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self-modifying code support 

git-svn-id: svn://svn.savannah.nongnu.org/qemu/trunk@163 c046a42c-6fe2-441c-8c8c-71466251a162
This commit is contained in:
bellard 2003-05-14 19:00:11 +00:00
parent 727d01d4f6
commit fd6ce8f660
3 changed files with 400 additions and 123 deletions
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82
cpu-i386.h
View File

@ -445,16 +445,21 @@ extern unsigned long host_page_mask;
#define HOST_PAGE_ALIGN(addr) (((addr) + host_page_size - 1) & host_page_mask)
/* same as PROT_xxx */
#define PAGE_READ 0x0001
#define PAGE_WRITE 0x0002
#define PAGE_EXEC 0x0004
#define PAGE_BITS (PAGE_READ | PAGE_WRITE | PAGE_EXEC)
#define PAGE_VALID 0x0008
#define PAGE_READ 0x0001
#define PAGE_WRITE 0x0002
#define PAGE_EXEC 0x0004
#define PAGE_BITS (PAGE_READ | PAGE_WRITE | PAGE_EXEC)
#define PAGE_VALID 0x0008
/* original state of the write flag (used when tracking self-modifying
code */
#define PAGE_WRITE_ORG 0x0010
void page_dump(FILE *f);
int page_get_flags(unsigned long address);
void page_set_flags(unsigned long start, unsigned long end, int flags);
void page_unprotect_range(uint8_t *data, unsigned long data_size);
/***************************************************/
/* internal functions */
#define GEN_FLAG_CODE32_SHIFT 0
@ -468,8 +473,73 @@ void page_set_flags(unsigned long start, unsigned long end, int flags);
int cpu_x86_gen_code(uint8_t *gen_code_buf, int max_code_size,
int *gen_code_size_ptr,
uint8_t *pc_start, uint8_t *cs_base, int flags);
uint8_t *pc_start, uint8_t *cs_base, int flags,
int *code_size_ptr);
void cpu_x86_tblocks_init(void);
void page_init(void);
int page_unprotect(unsigned long address);
#define CODE_GEN_MAX_SIZE 65536
#define CODE_GEN_ALIGN 16 /* must be >= of the size of a icache line */
#define CODE_GEN_HASH_BITS 15
#define CODE_GEN_HASH_SIZE (1 << CODE_GEN_HASH_BITS)
/* maximum total translate dcode allocated */
#define CODE_GEN_BUFFER_SIZE (2048 * 1024)
//#define CODE_GEN_BUFFER_SIZE (128 * 1024)
typedef struct TranslationBlock {
unsigned long pc; /* simulated PC corresponding to this block (EIP + CS base) */
unsigned long cs_base; /* CS base for this block */
unsigned int flags; /* flags defining in which context the code was generated */
uint16_t size; /* size of target code for this block (1 <=
size <= TARGET_PAGE_SIZE) */
uint8_t *tc_ptr; /* pointer to the translated code */
struct TranslationBlock *hash_next; /* next matching block */
struct TranslationBlock *page_next[2]; /* next blocks in even/odd page */
} TranslationBlock;
static inline unsigned int tb_hash_func(unsigned long pc)
{
return pc & (CODE_GEN_HASH_SIZE - 1);
}
void tb_flush(void);
TranslationBlock *tb_alloc(unsigned long pc,
unsigned long size);
extern TranslationBlock *tb_hash[CODE_GEN_HASH_SIZE];
extern uint8_t code_gen_buffer[CODE_GEN_BUFFER_SIZE];
extern uint8_t *code_gen_ptr;
/* find a translation block in the translation cache. If not found,
return NULL and the pointer to the last element of the list in pptb */
