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/*
* CDDL HEADER START
*
* The contents of this file are subject to the terms of the
* Common Development and Distribution License (the "License").
* You may not use this file except in compliance with the License.
*
* You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
* or http://www.opensolaris.org/os/licensing.
* See the License for the specific language governing permissions
* and limitations under the License.
*
* When distributing Covered Code, include this CDDL HEADER in each
* file and include the License file at usr/src/OPENSOLARIS.LICENSE.
* If applicable, add the following below this CDDL HEADER, with the
* fields enclosed by brackets "[]" replaced with your own identifying
* information: Portions Copyright [yyyy] [name of copyright owner]
*
* CDDL HEADER END
*/
/*
* Copyright (c) 2014 Joyent, Inc. All rights reserved.
*/

/*
* Don't Panic! If you find the blocks of assembly that follow confusing and
* you're questioning why they exist, please go read section 8 of the umem.c big
* theory statement. Next familiarize yourself with the malloc and free
* implementations in libumem's malloc.c.
*
* What follows is the i386 implementation of the thread caching automatic
* assembly generation. With i386 a function only has three registers it's
* allowed to change without restoring them: eax, ecx, and edx. All others have
* to be preserved. Since the set of registers we have available is so small, we
* have to make use of esi, ebx, and edi and save their original values to the
* stack.
*
* Malloc register usage:
* o. esi: Size of the malloc (passed into us and modified)
* o. edi: Size of the cache
* o. eax: Buffer to return
* o. ebx: Scratch space and temporary values
* o. ecx: Pointer to the tmem_t in the ulwp_t.
* o. edx: Pointer to the tmem_t array of roots
*
* Free register usage:
* o. esi: Size of the malloc (passed into us and modified)
* o. edi: Size of the cache
* o. eax: Buffer to free
* o. ebx: Scratch space and temporary values
* o. ecx: Pointer to the tmem_t in the ulwp_t.
* o. edx: Pointer to the tmem_t array of roots
*
* Once we determine what cache we are using, we increment %edx to the
* appropriate offset and set %edi with the size of the cache. This means that
* when we break out to the normal buffer allocation point %edx contains the
* head of the linked list and %edi is the amount that we have to adjust the
* total amount cached by the thread.
*
* Each block of assembly has psuedocode that describes its purpose.
*/

#include <inttypes.h>
#include <strings.h>
#include <umem_impl.h>
#include "umem_base.h"

#include <atomic.h>

const int umem_genasm_supported = 1;
static uintptr_t umem_genasm_mptr = (uintptr_t)&_malloc;
static size_t umem_genasm_msize = 512;
static uintptr_t umem_genasm_fptr = (uintptr_t)&_free;
static size_t umem_genasm_fsize = 512;
static uintptr_t umem_genasm_omptr = (uintptr_t)umem_malloc;
static uintptr_t umem_genasm_ofptr = (uintptr_t)umem_malloc_free;
/*
* The maximum number of caches we can support. We use a single byte addl so
* this is 255 (UINT8_MAX) / sizeof (uintptr_t). In this case 63
*/
#define UMEM_GENASM_MAX32 63

#define PTC_JMPADDR(dest, src) (dest - (src + 4))
#define PTC_ROOT_SIZE sizeof (uintptr_t)
#define MULTINOP 0x0000441f0f

