | LINK_CALL, 0 }; /* native_plt_ibl */
# endif
#if defined(X64) || defined(DEBUG)
static inline bool
is_empty_fragment(fragment_t *f)
{
return (f == (fragment_t *)&linkstub_empty_fragment
IF_X64(|| f == (fragment_t *)&linkstub_empty_fragment_x86));
}
#endif
#ifdef X64
fragment_t *
empty_fragment_mark_x86(fragment_t *f)
{
ASSERT(f == (fragment_t *)&linkstub_empty_fragment);
return (fragment_t *)&linkstub_empty_fragment_x86;
}
#endif
/* used to hold important fields for last_exits that are flushed */
typedef struct thread_link_data_t {
linkstub_t linkstub_deleted;
fragment_t linkstub_deleted_fragment;
/* The ordinal is the count from the end.
* -1 means invalid.
* The value corresponds to the get_deleted_linkstub() linkstub_t only and
* may be stale wrt dcontext->last_exit.
*/
int linkstub_deleted_ordinal;
} thread_link_data_t;
/* thread-shared initialization that should be repeated after a reset */
void
link_reset_init(void)
{
if (DYNAMO_OPTION(separate_private_stubs) ||
DYNAMO_OPTION(separate_shared_stubs)) {
stub_heap = special_heap_init(SEPARATE_STUB_ALLOC_SIZE(0/*default*/),
true /* must synch */, true /* +x */,
false /* not persistent */);
#ifdef X64
stub32_heap = special_heap_init(SEPARATE_STUB_ALLOC_SIZE(FRAG_32_BIT),
true /* must synch */, true /* +x */,
false /* not persistent */);
#endif
}
}
/* Free all thread-shared state not critical to forward progress;
* link_reset_init() will be called before continuing.
*/
void
link_reset_free(void)
{
if (DYNAMO_OPTION(separate_private_stubs) ||
DYNAMO_OPTION(separate_shared_stubs)) {
special_heap_exit(stub_heap);
#ifdef X64
special_heap_exit(stub32_heap);
#endif
}
}
void
link_init()
{
link_reset_init();
coarse_stubs_init();
}
void
link_exit()
{
coarse_stubs_free();
link_reset_free();
DELETE_RECURSIVE_LOCK(change_linking_lock);
}
void
link_thread_init(dcontext_t *dcontext)
{
thread_link_data_t *ldata =
HEAP_TYPE_ALLOC(dcontext, thread_link_data_t, ACCT_OTHER, PROTECTED);
dcontext->link_field = (void *) ldata;
memset(&ldata->linkstub_deleted, 0, sizeof(ldata->linkstub_deleted));
memset(&ldata->linkstub_deleted_fragment, 0,
sizeof(ldata->linkstub_deleted_fragment));
ldata->linkstub_deleted_ordinal = -1;
/* Mark as fake */
ldata->linkstub_deleted_fragment.flags = FRAG_FAKE;
ldata->linkstub_deleted.flags = LINK_FAKE;
}
void
link_thread_exit(dcontext_t *dcontext)
{
thread_link_data_t *ldata = (thread_link_data_t *) dcontext->link_field;
HEAP_TYPE_FREE(dcontext, ldata, thread_link_data_t, ACCT_OTHER, PROTECTED);
}
/* Initializes an array of linkstubs beginning with first */
void
linkstubs_init(linkstub_t *first, int num_direct, int num_indirect, fragment_t *f)
{
/* we don't know the sequencing of direct and indirect so all we do
* here is zero everything out
*/
uint size = linkstubs_heap_size(f->flags, num_direct, num_indirect);
ASSERT(num_direct + num_indirect > 0);
memset(first, 0, size);
/* place the offset to the fragment_t*, if necessary */
if (linkstub_frag_offs_at_end(f->flags, num_direct, num_indirect)) {
ushort offs;
/* size includes post_linkstub_t so we have to subtract it off */
post_linkstub_t *post = (post_linkstub_t *)
(((byte *)first) + size - sizeof(post_linkstub_t));
ASSERT_TRUNCATE(offs, ushort, (((byte *)post) - ((byte *)f)));
offs = (ushort) (((byte *)post) - ((byte *)f));
post->fragment_offset = offs;
}
}
uint
linkstub_size(dcontext_t *dcontext, fragment_t *f, linkstub_t *l)
{
ASSERT(linkstub_owned_by_fragment(dcontext, f, l));
/* FIXME: optimization: now for ind exits we compute a pc from
* flags and then exit_stub_size looks up the pc to find whether
* indirect -- should pass that flag.
* There are a number of uses of this idiom in emit_utils.c as well.
*/
return exit_stub_size(dcontext, EXIT_TARGET_TAG(dcontext, f, l), f->flags);
}
/* we don't want to propagate our cbr hack during trace building, etc. */
uint
linkstub_propagatable_flags(uint flags)
{
if (LINKSTUB_CBR_FALLTHROUGH(flags))
flags &= ~LINK_INDIRECT;
return flags;
}
/* is a post_linkstub_t structure required to store the fragment_t offset? */
bool
linkstub_frag_offs_at_end(uint flags, int direct_exits, int indirect_exits)
{
ASSERT((direct_exits + indirect_exits > 0) || TEST(FRAG_COARSE_GRAIN, flags));
/* common bb types do not have an offset at the end:
* 1) single indirect exit
* 2) two direct exits
* 3) coarse-grain, which of course have no fragment_t
* see linkstub_fragment() for how we find their owning fragment_t's.
* Since we have to assume sizeof(fragment_t) we can only allow
* shared fragments to not have an offset, unless we add a LINK_SHARED
* flag, which we can do if we end up having a product config w/ private bbs.
* FIXME: make the sizeof calculation dynamic such that the dominant
* type of bb fragment is the one w/o the post_linkstub_t.
*/
return !(!TEST(FRAG_IS_TRACE, flags) &&
TEST(FRAG_SHARED, flags) &&
/* We can't tell from the linkstub_t whether there is a
* translation field. FIXME: we could avoid this problem
* by storing the translation field after the linkstubs.
*/
!TEST(FRAG_HAS_TRANSLATION_INFO, flags) &&
((direct_exits == 2 && indirect_exits == 0) ||
(direct_exits == 0 && indirect_exits == 1)))
&& !TEST(FRAG_COARSE_GRAIN, flags);
}
bool
use_cbr_fallthrough_short(uint flags, int direct_exits, int indirect_exits)
{
ASSERT((direct_exits + indirect_exits > 0) || TEST(FRAG_COARSE_GRAIN, flags));
if (direct_exits != 2 || indirect_exits != 0)
return false;
#ifdef CLIENT_INTERFACE
/* cannot handle instrs inserted between cbr and fall-through jmp */
return false;
#else
/* we can only use the cbr_fallthrough_linkstub_t if these conditions
* apply:
* 1) separate stubs will not be individually freed -- we could
* have a fancy scheme that frees both at once, but we simply
* disallow the struct if any freeing will occur.
* 2) the fallthrough target is close to the start pc
* 3) the fallthrough exit immediately follows the cbr exit
* (we assume this is true if !CLIENT_INTERFACE)
* conditions 2 and 3 are asserted in emit.c
*/
return (TEST(FRAG_CBR_FALLTHROUGH_SHORT, flags) &&
!TEST(FRAG_COARSE_GRAIN, flags) &&
((TEST(FRAG_SHARED, flags) && !DYNAMO_OPTION(unsafe_free_shared_stubs)) ||
(!TEST(FRAG_SHARED, flags) && !DYNAMO_OPTION(free_private_stubs))));
#endif
}
/* includes the post_linkstub_t offset struct size */
uint
linkstubs_heap_size(uint flags, int direct_exits, int indirect_exits)
{
uint offset_sz, linkstub_size;
ASSERT((direct_exits + indirect_exits > 0) || TEST(FRAG_COARSE_GRAIN, flags));
if (use_cbr_fallthrough_short(flags, direct_exits, indirect_exits)) {
linkstub_size = sizeof(direct_linkstub_t) +
sizeof(cbr_fallthrough_linkstub_t);
} else {
linkstub_size = direct_exits * sizeof(direct_linkstub_t) +
indirect_exits * sizeof(indirect_linkstub_t);
}
if (linkstub_frag_offs_at_end(flags, direct_exits, indirect_exits))
offset_sz = sizeof(post_linkstub_t);
else
offset_sz = 0;
return linkstub_size + offset_sz;
}
/* Locate the owning fragment_t for a linkstub_t */
fragment_t *
linkstub_fragment(dcontext_t *dcontext, linkstub_t *l)
{
if (LINKSTUB_FAKE(l)) {
#ifdef WINDOWS
if (l == &linkstub_shared_syscall_trace)
return (fragment_t *)&linkstub_shared_syscall_trace_fragment;
else if (l == &linkstub_shared_syscall_bb)
return (fragment_t *)&linkstub_shared_syscall_bb_fragment;
#endif
if (l == &linkstub_ibl_trace_ret ||
l == &linkstub_ibl_trace_jmp ||
l == &linkstub_ibl_trace_call)
return (fragment_t *)&linkstub_ibl_trace_fragment;
else if (l == &linkstub_ibl_bb_ret ||
l == &linkstub_ibl_bb_jmp ||
l == &linkstub_ibl_bb_call)
return (fragment_t *)&linkstub_ibl_bb_fragment;
if (dcontext != NULL && dcontext != GLOBAL_DCONTEXT) {
thread_link_data_t *ldata = (thread_link_data_t *) dcontext->link_field;
if (l == &ldata->linkstub_deleted)
return &ldata->linkstub_deleted_fragment;
}
/* For coarse proxies, we need a fake FRAG_SHARED fragment_t for is_linkable */
if (LINKSTUB_COARSE_PROXY(l->flags))
return (fragment_t *)&coarse_fragment;
return (fragment_t *)&linkstub_empty_fragment;
}
/* To save space we no longer store a backpointer in the linkstub_t.
* Instead we use several schemes based on the type of owning
* fragment_t. We could walk backward but that gets complicated with
* hacks to distinguish types of structs by their final fields w/o
* adding secondary flags fields.
*/
if (TEST(LINK_FRAG_OFFS_AT_END, l->flags)) {
/* For traces and unusual bbs, we store an offset to the
* fragment_t at the end of the linkstub_t list.
*/
post_linkstub_t *post;
for (; !LINKSTUB_FINAL(l); l = LINKSTUB_NEXT_EXIT(l))
; /* nothing */
ASSERT(l != NULL && TEST(LINK_END_OF_LIST, l->flags));
post = (post_linkstub_t *) (((byte*)l) + LINKSTUB_SIZE(l));
return (fragment_t *) (((byte *)post) - post->fragment_offset);
} else {
/* Otherwise, we assume this is one of 2 types of basic block! */
if (LINKSTUB_INDIRECT(l->flags)) {
/* Option 1: a single indirect exit */
ASSERT(TEST(LINK_END_OF_LIST, l->flags));
return (fragment_t *) ( ((byte *)l) - sizeof(fragment_t) );
} else {
ASSERT(LINKSTUB_DIRECT(l->flags));
/* Option 2: two direct exits (doesn't matter if 2nd uses
* cbr_fallthrough_linkstub_t or not)
* (single direct exit is very rare but if later becomes common
* could add a LINK_ flag to distinguish)
*/
if (TEST(LINK_END_OF_LIST, l->flags)) {
return (fragment_t *) ( ((byte *)l) - sizeof(direct_linkstub_t) -
sizeof(fragment_t) );
} else {
return (fragment_t *) ( ((byte *)l) - sizeof(fragment_t) );
}
}
}
ASSERT_NOT_REACHED();
return NULL;
}
#ifdef DEBUG
bool
linkstub_owned_by_fragment(dcontext_t *dcontext, fragment_t *f, linkstub_t *l)
{
linkstub_t *ls;
/* handle fake linkstubs first since FRAGMENT_EXIT_STUBS shouldn't be called
* on fake fragments!
*/
if (LINKSTUB_FAKE(l)) {
ASSERT(TEST(FRAG_FAKE, f->flags) ||
/* during emit, coarse-grain has real fragment_t but sometimes fake
* linkstubs during linking
*/
TEST(FRAG_COARSE_GRAIN, f->flags));
/* Coarse-grain temp fragment_t's also have temp fake linkstub_t's */
if (TEST(FRAG_COARSE_GRAIN, f->flags))
return true;
else {
return (linkstub_fragment(dcontext, l) == f
/* For reset exit stub we need a fake empty fragment marked as x86 */
IF_X64(|| (is_empty_fragment(linkstub_fragment(dcontext, l)) &&
f == (fragment_t *)&linkstub_empty_fragment_x86)));
}
}
for (ls = FRAGMENT_EXIT_STUBS(f); ls != NULL; ls = LINKSTUB_NEXT_EXIT(ls)) {
if (ls == l)
return true;
}
return false;
}
#endif
/* N.B.: all the actions of this routine are mirrored in insert_set_last_exit(),
* so any changes here should be mirrored there.
*/
void
set_last_exit(dcontext_t *dcontext, linkstub_t *l)
{
/* We try to set last_fragment every time we set last_exit, rather than
* leaving it as a dangling pointer until the next dispatch entrance,
* to avoid cases like bug 7534. However, fcache_return only sets
* last_exit, though it hits the dispatch point that sets last_fragment
* soon after, and everyone who frees fragments that other threads can
* see should call last_exit_deleted() on the other threads.