static inline TranslationBlock *tb_find(TranslationBlock ***pptb,
unsigned long pc,
unsigned long cs_base,
unsigned int flags)
{
TranslationBlock **ptb, *tb;
unsigned int h;
h = tb_hash_func(pc);
ptb = &tb_hash[h];
for(;;) {
tb = *ptb;
if (!tb)
break;
if (tb->pc == pc && tb->cs_base == cs_base && tb->flags == flags)
return tb;
ptb = &tb->hash_next;
}
*pptb = ptb;
return NULL;
}
#ifndef offsetof
#define offsetof(type, field) ((size_t) &((type *)0)->field)
#endif
#endif /* CPU_I386_H */

128
exec-i386.c
View File

@ -21,39 +21,10 @@
#include "disas.h"
//#define DEBUG_EXEC
#define DEBUG_FLUSH
//#define DEBUG_SIGNAL
/* main execution loop */
/* maximum total translate dcode allocated */
#define CODE_GEN_BUFFER_SIZE (2048 * 1024)
//#define CODE_GEN_BUFFER_SIZE (128 * 1024)
#define CODE_GEN_MAX_SIZE 65536
#define CODE_GEN_ALIGN 16 /* must be >= of the size of a icache line */
/* threshold to flush the translated code buffer */
#define CODE_GEN_BUFFER_MAX_SIZE (CODE_GEN_BUFFER_SIZE - CODE_GEN_MAX_SIZE)
#define CODE_GEN_MAX_BLOCKS (CODE_GEN_BUFFER_SIZE / 64)
#define CODE_GEN_HASH_BITS 15
#define CODE_GEN_HASH_SIZE (1 << CODE_GEN_HASH_BITS)
typedef struct TranslationBlock {
unsigned long pc; /* simulated PC corresponding to this block (EIP + CS base) */
unsigned long cs_base; /* CS base for this block */
unsigned int flags; /* flags defining in which context the code was generated */
uint8_t *tc_ptr; /* pointer to the translated code */
struct TranslationBlock *hash_next; /* next matching block */
} TranslationBlock;
TranslationBlock tbs[CODE_GEN_MAX_BLOCKS];
TranslationBlock *tb_hash[CODE_GEN_HASH_SIZE];
int nb_tbs;
uint8_t code_gen_buffer[CODE_GEN_BUFFER_SIZE];
uint8_t *code_gen_ptr;
/* thread support */
#ifdef __powerpc__
@ -195,70 +166,6 @@ void raise_exception(int exception_index)
raise_exception_err(exception_index, 0);
}
void cpu_x86_tblocks_init(void)
{
if (!code_gen_ptr) {
code_gen_ptr = code_gen_buffer;
}
}
/* flush all the translation blocks */
static void tb_flush(void)
{
int i;
#ifdef DEBUG_FLUSH
printf("gemu: flush code_size=%d nb_tbs=%d avg_tb_size=%d\n",
code_gen_ptr - code_gen_buffer,
nb_tbs,
(code_gen_ptr - code_gen_buffer) / nb_tbs);
#endif
nb_tbs = 0;
for(i = 0;i < CODE_GEN_HASH_SIZE; i++)
tb_hash[i] = NULL;
code_gen_ptr = code_gen_buffer;
/* XXX: flush processor icache at this point */
}
/* find a translation block in the translation cache. If not found,
return NULL and the pointer to the last element of the list in pptb */
static inline TranslationBlock *tb_find(TranslationBlock ***pptb,
unsigned long pc,
unsigned long cs_base,
unsigned int flags)
{
TranslationBlock **ptb, *tb;
unsigned int h;
h = pc & (CODE_GEN_HASH_SIZE - 1);
ptb = &tb_hash[h];
#if 0
/* XXX: hack to handle 16 bit modyfing code */
if (flags & (1 << GEN_FLAG_CODE32_SHIFT))
#endif
for(;;) {
tb = *ptb;
if (!tb)
break;
if (tb->pc == pc && tb->cs_base == cs_base && tb->flags == flags)
return tb;
ptb = &tb->hash_next;
}
*pptb = ptb;
return NULL;
}