/*
* void *ptcmalloc(size_t orig_size);
*
* size_t size = orig_size + 8;
*
* if (size < orig_size)
* goto tomalloc; ! This is overflow
*
* if (size > cache_size)
* goto tomalloc;
*
* tmem_t *t = (uintptr_t)curthread() + umem_thr_offset;
* void **roots = t->tm_roots;
*/
#define PTC_MALINIT_JOUT 0x0e
#define PTC_MALINIT_MCS 0x14
#define PTC_MALINIT_JOV 0x1a
#define PTC_MALINIT_SOFF 0x27
static const uint8_t malinit[] = {
0x55, /* pushl %ebp */
0x89, 0xe5, /* movl %esp, %ebp */
0x57, /* pushl %edi */
0x56, /* pushl %esi */
0x53, /* pushl %ebx */
0x8b, 0x75, 0x08, /* movl 0x8(%ebp), %esi */
0x83, 0xc6, 0x08, /* addl $0x8,%esi */
0x0f, 0x82, 0x00, 0x00, 0x00, 0x00, /* jc +$JMP (errout) */
0x81, 0xfe, 0x00, 0x00, 0x00, 0x00, /* cmpl sizeof ($C0), %esi */
0x0f, 0x87, 0x00, 0x00, 0x00, 0x00, /* ja +$JMP (errout) */
0x65, 0x8b, 0x0d, 0x00, 0x00, 0x00, 0x00, /* movl %gs:0x0,%ecx */
0x81, 0xc1, 0x00, 0x00, 0x00, 0x00, /* addl $OFF, %ecx */
0x8d, 0x51, 0x04 /* leal 0x4(%ecx), %edx */
};

/*
* void ptcfree(void *buf);
*
* if (buf == NULL)
* return;
*
* malloc_data_t *tag = buf;
* tag--;
* int size = tag->malloc_size;
* int tagtval = UMEM_MALLOC_DECODE(tag->malloc_tag, size);
*
* if (tagval != MALLOC_MAGIC)
* goto tofree;
*
* if (size > cache_max)
* goto tofree;
*
* tmem_t *t = (uintptr_t)curthread() + umem_thr_offset;
* void **roots = t->tm_roots;
*/
#define PTC_FRINI_JDONE 0x0d
#define PTC_FRINI_JFREE 0x23
#define PTC_FRINI_MCS 0x29
#define PTC_FRINI_JOV 0x2f
#define PTC_FRINI_SOFF 0x3c
static const uint8_t freeinit[] = {
0x55, /* pushl %ebp */
0x89, 0xe5, /* movl %esp, %ebp */
0x57, /* pushl %edi */
0x56, /* pushl %esi */
0x53, /* pushl %ebx */
0x8b, 0x45, 0x08, /* movl 0x8(%ebp), %eax */
0x85, 0xc0, /* testl %eax, %eax */
0x0f, 0x84, 0x00, 0x00, 0x00, 0x00, /* je $JDONE (done) */
0x83, 0xe8, 0x08, /* subl $0x8,%eax */
0x8b, 0x30, /* movl (%eax),%esi */
0x8b, 0x50, 0x04, /* movl 0x4(%eax),%edx */
0x01, 0xf2, /* addl %esi,%edx */
0x81, 0xfa, 0x00, 0xc0, 0x10, 0x3a, /* cmpl MAGIC32, %edx */
0x0f, 0x85, 0x00, 0x00, 0x00, 0x00, /* jne +JFREE (goto freebuf) */

0x81, 0xfe, 0x00, 0x00, 0x00, 0x00, /* cmpl sizeof ($C0), %esi */
0x0f, 0x87, 0x00, 0x00, 0x00, 0x00, /* ja +$JMP (errout) */
0x65, 0x8b, 0x0d, 0x00, 0x0, 0x00, 0x00, /* movl %gs:0x0,%ecx */
0x81, 0xc1, 0x00, 0x00, 0x00, 0x00, /* addl $0xOFF, %ecx */
0x8d, 0x51, 0x04 /* leal 0x4(%ecx),%edx */
};

/*
* if (size <= $CACHE_SIZE) {
* csize = $CACHE_SIZE;
* } else ... ! goto next cache
*/
#define PTC_INICACHE_CMP 0x02
#define PTC_INICACHE_SIZE 0x09
#define PTC_INICACHE_JMP 0x0e
static const uint8_t inicache[] = {
0x81, 0xfe, 0xff, 0x00, 0x00, 0x00, /* cmpl sizeof ($C0), %esi */
0x77, 0x0a, /* ja +0xa */
0xbf, 0xff, 0x00, 0x00, 0x00, /* movl sizeof ($C0), %edi */
0xe9, 0x00, 0x00, 0x00, 0x00 /* jmp +$JMP (allocbuf) */
};