*/
ASSERT(l != NULL);
dcontext->last_exit = l;
dcontext->last_fragment = linkstub_fragment(dcontext, dcontext->last_exit);
ASSERT(dcontext->last_fragment != NULL);
/* We also cannot leave dir_exit as a dangling pointer */
dcontext->coarse_exit.dir_exit = NULL;
}
void
last_exit_deleted(dcontext_t *dcontext)
{
thread_link_data_t *ldata = (thread_link_data_t *) dcontext->link_field;
linkstub_t *l;
/* if this gets called twice, second is a nop
* FIXME: measure how often, reduce dup calls
*/
if (LINKSTUB_FAKE(dcontext->last_exit) &&
/* be defensive (remember case 7534!): re-do in case someone
* sets last_exit to FAKE but leaves last_fragment dangling
*/
dcontext->last_fragment == &ldata->linkstub_deleted_fragment)
return;
ASSERT(LINKSTUB_FAKE(&ldata->linkstub_deleted));
ASSERT(linkstub_fragment(dcontext, &ldata->linkstub_deleted) ==
&ldata->linkstub_deleted_fragment);
DOCHECK(1, {
/* easier to clear these and ensure whole thing is 0 for the fragment */
ldata->linkstub_deleted_fragment.tag = 0;
ldata->linkstub_deleted_fragment.flags = 0;
ldata->linkstub_deleted_fragment.id = 0;
ASSERT(is_region_memset_to_char((byte *)&ldata->linkstub_deleted_fragment,
sizeof(ldata->linkstub_deleted_fragment), 0));
});
/* FIME: should we have special dcontext fields last_exit_flags &
* last_fragment_{flags,tag} and make everyone use those to ensure
* nobody treats these as the real thing?
* But trace building and some others need the real thing, so would
* have to check whether valid anyway, so just as costly to check
* whether these are valid. FRAG_FAKE and LINK_FAKE tags help us out here.
*/
ldata->linkstub_deleted.flags = dcontext->last_exit->flags;
ldata->linkstub_deleted.flags |= LINK_FAKE;
ldata->linkstub_deleted_fragment.tag = dcontext->last_fragment->tag;
ldata->linkstub_deleted_fragment.flags |= FRAG_FAKE;
#ifdef DEBUG_MEMORY
ASSERT(dcontext->last_fragment->flags != HEAP_UNALLOCATED_UINT);
ASSERT(dcontext->last_fragment->id != HEAP_UNALLOCATED_UINT);
#endif
ldata->linkstub_deleted_fragment.flags = dcontext->last_fragment->flags;
DODEBUG({
ldata->linkstub_deleted_fragment.id = dcontext->last_fragment->id;
});
/* Store which exit this is, for trace building.
* Our ordinal is the count from the end.
*/
if (TEST(FRAG_FAKE, dcontext->last_fragment->flags))
ldata->linkstub_deleted_ordinal = -1; /* invalid */
else {
ldata->linkstub_deleted_ordinal = 0;
for (l = FRAGMENT_EXIT_STUBS(dcontext->last_fragment);
l != NULL && l != dcontext->last_exit;
l = LINKSTUB_NEXT_EXIT(l)) {
/* nothing */
}
if (l == dcontext->last_exit) {
/* 0 means the last one */
for (l = LINKSTUB_NEXT_EXIT(l); l != NULL; l = LINKSTUB_NEXT_EXIT(l))
ldata->linkstub_deleted_ordinal++;
} else {
ASSERT_NOT_REACHED();
ldata->linkstub_deleted_ordinal = -1; /* invalid */
}
}
/* now install the copy as the last exit, but don't overwrite an existing
* fake exit (like a native_exec exit: case 8033)
*/
if (!LINKSTUB_FAKE(dcontext->last_exit))
dcontext->last_exit = &ldata->linkstub_deleted;
dcontext->last_fragment = &ldata->linkstub_deleted_fragment;
/* We also cannot leave dir_exit as a dangling pointer */
dcontext->coarse_exit.dir_exit = NULL;
}
static inline bool
is_special_ibl_linkstub(const linkstub_t *l)
{
if (l == &linkstub_special_ibl_trace_ret ||
l == &linkstub_special_ibl_trace_call ||
l == &linkstub_special_ibl_bb_ret ||
l == &linkstub_special_ibl_bb_call)
return true;
return false;
}
void
set_coarse_ibl_exit(dcontext_t *dcontext)
{
thread_link_data_t *ldata = (thread_link_data_t *) dcontext->link_field;
app_pc src_tag;
/* Special ibl is incompatible with knowing the source tag (so can't use
* dr_redirect_native_target() with PROGRAM_SHEPHERDING).
*/
if (is_special_ibl_linkstub((const linkstub_t*)dcontext->last_exit))
return;
src_tag = dcontext->coarse_exit.src_tag;
ASSERT(src_tag != NULL);
if (!DYNAMO_OPTION(coarse_units) ||
!is_ibl_sourceless_linkstub((const linkstub_t*)dcontext->last_exit))
return;
/* We use the sourceless linkstubs for the ibl, but we do have source info
* in dcontext->coarse_exit.src_tag, so once back in DR we switch to our
* deleted structs to fill in the src info
*/
/* Re-use the deletion routine to fill in the fields for us.
* It won't replace last_exit itself as it's already fake, but it will
* replace last_fragment. FIXME: now we have last_fragment != result of
* linkstub_fragment()!
*/
last_exit_deleted(dcontext);
ldata->linkstub_deleted_fragment.tag = src_tag;
}
/* The ordinal is the count from the end.
* -1 means invalid.
* The value corresponds to the get_deleted_linkstub() linkstub_t only and
* may be stale wrt dcontext->last_exit.
*/
int
get_last_linkstub_ordinal(dcontext_t *dcontext)
{
thread_link_data_t *ldata;
ASSERT(dcontext != GLOBAL_DCONTEXT);
ldata = (thread_link_data_t *) dcontext->link_field;
return ldata->linkstub_deleted_ordinal;
}
linkstub_t *
get_deleted_linkstub(dcontext_t *dcontext)
{
thread_link_data_t *ldata;
ASSERT(dcontext != GLOBAL_DCONTEXT);
ldata = (thread_link_data_t *) dcontext->link_field;
return &ldata->linkstub_deleted;
}
const linkstub_t *
get_starting_linkstub()
{
return &linkstub_starting;
}
const linkstub_t *
get_reset_linkstub()
{
return &linkstub_reset;
}
const linkstub_t *
get_syscall_linkstub()
{
return &linkstub_syscall;
}
const linkstub_t *
get_selfmod_linkstub()
{
return &linkstub_selfmod;
}
const linkstub_t *
get_ibl_deleted_linkstub()
{
return &linkstub_ibl_deleted;
}
#ifdef UNIX
const linkstub_t *
get_sigreturn_linkstub()
{
return &linkstub_sigreturn;
}
#else /* WINDOWS */
const linkstub_t *
get_asynch_linkstub()
{
return &linkstub_asynch;
}
#endif
const linkstub_t *
get_native_exec_linkstub()
{
return &linkstub_native_exec;
}
const linkstub_t *
get_native_exec_syscall_linkstub()
{
return &linkstub_native_exec_syscall;
}
#ifdef WINDOWS
const linkstub_t *
get_shared_syscalls_unlinked_linkstub()
{
return &linkstub_shared_syscall_unlinked;
}
const linkstub_t *
get_shared_syscalls_trace_linkstub()
{
return &linkstub_shared_syscall_trace;
}
const linkstub_t *
get_shared_syscalls_bb_linkstub()
{
return &linkstub_shared_syscall_bb;
}
#endif /* WINDOWS */
#ifdef HOT_PATCHING_INTERFACE
const linkstub_t *
get_hot_patch_linkstub()
{
return &linkstub_hot_patch;
}
#endif
#ifdef CLIENT_INTERFACE
const linkstub_t *
get_client_linkstub()
{
return &linkstub_client;
}
#endif
bool
is_ibl_sourceless_linkstub(const linkstub_t *l)
{
return (l == &linkstub_ibl_trace_ret ||
l == &linkstub_ibl_trace_jmp ||
l == &linkstub_ibl_trace_call ||
l == &linkstub_ibl_bb_ret ||
l == &linkstub_ibl_bb_jmp ||
l == &linkstub_ibl_bb_call ||
is_special_ibl_linkstub(l));
}
const linkstub_t *
get_ibl_sourceless_linkstub(uint link_flags, uint frag_flags)
{
if (TEST(FRAG_IS_TRACE, frag_flags)) {
if (TEST(LINK_RETURN, link_flags))
return &linkstub_ibl_trace_ret;
if (EXIT_IS_JMP(link_flags))
return &linkstub_ibl_trace_jmp;
if (EXIT_IS_CALL(link_flags))
return &linkstub_ibl_trace_call;
} else {
if (TEST(LINK_RETURN, link_flags))
return &linkstub_ibl_bb_ret;
if (EXIT_IS_JMP(link_flags))
return &linkstub_ibl_bb_jmp;
if (EXIT_IS_CALL(link_flags))
return &linkstub_ibl_bb_call;
}
ASSERT_NOT_REACHED();
return NULL;
}
const linkstub_t *
get_special_ibl_linkstub(ibl_branch_type_t ibl_type, bool is_trace)
{
switch (ibl_type) {
case IBL_RETURN:
return (is_trace ?
&linkstub_special_ibl_trace_ret :
&linkstub_special_ibl_bb_ret);
case IBL_INDCALL:
return (is_trace ?
&linkstub_special_ibl_trace_call :
&linkstub_special_ibl_bb_call);
default:
/* we only have ret/call for client_ibl and native_plt_ibl */
ASSERT_NOT_REACHED();
}
return NULL;
}
/* Direct exit not targeting a trace head */
const linkstub_t *
get_coarse_exit_linkstub()
{
return &linkstub_coarse_exit;
}
/* Direct exit targeting a trace head */
const linkstub_t *
get_coarse_trace_head_exit_linkstub()
{
return &linkstub_coarse_trace_head_exit;
}
bool
should_separate_stub(dcontext_t *dcontext, app_pc target, uint fragment_flags)
{
return (local_exit_stub_size(dcontext, target, fragment_flags) == 0);
}
int
local_exit_stub_size(dcontext_t *dcontext, app_pc target, uint fragment_flags)
{
/* linking shared separate stubs is not yet atomic so we only support
* separate private stubs
* FIXME: optimization: some callers have a linkstub_t so we could provide
* a separate routine for that to avoid the now-costly computation of
* target for indirect exits.
*/
int sz = exit_stub_size(dcontext, target, fragment_flags);
if (((DYNAMO_OPTION(separate_private_stubs) &&
!TEST(FRAG_COARSE_GRAIN, fragment_flags) &&
!TEST(FRAG_SHARED, fragment_flags)) ||
(DYNAMO_OPTION(separate_shared_stubs) &&
!TEST(FRAG_COARSE_GRAIN, fragment_flags) &&
TEST(FRAG_SHARED, fragment_flags)) ||
/* entrance stubs are always separated */
(TEST(FRAG_COARSE_GRAIN, fragment_flags)
/* FIXME: for now we inline ind stubs but eventually we want to separate.
* We need this check only for coarse since its stubs are the same size
* as the direct stubs.
*/
&& !is_indirect_branch_lookup_routine(dcontext, (cache_pc)target))) &&
/* we only separate stubs of the regular type, which we determine
* by letting exit_stub_size dispatch on flags and return its
* results in the stub size
*/
sz == (TEST(FRAG_COARSE_GRAIN, fragment_flags) ?
STUB_COARSE_DIRECT_SIZE(fragment_flags) :
DIRECT_EXIT_STUB_SIZE(fragment_flags)))
return 0;
else
return sz;
}
static inline bool
is_cbr_of_cbr_fallthrough(linkstub_t *l)
{
linkstub_t *nxt = LINKSTUB_NEXT_EXIT(l);
bool yes = (nxt != NULL && LINKSTUB_CBR_FALLTHROUGH(nxt->flags));
ASSERT(!yes || LINKSTUB_FINAL(nxt));
return yes;
}
void
separate_stub_create(dcontext_t *dcontext, fragment_t *f, linkstub_t *l)
{
int emit_sz;
cache_pc stub_pc;
ASSERT(LINKSTUB_DIRECT(l->flags));
ASSERT(DYNAMO_OPTION(separate_private_stubs) ||
DYNAMO_OPTION(separate_shared_stubs));
ASSERT(linkstub_owned_by_fragment(dcontext, f, l));
ASSERT(TEST(LINK_SEPARATE_STUB, l->flags));
if (LINKSTUB_CBR_FALLTHROUGH(l->flags)) {
/* there is no field for the fallthrough of a short cbr -- it assumes
* the cbr and fallthrough stubs are contiguous, and calculates its
* stub pc from the cbr stub pc, which we assume here has already
* been created since we create them in forward order
*/
stub_pc = EXIT_STUB_PC(dcontext, f, l);
} else {
direct_linkstub_t *dl = (direct_linkstub_t *) l;
ASSERT(LINKSTUB_NORMAL_DIRECT(l->flags));
ASSERT(dl->stub_pc == NULL);
/* if -cbr_single_stub, LINKSTUB_CBR_FALLTHROUGH _always_ shares a stub,
* as its requirements are a superset of cbr stub sharing, so we don't
* need a separate flag. (if we do need one, we could use the 00 combo
* for both cbr linkstubs (except if 2nd is cbr-fallthrough, but then
* just -cbr_single_stub is enough), testing !FAKE.)