/* allocate a new translation block. flush the translation buffer if
too many translation blocks or too much generated code */
static inline TranslationBlock *tb_alloc(void)
{
TranslationBlock *tb;
if (nb_tbs >= CODE_GEN_MAX_BLOCKS ||
(code_gen_ptr - code_gen_buffer) >= CODE_GEN_BUFFER_MAX_SIZE)
tb_flush();
tb = &tbs[nb_tbs++];
return tb;
}
int cpu_x86_exec(CPUX86State *env1)
{
int saved_T0, saved_T1, saved_A0;
@ -287,7 +194,7 @@ int cpu_x86_exec(CPUX86State *env1)
#ifdef reg_EDI
int saved_EDI;
#endif
int code_gen_size, ret;
int code_gen_size, ret, code_size;
void (*gen_func)(void);
TranslationBlock *tb, **ptb;
uint8_t *tc_ptr, *cs_base, *pc;
@ -390,15 +297,15 @@ int cpu_x86_exec(CPUX86State *env1)
cpu_lock();
tc_ptr = code_gen_ptr;
ret = cpu_x86_gen_code(code_gen_ptr, CODE_GEN_MAX_SIZE,
&code_gen_size, pc, cs_base, flags);
&code_gen_size, pc, cs_base, flags,
&code_size);
/* if invalid instruction, signal it */
if (ret != 0) {
cpu_unlock();
raise_exception(EXCP06_ILLOP);
}
tb = tb_alloc();
tb = tb_alloc((unsigned long)pc, code_size);
*ptb = tb;
tb->pc = (unsigned long)pc;
tb->cs_base = (unsigned long)cs_base;
tb->flags = flags;
tb->tc_ptr = tc_ptr;
@ -493,15 +400,22 @@ void cpu_x86_load_seg(CPUX86State *s, int seg_reg, int selector)
#include <sys/ucontext.h>
/* 'pc' is the host PC at which the exception was raised. 'address' is
the effective address of the memory exception */
the effective address of the memory exception. 'is_write' is 1 if a
write caused the exception and otherwise 0'. 'old_set' is the
signal set which should be restored */
static inline int handle_cpu_signal(unsigned long pc,
unsigned long address,
int is_write,
sigset_t *old_set)
{
#ifdef DEBUG_SIGNAL
printf("gemu: SIGSEGV pc=0x%08lx oldset=0x%08lx\n",
pc, *(unsigned long *)old_set);
#if defined(DEBUG_SIGNAL)
printf("qemu: SIGSEGV pc=0x%08lx address=%08lx wr=%d oldset=0x%08lx\n",
pc, address, is_write, *(unsigned long *)old_set);
#endif
if (is_write && page_unprotect(address)) {
sigprocmask(SIG_SETMASK, old_set, NULL);
return 1;
}
if (pc >= (unsigned long)code_gen_buffer &&
pc < (unsigned long)code_gen_buffer + CODE_GEN_BUFFER_SIZE) {
/* the PC is inside the translated code. It means that we have
@ -512,8 +426,7 @@ static inline int handle_cpu_signal(unsigned long pc,
/* XXX: need to compute virtual pc position by retranslating
code. The rest of the CPU state should be correct. */
env->cr2 = address;
/* XXX: more precise exception code */
raise_exception_err(EXCP0E_PAGE, 4);
raise_exception_err(EXCP0E_PAGE, 4 | (is_write << 1));
/* never comes here */
return 1;
} else {
@ -531,11 +444,16 @@ int cpu_x86_signal_handler(int host_signum, struct siginfo *info,
#ifndef REG_EIP
/* for glibc 2.1 */
#define REG_EIP EIP
#define REG_EIP EIP
#define REG_ERR ERR
#define REG_TRAPNO TRAPNO
#endif
pc = uc->uc_mcontext.gregs[REG_EIP];
pold_set = &uc->uc_sigmask;
return handle_cpu_signal(pc, (unsigned long)info->si_addr, pold_set);
return handle_cpu_signal(pc, (unsigned long)info->si_addr,
uc->uc_mcontext.gregs[REG_TRAPNO] == 0xe ?
