src/pmm.c

// Post memory manager (PMM) calls
//
// Copyright (C) 2009  Kevin O'Connor <kevin@koconnor.net>
//
// This file may be distributed under the terms of the GNU LGPLv3 license.

#include "util.h" // checksum
#include "config.h" // BUILD_BIOS_ADDR
#include "memmap.h" // struct e820entry
#include "farptr.h" // GET_FARVAR
#include "biosvar.h" // GET_BDA


#if MODESEGMENT
// The 16bit pmm entry points runs in "big real" mode, and can
// therefore read/write to the 32bit malloc variables.
#define GET_PMMVAR(var) ({                      \
            SET_SEG(ES, 0);                     \
            __GET_VAR("addr32 ", ES, (var)); })
#define SET_PMMVAR(var, val) do {               \
        SET_SEG(ES, 0);                         \
        __SET_VAR("addr32 ", ES, (var), (val)); \
    } while (0)
#else
#define GET_PMMVAR(var) (var)
#define SET_PMMVAR(var, val) do { (var) = (val); } while (0)
#endif

// Information on a reserved area.
struct allocinfo_s {
    struct allocinfo_s *next, **pprev;
    void *data, *dataend, *allocend;
};

// Information on a tracked memory allocation.
struct allocdetail_s {
    struct allocinfo_s detailinfo;
    struct allocinfo_s datainfo;
    u32 handle;
};

// The various memory zones.
struct zone_s {
    struct allocinfo_s *info;
};

struct zone_s ZoneLow VAR32FLATVISIBLE;
struct zone_s ZoneHigh VAR32FLATVISIBLE;
struct zone_s ZoneFSeg VAR32FLATVISIBLE;
struct zone_s ZoneTmpLow VAR32FLATVISIBLE;
struct zone_s ZoneTmpHigh VAR32FLATVISIBLE;

struct zone_s *Zones[] VAR32FLATVISIBLE = {
    &ZoneTmpLow, &ZoneLow, &ZoneFSeg, &ZoneTmpHigh, &ZoneHigh
};


/****************************************************************
 * low-level memory reservations
 ****************************************************************/

// Find and reserve space from a given zone
static void *
allocSpace(struct zone_s *zone, u32 size, u32 align, struct allocinfo_s *fill)
{
    struct allocinfo_s *info;
    for (info = GET_PMMVAR(zone->info); info; info = GET_PMMVAR(info->next)) {
        void *dataend = GET_PMMVAR(info->dataend);
        void *allocend = GET_PMMVAR(info->allocend);
        void *newallocend = (void*)ALIGN_DOWN((u32)allocend - size, align);
        if (newallocend >= dataend && newallocend <= allocend) {
            // Found space - now reserve it.
            struct allocinfo_s **pprev = GET_PMMVAR(info->pprev);
            if (!fill)
                fill = newallocend;
            SET_PMMVAR(fill->next, info);
            SET_PMMVAR(fill->pprev, pprev);
            SET_PMMVAR(fill->data, newallocend);
            SET_PMMVAR(fill->dataend, newallocend + size);
            SET_PMMVAR(fill->allocend, allocend);

            SET_PMMVAR(info->allocend, newallocend);
            SET_PMMVAR(info->pprev, &fill->next);
            SET_PMMVAR(*pprev, fill);
            return newallocend;
        }
    }
    return NULL;
}

// Release space allocated with allocSpace()
static void
freeSpace(struct allocinfo_s *info)
{
    struct allocinfo_s *next = GET_PMMVAR(info->next);
    struct allocinfo_s **pprev = GET_PMMVAR(info->pprev);
    SET_PMMVAR(*pprev, next);
    if (next) {
        if (GET_PMMVAR(next->allocend) == GET_PMMVAR(info->data))
            SET_PMMVAR(next->allocend, GET_PMMVAR(info->allocend));
        SET_PMMVAR(next->pprev, pprev);
    }
}