/*
* if (size <= $CACHE_SIZE) {
* csize = $CACHE_SIZE;
* roots += $CACHE_NUM;
* } else ... ! goto next cache
*/
#define PTC_GENCACHE_CMP 0x02
#define PTC_GENCACHE_NUM 0x0a
#define PTC_GENCACHE_SIZE 0x0c
#define PTC_GENCACHE_JMP 0x11
static const uint8_t gencache[] = {
0x81, 0xfe, 0x00, 0x00, 0x00, 0x00, /* cmpl sizeof ($CACHE), %esi */
0x77, 0x0d, /* ja +0xd (next cache) */
0x83, 0xc2, 0x00, /* addl $4*$ii, %edx */
0xbf, 0x00, 0x00, 0x00, 0x00, /* movl sizeof ($CACHE), %edi */
0xe9, 0x00, 0x00, 0x00, 0x00 /* jmp +$JMP (allocbuf) */
};

/*
* else if (size <= $CACHE_SIZE) {
* csize = $CACHE_SIZE;
* roots += $CACHE_NUM;
* } else {
* goto tofunc; ! goto tomalloc if ptcmalloc.
* } ! goto tofree if ptcfree.
*/
#define PTC_FINCACHE_CMP 0x02
#define PTC_FINCACHE_JMP 0x07
#define PTC_FINCACHE_NUM 0x0a
#define PTC_FINCACHE_SIZE 0x0c
static const uint8_t fincache[] = {
0x81, 0xfe, 0xff, 0x00, 0x00, 0x00, /* cmpl sizeof ($CLAST), %esi */
0x77, 0x00, /* ja +$JMP (to errout) */
0x83, 0xc2, 0x00, /* addl $4*($NCACHES-1), %edx */
0xbf, 0x00, 0x00, 0x00, 0x00, /* movl sizeof ($CLAST), %edi */
};

/*
* if (*root == NULL)
* goto tomalloc;
*
* malloc_data_t *ret = *root;
* *root = *(void **)ret;
* t->tm_size += csize;
* ret->malloc_size = size;
*
* ret->malloc_data = UMEM_MALLOC_ENCODE(MALLOC_SECOND_MAGIC, size);
* ret++;
*
* return ((void *)ret);
* tomalloc:
* return (malloc(orig_size));
*/
#define PTC_MALFINI_ALLABEL 0x00
#define PTC_MALFINI_JMLABEL 0x20
#define PTC_MALFINI_JMADDR 0x25
static const uint8_t malfini[] = {
/* allocbuf: */
0x8b, 0x02, /* movl (%edx), %eax */
0x85, 0xc0, /* testl %eax, %eax */
0x74, 0x1a, /* je +0x1a (errout) */
0x8b, 0x18, /* movl (%eax), %esi */
0x89, 0x1a, /* movl %esi, (%edx) */
0x29, 0x39, /* subl %edi, (%ecx) */
0x89, 0x30, /* movl %esi, ($eax) */
0xba, 0x00, 0xc0, 0x10, 0x3a, /* movl $0x3a10c000,%edx */
0x29, 0xf2, /* subl %esi, %edx */
0x89, 0x50, 0x04, /* movl %edx, 0x4(%eax) */
0x83, 0xc0, 0x08, /* addl %0x8, %eax */
0x5b, /* popl %ebx */
0x5e, /* popl %esi */
0x5f, /* popl %edi */
0xc9, /* leave */
0xc3, /* ret */
/* errout: */
0x5b, /* popl %ebx */
0x5e, /* popl %esi */
0x5f, /* popl %edi */
0xc9, /* leave */
0xe9, 0x00, 0x00, 0x00, 0x00 /* jmp $malloc */
};