(uc->uc_mcontext.gregs[REG_ERR] >> 1) & 1 : 0,
pold_set);
#else
#warning No CPU specific signal handler: cannot handle target SIGSEGV events
return 0;

313
exec.c
View File

@ -1,5 +1,5 @@
/*
* virtual page mapping
* virtual page mapping and translated block handling
*
* Copyright (c) 2003 Fabrice Bellard
*
@ -24,13 +24,32 @@
#include <errno.h>
#include <unistd.h>
#include <inttypes.h>
#include <sys/mman.h>
#include "cpu-i386.h"
//#define DEBUG_TB_INVALIDATE
#define DEBUG_FLUSH
/* make various TB consistency checks */
//#define DEBUG_TB_CHECK
/* threshold to flush the translated code buffer */
#define CODE_GEN_BUFFER_MAX_SIZE (CODE_GEN_BUFFER_SIZE - CODE_GEN_MAX_SIZE)
#define CODE_GEN_MAX_BLOCKS (CODE_GEN_BUFFER_SIZE / 64)
TranslationBlock tbs[CODE_GEN_MAX_BLOCKS];
TranslationBlock *tb_hash[CODE_GEN_HASH_SIZE];
int nb_tbs;
uint8_t code_gen_buffer[CODE_GEN_BUFFER_SIZE];
uint8_t *code_gen_ptr;
/* XXX: pack the flags in the low bits of the pointer ? */
typedef struct PageDesc {
struct TranslationBlock *first_tb;
unsigned long flags;
TranslationBlock *first_tb;
} PageDesc;
#define L2_BITS 10
@ -39,6 +58,8 @@ typedef struct PageDesc {
#define L1_SIZE (1 << L1_BITS)
#define L2_SIZE (1 << L2_BITS)
static void tb_invalidate_page(unsigned long address);
unsigned long real_host_page_size;
unsigned long host_page_bits;
unsigned long host_page_size;
@ -104,36 +125,44 @@ void page_dump(FILE *f)
}
}
static inline PageDesc *page_find_alloc(unsigned long address)
static inline PageDesc *page_find_alloc(unsigned int index)
{
unsigned int index;
PageDesc **lp, *p;
index = address >> TARGET_PAGE_BITS;
lp = &l1_map[index >> L2_BITS];
p = *lp;
if (!p) {
/* allocate if not found */
p = malloc(sizeof(PageDesc) * L2_SIZE);
memset(p, 0, sizeof(sizeof(PageDesc) * L2_SIZE));
memset(p, 0, sizeof(PageDesc) * L2_SIZE);
*lp = p;
}
return p + (index & (L2_SIZE - 1));
}
int page_get_flags(unsigned long address)
static inline PageDesc *page_find(unsigned int index)
{
unsigned int index;
PageDesc *p;
index = address >> TARGET_PAGE_BITS;
p = l1_map[index >> L2_BITS];
if (!p)
return 0;
return p[index & (L2_SIZE - 1)].flags;
return p + (index & (L2_SIZE - 1));
}
int page_get_flags(unsigned long address)
{
PageDesc *p;
p = page_find(address >> TARGET_PAGE_BITS);
if (!p)
return 0;
return p->flags;
}
/* modify the flags of a page and invalidate the code if
necessary. The flag PAGE_WRITE_ORG is positionned automatically
depending on PAGE_WRITE */
void page_set_flags(unsigned long start, unsigned long end, int flags)
{
PageDesc *p;
@ -141,8 +170,268 @@ void page_set_flags(unsigned long start, unsigned long end, int flags)
start = start & TARGET_PAGE_MASK;
end = TARGET_PAGE_ALIGN(end);
if (flags & PAGE_WRITE)
flags |= PAGE_WRITE_ORG;
for(addr = start; addr < end; addr += TARGET_PAGE_SIZE) {
p = page_find_alloc(addr);
p = page_find_alloc(addr >> TARGET_PAGE_BITS);
/* if the write protection is set, then we invalidate the code
inside */
if (!(p->flags & PAGE_WRITE) &&
(flags & PAGE_WRITE) &&
p->first_tb) {
tb_invalidate_page(addr);
}
p->flags = flags;
}
}
