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chromium / external / dynamorio / 943803169438bfb21cc82c52f9b141574bb4b249 / . / core / dispatch.c
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/* **********************************************************
* Copyright (c) 2011-2014 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 */
/*
* dispatch.c - central dynamo control manager
*/
#include "globals.h"
#include "link.h"
#include "fragment.h"
#include "fcache.h"
#include "monitor.h"
#include "synch.h"
#include "perscache.h"
#include "native_exec.h"
#include "translate.h"
#include <string.h> /* for strstr */
#ifdef CLIENT_INTERFACE
# include "emit.h"
# include "arch.h"
# include "instrument.h"
#endif
#ifdef DGC_DIAGNOSTICS
# include "instr.h"
# include "disassemble.h"
#endif
#ifdef RCT_IND_BRANCH
# include "rct.h"
#endif
#ifdef VMX86_SERVER
# include "vmkuw.h"
#endif
/* forward declarations */
static void
dispatch_enter_dynamorio(dcontext_t *dcontext);
static bool
dispatch_enter_fcache(dcontext_t *dcontext, fragment_t *targetf);
static void
dispatch_enter_fcache_stats(dcontext_t *dcontext, fragment_t *targetf);
static void
enter_fcache(dcontext_t *dcontext, fcache_enter_func_t entry, cache_pc pc);
static void
dispatch_enter_native(dcontext_t *dcontext);
static void
dispatch_exit_fcache(dcontext_t *dcontext);
static void
dispatch_exit_fcache_stats(dcontext_t *dcontext);
static void
handle_post_system_call(dcontext_t *dcontext);
static void
handle_special_tag(dcontext_t *dcontext);
#ifdef WINDOWS
static void
handle_callback_return(dcontext_t *dcontext);
#endif
#ifdef CLIENT_INTERFACE
/* PR 356503: detect clients making syscalls via sysenter */
static inline void
found_client_sysenter(void)
{
CLIENT_ASSERT(false, "Is your client invoking raw system calls via vdso sysenter? "
"While such behavior is not recommended and can create problems, "
"it may work with the -sysenter_is_int80 runtime option.");
}
#endif
static bool
exited_due_to_ni_syscall(dcontext_t *dcontext)
{
if (TESTANY(LINK_NI_SYSCALL_ALL, dcontext->last_exit->flags))
return true;
if (TEST(LINK_SPECIAL_EXIT, dcontext->last_exit->flags) &&
(dcontext->upcontext.upcontext.exit_reason == EXIT_REASON_NI_SYSCALL_INT_0x81 ||
dcontext->upcontext.upcontext.exit_reason == EXIT_REASON_NI_SYSCALL_INT_0x82))
return true;
return false;
}
/* This is the central hub of control management in DynamoRIO.
* It is entered with a clean dstack at startup and after every cache
* exit, whether normal or kernel-mediated via a trampoline context switch.
* Having no stack state kept across cache executions avoids
* self-protection issues with the dstack.
*/
void
dispatch(dcontext_t *dcontext)
{
fragment_t *targetf;
fragment_t coarse_f;
#ifdef HAVE_TLS
ASSERT(dcontext == get_thread_private_dcontext());
#else
# ifdef UNIX
/* CAUTION: for !HAVE_TLS, upon a fork, the child's
* get_thread_private_dcontext() will return NULL because its thread
* id is different and tls_table hasn't been updated yet (will be
* done in post_system_call()). NULL dcontext thus returned causes
* logging/core dumping to malfunction; kstats trigger asserts.
*/
ASSERT(dcontext == get_thread_private_dcontext() || pid_cached != get_process_id());
# endif
#endif
dispatch_enter_dynamorio(dcontext);
LOG(THREAD, LOG_INTERP, 2, "\ndispatch: target = "PFX"\n", dcontext->next_tag);
/* This is really a 1-iter loop most of the time: we only iterate
* when we obtain a target fragment but then fail to enter the
* cache due to flushing before we get there.
*/
do {
if (is_in_dynamo_dll(dcontext->next_tag) ||
dcontext->next_tag == BACK_TO_NATIVE_AFTER_SYSCALL) {
handle_special_tag(dcontext);
}
/* Neither hotp_only nor thin_client should have any fragment
* fcache related work to do.
*/
ASSERT(!RUNNING_WITHOUT_CODE_CACHE());
targetf = fragment_lookup_fine_and_coarse(dcontext, dcontext->next_tag,
&coarse_f, dcontext->last_exit);
#ifdef UNIX
/* i#1276: dcontext->next_tag could be a special stub pc used by
* DR to maintain control in hybrid execution, in which case the
* target should be replaced with correct app target.
*/
if (targetf == NULL &&
DYNAMO_OPTION(native_exec) && DYNAMO_OPTION(native_exec_opt) &&
native_exec_replace_next_tag(dcontext))
continue;
#endif
do {
if (targetf != NULL) {
KSTART(monitor_enter);
/* invoke monitor to continue or start a trace
* may result in changing or nullifying targetf
*/
targetf = monitor_cache_enter(dcontext, targetf);
KSTOP_NOT_MATCHING(monitor_enter); /* or monitor_enter_thci */
}
if (targetf != NULL)
break;
/* must call outside of USE_BB_BUILDING_LOCK guard for bb_lock_would_have: */
SHARED_BB_LOCK();
if (USE_BB_BUILDING_LOCK() || targetf == NULL) {
/* must re-lookup while holding lock and keep the lock until we've
* built the bb and added it to the lookup table
* FIXME: optimize away redundant lookup: flags to know why came out?
*/
targetf = fragment_lookup_fine_and_coarse(dcontext, dcontext->next_tag,
&coarse_f, dcontext->last_exit);
}
if (targetf == NULL) {
SELF_PROTECT_LOCAL(dcontext, WRITABLE);
targetf =
build_basic_block_fragment(dcontext, dcontext->next_tag,
0, true/*link*/, true/*visible*/
_IF_CLIENT(false/*!for_trace*/)
_IF_CLIENT(NULL));
SELF_PROTECT_LOCAL(dcontext, READONLY);
}
if (targetf != NULL && TEST(FRAG_COARSE_GRAIN, targetf->flags)) {
/* targetf is a static temp fragment protected by bb_building_lock,
* so we must make a local copy to use before releasing the lock.
* FIXME: best to pass local wrapper to build_basic_block_fragment
* and all the way through emit and link? Would need linkstubs
* tailing the fragment_t.
*/
ASSERT(USE_BB_BUILDING_LOCK_STEADY_STATE());
fragment_coarse_wrapper(&coarse_f, targetf->tag,
FCACHE_ENTRY_PC(targetf));
targetf = &coarse_f;
}
SHARED_BB_UNLOCK();
if (targetf == NULL)
break;
/* loop around and re-do monitor check */
} while (true);
if (targetf != NULL) {
if (dispatch_enter_fcache(dcontext, targetf)) {
/* won't reach here: will re-enter dispatch() with a clean stack */
ASSERT_NOT_REACHED();
} else
targetf = NULL; /* targetf was flushed */
}
} while (true);
ASSERT_NOT_REACHED();
}
/* returns true if pc is a point at which DynamoRIO should stop interpreting */
bool
is_stopping_point(dcontext_t *dcontext, app_pc pc)
{
if ((pc == BACK_TO_NATIVE_AFTER_SYSCALL &&
/* case 6253: app may xfer to this "address" in which case pass
* exception to app
*/
dcontext->native_exec_postsyscall != NULL)
#ifdef DR_APP_EXPORTS
|| (!automatic_startup &&
(pc == (app_pc)dynamorio_app_exit ||
/* FIXME: Is this a holdover from long ago? dymamo_thread_exit
* should not be called from the cache.
*/
pc == (app_pc)dynamo_thread_exit ||
pc == (app_pc)dr_app_stop))
#endif
#ifdef WINDOWS
/* we go all the way to NtTerminateThread/NtTerminateProcess */
#else /* UNIX */
/* we go all the way to SYS_exit or SYS_{,t,tg}kill(SIGABRT) */
#endif
)
return true;
return false;
}
static void
dispatch_enter_fcache_stats(dcontext_t *dcontext, fragment_t *targetf)
{
#ifdef DEBUG
# ifdef DGC_DIAGNOSTICS
if (TEST(FRAG_DYNGEN, targetf->flags) && !is_dyngen_vsyscall(targetf->tag)) {
char buf[MAXIMUM_SYMBOL_LENGTH];
bool stack = is_address_on_stack(dcontext, targetf->tag);
LOG(THREAD, LOG_DISPATCH, 1, "Entry into dyngen F%d("PFX"%s%s) via:",
targetf->id, targetf->tag,
stack ? " stack":"",
(targetf->flags & FRAG_DYNGEN_RESTRICTED) != 0 ? " BAD":"");
if (!LINKSTUB_FAKE(dcontext->last_exit)) {
app_pc translated_pc;
/* can't recreate if fragment is deleted -- but should be fake then */
ASSERT(!TEST(FRAG_WAS_DELETED, dcontext->last_fragment->flags));
translated_pc = recreate_app_pc(dcontext, EXIT_CTI_PC(dcontext->last_fragment,
dcontext->last_exit),
dcontext->last_fragment);
if (translated_pc != NULL) {
disassemble(dcontext, translated_pc, THREAD);
print_symbolic_address(translated_pc, buf, sizeof(buf), false);
LOG(THREAD, LOG_DISPATCH, 1, " %s\n", buf);
}
if (!stack &&
(strstr(buf, "user32.dll") != NULL || strstr(buf, "USER32.DLL") != NULL)) {
/* try to find who set up user32 callback */
dump_mcontext_callstack(dcontext);
}
DOLOG(stack ? 1U : 2U, LOG_DISPATCH, {
LOG(THREAD, LOG_DISPATCH, 1, "Originating bb:\n");
disassemble_app_bb(dcontext, dcontext->last_fragment->tag, THREAD);
});
} else {
/* FIXME: print type from last_exit */
LOG(THREAD, LOG_DISPATCH, 1, "\n");
}
if (stack) {
/* try to understand where code is on stack */
LOG(THREAD, LOG_DISPATCH, 1, "cur esp="PFX" ebp="PFX"\n",
get_mcontext(dcontext)->xsp, get_mcontext(dcontext)->xbp);
dump_mcontext_callstack(dcontext);
}
}
# endif
if (stats->loglevel >= 2 && (stats->logmask & LOG_DISPATCH) != 0) {
/* FIXME: this should use a different mask - and get printed at level 2 when turned on */
DOLOG(4, LOG_DISPATCH, {
dump_mcontext(get_mcontext(dcontext), THREAD, DUMP_NOT_XML); });
DOLOG(6, LOG_DISPATCH, { dump_mcontext_callstack(dcontext); });
DOKSTATS({ DOLOG(6, LOG_DISPATCH, { kstats_dump_stack(dcontext); }); });
LOG(THREAD, LOG_DISPATCH, 2, "Entry into F%d("PFX")."PFX" %s%s%s",
targetf->id,
targetf->tag,
FCACHE_ENTRY_PC(targetf),
IF_X64_ELSE(FRAG_IS_32(targetf->flags) ? "(32-bit)" : "", ""),
TEST(FRAG_COARSE_GRAIN, targetf->flags) ? "(coarse)" : "",
((targetf->flags & FRAG_IS_TRACE_HEAD)!=0)?