*/
if (is_cbr_of_cbr_fallthrough(l) && !INTERNAL_OPTION(cbr_single_stub)) {
/* we have to allocate a pair together */
dl->stub_pc = (cache_pc) special_heap_calloc(SEPARATE_STUB_HEAP(f->flags), 2);
} else
dl->stub_pc = (cache_pc) special_heap_alloc(SEPARATE_STUB_HEAP(f->flags));
ASSERT(dl->stub_pc == EXIT_STUB_PC(dcontext, f, l));
stub_pc = dl->stub_pc;
}
emit_sz = insert_exit_stub(dcontext, f, l, stub_pc);
ASSERT(emit_sz <= SEPARATE_STUB_ALLOC_SIZE(f->flags));
DOSTATS({
size_t alloc_size = SEPARATE_STUB_ALLOC_SIZE(f->flags);
STATS_INC(num_separate_stubs);
if (TEST(FRAG_SHARED, f->flags)) {
if (TEST(FRAG_IS_TRACE, f->flags))
STATS_ADD(separate_shared_trace_direct_stubs, alloc_size);
else
STATS_ADD(separate_shared_bb_direct_stubs, alloc_size);
} else if (TEST(FRAG_IS_TRACE, f->flags))
STATS_ADD(separate_trace_direct_stubs, alloc_size);
else
STATS_ADD(separate_bb_direct_stubs, alloc_size);
});
}
/* deletion says are we freeing b/c we're freeing the whole fragment,
* or just freeing b/c we're linking and don't need this stub anymore?
*/
static void
separate_stub_free(dcontext_t *dcontext, fragment_t *f, linkstub_t *l,
bool deletion)
{
ASSERT(LINKSTUB_DIRECT(l->flags));
ASSERT(DYNAMO_OPTION(separate_private_stubs) ||
DYNAMO_OPTION(separate_shared_stubs));
ASSERT(linkstub_owned_by_fragment(dcontext, f, l));
ASSERT(TEST(LINK_SEPARATE_STUB, l->flags));
ASSERT(exit_stub_size(dcontext, EXIT_TARGET_TAG(dcontext, f, l), f->flags) <=
SEPARATE_STUB_ALLOC_SIZE(f->flags));
if (LINKSTUB_CBR_FALLTHROUGH(l->flags)) {
ASSERT(deletion);
/* was already freed by forward walk hitting 1st exit */
} else {
direct_linkstub_t *dl = (direct_linkstub_t *) l;
ASSERT(LINKSTUB_NORMAL_DIRECT(l->flags));
/* for -cbr_single_stub, non-deletion-freeing is disallowed, and
* for deletion freeing, up to caller to not call us twice.
* FIXME: we could support freeing when both stubs are linked if
* we either added an identifying flag or re-calculated whether should
* share (won't be able to use stub_pc equality anymore if can be NULL)
*/
ASSERT(dl->stub_pc == EXIT_STUB_PC(dcontext, f, l));
ASSERT(dl->stub_pc != NULL);
if (is_cbr_of_cbr_fallthrough(l) && !INTERNAL_OPTION(cbr_single_stub)) {
/* we allocated a pair */
special_heap_cfree(SEPARATE_STUB_HEAP(f->flags), dl->stub_pc, 2);
} else {
special_heap_free(SEPARATE_STUB_HEAP(f->flags), dl->stub_pc);
}
dl->stub_pc = NULL;
}
DOSTATS({
size_t alloc_size = SEPARATE_STUB_ALLOC_SIZE(f->flags);
if (TEST(FRAG_SHARED, f->flags)) {
if (TEST(FRAG_IS_TRACE, f->flags)) {
STATS_ADD(separate_shared_trace_direct_stubs, -(int)alloc_size);
} else {
STATS_ADD(separate_shared_bb_direct_stubs, -(int)alloc_size);
}
} else if (TEST(FRAG_IS_TRACE, f->flags))
STATS_SUB(separate_trace_direct_stubs, alloc_size);
else
STATS_SUB(separate_bb_direct_stubs, alloc_size);
});
}
/* if this linkstub shares the stub with the next linkstub, returns the
* next linkstub; else returns NULL
*/
linkstub_t *
linkstub_shares_next_stub(dcontext_t *dcontext, fragment_t *f, linkstub_t *l)
{
linkstub_t *nxt;
if (!INTERNAL_OPTION(cbr_single_stub))
return NULL;
nxt = LINKSTUB_NEXT_EXIT(l);
if (nxt != NULL &&
/* avoid stub computation for indirect, which fails if fcache is freed */
LINKSTUB_DIRECT(nxt->flags) && LINKSTUB_DIRECT(l->flags) &&
EXIT_STUB_PC(dcontext, f, nxt) == EXIT_STUB_PC(dcontext, f, l)) {
ASSERT(LINKSTUB_FINAL(nxt));
return nxt;
} else
return NULL;
}
void
linkstub_free_exitstubs(dcontext_t *dcontext, fragment_t *f)
{
linkstub_t *l;
for (l = FRAGMENT_EXIT_STUBS(f); l != NULL; l = LINKSTUB_NEXT_EXIT(l)) {
if (TEST(LINK_SEPARATE_STUB, l->flags) &&
EXIT_STUB_PC(dcontext, f, l) != NULL) {
linkstub_t *nxt = linkstub_shares_next_stub(dcontext, f, l);
if (nxt != NULL && !LINKSTUB_CBR_FALLTHROUGH(nxt->flags)) {
/* next linkstub shares our stub, so clear his now to avoid
* double free
*/
direct_linkstub_t *dl = (direct_linkstub_t *) nxt;
dl->stub_pc = NULL;
}
separate_stub_free(dcontext, f, l, true);
}
}
}
void
linkstubs_shift(dcontext_t *dcontext, fragment_t *f, ssize_t shift)
{
linkstub_t *l;
for (l = FRAGMENT_EXIT_STUBS(f); l != NULL; l = LINKSTUB_NEXT_EXIT(l)) {
/* don't need to shift separated b/c shift_ctis_in_fragment will detect
* as an out-of-cache target and shift for us.
* l->stub_pc does not change since it's an absolute pc pointing outside
* of the resized cache.
* we also don't need to shift indirect stubs as they do not store
* an absolute pointer to their stub pc.
*/
if (!TEST(LINK_SEPARATE_STUB, l->flags) && LINKSTUB_NORMAL_DIRECT(l->flags)) {
direct_linkstub_t *dl = (direct_linkstub_t *) l;
dl->stub_pc += shift;
} /* else, no change */
}
}
/* returns true if the exit l can be linked to the fragment f
* if mark_new_trace_head is false, this routine does not change any state.
*/
bool
is_linkable(dcontext_t *dcontext, fragment_t *from_f, linkstub_t *from_l, fragment_t *to_f,
bool have_link_lock, bool mark_new_trace_head)
{
/* monitor_is_linkable is what marks trace heads, so must
* call it no matter the result
*/
if (!monitor_is_linkable(dcontext, from_f, from_l, to_f,
have_link_lock, mark_new_trace_head))
return false;
/* cannot link between shared and private caches
* N.B.: we assume this in other places, like our use of fragment_lookup_same_sharing()
* for linking, so if we change this we need to change more than this routine here
*/
if ((from_f->flags & FRAG_SHARED) != (to_f->flags & FRAG_SHARED))
return false;
#ifdef DGC_DIAGNOSTICS
/* restrict linking so we can study entry/exit behavior */
if ((from_f->flags & FRAG_DYNGEN) != (to_f->flags & FRAG_DYNGEN))
return false;
#endif
/* do not link exit from non-ignorable syscall ending a frag */
if (TESTANY(LINK_NI_SYSCALL_ALL, from_l->flags))
return false;
#ifdef WINDOWS
if (TEST(LINK_CALLBACK_RETURN, from_l->flags))
return false;
#endif
/* never link a selfmod or any other unlinkable exit branch */
if (TEST(LINK_SPECIAL_EXIT, from_l->flags))
return false;
/* don't link from a non-outgoing-linked fragment, or to a
* non-incoming-linked fragment, except for self-loops
*/
if ((!TEST(FRAG_LINKED_OUTGOING, from_f->flags) ||
!TEST(FRAG_LINKED_INCOMING, to_f->flags)) &&
from_f != to_f)
return false;
/* rarely set so we test it last */
if (INTERNAL_OPTION(nolink))
return false;
#if defined(UNIX) && !defined(DGC_DIAGNOSTICS)
/* i#107, fragment having a OP_mov_seg instr cannot be linked. */
if (TEST(FRAG_HAS_MOV_SEG, to_f->flags))
return false;
#endif
return true;
}
/* links the branch at EXIT_CTI_PC(f, l) to jump directly to the entry point of
* fragment targetf
* Assumes that is_linkable has already been called!
* does not modify targetf's incoming branch list (because that should be done
* once while linking and unlinking may happen multiple times)
*/
static void
link_branch(dcontext_t *dcontext, fragment_t *f, linkstub_t *l, fragment_t *targetf,
bool hot_patch)
{
ASSERT(linkstub_owned_by_fragment(dcontext, f, l));
/* ASSUMPTION: always unlink before linking to somewhere else, so nop if linked */
if (INTERNAL_OPTION(nolink) || TEST(LINK_LINKED, l->flags))
return;
if (LINKSTUB_DIRECT(l->flags)) {
LOG(THREAD, LOG_LINKS, 4, " linking F%d("PFX")."PFX" -> F%d("PFX")="PFX"\n",
f->id, f->tag, EXIT_CTI_PC(f, l),
targetf->id, targetf->tag, FCACHE_ENTRY_PC(targetf));
#ifdef TRACE_HEAD_CACHE_INCR
{
common_direct_linkstub_t *cdl = (common_direct_linkstub_t *) l;
if (TEST(FRAG_IS_TRACE_HEAD, targetf->flags))
cdl->target_fragment = targetf;
else
cdl->target_fragment = NULL;
}
#endif
if (LINKSTUB_COARSE_PROXY(l->flags)) {
link_entrance_stub(dcontext, EXIT_STUB_PC(dcontext, f, l),
FCACHE_ENTRY_PC(targetf), HOT_PATCHABLE, NULL);
} else {
bool do_not_need_stub =
link_direct_exit(dcontext, f, l, targetf, hot_patch) &&
TEST(LINK_SEPARATE_STUB, l->flags) &&
((DYNAMO_OPTION(free_private_stubs) &&
!TEST(FRAG_SHARED, f->flags)) ||
(DYNAMO_OPTION(unsafe_free_shared_stubs) &&
TEST(FRAG_SHARED, f->flags)));
ASSERT(!TEST(FRAG_FAKE, f->flags) && !LINKSTUB_FAKE(l));
if (do_not_need_stub)
separate_stub_free(dcontext, f, l, false);
}
} else if (LINKSTUB_INDIRECT(l->flags)) {
if (INTERNAL_OPTION(link_ibl))
link_indirect_exit(dcontext, f, l, hot_patch);
} else
ASSERT_NOT_REACHED();
l->flags |= LINK_LINKED;
}
/* Unlinks one linked branch. Returns false if the linkstub_t should be removed
* from the target's incoming list; else returns true.
*/
static bool
unlink_branch(dcontext_t *dcontext, fragment_t *f, linkstub_t *l)
{
bool keep = true;
ASSERT(linkstub_owned_by_fragment(dcontext, f, l));
if ((l->flags & LINK_LINKED) == 0)
return keep;
if (LINKSTUB_DIRECT(l->flags)) {
LOG(THREAD, LOG_LINKS, 4, " unlinking branch F%d."PFX"\n",
f->id, EXIT_CTI_PC(f, l));
if (LINKSTUB_COARSE_PROXY(l->flags)) {
uint flags = 0;
cache_pc stub = EXIT_STUB_PC(dcontext, f, l);
/* When we create a trace from a coarse head, we point the head's
* entrance stub at the trace. If we later remove the trace we need
* to re-instate the link to the head (well, to the head inc
* routine).
*/
if (coarse_is_trace_head_in_own_unit(dcontext, f->tag, stub, NULL,
false, NULL))
flags = FRAG_IS_TRACE_HEAD;
unlink_entrance_stub(dcontext, stub, flags, NULL);
/* The caller is now supposed to remove the incoming entry and
* free the heap space for this proxy linkstub_t
*/
keep = false;
} else {
ASSERT(!LINKSTUB_FAKE(l));
/* stub may already exist for TRACE_HEAD_CACHE_INCR,
* linkcount profiling, etc. */
if (EXIT_STUB_PC(dcontext, f, l) == NULL &&
TEST(LINK_SEPARATE_STUB, l->flags))
separate_stub_create(dcontext, f, l);
unlink_direct_exit(dcontext, f, l);
}
} else if (LINKSTUB_INDIRECT(l->flags)) {
if (INTERNAL_OPTION(link_ibl))
unlink_indirect_exit(dcontext, f, l);
} else
ASSERT_NOT_REACHED();
l->flags &= ~LINK_LINKED;
return keep;
}
static inline bool
incoming_direct_linkstubs_match(common_direct_linkstub_t *dl1,
common_direct_linkstub_t *dl2)
{
return ((dl1 == dl2 && !LINKSTUB_FAKE(&dl1->l) && !LINKSTUB_FAKE(&dl2->l)) ||
/* For coarse-grain we must match by value */
(LINKSTUB_FAKE(&dl1->l) && LINKSTUB_FAKE(&dl2->l) &&
LINKSTUB_NORMAL_DIRECT(dl1->l.flags) &&
LINKSTUB_NORMAL_DIRECT(dl2->l.flags) &&
((direct_linkstub_t *)dl1)->stub_pc == ((direct_linkstub_t *)dl2)->stub_pc));
}
/* Returns the linkstub_t * for the link from f's exit l if it exists in
* targetf's incoming list. N.B.: if target is coarse, its unit lock
* is released prior to returning the pointer!