// Add new memory to a zone
static void
addSpace(struct zone_s *zone, void *start, void *end)
{
    // Find position to add space
    struct allocinfo_s **pprev = &zone->info, *info;
    for (;;) {
        info = GET_PMMVAR(*pprev);
        if (!info || GET_PMMVAR(info->data) < start)
            break;
        pprev = &info->next;
    }

    // Add space using temporary allocation info.
    struct allocdetail_s tempdetail;
    tempdetail.datainfo.next = info;
    tempdetail.datainfo.pprev = pprev;
    tempdetail.datainfo.data = tempdetail.datainfo.dataend = start;
    tempdetail.datainfo.allocend = end;
    struct allocdetail_s *tempdetailp = MAKE_FLATPTR(GET_SEG(SS), &tempdetail);
    SET_PMMVAR(*pprev, &tempdetailp->datainfo);
    if (info)
        SET_PMMVAR(info->pprev, &tempdetailp->datainfo.next);

    // Allocate final allocation info.
    struct allocdetail_s *detail = allocSpace(
        &ZoneTmpHigh, sizeof(*detail), MALLOC_MIN_ALIGN, NULL);
    if (!detail) {
        detail = allocSpace(&ZoneTmpLow, sizeof(*detail)
                            , MALLOC_MIN_ALIGN, NULL);
        if (!detail) {
            SET_PMMVAR(*tempdetail.datainfo.pprev, tempdetail.datainfo.next);
            if (tempdetail.datainfo.next)
                SET_PMMVAR(tempdetail.datainfo.next->pprev
                           , tempdetail.datainfo.pprev);
            warn_noalloc();
            return;
        }
    }

    // Replace temp alloc space with final alloc space
    memcpy_fl(&detail->datainfo, &tempdetailp->datainfo
              , sizeof(detail->datainfo));
    SET_PMMVAR(detail->handle, PMM_DEFAULT_HANDLE);

    SET_PMMVAR(*tempdetail.datainfo.pprev, &detail->datainfo);
    if (tempdetail.datainfo.next)
        SET_PMMVAR(tempdetail.datainfo.next->pprev, &detail->datainfo.next);
}

// Search all zones for an allocation obtained from allocSpace()
static struct allocinfo_s *
findAlloc(void *data)
{
    int i;
    for (i=0; i<ARRAY_SIZE(Zones); i++) {
        struct zone_s *zone = GET_PMMVAR(Zones[i]);
        struct allocinfo_s *info;
        for (info = GET_PMMVAR(zone->info); info; info = GET_PMMVAR(info->next))
            if (GET_PMMVAR(info->data) == data)
                return info;
    }
    return NULL;
}

// Return the last sentinal node of a zone
static struct allocinfo_s *
findLast(struct zone_s *zone)
{
    struct allocinfo_s *info = GET_PMMVAR(zone->info);
    if (!info)
        return NULL;
    for (;;) {
        struct allocinfo_s *next = GET_PMMVAR(info->next);
        if (!next)
            return info;
        info = next;
    }
}


/****************************************************************
 * Setup
 ****************************************************************/

void
malloc_setup(void)
{
    ASSERT32FLAT();
    dprintf(3, "malloc setup\n");

    // Populate temp high ram
    u32 highram = 0;
    int i;
    for (i=e820_count-1; i>=0; i--) {
        struct e820entry *en = &e820_list[i];
        u64 end = en->start + en->size;
        if (end < 1024*1024)
            break;
        if (en->type != E820_RAM || end > 0xffffffff)
            continue;
        u32 s = en->start, e = end;
        if (!highram) {
            u32 newe = ALIGN_DOWN(e - CONFIG_MAX_HIGHTABLE, MALLOC_MIN_ALIGN);
            if (newe <= e && newe >= s) {
                highram = newe;
                e = newe;
            }
        }
        addSpace(&ZoneTmpHigh, (void*)s, (void*)e);
    }