"(trace head)" : "",
((targetf->flags & FRAG_IS_TRACE)!=0)? "(trace)" : "");
LOG(THREAD, LOG_DISPATCH, 2, "%s",
TEST(FRAG_SHARED, targetf->flags) ? "(shared)":"");
# ifdef DGC_DIAGNOSTICS
LOG(THREAD, LOG_DISPATCH, 2, "%s",
TEST(FRAG_DYNGEN, targetf->flags) ? "(dyngen)":"");
# endif
LOG(THREAD, LOG_DISPATCH, 2, "\n");
DOLOG(3, LOG_SYMBOLS, {
char symbuf[MAXIMUM_SYMBOL_LENGTH];
print_symbolic_address(targetf->tag,
symbuf, sizeof(symbuf), true);
LOG(THREAD, LOG_SYMBOLS, 3, "\t%s\n", symbuf);
});
}
#endif /* DEBUG */
}
/* Executes a target fragment in the fragment cache */
static bool
dispatch_enter_fcache(dcontext_t *dcontext, fragment_t *targetf)
{
fcache_enter_func_t fcache_enter;
ASSERT(targetf != NULL);
/* ensure we don't take over when we should be going native */
ASSERT(dcontext->native_exec_postsyscall == NULL);
/* We wait until here, rather than at cache exit time, to do lazy
* linking so we can link to newly created fragments.
*/
if (dcontext->last_exit == get_coarse_exit_linkstub() ||
/* We need to lazy link if either of src or tgt is coarse */
(LINKSTUB_DIRECT(dcontext->last_exit->flags) &&
TEST(FRAG_COARSE_GRAIN, targetf->flags))) {
coarse_lazy_link(dcontext, targetf);
}
if (!enter_nolinking(dcontext, targetf, true)) {
/* not actually entering cache, so back to couldbelinking */
enter_couldbelinking(dcontext, NULL, true);
LOG(THREAD, LOG_DISPATCH, 2, "Just flushed targetf, next_tag is "PFX"\n",
dcontext->next_tag);
STATS_INC(num_entrances_aborted);
/* shared entrance cannot-tell-if-deleted -> invalidate targetf
* but then may double-do the trace!
* FIXME: for now, we abort every time, ok to abort twice (first time
* b/c there was a real flush of targetf), but could be perf hit.
*/
trace_abort(dcontext);
return false;
}
dispatch_enter_fcache_stats(dcontext, targetf);
/* FIXME: for now we do this before the synch point to avoid complexity of
* missing a KSTART(fcache_* for cases like NtSetContextThread where a thread
* appears back at dispatch() from the synch point w/o ever entering the cache.
* To truly fix we need to have the NtSetContextThread handler determine
* whether its suspended target is at this synch point or in the cache.
*/
DOKSTATS({
/* stopped in dispatch_exit_fcache_stats */
if (TEST(FRAG_IS_TRACE, targetf->flags))
KSTART(fcache_trace_trace);
else
KSTART(fcache_default); /* fcache_bb_bb or fcache_bb_trace */
/* FIXME: overestimates fcache time by counting in
* fcache_enter/fcache_return for it - proper reading of this
* value should discount the minimal cost of
* fcache_enter/fcache_return for actual code cache times
*/
/* FIXME: asynch events currently continue their current kstat
* until they get back to dispatch, so in-fcache kstats are counting
* the in-DR trampoline execution time!
*/
});
#ifdef WINDOWS
/* synch point for suspend, terminate, and detach */
/* assumes mcontext is valid including errno but not pc (which we fix here)
* assumes that thread is holding no locks
* also assumes past enter_nolinking, so could_be_linking is false
* for safety with respect to flush */
/* a fast check before the heavy lifting */
if (should_wait_at_safe_spot(dcontext)) {
/* FIXME : we could put this synch point in enter_fcache but would need
* to use SYSCALL_PC for syscalls (see issues with that in win32/os.c)
*/
priv_mcontext_t *mcontext = get_mcontext(dcontext);
cache_pc save_pc = mcontext->pc;
/* FIXME : implementation choice, we could do recreate_app_pc
* (fairly expensive but this is rare) instead of using the tag
* which is a little hacky but should always be right */
mcontext->pc = targetf->tag;
/* could be targeting interception code or our dll main, would be
* incorrect for GetContextThread and racy for detach, though we
* would expect it to be very rare */
if (!is_dynamo_address(mcontext->pc)) {
check_wait_at_safe_spot(dcontext, THREAD_SYNCH_VALID_MCONTEXT);
/* If we don't come back here synch-er is responsible for ensuring
* our kstat stack doesn't get off (have to do a KSTART here) -- we
* don't want to do the KSTART of fcache_* before this to avoid
* counting synch time.
*/
} else {
LOG(THREAD, LOG_SYNCH, 1,
"wait_at_safe_spot - unable to wait, targeting dr addr "PFX,
mcontext->pc);
STATS_INC(no_wait_entries);
}
mcontext->pc = save_pc;
}
#endif
#if defined(UNIX) && defined(DEBUG)
/* i#238/PR 499179: check that libc errno hasn't changed. It's
* not worth actually saving+restoring since to we'd also need to
* preserve on clean calls, a perf hit. Better to catch all libc
* routines that need it and wrap just those.
*/
ASSERT(get_libc_errno() == dcontext->libc_errno ||
/* w/ private loader, our errno is disjoint from app's */
IF_CLIENT_INTERFACE_ELSE(INTERNAL_OPTION(private_loader), false) ||
/* only when pthreads is loaded does libc switch to a per-thread
* errno, so our raw thread tests end up using the same errno
* for each thread!
*/
check_filter("linux.thread;linux.clone",
get_short_name(get_application_name())));
#endif
#if defined(UNIX) && !defined(DGC_DIAGNOSTICS)
/* i#107: handle segment register usage conflicts between app and dr:
* if the target fragment has an instr that updates the segment selector,
* update the corresponding information maintained by DR.
*/
if (INTERNAL_OPTION(mangle_app_seg) &&
TEST(FRAG_HAS_MOV_SEG, targetf->flags)) {
os_handle_mov_seg(dcontext, targetf->tag);
}
#endif
ASSERT(dr_get_isa_mode(dcontext) == FRAG_ISA_MODE(targetf->flags)
IF_X64(|| (dr_get_isa_mode(dcontext) == DR_ISA_IA32 &&
!FRAG_IS_32(targetf->flags) && DYNAMO_OPTION(x86_to_x64))));
if (TEST(FRAG_SHARED, targetf->flags))
fcache_enter = get_fcache_enter_shared_routine(dcontext);
else
fcache_enter = get_fcache_enter_private_routine(dcontext);
enter_fcache(dcontext, fcache_enter, FCACHE_ENTRY_PC(targetf));
ASSERT_NOT_REACHED();
return true;
}
/* Enters the cache at the specified entrance routine to execute the
* target pc.
* Does not return.
* Caller must do a KSTART to avoid kstats stack mismatches.
* FIXME: only allow access to fcache_enter routine through here?
* Indirect routine needs special treatment for handle_callback_return
*/
static void
enter_fcache(dcontext_t *dcontext, fcache_enter_func_t entry, cache_pc pc)
{
ASSERT(!is_couldbelinking(dcontext));
ASSERT(entry != NULL);
ASSERT(pc != NULL);
ASSERT(check_should_be_protected(DATASEC_RARELY_PROT));
/* CANNOT hold any locks across cache execution, as our thread synch
* assumes none are held
*/
ASSERT_OWN_NO_LOCKS();
ASSERT(dcontext->try_except.try_except_state == NULL);
/* prepare to enter fcache */
LOG(THREAD, LOG_DISPATCH, 4, "fcache_enter = "PFX", target = "PFX"\n", entry, pc);
set_fcache_target(dcontext, pc);
ASSERT(pc != NULL);
#ifdef PROFILE_RDTSC
if (dynamo_options.profile_times) {
/* prepare to enter fcache */
dcontext->prev_fragment = NULL;
/* top ten cache times */
dcontext->cache_frag_count = (uint64) 0;
dcontext->cache_enter_time = get_time();
}
#endif
dcontext->whereami = WHERE_FCACHE;
(*entry)(dcontext);
ASSERT_NOT_REACHED();
}
/* Handles special tags in DR or elsewhere that do interesting things.
* All PCs checked in here must be in DR or be BACK_TO_NATIVE_AFTER_SYSCALL.
* Does not return if we've hit a stopping point; otherwise returns with an
* updated next_tag for continued dispatch.
*/
static void
handle_special_tag(dcontext_t *dcontext)
{
if (native_exec_is_back_from_native(dcontext->next_tag)) {
/* This can happen if we start interpreting a native module. */
ASSERT(DYNAMO_OPTION(native_exec));
interpret_back_from_native(dcontext); /* updates next_tag */
}
if (is_stopping_point(dcontext, dcontext->next_tag)) {
LOG(THREAD, LOG_INTERP, 1,
"\nFound DynamoRIO stopping point: thread "TIDFMT" returning to app @"PFX"\n",
get_thread_id(), dcontext->next_tag);
dispatch_enter_native(dcontext);
ASSERT_NOT_REACHED(); /* noreturn */
}
}
#if defined(DR_APP_EXPORTS) || defined(UNIX)
static void
dispatch_at_stopping_point(dcontext_t *dcontext)
{
/* start/stop interface */
KSTOP_NOT_MATCHING(dispatch_num_exits);
/* if we stop in middle of tracing, thread-shared state may be messed
* up (e.g., monitor grabs fragment lock for unlinking),
* so abort the trace
*/
if (is_building_trace(dcontext)) {
LOG(THREAD, LOG_INTERP, 1, "squashing trace-in-progress\n");
trace_abort(dcontext);
}
LOG(THREAD, LOG_INTERP, 1, "\nappstart_cleanup: found stopping point\n");
# ifdef DEBUG
# ifdef DR_APP_EXPORTS
if (dcontext->next_tag == (app_pc)dynamo_thread_exit)
LOG(THREAD, LOG_INTERP, 1, "\t==dynamo_thread_exit\n");
else if (dcontext->next_tag == (app_pc)dynamorio_app_exit)
LOG(THREAD, LOG_INTERP, 1, "\t==dynamorio_app_exit\n");
else if (dcontext->next_tag == (app_pc)dr_app_stop) {
LOG(THREAD, LOG_INTERP, 1, "\t==dr_app_stop\n");
}
# endif
# endif
dynamo_thread_not_under_dynamo(dcontext);
}
#endif
/* Called when we reach an interpretation stopping point either for
* start/stop control of DR or for native_exec. In both cases we give up
* control and "go native", but we do not clean up the current thread,
* assuming we will either take control back, or the app will explicitly
* request we clean up.
*/
static void
dispatch_enter_native(dcontext_t *dcontext)
{
/* The new fcache_enter's clean dstack design makes it usable for
* entering native execution as well as the fcache.