*/
static linkstub_t *
incoming_find_link(dcontext_t *dcontext, fragment_t *f, linkstub_t *l,
fragment_t *targetf)
{
common_direct_linkstub_t *s;
common_direct_linkstub_t **inlist = FRAG_INCOMING_ADDR(targetf);
common_direct_linkstub_t *dl = (common_direct_linkstub_t *) l;
ASSERT(LINKSTUB_DIRECT(l->flags));
ASSERT(!LINKSTUB_FAKE(l) ||
(LINKSTUB_COARSE_PROXY(l->flags) &&
TEST(FRAG_COARSE_GRAIN, f->flags) && LINKSTUB_NORMAL_DIRECT(l->flags)));
if (TEST(FRAG_COARSE_GRAIN, targetf->flags)) {
coarse_incoming_t *e;
coarse_info_t *info = get_fragment_coarse_info(targetf);
ASSERT(info != NULL);
mutex_lock(&info->incoming_lock);
for (e = info->incoming; e != NULL; e = e->next) {
if (!e->coarse) {
linkstub_t *ls;
for (ls = e->in.fine_l; ls != NULL; ls = LINKSTUB_NEXT_INCOMING(ls)) {
if (incoming_direct_linkstubs_match(((common_direct_linkstub_t *)ls),
dl)) {
mutex_unlock(&info->incoming_lock);
return ls;
}
}
}
}
mutex_unlock(&info->incoming_lock);
} else {
for (s = *inlist; s != NULL; s = (common_direct_linkstub_t *) s->next_incoming) {
ASSERT(LINKSTUB_DIRECT(s->l.flags));
if (incoming_direct_linkstubs_match(s, dl))
return (linkstub_t *)s;
}
}
return NULL;
}
/* Returns true if the link from f's exit l exists in targetf's incoming list */
static bool
incoming_link_exists(dcontext_t *dcontext, fragment_t *f, linkstub_t *l,
fragment_t *targetf)
{
return incoming_find_link(dcontext, f, l, targetf) != NULL;
}
/* Removes the link from l to targetf from the incoming table
* N.B.: may end up deleting targetf!
* If l is a fake linkstub_t, then f must be coarse-grain, and this
* routine searches targetf's incoming links for a match (since the
* exact stored linkstub_t != l).
*/
static void
incoming_remove_link_nosearch(dcontext_t *dcontext, fragment_t *f, linkstub_t *l,
fragment_t *targetf, linkstub_t *prevl,
common_direct_linkstub_t **inlist)
{
common_direct_linkstub_t *dl = (common_direct_linkstub_t *) l;
common_direct_linkstub_t *dprev = (common_direct_linkstub_t *) prevl;
ASSERT(LINKSTUB_DIRECT(l->flags));
ASSERT(prevl == NULL || LINKSTUB_DIRECT(prevl->flags));
ASSERT(linkstub_owned_by_fragment(dcontext, f, l));
ASSERT(!LINKSTUB_FAKE(l) ||
(LINKSTUB_COARSE_PROXY(l->flags) &&
TEST(FRAG_COARSE_GRAIN, f->flags) && LINKSTUB_NORMAL_DIRECT(l->flags)));
/* no links across caches so only checking f's sharedness is enough */
ASSERT(!NEED_SHARED_LOCK(f->flags) ||
self_owns_recursive_lock(&change_linking_lock));
if (dprev != NULL)
dprev->next_incoming = dl->next_incoming;
else {
/* if no incoming links left, and targetf is future, we could
* delete it here, but adaptive wset and trace head
* counters wanting persistent info means we want to always
* have either the future or the real thing -- unless
* it was NEVER executed: then could remove it, which we do for
* shared cache temporary private futures (see below)
* FIXME: do this for other futures as well?
*/
if (dl->next_incoming == NULL) {
if (TESTALL(FRAG_TEMP_PRIVATE | FRAG_IS_FUTURE, targetf->flags) &&
!TEST(FRAG_WAS_DELETED, targetf->flags)) {
/* this is a future created only as an outgoing link of a private
* bb created solely for trace creation.
* since it never had a real fragment that was executed, we can
* toss it, and in fact if we don't we waste a bunch of memory.
*/
LOG(THREAD, LOG_LINKS, 3,
"incoming_remove_link: temp future "PFX" has no incoming, removing\n",
targetf->tag);
ASSERT(!LINKSTUB_FAKE(l));
DODEBUG({ ((future_fragment_t *)targetf)->incoming_stubs = NULL; });
fragment_delete_future(dcontext, (future_fragment_t *) targetf);
/* WARNING: do not reference targetf after this */
STATS_INC(num_trace_private_fut_del);
return;
}
}
*inlist = (common_direct_linkstub_t *) dl->next_incoming;
}
dl->next_incoming = NULL;
if (LINKSTUB_COARSE_PROXY(l->flags)) {
/* We don't have any place to keep l so we free now. We'll
* re-alloc if we lazily re-link.
*/
LOG(THREAD, LOG_LINKS, 4,
"freeing proxy incoming "PFX" from coarse "PFX" to fine tag "PFX"\n",
l, EXIT_STUB_PC(dcontext, f, l), EXIT_TARGET_TAG(dcontext, f, l));
NONPERSISTENT_HEAP_TYPE_FREE(GLOBAL_DCONTEXT, l, direct_linkstub_t,
ACCT_COARSE_LINK);
} else
ASSERT(!LINKSTUB_FAKE(l));
}
static bool
incoming_remove_link_search(dcontext_t *dcontext, fragment_t *f, linkstub_t *l,
fragment_t *targetf, common_direct_linkstub_t **inlist)
{
common_direct_linkstub_t *s, *prevs, *dl;
dl = (common_direct_linkstub_t *) l;
ASSERT(LINKSTUB_DIRECT(l->flags));
ASSERT(linkstub_owned_by_fragment(dcontext, f, l));
ASSERT(!LINKSTUB_FAKE(l) ||
(LINKSTUB_COARSE_PROXY(l->flags) &&
TEST(FRAG_COARSE_GRAIN, f->flags) && LINKSTUB_NORMAL_DIRECT(l->flags)));
for (s = *inlist, prevs = NULL; s;
prevs = s, s = (common_direct_linkstub_t *) s->next_incoming) {
ASSERT(LINKSTUB_DIRECT(s->l.flags));
if (incoming_direct_linkstubs_match(s, dl)) {
/* We must remove s and NOT the passed-in l as coarse_remove_outgoing()
* passes in a new proxy that we use only to match and find the
* entry in the list to remove.
*/
incoming_remove_link_nosearch(dcontext, f, (linkstub_t *)s,
targetf, (linkstub_t *)prevs, inlist);
return true;
}
}
return false;
}
/* Removes the link from l to targetf from the incoming table
* N.B.: may end up deleting targetf!
* If l is a fake linkstub_t, then f must be coarse-grain, and this
* routine searches targetf's incoming links for a match (since the
* exact stored linkstub_t != l).
*/
static void
incoming_remove_link(dcontext_t *dcontext, fragment_t *f, linkstub_t *l,
fragment_t *targetf)
{
/* no links across caches so only checking f's sharedness is enough */
ASSERT(!NEED_SHARED_LOCK(f->flags) ||
self_owns_recursive_lock(&change_linking_lock));
ASSERT(!LINKSTUB_COARSE_PROXY(l->flags) || TEST(FRAG_COARSE_GRAIN, f->flags));
ASSERT(!TEST(FRAG_COARSE_GRAIN, f->flags) ||
!TEST(FRAG_COARSE_GRAIN, targetf->flags));
if (TEST(FRAG_COARSE_GRAIN, targetf->flags)) {
coarse_remove_incoming(dcontext, f, l, targetf);
} else {
if (incoming_remove_link_search(dcontext, f, l, targetf,
FRAG_INCOMING_ADDR(targetf)))
return;
DODEBUG({
ASSERT(targetf != NULL && targetf->tag == EXIT_TARGET_TAG(dcontext, f, l));
LOG(THREAD, LOG_LINKS, 1,
"incoming_remove_link: no link from F%d("PFX")."PFX" -> "
"F%d("PFX")\n",
f->id, f->tag, EXIT_CTI_PC(f, l),
targetf->id, EXIT_TARGET_TAG(dcontext, f, l));
});
ASSERT_NOT_REACHED();
}
}
/* Adds the link from l to targetf to the list of incoming links
* for targetf.
*/
static inline void
add_to_incoming_list(dcontext_t *dcontext, fragment_t *f, linkstub_t *l,
fragment_t *targetf, bool linked)
{
ASSERT(LINKSTUB_DIRECT(l->flags));
ASSERT(linkstub_owned_by_fragment(dcontext, f, l));
ASSERT(!incoming_link_exists(dcontext, f, l, targetf));
/* no inter-cache incoming entries */
ASSERT((f->flags & FRAG_SHARED) == (targetf->flags & FRAG_SHARED));
if (TEST(FRAG_COARSE_GRAIN, targetf->flags)) {
coarse_info_t *info = get_fragment_coarse_info(targetf);
prepend_new_coarse_incoming(info, NULL, l);
} else {
common_direct_linkstub_t **inlist =
(common_direct_linkstub_t **) FRAG_INCOMING_ADDR(targetf);
common_direct_linkstub_t *dl = (common_direct_linkstub_t *) l;
/* ensure not added twice b/c future not unlinked, etc. */
ASSERT(*inlist != dl);
ASSERT(!LINKSTUB_FAKE(l) || LINKSTUB_COARSE_PROXY(l->flags));
ASSERT(!is_empty_fragment(linkstub_fragment(dcontext, l)));
dl->next_incoming = (linkstub_t *) *inlist;
*inlist = dl;
}
}
/* Private fragment outgoing links require extra processing
* First, a private fragment link produces both shared (for trace head
* marking) and private (for incoming) futures -- we ensure the shared
* exists here.
* Second, we need to mark shared future frags as secondary trace heads
* NOW since we won't put private traces on shared incoming lists.
* We can do primary trace heads now, too, not a problem.
*/
static void
add_private_check_shared(dcontext_t *dcontext, fragment_t *f, linkstub_t *l)
{
fragment_t *targetf;
app_pc target_tag = EXIT_TARGET_TAG(dcontext, f, l);
ASSERT(LINKSTUB_DIRECT(l->flags));
ASSERT(linkstub_owned_by_fragment(dcontext, f, l));
if (!SHARED_FRAGMENTS_ENABLED())
return;
ASSERT(!TEST(FRAG_SHARED, f->flags));
ASSERT(!SHARED_FRAGMENTS_ENABLED() || dynamo_exited ||
self_owns_recursive_lock(&change_linking_lock));
targetf = fragment_link_lookup_same_sharing(dcontext, target_tag, l, FRAG_SHARED);
if (targetf == NULL)
targetf = (fragment_t *) fragment_lookup_future(dcontext, target_tag);
if (targetf == NULL) {
targetf = (fragment_t *)
fragment_create_and_add_future(dcontext, target_tag, FRAG_SHARED);
}
if (!TEST(FRAG_IS_TRACE_HEAD, targetf->flags)) {
uint th = should_be_trace_head(dcontext, f, l, target_tag, targetf->flags,
true/* have linking lock*/);
if (TEST(TRACE_HEAD_YES, th)) {
if (TEST(FRAG_IS_FUTURE, targetf->flags)) {
LOG(THREAD, LOG_LINKS, 4,
" marking future ("PFX") as trace head\n",
target_tag);
targetf->flags |= FRAG_IS_TRACE_HEAD;
} else {
mark_trace_head(dcontext, targetf, f, l);
}
ASSERT(!TEST(TRACE_HEAD_OBTAINED_LOCK, th));
}
}
}
/* Adds the link l to the list of incoming future links
* for l's target.
*/
static void
add_future_incoming(dcontext_t *dcontext, fragment_t *f, linkstub_t *l)
{
future_fragment_t *targetf;
app_pc target_tag = EXIT_TARGET_TAG(dcontext, f, l);
ASSERT(LINKSTUB_DIRECT(l->flags));
ASSERT(!SHARED_FRAGMENTS_ENABLED() || !dynamo_exited ||
self_owns_recursive_lock(&change_linking_lock));
ASSERT(linkstub_owned_by_fragment(dcontext, f, l));
if (!TEST(FRAG_SHARED, f->flags))
targetf = fragment_lookup_private_future(dcontext, target_tag);
else
targetf = fragment_lookup_future(dcontext, target_tag);
if (targetf == NULL) {
/* if private, lookup-and-add being atomic is not an issue;
* for shared, the change_linking_lock atomicizes for us
*/
targetf = fragment_create_and_add_future(dcontext, target_tag,
/* take temp flag if present, so we
* know to remove this future later
* if never used
*/
(f->flags &
(FRAG_SHARED | FRAG_TEMP_PRIVATE)));
}
add_to_incoming_list(dcontext, f, l, (fragment_t*)targetf, false);
if (!TEST(FRAG_SHARED, f->flags)) {
/* private fragments need to ensure a shared fragment/future exists,
* and need to perform secondary trace head marking on it here!
*/
add_private_check_shared(dcontext, f, l);
}
}
/* Adds the link from l to targetf to the list of incoming links
* for targetf.
*/
static void
add_incoming(dcontext_t *dcontext, fragment_t *f, linkstub_t *l,
fragment_t *targetf, bool linked)
{
ASSERT(TEST(FRAG_SHARED, f->flags) == TEST(FRAG_SHARED, targetf->flags));
ASSERT(linkstub_owned_by_fragment(dcontext, f, l));
LOG(THREAD, LOG_LINKS, 4,
" add incoming F%d("PFX")."PFX" -> F%d("PFX")\n",
f->id, f->tag, EXIT_CTI_PC(f, l), targetf->id, targetf->tag);
add_to_incoming_list(dcontext, f, l, targetf, linked);
if (!TEST(FRAG_SHARED, f->flags)) {
/* private fragments need to ensure a shared fragment/future exists,
* and need to perform secondary trace head marking on it here!