void cpu_x86_tblocks_init(void)
{
if (!code_gen_ptr) {
code_gen_ptr = code_gen_buffer;
}
}
/* set to NULL all the 'first_tb' fields in all PageDescs */
static void page_flush_tb(void)
{
int i, j;
PageDesc *p;
for(i = 0; i < L1_SIZE; i++) {
p = l1_map[i];
if (p) {
for(j = 0; j < L2_SIZE; j++)
p[j].first_tb = NULL;
}
}
}
/* flush all the translation blocks */
void tb_flush(void)
{
int i;
#ifdef DEBUG_FLUSH
printf("qemu: flush code_size=%d nb_tbs=%d avg_tb_size=%d\n",
code_gen_ptr - code_gen_buffer,
nb_tbs,
(code_gen_ptr - code_gen_buffer) / nb_tbs);
#endif
nb_tbs = 0;
for(i = 0;i < CODE_GEN_HASH_SIZE; i++)
tb_hash[i] = NULL;
page_flush_tb();
code_gen_ptr = code_gen_buffer;
/* XXX: flush processor icache at this point */
}
#ifdef DEBUG_TB_CHECK
static void tb_invalidate_check(unsigned long address)
{
TranslationBlock *tb;
int i;
address &= TARGET_PAGE_MASK;
for(i = 0;i < CODE_GEN_HASH_SIZE; i++) {
for(tb = tb_hash[i]; tb != NULL; tb = tb->hash_next) {
if (!(address + TARGET_PAGE_SIZE <= tb->pc ||
address >= tb->pc + tb->size)) {
printf("ERROR invalidate: address=%08lx PC=%08lx size=%04x\n",
address, tb->pc, tb->size);
}
}
}
}
/* verify that all the pages have correct rights for code */
static void tb_page_check(void)
{
TranslationBlock *tb;
int i, flags1, flags2;
for(i = 0;i < CODE_GEN_HASH_SIZE; i++) {
for(tb = tb_hash[i]; tb != NULL; tb = tb->hash_next) {
flags1 = page_get_flags(tb->pc);
flags2 = page_get_flags(tb->pc + tb->size - 1);
if ((flags1 & PAGE_WRITE) || (flags2 & PAGE_WRITE)) {
printf("ERROR page flags: PC=%08lx size=%04x f1=%x f2=%x\n",
tb->pc, tb->size, flags1, flags2);
}
}
}
}
#endif
/* invalidate one TB */
static inline void tb_remove(TranslationBlock **ptb, TranslationBlock *tb,
int next_offset)
{
TranslationBlock *tb1;
for(;;) {
tb1 = *ptb;
if (tb1 == tb) {
*ptb = *(TranslationBlock **)((char *)tb1 + next_offset);
break;
}
ptb = (TranslationBlock **)((char *)tb1 + next_offset);
}
}
static inline void tb_invalidate(TranslationBlock *tb, int parity)
{
PageDesc *p;
unsigned int page_index1, page_index2;
unsigned int h;
/* remove the TB from the hash list */
h = tb_hash_func(tb->pc);
tb_remove(&tb_hash[h], tb,
offsetof(TranslationBlock, hash_next));
/* remove the TB from the page list */
page_index1 = tb->pc >> TARGET_PAGE_BITS;
if ((page_index1 & 1) == parity) {
p = page_find(page_index1);
tb_remove(&p->first_tb, tb,
offsetof(TranslationBlock, page_next[page_index1 & 1]));
}
page_index2 = (tb->pc + tb->size - 1) >> TARGET_PAGE_BITS;
if ((page_index2 & 1) == parity) {
p = page_find(page_index2);
tb_remove(&p->first_tb, tb,
offsetof(TranslationBlock, page_next[page_index2 & 1]));
}
}
/* invalidate all TBs which intersect with the target page starting at addr */
static void tb_invalidate_page(unsigned long address)
{
TranslationBlock *tb_next, *tb;
unsigned int page_index;
int parity1, parity2;
PageDesc *p;
#ifdef DEBUG_TB_INVALIDATE
printf("tb_invalidate_page: %lx\n", address);
#endif
page_index = address >> TARGET_PAGE_BITS;
p = page_find(page_index);
if (!p)
return;
tb = p->first_tb;
parity1 = page_index & 1;