/*
* if (t->tm_size + csize > umem_ptc_size)
* goto tofree;
*
* t->tm_size += csize
* *(void **)tag = *root;
* *root = tag;
* return;
* tofree:
* free(buf);
* return;
*/
#define PTC_FRFINI_RBUFLABEL 0x00
#define PTC_FRFINI_CACHEMAX 0x06
#define PTC_FRFINI_DONELABEL 0x14
#define PTC_FRFINI_JFLABEL 0x19
#define PTC_FRFINI_JFADDR 0x1e
static const uint8_t freefini[] = {
/* freebuf: */
0x8b, 0x19, /* movl (%ecx),%ebx */
0x01, 0xfb, /* addl %edi,%ebx */
0x81, 0xfb, 0x00, 0x00, 0x00, 0x00, /* cmpl maxsize, %ebx */
0x73, 0x0d, /* jae +0xd <tofree> */
0x01, 0x39, /* addl %edi,(%ecx) */
0x8b, 0x3a, /* movl (%edx),%edi */
0x89, 0x38, /* movl %edi,(%eax) */
0x89, 0x02, /* movl %eax,(%edx) */
/* done: */
0x5b, /* popl %ebx */
0x5e, /* popl %esi */
0x5f, /* popl %edi */
0xc9, /* leave */
0xc3, /* ret */
/* realfree: */
0x5b, /* popl %ebx */
0x5e, /* popl %esi */
0x5f, /* popl %edi */
0xc9, /* leave */
0xe9, 0x00, 0x00, 0x00, 0x00 /* jmp free */
};

/*
* Construct the initial part of malloc. off contains the offset from curthread
* to the root of the tmem structure. ep is the address of the label to error
* and jump to free. csize is the size of the largest umem_cache in ptcumem.
*/
static int
genasm_malinit(uint8_t *bp, uint32_t off, uint32_t ep, uint32_t csize)
{
uint32_t addr;

bcopy(malinit, bp, sizeof (malinit));
addr = PTC_JMPADDR(ep, PTC_MALINIT_JOUT);
bcopy(&addr, bp + PTC_MALINIT_JOUT, sizeof (addr));
bcopy(&csize, bp + PTC_MALINIT_MCS, sizeof (csize));
addr = PTC_JMPADDR(ep, PTC_MALINIT_JOV);
bcopy(&addr, bp + PTC_MALINIT_JOV, sizeof (addr));
bcopy(&off, bp + PTC_MALINIT_SOFF, sizeof (off));

return (sizeof (malinit));
}

static int
genasm_frinit(uint8_t *bp, uint32_t off, uint32_t dp, uint32_t ep, uint32_t mc)
{
uint32_t addr;

bcopy(freeinit, bp, sizeof (freeinit));
addr = PTC_JMPADDR(dp, PTC_FRINI_JDONE);
bcopy(&addr, bp + PTC_FRINI_JDONE, sizeof (addr));
addr = PTC_JMPADDR(ep, PTC_FRINI_JFREE);
bcopy(&addr, bp + PTC_FRINI_JFREE, sizeof (addr));
bcopy(&mc, bp + PTC_FRINI_MCS, sizeof (mc));
addr = PTC_JMPADDR(ep, PTC_FRINI_JOV);
bcopy(&addr, bp + PTC_FRINI_JOV, sizeof (addr));
bcopy(&off, bp + PTC_FRINI_SOFF, sizeof (off));
return (sizeof (freeinit));
}

/*
* Create the initial cache entry of the specified size. The value of ap tells
* us what the address of the label to try and allocate a buffer. This value is
* an offset from the current base to that value.
*/
static int
genasm_firstcache(uint8_t *bp, uint32_t csize, uint32_t ap)
{
uint32_t addr;

bcopy(inicache, bp, sizeof (inicache));
bcopy(&csize, bp + PTC_INICACHE_CMP, sizeof (csize));
bcopy(&csize, bp + PTC_INICACHE_SIZE, sizeof (csize));
addr = PTC_JMPADDR(ap, PTC_INICACHE_JMP);
ASSERT(addr != 0);
bcopy(&addr, bp + PTC_INICACHE_JMP, sizeof (addr));

return (sizeof (inicache));
}

static int
genasm_gencache(uint8_t *bp, int num, uint32_t csize, uint32_t ap)
{
uint32_t addr;
uint8_t coff;