*/
add_private_check_shared(dcontext, f, l);
}
}
/* fragment_t f is being removed */
future_fragment_t *
incoming_remove_fragment(dcontext_t *dcontext, fragment_t *f)
{
future_fragment_t *future = NULL;
linkstub_t *l;
/* pendel-del frags use fragment_t.in_xlate differently: they should
* never call this routine once they're marked for deletion
*/
ASSERT(!TEST(FRAG_WAS_DELETED, f->flags));
/* link data struct change in shared fragment must be synchronized
* no links across caches so only checking f's sharedness is enough
*/
ASSERT(!NEED_SHARED_LOCK(f->flags) ||
self_owns_recursive_lock(&change_linking_lock));
/* if removing shared trace, move its links back to the shadowed shared trace head */
/* flags not preserved for coarse so we have to check all coarse bbs */
if (TESTANY(FRAG_TRACE_LINKS_SHIFTED | FRAG_COARSE_GRAIN, f->flags)) {
if (TEST(FRAG_IS_TRACE, f->flags)) {
fragment_t wrapper;
/* FIXME case 8600: provide single lookup routine here */
fragment_t *bb = fragment_lookup_bb(dcontext, f->tag);
if (bb == NULL ||
(bb->flags & FRAG_SHARED) != (f->flags & FRAG_SHARED)) {
/* Can't use lookup_fine_and_coarse since trace will shadow coarse */
bb = fragment_coarse_lookup_wrapper(dcontext, f->tag, &wrapper);
LOG(THREAD, LOG_LINKS, 4,
"incoming_remove_fragment shared trace "PFX": %s coarse thead\n",
f->tag, bb == NULL ? "did not find" : "found");
}
if (bb != NULL && (TESTANY(FRAG_TRACE_LINKS_SHIFTED | FRAG_COARSE_GRAIN,
bb->flags))) {
ASSERT(TEST(FRAG_IS_TRACE_HEAD, bb->flags) ||
TEST(FRAG_COARSE_GRAIN, bb->flags));
/* FIXME: this will mark trace head as FRAG_LINKED_INCOMING --
* but then same thing for a new bb marked as a trace head
* before linking via its previous future, so not a new problem.
* won't actually link incoming since !linkable.
*/
if (TEST(FRAG_COARSE_GRAIN, bb->flags)) {
/* We assume the coarse-grain bb is a trace head -- our method
* of lookup is unable to mark it so we mark it here
*/
bb->flags |= FRAG_IS_TRACE_HEAD;
}
shift_links_to_new_fragment(dcontext, f, bb);
STATS_INC(links_shared_trace_to_head);
ASSERT(f->in_xlate.incoming_stubs == NULL);
return NULL;
}
} else if (TEST(FRAG_IS_TRACE_HEAD, f->flags)) {
fragment_t *trace = fragment_lookup_trace(dcontext, f->tag);
/* regardless of -remove_shared_trace_heads, a shared trace will
* at least briefly shadow and shift links from a shared trace head.
* FIXME: add a FRAG_LINKS_SHIFTED flag to know for sure?
*/
if (trace != NULL &&
(trace->flags & FRAG_SHARED) == (f->flags & FRAG_SHARED)) {
/* nothing to do -- links already shifted, no future needed */
STATS_INC(shadowed_trace_head_deleted);
ASSERT(f->in_xlate.incoming_stubs == NULL);
return NULL;
}
}
}
/* remove outgoing links from others' incoming lists */
for (l = FRAGMENT_EXIT_STUBS(f); l; l = LINKSTUB_NEXT_EXIT(l)) {
if (LINKSTUB_DIRECT(l->flags)) {
/* must explicitly check for self -- may not be in table, if
* flushing due to munmap
*/
fragment_t *targetf;
app_pc target_tag = EXIT_TARGET_TAG(dcontext, f, l);
if (target_tag == f->tag)
targetf = f;
else {
/* only want fragments in same shared/private cache */
targetf = fragment_link_lookup_same_sharing(dcontext, target_tag,
NULL, f->flags);
if (targetf == NULL) {
/* don't worry, all routines can handle fragment_t* that is really
* future_fragment_t*
*/
/* make sure future is in proper shared/private table */
if (!TEST(FRAG_SHARED, f->flags)) {
targetf = (fragment_t *)
fragment_lookup_private_future(dcontext, target_tag);
} else {
targetf = (fragment_t *)
fragment_lookup_future(dcontext, target_tag);
}
}
}
LOG(THREAD, LOG_LINKS, 4,
" removed F%d("PFX")."PFX" -> ("PFX") from incoming list\n",
f->id, f->tag, EXIT_CTI_PC(f, l), target_tag);
ASSERT(targetf != NULL);
if (targetf != NULL) /* play it safe */
incoming_remove_link(dcontext, f, l, targetf);
}
}
if (TEST(FRAG_TEMP_PRIVATE, f->flags) && f->in_xlate.incoming_stubs == NULL) {
/* if there are incoming stubs, the private displaced a prior future, which
* does need to be replaced -- if not, we don't need a future
*/
LOG(THREAD, LOG_LINKS, 4,
" not bothering with future for temp private F%d("PFX")\n", f->id, f->tag);
STATS_INC(num_trace_private_fut_avoid);
return NULL;
}
/* add future fragment
* FIXME: optimization is to convert f to future, that requires
* coordinating with fragment_remove, fragment_delete, etc.
*/
LOG(THREAD, LOG_LINKS, 4,
" adding future fragment for deleted F%d("PFX")\n",
f->id, f->tag);
DOCHECK(1, {
if (TEST(FRAG_SHARED, f->flags))
ASSERT(fragment_lookup_future(dcontext, f->tag) == NULL);
else
ASSERT(fragment_lookup_private_future(dcontext, f->tag) == NULL);
});
future = fragment_create_and_add_future(dcontext, f->tag,
/* make sure future is in proper shared/private table.
* Do not keep FRAG_TEMP_PRIVATE as getting here means
* there was a real future here before the private, so our
* future removal optimization does not apply.
*/
(FRAG_SHARED & f->flags) |
FRAG_WAS_DELETED);
future->incoming_stubs = f->in_xlate.incoming_stubs;
DODEBUG({ f->in_xlate.incoming_stubs = NULL; });
return future;
}
#ifdef DEBUG
static void inline
debug_after_link_change(dcontext_t *dcontext, fragment_t *f, const char *msg)
{
DOLOG(5, LOG_LINKS, {
LOG(THREAD, LOG_LINKS, 5, "%s\n", msg);
disassemble_fragment(dcontext, f, stats->loglevel < 3);
});
}
#endif
/* Link all incoming links from other fragments to f
*/
void
link_fragment_incoming(dcontext_t *dcontext, fragment_t *f, bool new_fragment)
{
linkstub_t *l;
LOG(THREAD, LOG_LINKS, 4, " linking incoming links for F%d("PFX")\n",
f->id, f->tag);
/* ensure some higher-level lock is held if f is shared
* no links across caches so only checking f's sharedness is enough
*/
ASSERT_OWN_RECURSIVE_LOCK(
NEED_SHARED_LOCK(f->flags) ||
(new_fragment && SHARED_FRAGMENTS_ENABLED()), &change_linking_lock);
ASSERT(!TEST(FRAG_LINKED_INCOMING, f->flags));
f->flags |= FRAG_LINKED_INCOMING;
/* link incoming links */
for (l = f->in_xlate.incoming_stubs; l != NULL; l = LINKSTUB_NEXT_INCOMING(l)) {
bool local_trace_head = false;
fragment_t *in_f = linkstub_fragment(dcontext, l);
if (TEST(FRAG_COARSE_GRAIN, f->flags)) {
/* Case 8907: remove trace headness markings, as each fine source
* should only consider this a trace head considering its own
* path to it.
*/
local_trace_head = TEST(FRAG_IS_TRACE_HEAD, f->flags);
f->flags &= ~FRAG_IS_TRACE_HEAD;
}
/* only direct branches are marked on targets' incoming */
ASSERT(LINKSTUB_DIRECT(l->flags));
if (is_linkable(dcontext, in_f, l, f,
NEED_SHARED_LOCK(f->flags) ||
(new_fragment && SHARED_FRAGMENTS_ENABLED()),
true/*mark new trace heads*/)) {
/* unprotect on demand, caller will re-protect */
SELF_PROTECT_CACHE(dcontext, in_f, WRITABLE);
link_branch(dcontext, in_f, l, f, HOT_PATCHABLE);
} else {
LOG(THREAD, LOG_LINKS, 4, " not linking F%d("PFX")."PFX" -> F%d("PFX")"
" is not linkable!\n",
in_f->id, in_f->tag, EXIT_CTI_PC(in_f, l),
f->id, f->tag);
}
/* Restore trace headness, if present before and not set in is_linkable */
if (local_trace_head && !TEST(FRAG_IS_TRACE_HEAD, f->flags))
f->flags |= FRAG_IS_TRACE_HEAD;
}
}
/* Link outgoing links of f to other fragments in the fcache (and
* itself if it has self loops). If new_fragment is true, all of f's
* outgoing links are recorded in the incoming link lists of their
* targets.
*/
void
link_fragment_outgoing(dcontext_t *dcontext, fragment_t *f, bool new_fragment)
{
linkstub_t *l;
LOG(THREAD, LOG_LINKS, 4, " linking outgoing links for F%d("PFX")\n",
f->id, f->tag);
/* ensure some higher-level lock is held if f is shared
* no links across caches so only checking f's sharedness is enough
*/
ASSERT_OWN_RECURSIVE_LOCK(
NEED_SHARED_LOCK(f->flags) ||
(new_fragment && SHARED_FRAGMENTS_ENABLED()), &change_linking_lock);
ASSERT(!TEST(FRAG_LINKED_OUTGOING, f->flags));
f->flags |= FRAG_LINKED_OUTGOING;
/* new_fragment: already protected
* unprotect on demand, caller will re-protect
*/
if (!new_fragment)
SELF_PROTECT_CACHE(dcontext, f, WRITABLE);
/* link outgoing exits */
for (l = FRAGMENT_EXIT_STUBS(f); l; l = LINKSTUB_NEXT_EXIT(l)) {
if (LINKSTUB_DIRECT(l->flags)) {
/* found a linkable direct branch */
app_pc target_tag = EXIT_TARGET_TAG(dcontext, f, l);
fragment_t *g;
/* f may be invisible, so explicitly check for self-loops */
if (target_tag == f->tag)
g = f;
else /* primarily interested in fragment of same sharing */
g = fragment_link_lookup_same_sharing(dcontext, target_tag, l, f->flags);
if (g != NULL) {
if (is_linkable(dcontext, f, l, g,
NEED_SHARED_LOCK(f->flags) ||
(new_fragment && SHARED_FRAGMENTS_ENABLED()),
true/*mark new trace heads*/)) {
link_branch(dcontext, f, l, g, HOT_PATCHABLE);
if (new_fragment)
add_incoming(dcontext, f, l, g, true);
} else {
if (new_fragment)
add_incoming(dcontext, f, l, g, false);
LOG(THREAD, LOG_LINKS, 4, " not linking F%d("PFX")."PFX" -> "
"F%d("PFX" == "PFX")%s%s%s\n",
f->id, f->tag, EXIT_CTI_PC(f, l),
g->id, g->tag, target_tag,
((g->flags & FRAG_IS_TRACE_HEAD)!=0)?