    // Populate other regions
    addSpace(&ZoneTmpLow, (void*)BUILD_STACK_ADDR, (void*)BUILD_EBDA_MINIMUM);
    addSpace(&ZoneFSeg, BiosTableSpace, &BiosTableSpace[CONFIG_MAX_BIOSTABLE]);
    addSpace(&ZoneLow, (void*)BUILD_LOWRAM_END, (void*)BUILD_LOWRAM_END);
    if (highram) {
        addSpace(&ZoneHigh, (void*)highram
                 , (void*)highram + CONFIG_MAX_HIGHTABLE);
        add_e820(highram, CONFIG_MAX_HIGHTABLE, E820_RESERVED);
    }
}

void
malloc_finalize(void)
{
    dprintf(3, "malloc finalize\n");

    // Reserve more low-mem if needed.
    u32 endlow = GET_BDA(mem_size_kb)*1024;
    add_e820(endlow, BUILD_LOWRAM_END-endlow, E820_RESERVED);

    // Give back unused high ram.
    struct allocinfo_s *info = findLast(&ZoneHigh);
    if (info) {
        u32 giveback = ALIGN_DOWN(info->allocend - info->dataend, PAGE_SIZE);
        add_e820((u32)info->dataend, giveback, E820_RAM);
        dprintf(1, "Returned %d bytes of ZoneHigh\n", giveback);
    }
}


/****************************************************************
 * ebda movement
 ****************************************************************/

// Move ebda
static int
relocate_ebda(u32 newebda, u32 oldebda, u8 ebda_size)
{
    u32 lowram = GET_BDA(mem_size_kb) * 1024;
    if (oldebda != lowram)
        // EBDA isn't at end of ram - give up.
        return -1;

    // Do copy (this assumes memcpy copies forward - otherwise memmove
    // is needed)
    memcpy_fl((void*)newebda, (void*)oldebda, ebda_size * 1024);

    // Update indexes
    dprintf(1, "ebda moved from %x to %x\n", oldebda, newebda);
    SET_BDA(mem_size_kb, newebda / 1024);
    SET_BDA(ebda_seg, FLATPTR_TO_SEG(newebda));
    return 0;
}

// Support expanding the ZoneLow dynamically.
static void
zonelow_expand(u32 size, u32 align)
{
    struct allocinfo_s *info = findLast(&ZoneLow);
    if (!info)
        return;
    u32 oldpos = (u32)GET_PMMVAR(info->allocend);
    u32 newpos = ALIGN_DOWN(oldpos - size, align);
    u32 bottom = (u32)GET_PMMVAR(info->dataend);
    if (newpos >= bottom && newpos <= oldpos)
        // Space already present.
        return;
    u16 ebda_seg = get_ebda_seg();
    u32 ebda_pos = (u32)MAKE_FLATPTR(ebda_seg, 0);
    u8 ebda_size = GET_EBDA2(ebda_seg, size);
    u32 ebda_end = ebda_pos + ebda_size * 1024;
    if (ebda_end != bottom)
        // Something else is after ebda - can't use any existing space.
        newpos = ALIGN_DOWN(ebda_end - size, align);
    u32 newbottom = ALIGN_DOWN(newpos, 1024);
    u32 newebda = ALIGN_DOWN(newbottom - ebda_size * 1024, 1024);
    if (newebda < BUILD_EBDA_MINIMUM)
        // Not enough space.
        return;

    // Move ebda
    int ret = relocate_ebda(newebda, ebda_pos, ebda_size);
    if (ret)
        return;

    // Update zone
    if (ebda_end == bottom) {
        SET_PMMVAR(info->data, (void*)newbottom);
        SET_PMMVAR(info->dataend, (void*)newbottom);
    } else
        addSpace(&ZoneLow, (void*)newbottom, (void*)ebda_end);
}

// Check if can expand the given zone to fulfill an allocation
static void *
allocExpandSpace(struct zone_s *zone, u32 size, u32 align
                 , struct allocinfo_s *fill)
{
    void *data = allocSpace(zone, size, align, fill);
    if (data || zone != &ZoneLow)
        return data;