ASSERT(256 / PTC_ROOT_SIZE > num);
ASSERT(num != 0);
bcopy(gencache, bp, sizeof (gencache));
bcopy(&csize, bp + PTC_GENCACHE_CMP, sizeof (csize));
bcopy(&csize, bp + PTC_GENCACHE_SIZE, sizeof (csize));
coff = num * PTC_ROOT_SIZE;
bcopy(&coff, bp + PTC_GENCACHE_NUM, sizeof (coff));
addr = PTC_JMPADDR(ap, PTC_GENCACHE_JMP);
bcopy(&addr, bp + PTC_GENCACHE_JMP, sizeof (addr));

return (sizeof (gencache));
}

static int
genasm_lastcache(uint8_t *bp, int num, uint32_t csize, uint32_t ep)
{
uint8_t addr;

ASSERT(ep <= 0xff && ep > 7);
ASSERT(256 / PTC_ROOT_SIZE > num);
bcopy(fincache, bp, sizeof (fincache));
bcopy(&csize, bp + PTC_FINCACHE_CMP, sizeof (csize));
bcopy(&csize, bp + PTC_FINCACHE_SIZE, sizeof (csize));
addr = num * PTC_ROOT_SIZE;
bcopy(&addr, bp + PTC_FINCACHE_NUM, sizeof (addr));
addr = ep - PTC_FINCACHE_JMP - 1;
bcopy(&addr, bp + PTC_FINCACHE_JMP, sizeof (addr));

return (sizeof (fincache));
}

static int
genasm_malfini(uint8_t *bp, uintptr_t mptr)
{
uint32_t addr;

bcopy(malfini, bp, sizeof (malfini));
addr = PTC_JMPADDR(mptr, ((uintptr_t)bp + PTC_MALFINI_JMADDR));
bcopy(&addr, bp + PTC_MALFINI_JMADDR, sizeof (addr));

return (sizeof (malfini));
}

static int
genasm_frfini(uint8_t *bp, uint32_t maxthr, uintptr_t fptr)
{
uint32_t addr;

bcopy(freefini, bp, sizeof (freefini));
bcopy(&maxthr, bp + PTC_FRFINI_CACHEMAX, sizeof (maxthr));
addr = PTC_JMPADDR(fptr, ((uintptr_t)bp + PTC_FRFINI_JFADDR));
bcopy(&addr, bp + PTC_FRFINI_JFADDR, sizeof (addr));

return (sizeof (freefini));
}

/*
* The malloc inline assembly is constructed as follows:
*
* o Malloc prologue assembly
* o Generic first-cache check
* o n Generic cache checks (where n = _tmem_get_entries() - 2)
* o Generic last-cache check
* o Malloc epilogue assembly
*
* Generally there are at least three caches. When there is only one cache we
* only use the generic last-cache. In the case where there are two caches, we
* just leave out the middle ones.
*/
static int
genasm_malloc(void *base, size_t len, int nents, int *umem_alloc_sizes)
{
int ii, off;
uint8_t *bp;
size_t total;
uint32_t allocoff, erroff;

total = sizeof (malinit) + sizeof (malfini) + sizeof (fincache);

if (nents >= 2)
total += sizeof (inicache) + sizeof (gencache) * (nents - 2);

if (total > len)
return (1);

erroff = total - sizeof (malfini) + PTC_MALFINI_JMLABEL;
allocoff = total - sizeof (malfini) + PTC_MALFINI_ALLABEL;

bp = base;

off = genasm_malinit(bp, umem_tmem_off, erroff,
umem_alloc_sizes[nents-1]);
bp += off;
allocoff -= off;
erroff -= off;

if (nents > 1) {
off = genasm_firstcache(bp, umem_alloc_sizes[0], allocoff);
bp += off;
allocoff -= off;
erroff -= off;
}