" (trace head)":"",
((l->flags & LINK_LINKED) != 0)?" (linked)":"",
((l->flags & LINK_SPECIAL_EXIT) != 0)?" (special)":"");
}
} else {
if (new_fragment)
add_future_incoming(dcontext, f, l);
LOG(THREAD, LOG_LINKS, 4,
" future-linking F%d("PFX")."PFX" -> ("PFX")\n",
f->id, f->tag, EXIT_CTI_PC(f, l),
target_tag);
}
} else {
ASSERT(LINKSTUB_INDIRECT(l->flags));
/* indirect branches: just let link_branch handle the
* exit stub target
*/
#ifdef DGC_DIAGNOSTICS
/* do not link outgoing indirect so we see where it's going to go */
if ((f->flags & FRAG_DYNGEN) == 0)
#endif
link_branch(dcontext, f, l, NULL, HOT_PATCHABLE);
}
}
#ifdef DEBUG
debug_after_link_change(dcontext, f, "Fragment after linking outgoing");
#endif
}
/* Unlinks all incoming branches into fragment f
*/
void
unlink_fragment_incoming(dcontext_t *dcontext, fragment_t *f)
{
linkstub_t *l, *nextl, *prevl;
LOG(THREAD, LOG_LINKS, 4, "unlinking incoming to frag F%d("PFX")\n",
f->id, f->tag);
/* ensure some higher-level lock is held if f is shared
* no links across caches so only checking f's sharedness is enough
*/
ASSERT(!NEED_SHARED_LOCK(f->flags) ||
self_owns_recursive_lock(&change_linking_lock));
/* allow for trace head to be unlinked in middle of being unlinked --
* see comments in mark_trace_head in monitor.c
*/
ASSERT(TESTANY(FRAG_LINKED_INCOMING|FRAG_IS_TRACE_HEAD, f->flags));
/* unlink incoming branches */
ASSERT(!TEST(FRAG_COARSE_GRAIN, f->flags));
for (prevl = NULL, l = f->in_xlate.incoming_stubs; l != NULL; l = nextl) {
fragment_t *in_f = linkstub_fragment(dcontext, l);
bool keep = true;
nextl = LINKSTUB_NEXT_INCOMING(l);
/* not all are linked (e.g., to trace head) */
if (TEST(LINK_LINKED, l->flags)) {
/* unprotect on demand, caller will re-protect */
SELF_PROTECT_CACHE(dcontext, in_f, WRITABLE);
keep = unlink_branch(dcontext, in_f, l);
} else
ASSERT(!LINKSTUB_FAKE(l));
if (!keep) {
incoming_remove_link_nosearch(dcontext, in_f, l, f, prevl,
FRAG_INCOMING_ADDR(f));
} else
prevl = l;
}
f->flags &= ~FRAG_LINKED_INCOMING;
}
/* Unlinks all outgoing branches from f
*/
void
unlink_fragment_outgoing(dcontext_t *dcontext, fragment_t *f)
{
linkstub_t *l;
DEBUG_DECLARE(bool keep;)
LOG(THREAD, LOG_LINKS, 4, "unlinking outgoing from frag F%d("PFX")\n",
f->id, f->tag);
/* ensure some higher-level lock is held if f is shared
* no links across caches so only checking f's sharedness is enough
*/
ASSERT(!NEED_SHARED_LOCK(f->flags) ||
self_owns_recursive_lock(&change_linking_lock));
ASSERT(TEST(FRAG_LINKED_OUTGOING, f->flags));
/* unprotect on demand, caller will re-protect */
SELF_PROTECT_CACHE(dcontext, f, WRITABLE);
/* unlink outgoing direct & indirect branches */
for (l = FRAGMENT_EXIT_STUBS(f); l; l = LINKSTUB_NEXT_EXIT(l)) {
if ((l->flags & LINK_LINKED) != 0) {
DEBUG_DECLARE(keep =)
unlink_branch(dcontext, f, l); /* works for fine and coarse targets */
ASSERT(keep);
}
}
f->flags &= ~FRAG_LINKED_OUTGOING;
#ifdef DEBUG
debug_after_link_change(dcontext, f, "Fragment after unlinking outgoing");
#endif
}
/* Performs proactive linking, and inserts all links into appropriate
* incoming links lists
* f may be visible or invisible
*/
void
link_new_fragment(dcontext_t *dcontext, fragment_t *f)
{
future_fragment_t *future;
if (TEST(FRAG_COARSE_GRAIN, f->flags)) {
link_new_coarse_grain_fragment(dcontext, f);
return;
}
LOG(THREAD, LOG_LINKS, 4, "linking new fragment F%d("PFX")\n", f->id, f->tag);
/* ensure some higher-level lock is held if f is shared
* no links across caches so only checking f's sharedness is enough
*/
ASSERT(!NEED_SHARED_LOCK(f->flags) ||
self_owns_recursive_lock(&change_linking_lock));
/* transfer existing future incoming links to this fragment */
if (!TEST(FRAG_SHARED, f->flags))
future = fragment_lookup_private_future(dcontext, f->tag);
else
future = fragment_lookup_future(dcontext, f->tag);
if (future != NULL) {
uint futflags = future->flags;
LOG(THREAD, LOG_LINKS, 4,
" transferring incoming links from existing future frag, flags=0x%08x\n",
futflags);
f->in_xlate.incoming_stubs = future->incoming_stubs;
DODEBUG({ future->incoming_stubs = NULL; });
/* also transfer any flags that were stored in future
* N.B.: these flags must not be anything that is required when creating
* a fragment, they may only be things like TRACE_HEAD if they are
* to work properly
*/
/* we only expect certain flags on future fragments */
ASSERT_CURIOSITY((futflags & ~(FUTURE_FLAGS_ALLOWED)) == 0);
/* sharedness must match */
ASSERT(TEST(FRAG_SHARED, f->flags) == TEST(FRAG_SHARED, futflags));
f->flags |= (futflags & (FUTURE_FLAGS_TRANSFER));
/* make sure existing flags and flags from build are compatible */
/* trace head and frag cannot be trace head incompatible */
if ((f->flags & FRAG_CANNOT_BE_TRACE) != 0 &&
(f->flags & FRAG_IS_TRACE_HEAD) != 0) {
f->flags &= ~FRAG_IS_TRACE_HEAD;
LOG(THREAD, LOG_MONITOR, 2,
"fragment marked as trace head before being built, but now "
"cannot be trace head, unmarking trace head : address "PFX"\n", f->tag);
}
if (TESTALL(FRAG_IS_TRACE|FRAG_IS_TRACE_HEAD, f->flags)) {
/* we put the trace head flag on futures to mark secondary
* shared trace heads from private traces -- but it can end up
* marking traces. remove it in that case as it WILL mess up
* linking (case 7465).
*/
ASSERT(SHARED_FRAGMENTS_ENABLED());
LOG(THREAD, LOG_MONITOR, 2,
"trace F%d("PFX") inheriting trace head from future: discarding\n",
f->id, f->tag);
f->flags &= ~FRAG_IS_TRACE_HEAD;
}
fragment_delete_future(dcontext, future);
}
DOCHECK(1, {
if (TEST(FRAG_SHARED, f->flags))
ASSERT(fragment_lookup_future(dcontext, f->tag) == NULL);
else
ASSERT(fragment_lookup_private_future(dcontext, f->tag) == NULL);
});
/* link incoming branches first, so no conflicts w/ self-loops
* that were just linked being added to future unlinked list
*/
link_fragment_incoming(dcontext, f, true/*new*/);
link_fragment_outgoing(dcontext, f, true/*new*/);
}
/* Changes all incoming links to old_f to point to new_f
* old_f and new_f must have the same tag
* Links up all new_f's outgoing links
* (regardless of whether old_f is linked or not)
* These changes are all atomic, so this routine can be run by another
* thread while the owning thread is in the code cache (but not while it
* is in dynamo code!)
*/
void
shift_links_to_new_fragment(dcontext_t *dcontext,
fragment_t *old_f, fragment_t *new_f)
{
linkstub_t *l;
bool have_link_lock =
(TEST(FRAG_SHARED, old_f->flags) || TEST(FRAG_SHARED, new_f->flags)) &&
!INTERNAL_OPTION(single_thread_in_DR);
cache_pc old_stub = NULL;
cache_pc old_body = NULL;
coarse_info_t *info = NULL;
DEBUG_DECLARE(bool keep;)
ASSERT(old_f->tag == new_f->tag);
/* usually f's flags are just copied to new, so don't assert
* that new_f's LINKED_ flags are 0, but we do assume it has
* never been linked!
*/
LOG(THREAD, LOG_LINKS, 4, "shifting links from F%d("PFX") to F%d("PFX")\n",
old_f->id, old_f->tag, new_f->id, new_f->tag);
/* ensure some higher-level lock is held if f is shared
* no links across caches so only checking f's sharedness is enough
*/
ASSERT(!have_link_lock || self_owns_recursive_lock(&change_linking_lock));
/* if the new fragment had the exact same sequence of exits as the old,
* we could walk in lockstep, calling incoming_table_change_linkstub,
* but the new fragment could have completely different exits, so we'd
* better remove all the old from others' incoming lists, and then add
* the new -- don't worry about synchronization, owning thread can
* only be in fcache, not in dynamo code
*/
/* remove old outgoing links from others' incoming lists */
LOG(THREAD, LOG_LINKS, 4, " removing outgoing links for F%d("PFX")\n",
old_f->id, old_f->tag);\
if (TEST(FRAG_COARSE_GRAIN, old_f->flags)) {
/* FIXME: we could implement full non-fake fragment_t recovery, and
* engineer the normal link paths to do the right thing for coarse
* fragments, to avoid all the coarse checks in this routine
*/
info = get_fragment_coarse_info(old_f);
ASSERT(info != NULL);
fragment_coarse_lookup_in_unit(dcontext, info, old_f->tag, &old_stub, &old_body);
ASSERT(old_stub != NULL || info->frozen);
ASSERT(old_body == FCACHE_ENTRY_PC(old_f));
/* We should only call this when emitting a trace */
ASSERT(TESTALL(FRAG_IS_TRACE | FRAG_SHARED, new_f->flags));
/* Case 8627: Since we can't really remove the fragment, we may as well
* leave the links intact. Besides, it's difficult to walk the outgoing
* links: the best way is to decode_fragment() and then walk the exit
* ctis (xref case 8571 on decoding up to linkstub_t level). There are no
* uniqueness requirements on incoming entries so long as there aren't
* two from the same coarse unit, so it's fine for the trace to also be
* in target incoming lists. Plus, this means we don't have to do
* anything if we later delete the trace.
*/
ASSERT(!TEST(FRAG_COARSE_GRAIN, new_f->flags)); /* ensure distinct incomings */
} else {
for (l = FRAGMENT_EXIT_STUBS(old_f); l; l = LINKSTUB_NEXT_EXIT(l)) {
if (LINKSTUB_DIRECT(l->flags)) {
/* incoming links do not cross sharedness boundaries */
app_pc target_tag = EXIT_TARGET_TAG(dcontext, old_f, l);
fragment_t *targetf =
fragment_link_lookup_same_sharing(dcontext, target_tag,
l, old_f->flags);
if (targetf == NULL) {
/* don't worry, all routines can handle fragment_t* that is really
* future_fragment_t*
*/
/* make sure future is in proper shared/private table */
if (!TEST(FRAG_SHARED, old_f->flags)) {
targetf = (fragment_t *)
fragment_lookup_private_future(dcontext, target_tag);
} else {
targetf = (fragment_t *)
fragment_lookup_future(dcontext, target_tag);
}
}
ASSERT(targetf != NULL);
/* if targetf == old_f, must remove self-link, b/c it won't be
* redirected below as it won't appear on incoming list (new
* self-link will).
*
* to avoid dangling links to other fragments (that may be deleted
* and leave the link there since not in incoming) we also unlink
* everything else.
*/
if (TEST(LINK_LINKED, l->flags)) {
DEBUG_DECLARE(keep =) unlink_branch(dcontext, old_f, l);
ASSERT(keep);
}
LOG(THREAD, LOG_LINKS, 4,
" removed F%d("PFX")."PFX" -> ("PFX") from incoming lists\n",
old_f->id, old_f->tag, EXIT_CTI_PC(old_f, l), target_tag);
incoming_remove_link(dcontext, old_f, l, targetf);
} else {
ASSERT(LINKSTUB_INDIRECT(l->flags));
if (TEST(LINK_LINKED, l->flags)) {
DEBUG_DECLARE(keep =) unlink_branch(dcontext, old_f, l);
ASSERT(keep);
}
}
}
}
old_f->flags &= ~FRAG_LINKED_OUTGOING;
/* We copy prior to link-outgoing as that can add to incoming for self-links */
ASSERT(new_f->in_xlate.incoming_stubs == NULL);
ASSERT(!TEST(FRAG_COARSE_GRAIN, old_f->flags) ||
old_f->in_xlate.incoming_stubs == NULL);
new_f->in_xlate.incoming_stubs = old_f->in_xlate.incoming_stubs;
old_f->in_xlate.incoming_stubs = NULL;
if (TEST(FRAG_COARSE_GRAIN, new_f->flags) &&
new_f->in_xlate.incoming_stubs != NULL) {
if (info == NULL)
info = get_fragment_coarse_info(new_f);
prepend_new_coarse_incoming(info, NULL, new_f->in_xlate.incoming_stubs);
}
/* N.B.: unlike linking a new fragment, the owning thread could be in
* the fcache, and the 1st link is NOT guaranteed to be atomic,
* so we have to link the outgoing links for the new fragment before
* we ever link anybody up to it
*/
/* link outgoing exits
* linking an already-linked branch is a nop, but as an optimization,
* rather than unlinking we mark them as not linked and put the proper
* link in with one cache write rather than two
*/
if (!TEST(FRAG_COARSE_GRAIN, new_f->flags)) {
if (TEST(FRAG_LINKED_OUTGOING, new_f->flags)) {
for (l = FRAGMENT_EXIT_STUBS(new_f); l; l = LINKSTUB_NEXT_EXIT(l)) {
if (LINKSTUB_DIRECT(l->flags) && TEST(LINK_LINKED, l->flags)) {
l->flags &= ~LINK_LINKED; /* leave inconsistent briefly */
}
}
}
new_f->flags &= ~FRAG_LINKED_OUTGOING; /* avoid assertion failure */
link_fragment_outgoing(dcontext, new_f, true/*add incoming*/);
} else {
ASSERT(TESTALL(FRAG_IS_TRACE | FRAG_SHARED, old_f->flags));
/* We assume this is re-instating a coarse trace head upon deleting
* a shared trace -- and that we never did unlink the trace head's outgoing
*/
}
ASSERT(TEST(FRAG_LINKED_OUTGOING, new_f->flags));
/* now shift incoming links from old fragment to new one */
LOG(THREAD, LOG_LINKS, 4, " transferring incoming links from F%d to F%d\n",
old_f->id, new_f->id);
old_f->flags &= ~FRAG_LINKED_INCOMING;
LOG(THREAD, LOG_LINKS, 4, " linking incoming links for F%d("PFX")\n",
new_f->id, new_f->tag);
if (TEST(FRAG_COARSE_GRAIN, old_f->flags)) {
coarse_incoming_t *e, *prev_e = NULL, *next_e;
bool remove_entry;
/* We don't yet support coarse to coarse shifts (see above for one reason) */
ASSERT(!TEST(FRAG_COARSE_GRAIN, new_f->flags));
/* Change the entrance stub to point to the trace, which redirects
* all incoming from inside the unit.
*/
if (old_stub != NULL) {
ASSERT(!entrance_stub_linked(old_stub, info) ||
entrance_stub_jmp_target(old_stub) == FCACHE_ENTRY_PC(old_f));
if (entrance_stub_linked(old_stub, info)) {
/* If was never marked as trace head we must mark now,
* else we will lose track of the body pc!