parity2 = parity1 ^ 1;
while (tb != NULL) {
tb_next = tb->page_next[parity1];
tb_invalidate(tb, parity2);
tb = tb_next;
}
p->first_tb = NULL;
}
/* add the tb in the target page and protect it if necessary */
static inline void tb_alloc_page(TranslationBlock *tb, unsigned int page_index)
{
PageDesc *p;
unsigned long host_start, host_end, addr, page_addr;
int prot;
p = page_find_alloc(page_index);
tb->page_next[page_index & 1] = p->first_tb;
p->first_tb = tb;
if (p->flags & PAGE_WRITE) {
/* force the host page as non writable (writes will have a
page fault + mprotect overhead) */
page_addr = (page_index << TARGET_PAGE_BITS);
host_start = page_addr & host_page_mask;
host_end = host_start + host_page_size;
prot = 0;
for(addr = host_start; addr < host_end; addr += TARGET_PAGE_SIZE)
prot |= page_get_flags(addr);
mprotect((void *)host_start, host_page_size,
(prot & PAGE_BITS) & ~PAGE_WRITE);
#ifdef DEBUG_TB_INVALIDATE
printf("protecting code page: 0x%08lx\n",
host_start);
#endif
p->flags &= ~PAGE_WRITE;
#ifdef DEBUG_TB_CHECK
tb_page_check();
#endif
}
}
/* Allocate a new translation block. Flush the translation buffer if
too many translation blocks or too much generated code. */
TranslationBlock *tb_alloc(unsigned long pc,
unsigned long size)
{
TranslationBlock *tb;
unsigned int page_index1, page_index2;
if (nb_tbs >= CODE_GEN_MAX_BLOCKS ||
(code_gen_ptr - code_gen_buffer) >= CODE_GEN_BUFFER_MAX_SIZE)
tb_flush();
tb = &tbs[nb_tbs++];
tb->pc = pc;
tb->size = size;
/* add in the page list */
page_index1 = pc >> TARGET_PAGE_BITS;
tb_alloc_page(tb, page_index1);
page_index2 = (pc + size - 1) >> TARGET_PAGE_BITS;
if (page_index2 != page_index1) {
tb_alloc_page(tb, page_index2);
}
return tb;
}
/* called from signal handler: invalidate the code and unprotect the
page. Return TRUE if the fault was succesfully handled. */
int page_unprotect(unsigned long address)
{
unsigned int page_index, prot;
PageDesc *p;
unsigned long host_start, host_end, addr;
page_index = address >> TARGET_PAGE_BITS;
p = page_find(page_index);
if (!p)
return 0;
if ((p->flags & (PAGE_WRITE_ORG | PAGE_WRITE)) == PAGE_WRITE_ORG) {
/* if the page was really writable, then we change its
protection back to writable */
host_start = address & host_page_mask;
host_end = host_start + host_page_size;
prot = 0;
for(addr = host_start; addr < host_end; addr += TARGET_PAGE_SIZE)
prot |= page_get_flags(addr);
mprotect((void *)host_start, host_page_size,
(prot & PAGE_BITS) | PAGE_WRITE);
p->flags |= PAGE_WRITE;
/* and since the content will be modified, we must invalidate
the corresponding translated code. */
tb_invalidate_page(address);
#ifdef DEBUG_TB_CHECK
tb_invalidate_check(address);
#endif
return 1;
} else {
return 0;
}
}
/* call this function when system calls directly modify a memory area */
void page_unprotect_range(uint8_t *data, unsigned long data_size)
{
unsigned long start, end, addr;
start = (unsigned long)data;
end = start + data_size;
start &= TARGET_PAGE_MASK;
end = TARGET_PAGE_ALIGN(end);
for(addr = start; addr < end; addr += TARGET_PAGE_SIZE) {
page_unprotect(addr);
}
}