*/
fcache_enter_func_t go_native = get_fcache_enter_private_routine(dcontext);
set_last_exit(dcontext, (linkstub_t *) get_native_exec_linkstub());
ASSERT_OWN_NO_LOCKS();
if (dcontext->next_tag == BACK_TO_NATIVE_AFTER_SYSCALL) {
/* we're simply going native again after an intercepted syscall,
* not finalizing this thread or anything
*/
IF_WINDOWS(DEBUG_DECLARE(extern dcontext_t *early_inject_load_helper_dcontext;))
ASSERT(DYNAMO_OPTION(native_exec_syscalls)); /* else wouldn't have intercepted */
/* Assert here we have a reason for going back to native (-native_exec and
* non-empty native_exec_areas, RUNNING_WITHOUT_CODE_CACHE, hotp nudge thread
* pretending to be native while loading a dll, or on win2k
* early_inject_init() pretending to be native to find the inject address). */
ASSERT((DYNAMO_OPTION(native_exec) && native_exec_areas != NULL &&
!vmvector_empty(native_exec_areas)) ||
IF_WINDOWS((DYNAMO_OPTION(early_inject) &&
early_inject_load_helper_dcontext ==
get_thread_private_dcontext()) ||)
IF_HOTP(dcontext->nudge_thread ||)
/* clients requesting native execution come here */
IF_CLIENT_INTERFACE(dr_bb_hook_exists() ||)
dcontext->currently_stopped ||
RUNNING_WITHOUT_CODE_CACHE());
ASSERT(dcontext->native_exec_postsyscall != NULL);
LOG(THREAD, LOG_ASYNCH, 1, "Returning to native "PFX" after a syscall\n",
dcontext->native_exec_postsyscall);
dcontext->next_tag = dcontext->native_exec_postsyscall;
dcontext->native_exec_postsyscall = NULL;
LOG(THREAD, LOG_DISPATCH, 2, "Entry into native_exec after intercepted syscall\n");
/* restore state as though never came out for syscall */
KSTOP_NOT_MATCHING(dispatch_num_exits);
#ifdef KSTATS
if (!dcontext->currently_stopped)
KSTART_DC(dcontext, fcache_default);
#endif
enter_nolinking(dcontext, NULL, true);
}
else {
#if defined(DR_APP_EXPORTS) || defined(UNIX)
dispatch_at_stopping_point(dcontext);
enter_nolinking(dcontext, NULL, false);
#else
ASSERT_NOT_REACHED();
#endif
}
set_fcache_target(dcontext, dcontext->next_tag);
dcontext->whereami = WHERE_APP;
(*go_native)(dcontext);
ASSERT_NOT_REACHED();
}
static void
dispatch_enter_dynamorio(dcontext_t *dcontext)
{
/* We're transitioning to DynamoRIO from somewhere: either the fcache,
* the kernel (WHERE_TRAMPOLINE), or the app itself via our start/stop API.
* N.B.: set whereami to WHERE_APP iff this is the first dispatch() entry
* for this thread!
*/
where_am_i_t wherewasi = dcontext->whereami;
#ifdef UNIX
if (!(wherewasi == WHERE_FCACHE || wherewasi == WHERE_TRAMPOLINE ||
wherewasi == WHERE_APP)) {
/* This is probably our own syscalls hitting our own sysenter
* hook (PR 212570), since we're not completely user library
* independent (PR 206369).
* The primary calls I'm worried about are dl{open,close}.
* Note that we can't go jump to vsyscall_syscall_end_pc here b/c
* fcache_return cleared the dstack, so we can't really recover.
* We could put in a custom exit stub and return routine and recover,
* but we need to get library independent anyway so it's not worth it.
*/
ASSERT(get_syscall_method() == SYSCALL_METHOD_SYSENTER);
IF_X64(ASSERT_NOT_REACHED()); /* no sysenter support on x64 */
/* PR 356503: clients using libraries that make syscalls can end up here */
IF_CLIENT_INTERFACE(found_client_sysenter());
ASSERT_BUG_NUM(206369, false &&
"DR's own syscall (via user library) hit the sysenter hook");
}
#endif
ASSERT(wherewasi == WHERE_FCACHE || wherewasi == WHERE_TRAMPOLINE ||
wherewasi == WHERE_APP);
dcontext->whereami = WHERE_DISPATCH;
ASSERT_LOCAL_HEAP_UNPROTECTED(dcontext);
ASSERT(check_should_be_protected(DATASEC_RARELY_PROT));
/* CANNOT hold any locks across cache execution, as our thread synch
* assumes none are held
*/
ASSERT_OWN_NO_LOCKS();
#if defined(UNIX) && defined(DEBUG)
/* i#238/PR 499179: check that libc errno hasn't changed */
/* w/ private loader, our errno is disjoint from app's */
if (IF_CLIENT_INTERFACE_ELSE(!INTERNAL_OPTION(private_loader), true))
dcontext->libc_errno = get_libc_errno();
#endif
DOLOG(2, LOG_INTERP, {
if (wherewasi == WHERE_APP) {
LOG(THREAD, LOG_INTERP, 2, "\ninitial dispatch: target = "PFX"\n",
dcontext->next_tag);
dump_mcontext_callstack(dcontext);
dump_mcontext(get_mcontext(dcontext), THREAD, DUMP_NOT_XML);
}
});
/* We have to perform some tasks with last_exit early, before we
* become couldbelinking -- the rest are done in dispatch_exit_fcache().
* It's ok to de-reference last_exit since even though deleter may assume
* no one has ptrs to it, cannot delete until we're officially out of the
* cache, which doesn't happen until enter_couldbelinking -- still kind of
* messy that we're violating assumption of no ptrs...
*/
if (wherewasi == WHERE_APP) { /* first entrance */
if (dcontext->last_exit == get_syscall_linkstub()) {
/* i#813: the app hit our post-sysenter hook while native.
* XXX: should we try to process ni syscalls here? But we're only
* seeing post- and not pre-.
*/
LOG(THREAD, LOG_INTERP, 2, "hit post-sysenter hook while native\n");
ASSERT(dcontext->currently_stopped);
dcontext->next_tag = BACK_TO_NATIVE_AFTER_SYSCALL;
dcontext->native_exec_postsyscall = vsyscall_syscall_end_pc;
} else {
ASSERT(dcontext->last_exit == get_starting_linkstub() ||
/* The start/stop API will set this linkstub. */
IF_APP_EXPORTS(dcontext->last_exit == get_native_exec_linkstub() ||)
/* new thread */
IF_WINDOWS_ELSE_0(dcontext->last_exit == get_asynch_linkstub()));
}
} else {
ASSERT(dcontext->last_exit != NULL); /* MUST be set, if only to a fake linkstub_t */
/* cache last_exit's fragment */
dcontext->last_fragment = linkstub_fragment(dcontext, dcontext->last_exit);
/* If we exited from an indirect branch then dcontext->next_tag
* already has the next tag value; otherwise we must set it here,
* before we might dive back into the cache for a system call.
*/
if (LINKSTUB_DIRECT(dcontext->last_exit->flags)) {
if (INTERNAL_OPTION(cbr_single_stub)) {
linkstub_t *nxt =
linkstub_shares_next_stub(dcontext, dcontext->last_fragment,
dcontext->last_exit);
if (nxt != NULL) {
/* must distinguish the two based on eflags */
dcontext->last_exit =
linkstub_cbr_disambiguate(dcontext, dcontext->last_fragment,
dcontext->last_exit, nxt);
ASSERT(dcontext->last_fragment ==
linkstub_fragment(dcontext, dcontext->last_exit));
STATS_INC(cbr_disambiguations);
}
}
dcontext->next_tag = EXIT_TARGET_TAG(dcontext, dcontext->last_fragment,
dcontext->last_exit);
} else {
/* get src info from coarse ibl exit into the right place */
if (DYNAMO_OPTION(coarse_units)) {
if (is_ibl_sourceless_linkstub((const linkstub_t*)dcontext->last_exit))
set_coarse_ibl_exit(dcontext);
else if (DYNAMO_OPTION(use_persisted) &&
dcontext->last_exit == get_coarse_exit_linkstub()) {
/* i#670: for frozen unit, shift from persist-time mod base
* to use-time mod base
*/
coarse_info_t *info = dcontext->coarse_exit.dir_exit;
ASSERT(info != NULL);
if (info->mod_shift != 0 &&
dcontext->next_tag >= info->persist_base &&
dcontext->next_tag < info->persist_base +
(info->end_pc - info->base_pc))
dcontext->next_tag -= info->mod_shift;
}
}
}
dispatch_exit_fcache_stats(dcontext);
/* Maybe-permanent native transitions (dr_app_stop()) have to pop kstack,
* and thus so do temporary native_exec transitions. Thus, for neither
* is there anything to pop here.
*/
if (dcontext->last_exit != get_native_exec_linkstub() &&
dcontext->last_exit != get_native_exec_syscall_linkstub())
KSTOP_NOT_MATCHING(dispatch_num_exits);
}
/* KSWITCHed next time around for a better explanation */
KSTART_DC(dcontext, dispatch_num_exits);
if (wherewasi != WHERE_APP) { /* if not first entrance */
if (get_at_syscall(dcontext))
handle_post_system_call(dcontext);
/* A non-ignorable syscall or cb return ending a bb must be acted on
* We do it here to avoid becoming couldbelinking twice.
*
*/
if (exited_due_to_ni_syscall(dcontext)
IF_CLIENT_INTERFACE(|| instrument_invoke_another_syscall(dcontext))) {
handle_system_call(dcontext);
/* will return here if decided to skip the syscall; else, back to dispatch() */
}
#ifdef WINDOWS
else if (TEST(LINK_CALLBACK_RETURN, dcontext->last_exit->flags)) {
handle_callback_return(dcontext);
ASSERT_NOT_REACHED();
}
#endif
if (TEST(LINK_SPECIAL_EXIT, dcontext->last_exit->flags)) {
if (dcontext->upcontext.upcontext.exit_reason == EXIT_REASON_SELFMOD) {
/* Case 8177: If we have a flushed fragment hit a self-write, we
* cannot delete it in our self-write handler (b/c of case 3559's
* incoming links union). But, our self-write handler needs to be
* nolinking and needs to check sandbox2ro_threshold. So, we do our
* self-write check first, but we don't actually delete there for
* FRAG_WAS_DELETED fragments.
*/
SELF_PROTECT_LOCAL(dcontext, WRITABLE);
/* this fragment overwrote its original memory image */
fragment_self_write(dcontext);
/* FIXME: optimize this to stay writable if we're going to
* be exiting dispatch as well -- no very quick check though
*/
SELF_PROTECT_LOCAL(dcontext, READONLY);
} else if (dcontext->upcontext.upcontext.exit_reason >=
EXIT_REASON_FLOAT_PC_FNSAVE &&
dcontext->upcontext.upcontext.exit_reason <=
EXIT_REASON_FLOAT_PC_XSAVE64) {
float_pc_update(dcontext);
STATS_INC(float_pc_from_dispatch);
/* Restore */
dcontext->upcontext.upcontext.exit_reason = EXIT_REASON_SELFMOD;
} else {
/* When adding any new reason, be sure to clear exit_reason,
* as selfmod exits do not bother to set the reason field to
* 0 for performance reasons (they are assumed to be more common
* than any other "special exit").
*/
ASSERT_NOT_REACHED();
}
}
}
/* make sure to tell flushers that we are now going to be mucking
* with link info
*/
if (!enter_couldbelinking(dcontext, dcontext->last_fragment, true)) {
LOG(THREAD, LOG_DISPATCH, 2, "Just flushed last_fragment\n");
/* last_fragment flushed, but cannot access here to copy it
* to fake linkstub_t, so assert that callee did (either when freeing or
* when noticing pending deletion flag)
*/
ASSERT(LINKSTUB_FAKE(dcontext->last_exit));
}
if (wherewasi != WHERE_APP) { /* if not first entrance */
/* now fully process the last cache exit as couldbelinking */
dispatch_exit_fcache(dcontext);
}
}
/* Processing of the last exit from the cache.