*/
coarse_mark_trace_head(dcontext, old_f, info, old_stub,
FCACHE_ENTRY_PC(old_f));
STATS_INC(coarse_th_on_shift);
}
coarse_link_to_fine(dcontext, old_stub, old_f, new_f, true/*do link*/);
} else {
/* FIXME: patch the frozen trace head to redirect?
* Else once in the unit will not go to trace.
* But by case 8151 this is only a trace head for paths coming
* from outside, which will go to the trace, so it should be ok.
*/
ASSERT(info->frozen);
}
new_f->flags |= FRAG_LINKED_INCOMING;
/* Now re-route incoming from outside the unit */
mutex_lock(&info->incoming_lock);
for (e = info->incoming; e != NULL; e = next_e) {
next_e = e->next;
remove_entry = false;
if (!e->coarse) {
app_pc tgt = NULL;
linkstub_t *next_l;
for (l = e->in.fine_l; l != NULL; l = next_l) {
fragment_t *in_f = linkstub_fragment(dcontext, l);
next_l = LINKSTUB_NEXT_INCOMING(l);
ASSERT(!TEST(LINK_FAKE, l->flags));
if (tgt == NULL) {
tgt = EXIT_TARGET_TAG(dcontext, in_f, l);
} else {
/* Every fine incoming in a single coarse-list entry should
* target the same tag
*/
ASSERT(EXIT_TARGET_TAG(dcontext, in_f, l) == tgt);
}
if (tgt == old_f->tag) {
/* unprotect on demand (caller will re-protect)
* FIXME: perhaps that's true for other link routines,
* but shift_links_to_new_fragment() is called from
* places where we need to double-check
*/
SELF_PROTECT_CACHE(dcontext, in_f, WRITABLE);
DEBUG_DECLARE(keep =) unlink_branch(dcontext, in_f, l);
ASSERT(keep);
if (is_linkable(dcontext, in_f, l, new_f, have_link_lock,
true/*mark trace heads*/)) {
link_branch(dcontext, in_f, l, new_f, HOT_PATCHABLE);
add_incoming(dcontext, in_f, l, new_f, true/*linked*/);
} else {
LOG(THREAD, LOG_LINKS, 4,
" not linking F%d("PFX")."PFX" -> F%d("PFX")"
" is not linkable!\n",
in_f->id, in_f->tag, EXIT_CTI_PC(in_f, l),
new_f->id, new_f->tag);
add_incoming(dcontext, in_f, l, new_f, false/*!linked*/);
}
remove_entry = true;
}
}
} else if (entrance_stub_jmp_target(e->in.stub_pc) ==
FCACHE_ENTRY_PC(old_f)) {
/* FIXME: we don't know the tag of the src (and cannot find it
* (case 8565))! We'll use old_f's tag to avoid triggering any
* new trace head rules. Presumably they would have already
* been triggered unless they vary based on coarse or fine.
*/
fragment_t *src_f = fragment_coarse_link_wrapper(dcontext, old_f->tag,
e->in.stub_pc);
set_fake_direct_linkstub(&temp_linkstub, old_f->tag, e->in.stub_pc);
LOG(THREAD, LOG_LINKS, 4,
" shifting coarse link "PFX" -> %s "PFX" to F%d("PFX")\n",
e->in.stub_pc, info->module, old_f->tag, new_f->id, new_f->tag);
if (is_linkable(dcontext, src_f, (linkstub_t *) &temp_linkstub,
new_f, have_link_lock, true/*mark trace heads*/)) {
DODEBUG({
/* avoid assert about being already linked */
unlink_entrance_stub(dcontext, e->in.stub_pc, new_f->flags,
NULL);
});
coarse_link_to_fine(dcontext, e->in.stub_pc, src_f, new_f,
true/*do link*/);
}
remove_entry = true;
}
if (remove_entry) {
if (prev_e == NULL)
info->incoming = e->next;
else
prev_e->next = e->next;
LOG(THREAD, LOG_LINKS, 4,
"freeing coarse_incoming_t "PFX"\n", e);
NONPERSISTENT_HEAP_TYPE_FREE(GLOBAL_DCONTEXT, e, coarse_incoming_t,
ACCT_COARSE_LINK);
} else
prev_e = e;
}
mutex_unlock(&info->incoming_lock);
} else if (TEST(FRAG_COARSE_GRAIN, new_f->flags)) {
/* Change the entrance stub to point to the trace head routine again
* (we only shift to coarse trace heads).
*/
coarse_info_t *info = get_fragment_coarse_info(new_f);
cache_pc new_stub, new_body;
ASSERT(info != NULL);
fragment_coarse_lookup_in_unit(dcontext, info, old_f->tag, &new_stub, &new_body);
ASSERT(new_body == FCACHE_ENTRY_PC(new_f));
if (new_stub != NULL) {
unlink_entrance_stub(dcontext, new_stub, FRAG_IS_TRACE_HEAD, info);
ASSERT(coarse_is_trace_head_in_own_unit(dcontext, new_f->tag,
new_stub, new_body, true, info));
/* If we ever support shifting to non-trace-heads we'll want to point the
* stub at the fragment and not at the head incr routine
*/
} else
ASSERT(info->frozen);
/* We can re-use link_fragment_incoming, but be careful of any future
* changes that require splitting out the coarse-and-fine-shared part.
*/
new_f->flags &= ~FRAG_LINKED_INCOMING; /* wrapper is marked as linked */
link_fragment_incoming(dcontext, new_f, true/*new*/);
ASSERT(TEST(FRAG_LINKED_INCOMING, new_f->flags));
} else {
new_f->flags |= FRAG_LINKED_INCOMING;
for (l = new_f->in_xlate.incoming_stubs; l != NULL;
l = LINKSTUB_NEXT_INCOMING(l)) {
fragment_t *in_f = linkstub_fragment(dcontext, l);
ASSERT(!is_empty_fragment(in_f));
if (is_linkable(dcontext, in_f, l, new_f, have_link_lock,
true/*mark new trace heads*/)) {
/* used to check to make sure was linked but no reason to? */
/* already did self-links */
if (in_f != new_f) {
if (TEST(LINK_LINKED, l->flags))
l->flags &= ~LINK_LINKED; /* else, link_branch is a nop */
link_branch(dcontext, in_f, l, new_f, HOT_PATCHABLE);
} else {
LOG(THREAD, LOG_LINKS, 4, " not linking F%d("PFX")."PFX" -> "
"F%d("PFX" == "PFX") (self-link already linked)\n",
in_f->id, in_f->tag, EXIT_CTI_PC(in_f, l),
new_f->id, new_f->tag);
}
} else if ((l->flags & LINK_LINKED) != 0) {
DEBUG_DECLARE(keep =) unlink_branch(dcontext, in_f, l);
ASSERT(keep);
LOG(THREAD, LOG_LINKS, 4,
" not linking F%d("PFX")."PFX" -> F%d("PFX")"
"(src not outgoing-linked)\n",
in_f->id, in_f->tag, EXIT_CTI_PC(in_f, l),
new_f->id, new_f->tag);
} else {
LOG(THREAD, LOG_LINKS, 4, " not linking F%d("PFX")."PFX" -> "
"F%d("PFX" == "PFX")\n",
in_f->id, in_f->tag, EXIT_CTI_PC(in_f, l),
new_f->id, new_f->tag);
}
}
}
/* For the common case of a trace shadowing a trace head
* (happens w/ shared traces, and with CUSTOM_TRACES),
* ensure that when we delete the trace we shift back and
* when we delete the head we don't complain that we're
* missing links.
*/
if (TEST(FRAG_IS_TRACE, new_f->flags) &&
TEST(FRAG_IS_TRACE_HEAD, old_f->flags)) {
ASSERT((!NEED_SHARED_LOCK(new_f->flags) &&
!NEED_SHARED_LOCK(old_f->flags)) ||
self_owns_recursive_lock(&change_linking_lock));
LOG(THREAD, LOG_LINKS, 4, "Marking old and new as FRAG_TRACE_LINKS_SHIFTED\n");
new_f->flags |= FRAG_TRACE_LINKS_SHIFTED;
old_f->flags |= FRAG_TRACE_LINKS_SHIFTED;
}
DOLOG(4, LOG_LINKS, {
LOG(THREAD, LOG_LINKS, 4, "Old fragment after shift:\n");
disassemble_fragment(dcontext, old_f, stats->loglevel < 4);
LOG(THREAD, LOG_LINKS, 4, "New fragment after shift:\n");
disassemble_fragment(dcontext, new_f, stats->loglevel < 4);
});
}
/***************************************************************************
* COARSE-GRAIN UNITS
*/
static vm_area_vector_t *coarse_stub_areas;
static void
coarse_stubs_init()
{
VMVECTOR_ALLOC_VECTOR(coarse_stub_areas, GLOBAL_DCONTEXT,
VECTOR_SHARED | VECTOR_NEVER_MERGE,
coarse_stub_areas);
}
static void
coarse_stubs_free()
{
ASSERT(coarse_stub_areas != NULL);
/* should be empty from special_heap_exit(), from vm_area_coarse_units_reset_free() */
ASSERT(vmvector_empty(coarse_stub_areas));
vmvector_delete_vector(GLOBAL_DCONTEXT, coarse_stub_areas);
}
/* current prefix size is 37 bytes, so need 3 stub slots */
static inline uint
num_coarse_stubs_for_prefix(coarse_info_t *info)
{
uint prefix_size = coarse_exit_prefix_size(info);
size_t stub_size = COARSE_STUB_ALLOC_SIZE(COARSE_32_FLAG(info));
ASSERT(CHECK_TRUNCATE_TYPE_uint(ALIGN_FORWARD(prefix_size, stub_size)));
return (uint) (ALIGN_FORWARD(prefix_size, stub_size) / stub_size);
}
uint
coarse_stub_alignment(coarse_info_t *info)
{
return (uint) COARSE_STUB_ALLOC_SIZE(COARSE_32_FLAG(info));
}
/* Pass in NULL for pc to have stubs created.
* Size must include room for prefixes as well as stubs.
*/
cache_pc
coarse_stubs_create(coarse_info_t *info, cache_pc pc, size_t size)
{
byte *end_pc;
ASSERT(coarse_stub_areas != NULL);
info->stubs = special_heap_pclookup_init((uint)
COARSE_STUB_ALLOC_SIZE(COARSE_32_FLAG(info)),
true /* must synch */, true /* +x */,
false /* not persistent */,
coarse_stub_areas,
info /* support pclookup w/ info retval */,
pc, size, pc != NULL/*full if pre-alloc*/);
/* Create the fcache_return_coarse prefix for this unit.
* We keep it here rather than at the top of the fcache unit because:
* 1) stubs are writable while fcache should be read-only, and we may want
* to patch the prefix when persistent to point to the current fcache_return
* 2) we need to find the prefix given just a stub and no info on the
* src body in fcache
* We have to make sure stub walks skip over the prefix.
*/
if (pc != NULL) {
/* Header is separate, so we know we can start at the top */
info->fcache_return_prefix = pc;
} else {
info->fcache_return_prefix = (cache_pc)
special_heap_calloc(info->stubs, num_coarse_stubs_for_prefix(info));
}
end_pc = emit_coarse_exit_prefix(GLOBAL_DCONTEXT, info->fcache_return_prefix, info);
/* we have to align for pc != NULL;
* caller should be using calloc if pc==NULL but we align just in case
*/
end_pc = (cache_pc) ALIGN_FORWARD(end_pc, coarse_stub_alignment(info));
ASSERT(pc == NULL || end_pc <= pc+size);
ASSERT(info->trace_head_return_prefix != NULL);
ASSERT(info->ibl_ret_prefix != NULL);
ASSERT(info->ibl_call_prefix != NULL);
ASSERT(info->ibl_jmp_prefix != NULL);
ASSERT(end_pc - info->fcache_return_prefix <=
(int)(COARSE_STUB_ALLOC_SIZE(COARSE_32_FLAG(info))*
num_coarse_stubs_for_prefix(info)));
DOCHECK(1, {
SET_TO_NOPS(end_pc, info->fcache_return_prefix +
COARSE_STUB_ALLOC_SIZE(COARSE_32_FLAG(info))*
num_coarse_stubs_for_prefix(info) - end_pc);
});
return end_pc;
}
/* Iteration support over coarse entrance stubs */
typedef struct {
special_heap_iterator_t shi;
cache_pc start, end, pc;
coarse_info_t *info;
} coarse_stubs_iterator_t;
static void
coarse_stubs_iterator_start(coarse_info_t *info, coarse_stubs_iterator_t *csi)
{
special_heap_iterator_start(info->stubs, &csi->shi);
csi->info = info;
if (special_heap_iterator_hasnext(&csi->shi)) {
special_heap_iterator_next(&csi->shi, &csi->start, &csi->end);
/* skip the prefix kept at the top of the first unit */
ASSERT(csi->start == info->fcache_return_prefix);
/* coarse_stubs_iterator_next() will add 1 */
csi->pc = csi->start + COARSE_STUB_ALLOC_SIZE(COARSE_32_FLAG(info))*
(num_coarse_stubs_for_prefix(info)-1);
} else {
csi->start = NULL;
csi->end = NULL;
csi->pc = NULL;
}
}
/* If we wanted coarse_stubs_iterator_hasnext() it would look like this:
* return (csi->pc < csi->end || special_heap_iterator_hasnext(&csi->shi))
*/
static cache_pc inline
coarse_stubs_iterator_next(coarse_stubs_iterator_t *csi)
{
if (csi->pc == NULL)
return NULL;
ASSERT(csi->pc < csi->end);
csi->pc += COARSE_STUB_ALLOC_SIZE(COARSE_32_FLAG(csi->info));
if (csi->pc >= csi->end) {
if (special_heap_iterator_hasnext(&csi->shi)) {
special_heap_iterator_next(&csi->shi, &csi->start, &csi->end);
csi->pc = csi->start;
} else
return NULL;
}
/* N.B.: once we free entrance stubs we'll need to identify a
* freed pattern here. For now we assume everything is
* a stub.