    // Make sure to not move ebda while an optionrom is running.
    if (unlikely(wait_preempt())) {
        data = allocSpace(zone, size, align, fill);
        if (data)
            return data;
    }

    zonelow_expand(size, align);
    return allocSpace(zone, size, align, fill);
}


/****************************************************************
 * tracked memory allocations
 ****************************************************************/

// Allocate memory from the given zone and track it as a PMM allocation
void * __malloc
pmm_malloc(struct zone_s *zone, u32 handle, u32 size, u32 align)
{
    if (!size)
        return NULL;

    // Find and reserve space for bookkeeping.
    struct allocdetail_s *detail = allocSpace(
        &ZoneTmpHigh, sizeof(*detail), MALLOC_MIN_ALIGN, NULL);
    if (!detail) {
        detail = allocSpace(&ZoneTmpLow, sizeof(*detail)
                            , MALLOC_MIN_ALIGN, NULL);
        if (!detail)
            return NULL;
    }

    // Find and reserve space for main allocation
    void *data = allocExpandSpace(zone, size, align, &detail->datainfo);
    if (!data) {
        freeSpace(&detail->detailinfo);
        return NULL;
    }

    dprintf(8, "pmm_malloc zone=%p handle=%x size=%d align=%x"
            " ret=%p (detail=%p)\n"
            , zone, handle, size, align
            , data, detail);
    SET_PMMVAR(detail->handle, handle);

    return data;
}

// Free a data block allocated with pmm_malloc
int
pmm_free(void *data)
{
    struct allocinfo_s *info = findAlloc(data);
    if (!info || data == (void*)info || data == GET_PMMVAR(info->dataend))
        return -1;
    struct allocdetail_s *detail = container_of(
        info, struct allocdetail_s, datainfo);
    dprintf(8, "pmm_free %p (detail=%p)\n", data, detail);
    freeSpace(info);
    freeSpace(&detail->detailinfo);
    return 0;
}

// Find the amount of free space in a given zone.
static u32
pmm_getspace(struct zone_s *zone)
{
    // XXX - doesn't account for ZoneLow being able to grow.
    // XXX - results not reliable when CONFIG_THREAD_OPTIONROMS
    u32 maxspace = 0;
    struct allocinfo_s *info;
    for (info = GET_PMMVAR(zone->info); info; info = GET_PMMVAR(info->next)) {
        u32 space = GET_PMMVAR(info->allocend) - GET_PMMVAR(info->dataend);
        if (space > maxspace)
            maxspace = space;
    }

    if (zone != &ZoneTmpHigh && zone != &ZoneTmpLow)
        return maxspace;
    // Account for space needed for PMM tracking.
    u32 reserve = ALIGN(sizeof(struct allocdetail_s), MALLOC_MIN_ALIGN);
    if (maxspace <= reserve)
        return 0;
    return maxspace - reserve;
}

// Find the data block allocated with pmm_malloc with a given handle.
static void *
pmm_find(u32 handle)
{
    int i;
    for (i=0; i<ARRAY_SIZE(Zones); i++) {
        struct zone_s *zone = GET_PMMVAR(Zones[i]);
        struct allocinfo_s *info;
        for (info = GET_PMMVAR(zone->info); info
                 ; info = GET_PMMVAR(info->next)) {
            if (GET_PMMVAR(info->data) != (void*)info)
                continue;
            struct allocdetail_s *detail = container_of(
                info, struct allocdetail_s, detailinfo);
            if (GET_PMMVAR(detail->handle) == handle)
                return GET_PMMVAR(detail->datainfo.data);
        }
    }
    return NULL;
}


/****************************************************************
 * pmm interface
 ****************************************************************/

struct pmmheader {
    u32 signature;
    u8 version;
    u8 length;
    u8 checksum;
    u16 entry_offset;
    u16 entry_seg;
    u8 reserved[5];
} PACKED;

extern struct pmmheader PMMHEADER;