* Invariant: dcontext->last_exit != NULL, though it may be a sentinel (see below).
*
* Note that the last exit and its owning fragment may be _fake_, i.e., just
* a copy of the key fields we typically check, for the following cases:
* - last fragment was flushed: fully deleted at cache exit synch point
* - last fragment was deleted since it overwrote itself (selfmod)
* - last fragment was deleted since it was a private trace building copy
* - last fragment was deleted for other reasons?!?
* - briefly during trace emitting, nobody should care though
* - coarse grain fragment exits, for which we have no linkstub_t or other
* extraneous bookkeeping
*
* For some cases we do not currently keep the key fields at all:
* - last fragment was flushed: detected at write fault
* And some times we are unable to keep the key fields:
* - last fragment was flushed: targeted in ibl via target_deleted path
* These last two cases are the only exits from fragment for which we
* do not know the key fields. For the former, we exit in the middle of
* a fragment that was already created, so not knowing does not affect
* security policies or other checks much. The latter is the most problematic,
* as we have a number of checks depending on knowing the last exit when indirect.
*
* We have other types of exits from the cache that never involved a real
* fragment, for which we also use fake linkstubs:
* - no real last fragment: system call
* - no real last fragment: sigreturn
* - no real last fragment: native_exec return
* - callbacks clear last_exit, but should come out of the cache at a syscall
* (bug 2464 was back when tried to carry last_exit through syscall)
* so this will end up looking like the system call case
*/
static void
dispatch_exit_fcache(dcontext_t *dcontext)
{
/* case 7966: no distinction of islinking-ness for hotp_only & thin_client */
ASSERT(RUNNING_WITHOUT_CODE_CACHE() || is_couldbelinking(dcontext));
#if defined(WINDOWS) && defined (CLIENT_INTERFACE)
ASSERT(!is_dynamo_address(dcontext->app_fls_data));
ASSERT(dcontext->app_fls_data == NULL ||
dcontext->app_fls_data != dcontext->priv_fls_data);
ASSERT(!is_dynamo_address(dcontext->app_nt_rpc));
ASSERT(dcontext->app_nt_rpc == NULL ||
dcontext->app_nt_rpc != dcontext->priv_nt_rpc);
ASSERT(!is_dynamo_address(dcontext->app_nls_cache));
IF_X64(ASSERT(!is_dynamo_address(dcontext->app_stack_limit) ||
IS_CLIENT_THREAD(dcontext)));
ASSERT(dcontext->app_nls_cache == NULL ||
dcontext->app_nls_cache != dcontext->priv_nls_cache);
#endif
if (LINKSTUB_INDIRECT(dcontext->last_exit->flags)) {
/* indirect branch exit processing */
#if defined(RETURN_AFTER_CALL) || defined(RCT_IND_BRANCH)
/* PR 204770: use trace component bb tag for RCT source address */
app_pc src_tag = dcontext->last_fragment->tag;
if (!LINKSTUB_FAKE(dcontext->last_exit) &&
TEST(FRAG_IS_TRACE, dcontext->last_fragment->flags)) {
/* FIXME: should we call this for direct exits as well, up front? */
src_tag = get_trace_exit_component_tag
(dcontext, dcontext->last_fragment, dcontext->last_exit);
}
#endif
#ifdef RETURN_AFTER_CALL
/* This is the permission check for any new return target, it
* also double checks the findings of the indirect lookup
* routine
*/
if (dynamo_options.ret_after_call && TEST(LINK_RETURN, dcontext->last_exit->flags)) {
/* ret_after_call will raise a security violation on failure */
SELF_PROTECT_LOCAL(dcontext, WRITABLE);
ret_after_call_check(dcontext, dcontext->next_tag, src_tag);
SELF_PROTECT_LOCAL(dcontext, READONLY);
}
#endif /* RETURN_AFTER_CALL */
#ifdef RCT_IND_BRANCH
/* permission check for any new indirect call or jump target */
/* we care to detect violations only if blocking or at least
* reporting the corresponding branch types
*/
if (TESTANY(OPTION_REPORT|OPTION_BLOCK, DYNAMO_OPTION(rct_ind_call)) ||
TESTANY(OPTION_REPORT|OPTION_BLOCK, DYNAMO_OPTION(rct_ind_jump))) {
if ((EXIT_IS_CALL(dcontext->last_exit->flags)
&& TESTANY(OPTION_REPORT|OPTION_BLOCK, DYNAMO_OPTION(rct_ind_call))) ||
(EXIT_IS_JMP(dcontext->last_exit->flags)
&& TESTANY(OPTION_REPORT|OPTION_BLOCK, DYNAMO_OPTION(rct_ind_jump)))
) {
/* case 4995: current shared syscalls implementation
* reuses the indirect jump table and marks its
* fake linkstub as such.
*/
if (LINKSTUB_FAKE(dcontext->last_exit) /* quick check */ &&
IS_SHARED_SYSCALLS_LINKSTUB(dcontext->last_exit)) {
ASSERT(IF_WINDOWS_ELSE(DYNAMO_OPTION(shared_syscalls), false));
ASSERT(EXIT_IS_JMP(dcontext->last_exit->flags));
} else {
/* rct_ind_branch_check will raise a security violation on failure */
rct_ind_branch_check(dcontext, dcontext->next_tag, src_tag);
}
}
}
#endif /* RCT_IND_BRANCH */
/* update IBL target tables for any indirect branch exit */
SELF_PROTECT_LOCAL(dcontext, WRITABLE);
/* update IBL target table if target is a valid IBT */
/* FIXME: This is good for modularity but adds
* extra lookups in the fragment table. If it is
* performance problem can we do it better?
* Probably best to get bb2bb to work better and
* not worry about optimizing DR code.
*/
fragment_add_ibl_target(dcontext, dcontext->next_tag,
extract_branchtype(dcontext->last_exit->flags));
/* FIXME: optimize this to stay writable if we're going to
* be building a bb as well -- no very quick check though
*/
SELF_PROTECT_LOCAL(dcontext, READONLY);
} /* LINKSTUB_INDIRECT */
/* ref bug 2323, we need monitor to restore last fragment now,
* before we break out of the loop to build a new fragment
* ASSUMPTION: all unusual cache exits (asynch events) abort the current
* trace, so this is the only place we need to restore anything.
* monitor_cache_enter() asserts that for us.
* NOTE : we wait till after the cache exit stats and logs to call
* monitor_cache_exit since it might change the flags of the last
* fragment and screw up the stats
*/
monitor_cache_exit(dcontext);
#ifdef SIDELINE
/* sideline synchronization */
if (dynamo_options.sideline) {
thread_id_t tid = get_thread_id();
if (pause_for_sideline == tid) {
mutex_lock(&sideline_lock);
if (pause_for_sideline == tid) {
LOG(THREAD, LOG_DISPATCH|LOG_THREADS|LOG_SIDELINE, 2,
"Thread %d waiting for sideline thread\n", tid);
signal_event(paused_for_sideline_event);
STATS_INC(num_wait_sideline);
wait_for_event(resume_from_sideline_event);
mutex_unlock(&sideline_lock);
LOG(THREAD, LOG_DISPATCH|LOG_THREADS|LOG_SIDELINE, 2,
"Thread %d resuming after sideline thread\n", tid);
sideline_cleanup_replacement(dcontext);
} else
mutex_unlock(&sideline_lock);
}
}
#endif
#ifdef UNIX
if (dcontext->signals_pending) {
/* FIXME: can overflow app stack if stack up too many signals
* by interrupting prev handlers -- exacerbated by RAC lack of
* caching (case 1858), which causes a cache exit prior to
* executing every single sigreturn!
*/
receive_pending_signal(dcontext);
}
#endif
#ifdef CLIENT_INTERFACE
/* is ok to put the lock after the null check, this is only
* place they can be deleted
*/
if (dcontext->client_data != NULL && dcontext->client_data->to_do != NULL) {
client_todo_list_t *todo;
/* FIXME PR 200409: we're removing all API routines that use this
* todo list so we should never get here
*/
if (SHARED_FRAGMENTS_ENABLED()) {
USAGE_ERROR("CLIENT_INTERFACE incompatible with -shared_{bbs,traces}"
" at this time");
}
# ifdef CLIENT_SIDELINE
mutex_lock(&(dcontext->client_data->sideline_mutex));
# endif
todo = dcontext->client_data->to_do;
while (todo != NULL) {
client_todo_list_t *next_todo = todo->next;
fragment_t *f = fragment_lookup(dcontext, todo->tag);
if (f != NULL) {
if (todo->ilist != NULL) {
/* doing a replacement */
fragment_t * new_f;
uint orig_flags = f->flags;
void *vmlist = NULL;
DEBUG_DECLARE(bool ok;)
LOG(THREAD, LOG_INTERP, 3,
"Going to do a client fragment replacement at "PFX" F%d\n",
f->tag, f->id);
/* prevent emit from deleting f, we still need it */
/* FIXME: if f is shared we must hold change_linking_lock
* for the flags and vm area operations here
*/
ASSERT(!TEST(FRAG_SHARED, f->flags));
f->flags |= FRAG_CANNOT_DELETE;
DEBUG_DECLARE(ok =)
vm_area_add_to_list(dcontext, f->tag, &vmlist, orig_flags, f,
false/*no locks*/);
ASSERT(ok); /* should never fail for private fragments */
mangle(dcontext, todo->ilist, &f->flags, true, true);
/* mangle shouldn't change the flags here */
ASSERT(f->flags == (orig_flags | FRAG_CANNOT_DELETE));
new_f = emit_invisible_fragment(dcontext, todo->tag, todo->ilist,
orig_flags, vmlist);
f->flags = orig_flags; /* FIXME: ditto about change_linking_lock */
instrlist_clear_and_destroy(dcontext, todo->ilist);
fragment_copy_data_fields(dcontext, f, new_f);
shift_links_to_new_fragment(dcontext, f, new_f);
fragment_replace(dcontext, f, new_f);
DOLOG(2, LOG_INTERP, {
LOG(THREAD, LOG_INTERP, 3,
"Finished emitting replacement fragment %d\n", new_f->id);
disassemble_fragment(dcontext, new_f, stats->loglevel < 3);
});
}
/* delete [old] fragment */
if ((f->flags & FRAG_CANNOT_DELETE) == 0) {
uint actions;
LOG(THREAD, LOG_INTERP, 3, "Client deleting old F%d\n", f->id);
if (todo->ilist != NULL) {
/* for the fragment replacement case, the fragment should
* already be unlinked and removed from the hash table.