for (ii = 1; ii < nents - 1; ii++) {
off = genasm_gencache(bp, ii, umem_alloc_sizes[ii], allocoff);
bp += off;
allocoff -= off;
erroff -= off;
}

bp += genasm_lastcache(bp, nents - 1, umem_alloc_sizes[nents - 1],
erroff);
bp += genasm_malfini(bp, umem_genasm_omptr);
ASSERT(((uintptr_t)bp - total) == (uintptr_t)base);

return (0);
}

static int
genasm_free(void *base, size_t len, int nents, int *umem_alloc_sizes)
{
uint8_t *bp;
int ii, off;
size_t total;
uint32_t rbufoff, retoff, erroff;

/* Assume that nents has already been audited for us */
total = sizeof (freeinit) + sizeof (freefini) + sizeof (fincache);
if (nents >= 2)
total += sizeof (inicache) + sizeof (gencache) * (nents - 2);

if (total > len)
return (1);

erroff = total - (sizeof (freefini) - PTC_FRFINI_JFLABEL);
rbufoff = total - (sizeof (freefini) - PTC_FRFINI_RBUFLABEL);
retoff = total - (sizeof (freefini) - PTC_FRFINI_DONELABEL);

bp = base;

off = genasm_frinit(bp, umem_tmem_off, retoff, erroff,
umem_alloc_sizes[nents - 1]);
bp += off;
erroff -= off;
rbufoff -= off;

if (nents > 1) {
off = genasm_firstcache(bp, umem_alloc_sizes[0], rbufoff);
bp += off;
erroff -= off;
rbufoff -= off;
}

for (ii = 1; ii < nents - 1; ii++) {
off = genasm_gencache(bp, ii, umem_alloc_sizes[ii], rbufoff);
bp += off;
rbufoff -= off;
erroff -= off;
}

bp += genasm_lastcache(bp, nents - 1, umem_alloc_sizes[nents - 1],
erroff);
bp += genasm_frfini(bp, umem_ptc_size, umem_genasm_ofptr);
ASSERT(((uintptr_t)bp - total) == (uintptr_t)base);

return (0);
}

int
umem_genasm(int *alloc_sizes, umem_cache_t **caches, int ncaches)
{
int nents, i;
uint8_t *mptr;
uint8_t *fptr;
uint64_t v, *vptr;

mptr = (void *)((uintptr_t)umem_genasm_mptr + 5);
fptr = (void *)((uintptr_t)umem_genasm_fptr + 5);
if (umem_genasm_mptr == 0 || umem_genasm_msize == 0 ||
umem_genasm_fptr == 0 || umem_genasm_fsize == 0)
return (1);

/*
* The total number of caches that we can service is the minimum of:
* o the amount supported by libc
* o the total number of umem caches
* o we use a single byte addl, so it's 255 / sizeof (uintptr_t). For
* 32-bit, this is 63.
*/
nents = _tmem_get_nentries();

if (UMEM_GENASM_MAX32 < nents)
nents = UMEM_GENASM_MAX32;

if (ncaches < nents)
nents = ncaches;

/* Based on our constraints, this is not an error */
if (nents == 0 || umem_ptc_size == 0)
return (0);

/* Take into account the jump */
if (genasm_malloc(mptr, umem_genasm_msize, nents,
alloc_sizes) != 0)
return (1);

if (genasm_free(fptr, umem_genasm_fsize, nents,
alloc_sizes) != 0)
return (1);

/* nop out the jump with a multibyte jump */
vptr = (void *)umem_genasm_mptr;
v = MULTINOP;
v |= *vptr & (0xffffffULL << 40);
(void) atomic_swap_64(vptr, v);
vptr = (void *)umem_genasm_fptr;
v = MULTINOP;
v |= *vptr & (0xffffffULL << 40);
(void) atomic_swap_64(vptr, v);

for (i = 0; i < nents; i++)
caches[i]->cache_flags |= UMF_PTC;

return (0);
}
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