*/
ASSERT(coarse_is_entrance_stub(csi->pc));
return csi->pc;
}
static void inline
coarse_stubs_iterator_stop(coarse_stubs_iterator_t *csi)
{
special_heap_iterator_stop(&csi->shi);
}
void
coarse_stubs_delete(coarse_info_t *info)
{
DEBUG_DECLARE(coarse_stubs_iterator_t csi;)
DEBUG_DECLARE(cache_pc pc;)
ASSERT_OWN_MUTEX(!dynamo_all_threads_synched && !info->is_local, &info->lock);
if (info->stubs == NULL) {
/* lazily initialized, so common to have empty units */
ASSERT(info->fcache_return_prefix == NULL);
return;
}
#ifdef DEBUG
if (info->frozen) {
/* We allocated the stub unit ourselves so nothing to free here */
} else {
special_heap_cfree(info->stubs, info->fcache_return_prefix,
num_coarse_stubs_for_prefix(info));
/* We can't free while using the iterator (lock issues) so we
* free all at once
*/
coarse_stubs_iterator_start(info, &csi);
for (pc = coarse_stubs_iterator_next(&csi); pc != NULL;
pc = coarse_stubs_iterator_next(&csi)) {
special_heap_free(info->stubs, pc);
}
coarse_stubs_iterator_stop(&csi);
}
#endif
LOG(THREAD_GET, LOG_LINKS|LOG_HEAP, 1,
"Coarse special heap exit %s\n", info->module);
special_heap_exit(info->stubs);
info->stubs = NULL;
info->fcache_return_prefix = NULL;
info->trace_head_return_prefix = NULL;
info->ibl_ret_prefix = NULL;
info->ibl_call_prefix = NULL;
info->ibl_jmp_prefix = NULL;
}
/* N.B.: once we start freeing entrance stubs, we need to fill the space,
* so that our stub walk can identify live stubs
*/
static cache_pc
entrance_stub_create(dcontext_t *dcontext, coarse_info_t *info,
fragment_t *f, linkstub_t *l)
{
uint emit_sz;
cache_pc stub_pc;
DEBUG_DECLARE(size_t stub_size = COARSE_STUB_ALLOC_SIZE(COARSE_32_FLAG(info));)
ASSERT(DYNAMO_OPTION(coarse_units));
ASSERT(info != NULL && info->stubs != NULL);
ASSERT(LINKSTUB_DIRECT(l->flags));
ASSERT(TEST(LINK_SEPARATE_STUB, l->flags));
ASSERT(exit_stub_size(dcontext, EXIT_TARGET_TAG(dcontext, f, l), f->flags) <=
(ssize_t) stub_size);
/* We hot-patch our stubs and we assume that aligning them to 16 is enough */
ASSERT((cache_line_size % stub_size) == 0);
stub_pc = (cache_pc) special_heap_alloc(info->stubs);
ASSERT(ALIGNED(stub_pc, coarse_stub_alignment(info)));
emit_sz = insert_exit_stub(dcontext, f, l, stub_pc);
LOG(THREAD, LOG_LINKS, 4,
"created new entrance stub @"PFX" for "PFX" w/ source F%d("PFX")."PFX"\n",
stub_pc, EXIT_TARGET_TAG(dcontext, f, l), f->id, f->tag, FCACHE_ENTRY_PC(f));
ASSERT(emit_sz <= stub_size);
DOCHECK(1, {
SET_TO_NOPS(stub_pc + emit_sz, stub_size - emit_sz);
});
STATS_ADD(separate_shared_bb_entrance_stubs, stub_size);
STATS_INC(num_entrance_stubs);
return stub_pc;
}
/* Sets flags for a fake linkstub_t for an incoming list entry for a coarse source */
static void
set_fake_direct_linkstub(direct_linkstub_t *proxy, app_pc target, cache_pc stub)
{
/* ASSUMPTION: this combination is unique to coarse-grain proxy stubs.
* The LINKSTUB_COARSE_PROXY() macro tests these (except LINK_LINKED).
*/
proxy->cdl.l.flags = LINK_FAKE | LINK_DIRECT | LINK_LINKED | LINK_SEPARATE_STUB;
proxy->cdl.l.cti_offset = 0;
proxy->target_tag = target;
proxy->stub_pc = stub;
}
#if defined(DEBUG) && defined(INTERNAL)
static void
print_coarse_incoming(dcontext_t *dcontext, coarse_info_t *info)
{
coarse_incoming_t *e;
ASSERT_OWN_MUTEX(true, &info->incoming_lock);
LOG(THREAD, LOG_LINKS, 1, "coarse incoming entries for %s\n", info->module);
for (e = info->incoming; e != NULL; e = e->next) {
LOG(THREAD, LOG_LINKS, 1, "\t"PFX" %d ",
e, e->coarse);
if (e->coarse)
LOG(THREAD, LOG_LINKS, 1, PFX"\n", e->in.stub_pc);
else {
fragment_t *f = linkstub_fragment(dcontext, e->in.fine_l);
LOG(THREAD, LOG_LINKS, 1, "F%d("PFX")\n", f->id, f->tag);
}
}
}
#endif
/* Must pass NULL for exactly one of coarse or fine */
static coarse_incoming_t *
prepend_new_coarse_incoming(coarse_info_t *info, cache_pc coarse, linkstub_t *fine)
{
coarse_incoming_t *entry =
NONPERSISTENT_HEAP_TYPE_ALLOC(GLOBAL_DCONTEXT, coarse_incoming_t,
ACCT_COARSE_LINK);
/* entries are freed in coarse_remove_outgoing()/coarse_unit_unlink() */
if (fine == NULL) {
/* FIXME: rather than separate entries per stub pc, to save memory
* we could have a single one for the whole unit (and we'd search
* here to see if it already exists) and search when unlinking to
* find the individual stubs
*/
ASSERT(coarse != NULL);
entry->coarse = true;
entry->in.stub_pc = coarse;
LOG(THREAD_GET, LOG_LINKS, 4,
"created new coarse_incoming_t "PFX" coarse from "PFX"\n",
entry, entry->in.stub_pc);
} else {
ASSERT(coarse == NULL);
entry->coarse = false;
/* We put the whole linkstub_t list as one entry */
entry->in.fine_l = fine;
LOG(THREAD_GET, LOG_LINKS, 4,
"created new coarse_incoming_t "PFX" fine from "PFX"\n",
entry, entry->in.fine_l);
DOCHECK(1, {
linkstub_t *l;
for (l = fine; l != NULL; l = LINKSTUB_NEXT_INCOMING(l))
ASSERT(!TEST(LINK_FAKE, l->flags));
});
}
ASSERT(info != NULL);
mutex_lock(&info->incoming_lock);
entry->next = info->incoming;
info->incoming = entry;
DOLOG(5, LOG_LINKS, {
LOG(GLOBAL, LOG_LINKS, 4, "after adding new incoming "PFX":\n", entry);
print_coarse_incoming(GLOBAL_DCONTEXT, info);
});
mutex_unlock(&info->incoming_lock);
return entry;
}
/* Pass in coarse if you already know it; else, this routine will look it up */
static fragment_t *
fragment_coarse_link_wrapper(dcontext_t *dcontext, app_pc target_tag,
cache_pc know_coarse)
{
ASSERT(self_owns_recursive_lock(&change_linking_lock));
if (know_coarse == NULL) {
return fragment_coarse_lookup_wrapper(dcontext, target_tag, &temp_targetf);
} else {
fragment_coarse_wrapper(&temp_targetf, target_tag, know_coarse);
return &temp_targetf;
}
return NULL;
}
static fragment_t *
fragment_link_lookup_same_sharing(dcontext_t *dcontext, app_pc tag,
linkstub_t *last_exit, uint flags)
{
/* Assumption: if asking for private won't use temp_targetf.
* Else need to grab the lock when linking private fragments
* (in particular, temps for trace building)
*/
ASSERT(!TEST(FRAG_SHARED, flags) || self_owns_recursive_lock(&change_linking_lock));
return fragment_lookup_fine_and_coarse_sharing(dcontext, tag,
&temp_targetf, last_exit, flags);
}
static void
coarse_link_to_fine(dcontext_t *dcontext, cache_pc src_stub, fragment_t *src_f,
fragment_t *target_f, bool do_link/*else just add incoming*/)
{
/* We may call this multiple times for multiple sources going through the
* same entrance stub
*/
ASSERT(self_owns_recursive_lock(&change_linking_lock));
set_fake_direct_linkstub(&temp_linkstub, target_f->tag, src_stub);
if (incoming_link_exists(dcontext, src_f, (linkstub_t *)&temp_linkstub, target_f)) {
ASSERT(entrance_stub_jmp_target(src_stub) == FCACHE_ENTRY_PC(target_f));
LOG(THREAD, LOG_LINKS, 4,
" already linked coarse "PFX"."PFX"->F%d("PFX")\n",
src_f->tag, FCACHE_ENTRY_PC(src_f), target_f->id, target_f->tag);
} else {
direct_linkstub_t *proxy =
NONPERSISTENT_HEAP_TYPE_ALLOC(GLOBAL_DCONTEXT, direct_linkstub_t,
ACCT_COARSE_LINK);
LOG(THREAD, LOG_LINKS, 4,
"created new proxy incoming "PFX" from coarse "PFX" to fine F%d\n",
proxy, src_stub, target_f->id);
LOG(THREAD, LOG_LINKS, 4,
" linking coarse stub "PFX"->F%d("PFX")\n",
src_stub, target_f->id, target_f->tag);
/* Freed in incoming_remove_link() called from unlink_fragment_incoming()
* or from coarse_unit_unlink() calling coarse_remove_outgoing().
* Note that we do not unlink fine fragments on reset/exit (case 7697)
* so we can't rely solely on unlink_fragment_incoming() to free these
* for us.
*/
set_fake_direct_linkstub(proxy, target_f->tag, src_stub);
add_incoming(dcontext, src_f, (linkstub_t *) proxy, target_f, true/*linked*/);
if (do_link) {
/* Should not be linked somewhere else */
ASSERT(!entrance_stub_linked(src_stub, NULL) ||
entrance_stub_jmp_target(src_stub) == FCACHE_ENTRY_PC(target_f));
proxy->cdl.l.flags &= ~LINK_LINKED; /* so link_branch isn't a nop */
link_branch(dcontext, src_f, (linkstub_t *) proxy, target_f, HOT_PATCHABLE);
} else {
/* Already linked (we're freezing or shifting) */
ASSERT(entrance_stub_linked(src_stub, NULL) &&
entrance_stub_jmp_target(src_stub) == FCACHE_ENTRY_PC(target_f));
}
}
}
/* Links up an entrance stub to its target, whether that is a local coarse,
* remote coarse, or remote fine fragment.
* Takes in f and l since for a new coarse fragment those already exist;
* other callers will have to fabricate.
* Returns true if the link was enacted.
*/
static bool
coarse_link_direct(dcontext_t *dcontext, fragment_t *f, linkstub_t *l,
coarse_info_t *src_info, cache_pc stub, app_pc target_tag,
cache_pc local_tgt_in, bool new_stub)
{
bool linked = false;
/* Targets are always body pcs. stub is the stub pc we'll link through. */
cache_pc local_tgt = NULL;
cache_pc remote_tgt = NULL;
cache_pc coarse_tgt = NULL;
fragment_t *target_f = NULL;
ASSERT(self_owns_recursive_lock(&change_linking_lock));
ASSERT(entrance_stub_target_tag(stub, src_info) == target_tag);
/* Note that it is common for stub to already be linked (b/c we have
* entrance stubs shared by multiple sources), yet we still need to call
* is_linkable
*/
DOSTATS({
if (entrance_stub_linked(stub, src_info))
STATS_INC(coarse_relinks);
});
/* Since we leave shadowed trace heads visible we must first look in the
* fine tables
*/
ASSERT(TEST(FRAG_SHARED, f->flags));
target_f = fragment_lookup_same_sharing(dcontext, target_tag, FRAG_SHARED);
if (target_f == NULL) {
if (local_tgt_in == NULL) {
/* Use src_info if available -- else look up by tag */
coarse_info_t *info = src_info;
if (info == NULL) {
ASSERT(f->tag != NULL);
info = get_fragment_coarse_info(f);
}
if (info != NULL) {
fragment_coarse_lookup_in_unit(dcontext, info, target_tag, NULL,
&local_tgt);
}
} else
local_tgt = local_tgt_in;
if (local_tgt == NULL) {
remote_tgt = fragment_coarse_lookup(dcontext, target_tag);
coarse_tgt = remote_tgt;
} else
coarse_tgt = local_tgt;
} else
ASSERT(!TEST(FRAG_COARSE_GRAIN, target_f->flags));
if (coarse_tgt != NULL || target_f != NULL) {
if (target_f == NULL) {
/* No fine-grain fragment_t so make a fake one to use for the
* is_linkable() and mark_trace_head() paths.
* We can only recover certain flags, and we assume that others
* cannot be represented in a coarse unit anyway.
*/
target_f = fragment_coarse_link_wrapper(dcontext, target_tag, coarse_tgt);
if (stub != NULL && coarse_is_trace_head(stub))
target_f->flags |= FRAG_IS_TRACE_HEAD;
}
if (is_linkable(dcontext, f, l, target_f,
NEED_SHARED_LOCK(f->flags) || SHARED_FRAGMENTS_ENABLED(),
true/*mark new trace heads*/)) {
linked = true;
if (local_tgt ==<