*/
actions = FRAGDEL_NO_UNLINK | FRAGDEL_NO_HTABLE;
}
else {
actions = FRAGDEL_ALL;
}
fragment_delete(dcontext, f, actions);
STATS_INC(num_fragments_deleted_client);
} else {
LOG(THREAD, LOG_INTERP, 2, "Couldn't let client delete F%d\n",
f->id);
}
} else {
LOG(THREAD, LOG_INTERP, 2,
"Failed to delete/replace fragment at tag "PFX" because was already deleted",
todo->tag);
}
HEAP_TYPE_FREE(dcontext, todo, client_todo_list_t, ACCT_CLIENT, UNPROTECTED);
todo = next_todo;
}
dcontext->client_data->to_do = NULL;
# ifdef CLIENT_SIDELINE
mutex_unlock(&(dcontext->client_data->sideline_mutex));
# endif
}
#endif /* CLIENT_INTERFACE */
}
/* stats and logs on why we exited the code cache */
static void
dispatch_exit_fcache_stats(dcontext_t *dcontext)
{
#if defined(DEBUG) || defined(KSTATS)
fragment_t *next_f;
fragment_t *last_f;
fragment_t coarse_f;
#endif
#ifdef PROFILE_RDTSC
if (dynamo_options.profile_times) {
int i,j;
uint64 end_time, total_time;
profile_fragment_dispatch(dcontext);
/* top ten cache times */
end_time = get_time();
total_time = end_time - dcontext->cache_enter_time;
for (i=0; i<10; i++) {
if (total_time > dcontext->cache_time[i]) {
/* insert */
for (j=9; j>i; j--) {
dcontext->cache_time[j] = dcontext->cache_time[j-1];
dcontext->cache_count[j] = dcontext->cache_count[j-1];
}
dcontext->cache_time[i] = total_time;
dcontext->cache_count[i] = dcontext->cache_frag_count;
break;
}
}
}
#endif
#if defined(DEBUG) || defined(KSTATS)
STATS_INC(num_exits);
ASSERT(dcontext->last_exit != NULL);
/* special exits that aren't from real fragments */
if (dcontext->last_exit == get_syscall_linkstub()) {
LOG(THREAD, LOG_DISPATCH, 2, "Exit from system call\n");
STATS_INC(num_exits_syscalls);
# ifdef CLIENT_INTERFACE
/* PR 356503: clients using libraries that make syscalls, invoked from
* a clean call, will not trigger the whereami check below: so we
* locate here via mismatching kstat top-of-stack.
*/
KSTAT_THREAD(fcache_default, {
if (ks->node[ks->depth - 1].var == pv) {
found_client_sysenter();
}
});
# endif
KSTOP_NOT_PROPAGATED(syscall_fcache);
return;
}
else if (dcontext->last_exit == get_selfmod_linkstub()) {
LOG(THREAD, LOG_DISPATCH, 2, "Exit from fragment that self-flushed via code mod\n");
STATS_INC(num_exits_code_mod_flush);
KSWITCH_STOP_NOT_PROPAGATED(fcache_default);
return;
}
else if (dcontext->last_exit == get_ibl_deleted_linkstub()) {
LOG(THREAD, LOG_DISPATCH, 2, "Exit from fragment deleted but hit in ibl\n");
STATS_INC(num_exits_ibl_deleted);
KSWITCH_STOP_NOT_PROPAGATED(fcache_default);
return;
}
# ifdef UNIX
else if (dcontext->last_exit == get_sigreturn_linkstub()) {
LOG(THREAD, LOG_DISPATCH, 2, "Exit from sigreturn, or os_forge_exception\n");
STATS_INC(num_exits_sigreturn);
KSTOP_NOT_MATCHING_NOT_PROPAGATED(syscall_fcache);
return;
}
# else /* WINDOWS */
else if (dcontext->last_exit == get_asynch_linkstub()) {
LOG(THREAD, LOG_DISPATCH, 2, "Exit from asynch event\n");
STATS_INC(num_exits_asynch);
/* w/ -shared_syscalls can also be a fragment kstart */
KSTOP_NOT_MATCHING_NOT_PROPAGATED(syscall_fcache);
return;
}
# endif
else if (dcontext->last_exit == get_native_exec_linkstub()) {
LOG(THREAD, LOG_DISPATCH, 2, "Exit from native_exec execution\n");
STATS_INC(num_exits_native_exec);
/* may be a quite large kstat count */
KSWITCH_STOP_NOT_PROPAGATED(native_exec_fcache);
return;
}
else if (dcontext->last_exit == get_native_exec_syscall_linkstub()) {
LOG(THREAD, LOG_DISPATCH, 2, "Exit from native_exec syscall trampoline\n");
STATS_INC(num_exits_native_exec_syscall);
/* may be a quite large kstat count */
# if defined(DEBUG) || defined(KSTATS)
/* Being native for the start/stop API is different from native_exec:
* the former has the kstack cleared, so there's nothing to stop here
* (xref i#813, i#1140).
*/
if (dcontext->currently_stopped)
LOG(THREAD, LOG_DISPATCH, 2, "Thread is start/stop native\n");
else
KSWITCH_STOP_NOT_PROPAGATED(native_exec_fcache);
# endif
return;
}
else if (dcontext->last_exit == get_reset_linkstub()) {
LOG(THREAD, LOG_DISPATCH, 2, "Exit due to proactive reset\n");
STATS_INC(num_exits_reset);
KSWITCH_STOP_NOT_PROPAGATED(fcache_default);
return;
}
# ifdef WINDOWS
else if (IS_SHARED_SYSCALLS_UNLINKED_LINKSTUB(dcontext->last_exit)) {
LOG(THREAD, LOG_DISPATCH, 2,
"Exit from unlinked shared syscall\n");
STATS_INC(num_unlinked_shared_syscalls_exits);
KSWITCH_STOP_NOT_PROPAGATED(fcache_default);
return;
}
else if (IS_SHARED_SYSCALLS_LINKSTUB(dcontext->last_exit)) {
LOG(THREAD, LOG_DISPATCH, 2, "Exit from shared syscall (%s)\n",
IS_SHARED_SYSCALLS_TRACE_LINKSTUB(dcontext->last_exit) ?
"trace" : "bb");
DOSTATS({
if (IS_SHARED_SYSCALLS_TRACE_LINKSTUB(dcontext->last_exit))
STATS_INC(num_shared_syscalls_trace_exits);
else
STATS_INC(num_shared_syscalls_bb_exits);
});
KSWITCH_STOP_NOT_PROPAGATED(fcache_default);
return;
}
# endif
# ifdef HOT_PATCHING_INTERFACE
else if (dcontext->last_exit == get_hot_patch_linkstub()) {
LOG(THREAD, LOG_DISPATCH, 2, "Exit from hot patch routine\n");
STATS_INC(num_exits_hot_patch);
KSWITCH_STOP_NOT_PROPAGATED(fcache_default);
return;
}
# endif
# ifdef CLIENT_INTERFACE
else if (dcontext->last_exit == get_client_linkstub()) {
LOG(THREAD, LOG_DISPATCH, 2, "Exit from client redirection\n");
STATS_INC(num_exits_client_redirect);
KSWITCH_STOP_NOT_PROPAGATED(fcache_default);
return;
}
# endif
/* normal exits from real fragments, though the last_fragment may
* be deleted and we are working off a copy of its important fields
*/
/* FIXME: this lookup is needed for KSTATS and STATS_*. STATS_* are only
* printed at loglevel 1, but maintained at loglevel 0, and if
* we want an external agent to examine them at 0 we will want
* to keep this...leaving for now
*/
next_f = fragment_lookup_fine_and_coarse(dcontext, dcontext->next_tag,
&coarse_f, dcontext->last_exit);
last_f = dcontext->last_fragment;
DOKSTATS({
/* FIXME (case 4988): read top of kstats stack to get src
* type, and then split by last_fragment type as well
*/
KSWITCH_STOP_NOT_PROPAGATED(fcache_default);
});
if (is_ibl_sourceless_linkstub((const linkstub_t*)dcontext->last_exit)) {
if (DYNAMO_OPTION(coarse_units)) {
LOG(THREAD, LOG_DISPATCH, 2, "Exit from coarse ibl from tag "PFX": %s %s",
dcontext->coarse_exit.src_tag,
TEST(FRAG_IS_TRACE, last_f->flags) ? "trace" : "bb",
TEST(LINK_RETURN, dcontext->last_exit->flags) ? "ret" :
EXIT_IS_CALL(dcontext->last_exit->flags) ? "call*" : "jmp*");
} else {
ASSERT(!DYNAMO_OPTION(indirect_stubs));
LOG(THREAD, LOG_DISPATCH, 2, "Exit from sourceless ibl: %s %s",
TEST(FRAG_IS_TRACE, last_f->flags) ? "trace" : "bb",
TEST(LINK_RETURN, dcontext->last_exit->flags) ? "ret" :
EXIT_IS_CALL(dcontext->last_exit->flags) ? "call*" : "jmp*");
}
} else if (dcontext->last_exit == get_coarse_exit_linkstub()) {
DOLOG(2, LOG_DISPATCH, {
coarse_info_t *info = dcontext->coarse_exit.dir_exit;
cache_pc stub;
ASSERT(info != NULL); /* though not initialized to NULL... */
stub = coarse_stub_lookup_by_target(dcontext, info, dcontext->next_tag);
LOG(THREAD, LOG_DISPATCH, 2,
"Exit from sourceless coarse-grain fragment via stub "PFX"\n", stub);
});
/* FIXME: this stat is not mutually exclusive of reason-for-exit stats */
STATS_INC(num_exits_coarse);
}
else if (dcontext->last_exit == get_coarse_trace_head_exit_linkstub()) {
LOG(THREAD, LOG_DISPATCH, 2,
"Exit from sourceless coarse-grain fragment targeting trace head");
/* FIXME: this stat is not mutually exclusive of reason-for-exit stats */
STATS_INC(num_exits_coarse_trace_head);
} else {
LOG(THREAD, LOG_DISPATCH, 2, "Exit from F%d("PFX")."PFX,
last_f->id, last_f->tag, EXIT_CTI_PC(dcontext->last_fragment,
dcontext->last_exit));
}
DOSTATS({
if (TEST(FRAG_IS_TRACE, last_f->flags))
STATS_INC(num_trace_exits);
else
STATS_INC(num_bb_exits);
});
LOG(THREAD, LOG_DISPATCH, 2, "%s%s",
IF_X64_ELSE(FRAG_IS_32(last_f->flags) ? " (32-bit)" : "", ""),
TEST(FRAG_SHARED, last_f->flags) ? " (shared)":"");
DOLOG(2, LOG_SYMBOLS, {
char symbuf[MAXIMUM_SYMBOL_LENGTH];
print_symbolic_address(last_f->tag, symbuf, sizeof(symbuf), true);
LOG(THREAD, LOG_SYMBOLS, 2, "\t%s\n", symbuf);
});
# if defined(DEBUG) && defined(DGC_DIAGNOSTICS)
if (TEST(FRAG_DYNGEN, last_f->flags) && !is_dyngen_vsyscall(last_f->tag)) {
char buf[MAXIMUM_SYMBOL_LENGTH];
bool stack = is_address_on_stack(dcontext, last_f->tag);
app_pc translated_pc;
print_symbolic_address(dcontext->next_tag, buf, sizeof(buf), false);
LOG(THREAD, LOG_DISPATCH, 1,
"Exit from dyngen F%d("PFX"%s%s) w/ %s targeting "PFX" %s:",
last_f->id, last_f->tag, stack ? " stack":"",