#define PMM_SIGNATURE 0x4d4d5024 // $PMM

#if CONFIG_PMM
struct pmmheader PMMHEADER __aligned(16) VAR16EXPORT = {
    .version = 0x01,
    .length = sizeof(PMMHEADER),
    .entry_seg = SEG_BIOS,
};
#endif

#define PMM_FUNCTION_NOT_SUPPORTED 0xffffffff

// PMM - allocate
static u32
handle_pmm00(u16 *args)
{
    u32 length = *(u32*)&args[1], handle = *(u32*)&args[3];
    u16 flags = args[5];
    dprintf(3, "pmm00: length=%x handle=%x flags=%x\n"
            , length, handle, flags);
    struct zone_s *lowzone = &ZoneTmpLow, *highzone = &ZoneTmpHigh;
    if (flags & 8) {
        // Permanent memory request.
        lowzone = &ZoneLow;
        highzone = &ZoneHigh;
    }
    if (!length) {
        // Memory size request
        switch (flags & 3) {
        default:
        case 0:
            return 0;
        case 1:
            return pmm_getspace(lowzone);
        case 2:
            return pmm_getspace(highzone);
        case 3: {
            u32 spacelow = pmm_getspace(lowzone);
            u32 spacehigh = pmm_getspace(highzone);
            if (spacelow > spacehigh)
                return spacelow;
            return spacehigh;
        }
        }
    }
    u32 size = length * 16;
    if ((s32)size <= 0)
        return 0;
    u32 align = MALLOC_MIN_ALIGN;
    if (flags & 4) {
        align = 1<<__ffs(size);
        if (align < MALLOC_MIN_ALIGN)
            align = MALLOC_MIN_ALIGN;
    }
    switch (flags & 3) {
    default:
    case 0:
        return 0;
    case 1:
        return (u32)pmm_malloc(lowzone, handle, size, align);
    case 2:
        return (u32)pmm_malloc(highzone, handle, size, align);
    case 3: {
        void *data = pmm_malloc(lowzone, handle, size, align);
        if (data)
            return (u32)data;
        return (u32)pmm_malloc(highzone, handle, size, align);
    }
    }
}

// PMM - find
static u32
handle_pmm01(u16 *args)
{
    u32 handle = *(u32*)&args[1];
    dprintf(3, "pmm01: handle=%x\n", handle);
    if (handle == PMM_DEFAULT_HANDLE)
        return 0;
    return (u32)pmm_find(handle);
}

// PMM - deallocate
static u32
handle_pmm02(u16 *args)
{
    u32 buffer = *(u32*)&args[1];
    dprintf(3, "pmm02: buffer=%x\n", buffer);
    int ret = pmm_free((void*)buffer);
    if (ret)
        // Error
        return 1;
    return 0;
}

static u32
handle_pmmXX(u16 *args)
{
    return PMM_FUNCTION_NOT_SUPPORTED;
}

u32 VISIBLE16
handle_pmm(u16 *args)
{
    if (! CONFIG_PMM)
        return PMM_FUNCTION_NOT_SUPPORTED;

    u16 arg1 = args[0];
    dprintf(DEBUG_HDL_pmm, "pmm call arg1=%x\n", arg1);

    switch (arg1) {
    case 0x00: return handle_pmm00(args);
    case 0x01: return handle_pmm01(args);
    case 0x02: return handle_pmm02(args);
    default:   return handle_pmmXX(args);
    }
}

// romlayout.S
extern void entry_pmm(void);

void
pmm_setup(void)
{
    if (! CONFIG_PMM)
        return;

    dprintf(3, "init PMM\n");

    PMMHEADER.signature = PMM_SIGNATURE;
    PMMHEADER.entry_offset = (u32)entry_pmm - BUILD_BIOS_ADDR;
    PMMHEADER.checksum -= checksum(&PMMHEADER, sizeof(PMMHEADER));
}

void
pmm_finalize(void)
{
    if (! CONFIG_PMM)
        return;

    dprintf(3, "finalize PMM\n");

    PMMHEADER.signature = 0;
    PMMHEADER.entry_offset = 0;
}