(last_f->flags & FRAG_DYNGEN_RESTRICTED) != 0 ? " BAD":"",
LINKSTUB_DIRECT(dcontext->last_exit->flags) ? "db":"ib",
dcontext->next_tag, buf);
/* FIXME: risky if last fragment is deleted -- should check for that
* here and instead just print type from last_exit, since recreate
* may fail
*/
translated_pc = recreate_app_pc(dcontext, EXIT_CTI_PC(dcontext->last_fragment,
dcontext->last_exit),
dcontext->last_fragment);
if (translated_pc != NULL) {
disassemble(dcontext, translated_pc, THREAD);
LOG(THREAD, LOG_DISPATCH, 1, "\n");
}
DOLOG(stack ? 1U : 2U, LOG_DISPATCH, {
LOG(THREAD, LOG_DISPATCH, 1, "DGC bb:\n");
disassemble_app_bb(dcontext, last_f->tag, THREAD);
});
}
# endif /* defined(DEBUG) && defined(DGC_DIAGNOSTICS) */
if (LINKSTUB_INDIRECT(dcontext->last_exit->flags)) {
#ifdef RETURN_AFTER_CALL
bool ok = false;
#endif
STATS_INC(num_exits_ind_total);
if (next_f == NULL) {
LOG(THREAD, LOG_DISPATCH, 2, " (target "PFX" not in cache)",
dcontext->next_tag);
STATS_INC(num_exits_ind_good_miss);
KSWITCH(num_exits_ind_good_miss);
} else if (is_building_trace(dcontext) &&
!TEST(LINK_LINKED, dcontext->last_exit->flags)) {
LOG(THREAD, LOG_DISPATCH, 2, " (in trace-building mode)");
STATS_INC(num_exits_ind_trace_build);
} else if (TEST(FRAG_WAS_DELETED, last_f->flags) ||
!INTERNAL_OPTION(link_ibl)) {
LOG(THREAD, LOG_DISPATCH, 2, " (src unlinked)");
STATS_INC(num_exits_ind_src_unlinked);
} else {
LOG(THREAD, LOG_DISPATCH, 2, " (target "PFX" in cache but not lookup table)",
dcontext->next_tag);
STATS_INC(num_exits_ind_bad_miss);
if (TEST(FRAG_IS_TRACE, last_f->flags)) {
STATS_INC(num_exits_ind_bad_miss_trace);
if (next_f && TEST(FRAG_IS_TRACE, next_f->flags)) {
STATS_INC(num_exits_ind_bad_miss_trace2trace);
KSWITCH(num_exits_ind_bad_miss_trace2trace);
} else if (next_f &&
!TEST(FRAG_IS_TRACE, next_f->flags)) {
if (!TEST(FRAG_IS_TRACE_HEAD, next_f->flags)) {
STATS_INC(num_exits_ind_bad_miss_trace2bb_nth);
KSWITCH(num_exits_ind_bad_miss_trace2bb_nth);
} else {
STATS_INC(num_exits_ind_bad_miss_trace2bb_th);
KSWITCH(num_exits_ind_bad_miss_trace2bb_th);
}
}
}
else {
STATS_INC(num_exits_ind_bad_miss_bb);
if (next_f && TEST(FRAG_IS_TRACE, next_f->flags)) {
STATS_INC(num_exits_ind_bad_miss_bb2trace);
KSWITCH(num_exits_ind_bad_miss_bb2trace);
} else if (next_f &&
!TEST(FRAG_IS_TRACE, next_f->flags)) {
DOSTATS({
if (TEST(FRAG_IS_TRACE_HEAD, next_f->flags))
STATS_INC(num_exits_ind_bad_miss_bb2bb_th);
});
STATS_INC(num_exits_ind_bad_miss_bb2bb);
KSWITCH(num_exits_ind_bad_miss_bb2bb);
}
}
}
DOSTATS({
if (!TEST(FRAG_IS_TRACE, last_f->flags))
STATS_INC(num_exits_ind_non_trace);
});
# ifdef RETURN_AFTER_CALL
/* split by ind branch type */
if (TEST(LINK_RETURN, dcontext->last_exit->flags)) {
LOG(THREAD, LOG_DISPATCH, 2, " (return from "PFX" non-trace tgt "PFX")",
EXIT_CTI_PC(dcontext->last_fragment, dcontext->last_exit),
dcontext->next_tag);
STATS_INC(num_exits_ret);
DOSTATS({
if (TEST(FRAG_IS_TRACE, last_f->flags))
STATS_INC(num_exits_ret_trace);
});
}
else if (TESTANY(LINK_CALL|LINK_JMP, dcontext->last_exit->flags)) {
LOG(THREAD, LOG_DISPATCH, 2, " (ind %s from "PFX" non-trace tgt "PFX")",
EXIT_IS_CALL(dcontext->last_exit->flags) ? "call" : "jmp",
EXIT_CTI_PC(dcontext->last_fragment, dcontext->last_exit),
dcontext->next_tag);
DOSTATS({
if (EXIT_IS_CALL(dcontext->last_exit->flags)) {
STATS_INC(num_exits_ind_call);
} else if (EXIT_IS_JMP(dcontext->last_exit->flags)) {
STATS_INC(num_exits_ind_jmp);
} else
ASSERT_NOT_REACHED();
});
} else if (!ok) {
LOG(THREAD, LOG_DISPATCH, 2,
"WARNING: unknown indirect exit from "PFX", in %s fragment "PFX,
EXIT_CTI_PC(dcontext->last_fragment, dcontext->last_exit),
(TEST(FRAG_IS_TRACE, last_f->flags)) ? "trace" : "bb",
last_f);
STATS_INC(num_exits_ind_unknown);
ASSERT_NOT_REACHED();
}
# endif /* RETURN_AFTER_CALL */
} else { /* DIRECT LINK */
ASSERT(LINKSTUB_DIRECT(dcontext->last_exit->flags) ||
IS_COARSE_LINKSTUB(dcontext->last_exit));
if (exited_due_to_ni_syscall(dcontext)) {
LOG(THREAD, LOG_DISPATCH, 2, " (block ends with syscall)");
STATS_INC(num_exits_dir_syscall);
/* FIXME: it doesn't matter whether next_f exists or not we're still in a syscall */
KSWITCH(num_exits_dir_syscall);
}
# ifdef WINDOWS
else if (TEST(LINK_CALLBACK_RETURN, dcontext->last_exit->flags)) {
LOG(THREAD, LOG_DISPATCH, 2, " (block ends with callback return)");
STATS_INC(num_exits_dir_cbret);
}
# endif
else if (next_f == NULL) {
LOG(THREAD, LOG_DISPATCH, 2, " (target "PFX" not in cache)",
dcontext->next_tag);
STATS_INC(num_exits_dir_miss);
KSWITCH(num_exits_dir_miss);
}
/* for SHARED_FRAGMENTS_ENABLED(), we do not grab the change_linking_lock
* for our is_linkable call since that leads to a lot of
* contention (and we don't want to go to a read-write model
* when most uses, and all non-debug uses, are writes!).
* instead, since we don't want to change state, we have no synch
* at all, which is ok since the state could have changed anyway
* (see comment at end of cases below)
*/
# ifdef DEBUG
else if (IS_COARSE_LINKSTUB(dcontext->last_exit)) {
LOG(THREAD, LOG_DISPATCH, 2, " (not lazily linked yet)");
}
else if (!is_linkable(dcontext, dcontext->last_fragment,
dcontext->last_exit, next_f,
false/*don't own link lock*/,
false/*do not change trace head state*/)) {
STATS_INC(num_exits_dir_nolink);
LOG(THREAD, LOG_DISPATCH, 2, " (cannot link F%d->F%d)",
last_f->id, next_f->id);
if (is_building_trace(dcontext) &&
!TEST(LINK_LINKED, dcontext->last_exit->flags)) {
LOG(THREAD, LOG_DISPATCH, 2, " (in trace-building mode)");
STATS_INC(num_exits_dir_trace_build);
}
# ifndef TRACE_HEAD_CACHE_INCR
else if (TEST(FRAG_IS_TRACE_HEAD, next_f->flags)) {
LOG(THREAD, LOG_DISPATCH, 2, " (target F%d is trace head)",
next_f->id);
STATS_INC(num_exits_dir_trace_head);
}
# endif
else if ((last_f->flags & FRAG_SHARED) != (next_f->flags & FRAG_SHARED)) {
LOG(THREAD, LOG_DISPATCH, 2, " (cannot link shared to private)",
last_f->id, next_f->id);
STATS_INC(num_exits_dir_nolink_sharing);
}
# ifdef DGC_DIAGNOSTICS
else if ((next_f->flags & FRAG_DYNGEN) != (last_f->flags & FRAG_DYNGEN)) {
LOG(THREAD, LOG_DISPATCH, 2, " (cannot link DGC to non-DGC)",
last_f->id, next_f->id);
}
# endif
else if (INTERNAL_OPTION(nolink)) {
LOG(THREAD, LOG_DISPATCH, 2, " (nolink option is on)");
}
else if (!TEST(FRAG_LINKED_OUTGOING, last_f->flags)) {
LOG(THREAD, LOG_DISPATCH, 2, " (F%d is unlinked-out)", last_f->id);
}
else if (!TEST(FRAG_LINKED_INCOMING, next_f->flags)) {
LOG(THREAD, LOG_DISPATCH, 2, " (F%d is unlinked-in)", next_f->id);
}
else {
LOG(THREAD, LOG_DISPATCH, 2, " (unknown reason)");
/* link info could have changed after we exited cache so
* this is probably not a problem, not much we can do
* to distinguish race from real problem, so no assertion.
* race can happen even w/ single_thread_in_DR.
*/
STATS_INC(num_exits_dir_race);
}
}
# ifdef TRACE_HEAD_CACHE_INCR
else if (TEST(FRAG_IS_TRACE_HEAD, next_f->flags)) {
LOG(THREAD, LOG_DISPATCH, 2, " (trace head F%d now hot!)", next_f->id);
STATS_INC(num_exits_dir_trace_hot);
}
# endif
else if (TEST(FRAG_IS_TRACE, next_f->flags) && TEST(FRAG_SHARED, last_f->flags)) {
LOG(THREAD, LOG_DISPATCH, 2,
" (shared trace head shadowed by private trace F%d)", next_f->id);
STATS_INC(num_exits_dir_nolink_sharing);
}
else if (dcontext->next_tag == last_f->tag && next_f != last_f) {
/* invisible emission and replacement */
LOG(THREAD, LOG_DISPATCH, 2, " (self-loop in F%d, replaced by F%d)",
last_f->id, next_f->id);
STATS_INC(num_exits_dir_self_replacement);
}
# ifdef UNIX
else if (dcontext->signals_pending) {
/* this may not always be the reason...the interrupted fragment
* field is modularly hidden in unix/signal.c though
*/
LOG(THREAD, LOG_DISPATCH, 2, " (interrupted by delayable signal)");
STATS_INC(num_exits_dir_signal);
}
# endif
else if (TEST(FRAG_COARSE_GRAIN, next_f->flags) &&
!TEST(FRAG_COARSE_GRAIN, last_f->flags)) {
LOG(THREAD, LOG_DISPATCH, 2, " (fine fragment targeting coarse trace head)");
/* FIXME: We would assert that FRAG_IS_TRACE_HEAD is set, but
* we have no way of setting that up for fine to coarse links
*/
/* stats are done in monitor_cache_enter() */
}
else {
LOG(THREAD, LOG_DISPATCH, 2,
" (UNKNOWN DIRECT EXIT F%d."PFX"->F%d)",
last_f->id, EXIT_CTI_PC(dcontext->last_fragment, dcontext->last_exit),
next_f->id);
/* link info could have changed after we exited cache so
* this is probably not a problem, not much we can do
* to distinguish race from real problem, so no assertion.
* race can happen even w/ single_thread_in_DR.
*/
STATS_INC(num_exits_dir_race);
}
# endif /* DEBUG */
}
if (dcontext->last_exit == get_deleted_linkstub(dcontext)) {
LOG(THREAD, LOG_DISPATCH, 2, " (fragment was flushed)");
}
LOG(THREAD, LOG_DISPATCH, 2, "\n");
DOLOG(5, LOG_DISPATCH, {
dump_mcontext(get_mcontext(dcontext), THREAD, DUMP_NOT_XML); });
DOLOG(6, LOG_DISPATCH, { dump_mcontext_callstack(dcontext); });
DOKSTATS({ DOLOG(6, LOG_DISPATCH, { kstats_dump_stack(dcontext); }); });
#endif /* defined(DEBUG) || defined(KSTATS) */
}
/***************************************************************************
* SYSTEM CALLS
*/
#ifdef UNIX
static void
adjust_syscall_continuation(dcontext_t *dcontext)
{
/* PR 212570: for linux sysenter, we hooked the sysenter return-to-user-mode
* point to go to post-do-vsyscall. So we end up here w/o any extra
* work pre-syscall; and since we put the hook-displaced code in the nop
* space immediately after the sysenter instr, which is our normal
* continuation pc, we have no work to do here either!
*/
if (get_syscall_method() == SYSCALL_METHOD_SYSENTER) {
# ifdef MACOS
if (!dcontext->sys_was_int) {
priv_mcontext_t *mc = get_mcontext(dcontext);
LOG(THREAD, LOG_SYSCALLS, 3,
"post-sysenter: xdx + asynch_target => "PFX" (were "PFX", "PFX")\n",
dcontext->app_xdx, mc->xdx, dcontext->asynch_target);
mc->xdx = dcontext->app_xdx;
dcontext->asynch_target = (app_pc) mc->xdx;
}
# else
/* we still see some int syscalls (for SYS_clone in particular) */
ASSERT(dcontext->sys_was_int ||
dcontext->asynch_target == vsyscall_syscall_end_pc);
# endif
} else if (vsyscall_syscall_end_pc != NULL &&
/* PR 341469: 32-bit apps (LOL64) on AMD hardware have
* OP_syscall in a vsyscall page
*/
get_syscall_method() != SYSCALL_METHOD_SYSCALL) {
/* If we fail to hook we currently bail out to int; but we then
* need to manually jump to the sysenter return point.
* Once we have PR 288330 we can remove this.
*/
if (dcontext->asynch_target == vsyscall_syscall_end_pc) {
ASSERT(vsyscall_sysenter_return_pc != NULL);
dcontext->asynch_target = vsyscall_sysenter_return_pc;
}
}
}
#endif
/* used to execute a system call instruction in the code cache
* dcontext->next_tag is store elsewhere and restored after the system call
* for resumption of execution post-syscall
*/
void
handle_system_call(dcontext_t *dcontext)
{
fcache_enter_func_t fcache_enter = get_fcache_enter_private_routine(dcontext);
app_pc do_syscall = (app_pc) get_do_syscall_entry(dcontext);
#ifdef CLIENT_INTERFACE
bool execute_syscall = true;
priv_mcontext_t *mc = get_mcontext(dcontext);
int sysnum = os_normalized_sysnum((int)MCXT_SYSNUM_REG(mc), NULL, dcontext);
#endif
#ifdef WINDOWS
/* make sure to ask about syscall before pre_syscall, which will swap new mc in! */
bool use_prev_dcontext = is_cb_return_syscall(dcontext);
#else
if (TEST(LINK_NI_SYSCALL_INT, dcontext->last_exit->flags)) {
LOG(THREAD, LOG_SYSCALLS, 2, "Using do_int_syscall\n");
do_syscall = (app_pc) get_do_int_syscall_entry(dcontext);
/* last_exit will be for the syscall so set a flag (could alternatively
* set up a separate exit stub but this is simpler) */
dcontext->sys_was_int = true;
# ifdef VMX86_SERVER
if (is_vmkuw_sysnum(mc->xax)) {
/* Even w/ syscall # shift int80 => ENOSYS */
do_syscall = get_do_vmkuw_syscall_entry(dcontext);
LOG(THREAD, LOG_SYSCALLS, 2, "Using do_vmkuw_syscall\n");
}
# endif
} else if (TEST(LINK_SPECIAL_EXIT, dcontext->last_exit->flags)) {
if (dcontext->upcontext.upcontext.exit_reason == EXIT_REASON_NI_SYSCALL_INT_0x81)
do_syscall = (app_pc) get_do_int81_syscall_entry(dcontext);
else {
ASSERT(dcontext->upcontext.upcontext.exit_reason ==
EXIT_REASON_NI_SYSCALL_INT_0x82);
do_syscall = (app_pc) get_do_int82_syscall_entry(dcontext);
}
dcontext->sys_was_int = true;
} else {
dcontext->sys_was_int = false;
IF_NOT_X64(IF_VMX86(ASSERT(!is_vmkuw_sysnum(mc->xax))));
}
#endif
#ifdef CLIENT_INTERFACE
/* We invoke here rather than inside pre_syscall() primarily so we can
* set use_prev_dcontext(), but also b/c the windows and linux uses
* are identical. We do want this prior to xbp-param changes for linux
* sysenter-to-int (PR 313715) since to client this should
* look like the original sysenter. For Windows we could put this
* after sysenter handling but it's not clear which is better: we'll
* assert if client changes xsp/xdx but that's fine.
*/
/* set pc so client can tell where syscall invoked from.
* note that this is pc _after_ syscall instr.
*/
get_mcontext(dcontext)->pc = get_fcache_target(dcontext);
/* i#202: ignore native syscalls in early_inject_init() */
if (IF_WINDOWS(dynamo_initialized &&)
!instrument_pre_syscall(dcontext, sysnum)) {
/* we won't execute post-syscall so we do not need to store
* dcontext->sys_*
*/
execute_syscall = false;
LOG(THREAD, LOG_SYSCALLS, 2, "skipping syscall %d on client request\n",
MCXT_SYSNUM_REG(mc));
}
# ifdef WINDOWS
/* re-set in case client changed the number */
use_prev_dcontext = is_cb_return_syscall(dcontext);
# endif
#endif
/* some syscalls require modifying local memory
* FIXME: move this unprot down to those syscalls to avoid unprot-prot-unprot-prot
* with the new clean dstack design -- though w/ shared_syscalls perhaps most
* syscalls coming through here will need this
*/
SELF_PROTECT_LOCAL(dcontext, WRITABLE);
KSWITCH(num_exits_dir_syscall); /* encapsulates syscall overhead */
LOG(THREAD, LOG_SYSCALLS, 2,
"Entry into do_syscall to execute a non-ignorable system call\n");
#ifdef SIDELINE
/* clear cur-trace field so we don't think cur trace is still running */
sideline_trace = NULL;
#endif
/* our flushing design assumes our syscall handlers are nolinking,
* to avoid multiple-flusher deadlocks
*/
ASSERT(!is_couldbelinking(dcontext));
/* we need to store the next pc since entering the fcache will clobber it
* with the do_syscall entry point.
* we store in a dcontext slot since some syscalls need to view or modify it
* (the asynch ones: sigreturn, ntcontinue, etc., hence the name asynch_target).
* Yes this works with an NtContinue being interrupted in the kernel for an APC --
* we want to know the NtContinue target, there is no other target to remember.
* The only problem is if a syscall that modifies asynch_target fails -- then we
* want the old value, so we store it here.
*/
dcontext->asynch_target = get_fcache_target(dcontext);
#ifdef WINDOWS
if (get_syscall_method() == SYSCALL_METHOD_SYSENTER) {
/* kernel sends control directly to 0x7ffe0304 so we need
* to mangle the return address
*/
/* Ref case 5461 - edx will become top of stack post-syscall */
ASSERT(get_mcontext(dcontext)->xsp == get_mcontext(dcontext)->xdx);
#ifdef HOT_PATCHING_INTERFACE
/* For hotp_only, vsyscall_syscall_end_pc can be NULL as dr will never
* interp a system call. Also, for hotp_only, control can came here
* from native only to do a syscall that was hooked.
*/
ASSERT(!DYNAMO_OPTION(hotp_only) ||
(DYNAMO_OPTION(hotp_only) &&
dcontext->next_tag == BACK_TO_NATIVE_AFTER_SYSCALL));
#else
ASSERT(vsyscall_syscall_end_pc != NULL ||
get_os_version() >= WINDOWS_VERSION_8);
#endif
/* NOTE - the stack mangling must match that of intercept_nt_continue()
* and shared_syscall as not all routines looking at the stack
* differentiate. */
if (dcontext->asynch_target == vsyscall_syscall_end_pc ||
/* win8 x86 syscalls have inlined sysenter routines */
(get_os_version() >= WINDOWS_VERSION_8 &&
dcontext->thread_record->under_dynamo_control)) {
#ifdef HOT_PATCHING_INTERFACE
/* Don't expect to be here for -hotp_only */
ASSERT_CURIOSITY(!DYNAMO_OPTION(hotp_only));
#endif
ASSERT(dcontext->next_tag != BACK_TO_NATIVE_AFTER_SYSCALL);
/* currently pc is the ret after sysenter, we need it to be the return point
* (the ret after the call to the vsyscall sysenter)
* we do not need to keep the old asynch_target -- if we decide not to do
* the syscall we just have to pop the retaddr
*/
dcontext->asynch_target = *((app_pc *)get_mcontext(dcontext)->xsp);
ASSERT(dcontext->thread_record->under_dynamo_control);
} else {
/* else, special case like native_exec_syscall */
LOG(THREAD, LOG_ALL, 2, "post-sysenter target is non-vsyscall "PFX"\n",
dcontext->asynch_target);
ASSERT(DYNAMO_OPTION(native_exec_syscalls) &&
!dcontext->thread_record->under_dynamo_control);
}
/* FIXME A lack of write access to %esp will generate an exception
* originating from DR though it's really an app problem (unless we
* screwed up wildly). Should we call is_writeable(%esp) and force
* a new UNWRITEABLE_MEMORY_EXECUTION_EXCEPTION so that we don't take
* the blame?
*/
if (DYNAMO_OPTION(sygate_sysenter)) {
/* So stack looks like
* esp +0 app_ret_addr
* +4 app_val1
* for the case 5441 Sygate hack the sysenter needs to have a ret
* address that's in ntdll.dll, but we also need to redirect
* control back to do_syscall. So we mangle to
* esp +0 sysenter_ret_address (ret in ntdll)
* +4 after_do_syscall
* dc->sysenter_storage app_val1
* dc->asynch_target app_ret_addr
* After do_syscall we push app_val1 (since stack is popped twice)
* and send control to asynch_target (implicitly doing the
* post_sysenter ret instr).
*/
dcontext->sysenter_storage =
*((app_pc *)(get_mcontext(dcontext)->xsp+XSP_SZ));
*((app_pc *)get_mcontext(dcontext)->xsp) = sysenter_ret_address;
*((app_pc *)(get_mcontext(dcontext)->xsp+XSP_SZ)) =
after_do_syscall_code(dcontext);
} else {
*((app_pc *)get_mcontext(dcontext)->xsp) =
after_do_syscall_code(dcontext);
}
}
#endif
#ifdef MACOS
if (get_syscall_method() == SYSCALL_METHOD_SYSENTER && !dcontext->sys_was_int) {
/* The kernel returns control to whatever user-mode places in edx.
* We want to put this in even if we skip the syscall as we'll still call
* adjust_syscall_continuation for a skip.
*/
byte *post_sysenter = after_do_syscall_addr(dcontext);
priv_mcontext_t *mc = get_mcontext(dcontext);
dcontext->app_xdx = mc->xdx;
mc->xdx = (reg_t) post_sysenter;
}
#endif
/* first do the pre-system-call */
if (IF_CLIENT_INTERFACE(execute_syscall &&) pre_system_call(dcontext)) {
/* now do the actual syscall instruction */
#ifdef UNIX
/* FIXME: move into some routine inside unix/?
* if so, move #include of sys/syscall.h too
*/
if (is_thread_create_syscall(dcontext)) {
/* Code for after clone is in generated code do_clone_syscall. */
do_syscall = (app_pc) get_do_clone_syscall_entry(dcontext);
} else if (is_sigreturn_syscall(dcontext)) {
/* HACK: sigreturn goes straight to fcache_return, which expects
* app eax to already be in mcontext. pre-syscall cannot do that since
* do_syscall needs the syscall num in eax!
* so we have to do it here (alternative is to be like NtContinue handling
* with a special entry point, ends up being same sort of thing as here)
*/
/* pre-sigreturn handler put dest eax in next_tag
* save it in sys_param1, which is not used already in pre/post
*/
/* for CLIENT_INTERFACE, pre-sigreturn handler took eax after
* client had chance to change it, so we have the proper value here.
*/
dcontext->sys_param1 = (reg_t) dcontext->next_tag;
LOG(THREAD, LOG_SYSCALLS, 3, "for sigreturn, set sys_param1 to "PFX"\n",
dcontext->sys_param1);
}
#else
if (use_prev_dcontext) {
/* get the current, but now swapped out, dcontext */
dcontext_t *tmp_dcontext = dcontext;
LOG(THREAD, LOG_SYSCALLS, 1, "handling a callback return\n");
dcontext = get_prev_swapped_dcontext(tmp_dcontext);
LOG(THREAD, LOG_SYSCALLS, 1, "swapped dcontext from "PFX" to "PFX"\n",
tmp_dcontext, dcontext);
/* we have special fcache_enter that uses different dcontext,
* FIXME: but what if syscall fails? need to unswap dcontexts!
*/
fcache_enter = get_fcache_enter_indirect_routine(dcontext);
/* avoid synch errors with dispatch -- since enter_fcache will set
* whereami for prev dcontext, not real one!
*/
tmp_dcontext->whereami = WHERE_FCACHE;
}
#endif
SELF_PROTECT_LOCAL(dcontext, READONLY);
set_at_syscall(dcontext, true);
KSTART_DC(dcontext, syscall_fcache); /* stopped in dispatch_exit_fcache_stats */
enter_fcache(dcontext, fcache_enter, do_syscall);
/* will handle post processing in handle_post_system_call */
ASSERT_NOT_REACHED();
}
else {
#ifdef CLIENT_INTERFACE
/* give the client its post-syscall event since we won't be calling
* post_system_call(), unless the client itself was the one who skipped.
*/
if (execute_syscall) {
instrument_post_syscall(dcontext, dcontext->sys_num);
}
#endif
#ifdef WINDOWS
if (get_syscall_method() == SYSCALL_METHOD_SYSENTER) {
/* decided to skip syscall -- pop retaddr, restore sysenter storage
* (if applicable) and set next target */
get_mcontext(dcontext)->xsp += XSP_SZ;
if (DYNAMO_OPTION(sygate_sysenter)) {
*((app_pc *)get_mcontext(dcontext)->xsp) =
dcontext->sysenter_storage;
}
set_fcache_target(dcontext, dcontext->asynch_target);
} else if (get_syscall_method() == SYSCALL_METHOD_WOW64 &&
get_os_version() == WINDOWS_VERSION_7) {
/* win7 has an add 4,esp after the call* in the syscall wrapper,
* so we need to negate it since not making the call*
*/
get_mcontext(dcontext)->xsp -= XSP_SZ;
}
#else
adjust_syscall_continuation(dcontext);
set_fcache_target(dcontext, dcontext->asynch_target);
#endif
}
SELF_PROTECT_LOCAL(dcontext, READONLY);
}
static void
handle_post_system_call(dcontext_t *dcontext)
{
priv_mcontext_t *mc = get_mcontext(dcontext);
bool skip_adjust = false;
ASSERT(!is_couldbelinking(dcontext));
ASSERT(get_at_syscall(dcontext));
set_at_syscall(dcontext, false);
/* some syscalls require modifying local memory */
SELF_PROTECT_LOCAL(dcontext, WRITABLE);
#ifdef UNIX
/* restore mcontext values prior to invoking instrument_post_syscall() */
if (was_sigreturn_syscall(dcontext)) {
# ifdef X86
/* restore app xax */
LOG(THREAD, LOG_SYSCALLS, 3,
"post-sigreturn: setting xax to "PFX", asynch_target="PFX"\n",
dcontext->sys_param1, dcontext->asynch_target);
mc->xax = dcontext->sys_param1;
# elif defined(ARM)
/* i#1551: NYI on ARM */
ASSERT_NOT_IMPLEMENTED(false);
mc->r7 = dcontext->sys_param1;
# endif /* X86/ARM */
# ifdef MACOS
/* We need to skip the use app_xdx, as we've changed the context.
* We can't just set app_xdx from handle_sigreturn() as the
* pre-sysenter code clobbers app_xdx, and we want to handle
* a failed SYS_sigreturn.
*/
skip_adjust = true;
# endif
}
#endif
post_system_call(dcontext);
/* restore state for continuation in instruction after syscall */
/* FIXME: need to handle syscall failure -- those that clobbered asynch_target
* need to restore it to its previous value, which has to be stored somewhere!
*/
#ifdef WINDOWS
if (DYNAMO_OPTION(sygate_sysenter) &&
get_syscall_method() == SYSCALL_METHOD_SYSENTER) {
/* restore sysenter_storage, note stack was popped twice for
* syscall so need to push the value */
get_mcontext(dcontext)->xsp -= XSP_SZ;
*((app_pc *)get_mcontext(dcontext)->xsp) = dcontext->sysenter_storage;
}
#else
if (!skip_adjust)
adjust_syscall_continuation(dcontext);
#endif
set_fcache_target(dcontext, dcontext->asynch_target);
#ifdef WINDOWS
/* We no longer need asynch_target so zero it out. Other pieces of DR
* -- callback & APC handling, detach -- test asynch_target to determine
* where the next app pc to execute is stored. If asynch_target != 0,
* it holds the value, else it's in the esi slot.
*/
dcontext->asynch_target = 0;
#endif
LOG(THREAD, LOG_SYSCALLS, 3, "finished handling system call\n");
SELF_PROTECT_LOCAL(dcontext, READONLY);
/* caller will go back to couldbelinking status */
}
#ifdef WINDOWS
/* in callback.c */
extern void callback_start_return(priv_mcontext_t *mc);
/* used to execute an int 2b instruction in code cache */
static void
handle_callback_return(dcontext_t *dcontext)
{
dcontext_t *prev_dcontext;
priv_mcontext_t *mc = get_mcontext(dcontext);
fcache_enter_func_t fcache_enter = get_fcache_enter_indirect_routine(dcontext);
LOG(THREAD, LOG_ASYNCH, 3, "handling a callback return\n");
/* may have to abort trace -> local heap */
SELF_PROTECT_LOCAL(dcontext, WRITABLE);
KSWITCH(num_exits_dir_cbret);
callback_start_return(mc);
/* get the current, but now swapped out, dcontext */
prev_dcontext = get_prev_swapped_dcontext(dcontext);
SELF_PROTECT_LOCAL(dcontext, READONLY);
/* obey flushing protocol, plus set whereami (both using real dcontext) */
dcontext->whereami = WHERE_FCACHE;
set_at_syscall(dcontext, true); /* will be set to false on other end's post-syscall */
ASSERT(!is_couldbelinking(dcontext));
/* if we get an APC it should be after returning to prev cxt, so don't need
* to worry about asynch_target
*/
/* make sure set the next_tag of prev_dcontext, not dcontext! */
set_fcache_target(prev_dcontext, (app_pc) get_do_callback_return_entry(prev_dcontext));
DOLOG(4, LOG_ASYNCH, {
LOG(THREAD, LOG_ASYNCH, 3, "passing prev dcontext "PFX", next_tag "PFX":\n",
prev_dcontext, prev_dcontext->next_tag);
dump_mcontext(get_mcontext(prev_dcontext), THREAD, DUMP_NOT_XML);
});
/* make sure to pass prev_dcontext, this is a special fcache enter routine
* that indirects through the dcontext passed to it (so ignores the switch-to
* dcontext that callback_start_return swapped into the main dcontext)
*/
KSTART_DC(dcontext, syscall_fcache); /* continue the interrupted syscall handling */
(*fcache_enter)(prev_dcontext);
/* callback return does not return to here! */
DOLOG(1, LOG_ASYNCH, {
LOG(THREAD, LOG_SYSCALLS, 1, "ERROR: int 2b returned!\n");
dump_mcontext(get_mcontext(dcontext), THREAD, DUMP_NOT_XML);
});
ASSERT_NOT_REACHED();
}
#endif /* WINDOWS */
/* used to execute a system call instruction in code cache
* not expected to return
* caller must set up mcontext with proper system call number and arguments
*/
void
issue_last_system_call_from_app(dcontext_t *dcontext)
{
LOG(THREAD, LOG_SYSCALLS, 2, "issue_last_system_call_from_app("PIFX")\n",
MCXT_SYSNUM_REG(get_mcontext(dcontext)));
/* it's up to the caller to let go of the bb building lock if it was held
* on this path, since not all paths to here hold it
*/
if (is_couldbelinking(dcontext))
enter_nolinking(dcontext, NULL, true);
KSTART(syscall_fcache); /* stopped in dispatch_exit_fcache_stats */
enter_fcache(dcontext, get_fcache_enter_private_routine(dcontext),
(app_pc) get_global_do_syscall_entry());
ASSERT_NOT_REACHED();
}
/* Stores the register parameters into the mcontext and calls dispatch.
* Checks whether currently on initstack and if so clears the initstack_mutex.
* Does not return.
*/
void
transfer_to_dispatch(dcontext_t *dcontext, priv_mcontext_t *mc, bool full_DR_state)
{
app_pc cur_xsp;
bool using_initstack = false;
copy_mcontext(mc, get_mcontext(dcontext));
GET_STACK_PTR(cur_xsp);
if (is_on_initstack(cur_xsp))
using_initstack = true;
#if defined(WINDOWS) && defined(CLIENT_INTERFACE)
/* i#249: swap PEB pointers unless already in DR state */
if (!full_DR_state && INTERNAL_OPTION(private_peb) && should_swap_peb_pointer())
swap_peb_pointer(dcontext, true/*to priv*/);
#endif
LOG(THREAD, LOG_ASYNCH, 2,
"transfer_to_dispatch: pc=0x%08x, xsp="PFX", initstack=%d\n",
dcontext->next_tag, mc->xsp, using_initstack);
/* next, want to switch to dstack, and if using initstack, free mutex.
* finally, call dispatch(dcontext).
* note that we switch to the base of dstack, deliberately squashing
* what may have been there before, for both new dcontext and reuse dcontext
* options.
*/
call_switch_stack(dcontext, dcontext->dstack, dispatch,
using_initstack ? &initstack_mutex : NULL,
false/*do not return on error*/);
ASSERT_NOT_REACHED();
}