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Reorganize and fix placement of generated machine code on x64.

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This commit is contained in:
Mike Pall 2010-04-25 14:52:29 +02:00
parent 2e24770ed3
commit 87e4daf89c
1 changed files with 58 additions and 54 deletions
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112
src/lj_mcode.c
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@ -32,7 +32,7 @@ static void *mcode_alloc_at(jit_State *J, uintptr_t hint, size_t sz, DWORD prot)
{
void *p = VirtualAlloc((void *)hint, sz,
MEM_RESERVE|MEM_COMMIT|MEM_TOP_DOWN, prot);
if (!p)
if (!p && !hint)
lj_trace_err(J, LJ_TRERR_MCODEAL);
return p;
}
@ -64,7 +64,7 @@ static void mcode_setprot(void *p, size_t sz, DWORD prot)
static void *mcode_alloc_at(jit_State *J, uintptr_t hint, size_t sz, int prot)
{
void *p = mmap((void *)hint, sz, prot, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0);
if (p == MAP_FAILED)
if (p == MAP_FAILED && !hint)
lj_trace_err(J, LJ_TRERR_MCODEAL);
return p;
}
@ -80,6 +80,10 @@ static void mcode_setprot(void *p, size_t sz, int prot)
mprotect(p, sz, prot);
}
#elif LJ_64
#error "Missing OS support for allocating executable memory"
#else
/* Fallback allocator. This will fail if memory is not executable by default. */
@ -103,51 +107,7 @@ static void mcode_free(jit_State *J, void *p, size_t sz)
#endif
/* -- MCode area allocation ----------------------------------------------- */
#if LJ_64
/* Get memory within relative jump distance of our code in 64 bit mode. */
static void *mcode_alloc(jit_State *J, size_t sz, int prot)
{
/* Target an address in the static assembler code (64K aligned).
** Try addresses within a distance of target-1GB+1MB .. target+1GB-1MB.
*/
uintptr_t target = (uintptr_t)(void *)lj_vm_exit_handler & ~(uintptr_t)0xffff;
const uintptr_t range = (1u<<31) - (1u << 21);
int i;
/* First try a contiguous area below the last one. */
if (J->mcarea && (uintptr_t)J->mcarea - sz < (uintptr_t)1<<47) {
void *p = mcode_alloc_at(J, (uintptr_t)J->mcarea - sz, sz, prot);
if ((uintptr_t)p + sz - target < range || target - (uintptr_t)p < range)
return p;
mcode_free(J, p, sz); /* Free badly placed area. */
}
/* Next try probing with hinted addresses. */
for (i = 0; i < 32; i++) { /* 32 attempts ought to be enough ... */
uintptr_t hint;
void *p;
do {
hint = (0x78fb ^ LJ_PRNG_BITS(J, 15)) << 16; /* 64K aligned. */
} while (!(hint + sz < range &&
target + hint - (range>>1) < (uintptr_t)1<<47));
p = mcode_alloc_at(J, target + hint - (range>>1), sz, prot);
if ((uintptr_t)p + sz - target < range || target - (uintptr_t)p < range)
return p;
mcode_free(J, p, sz); /* Free badly placed area. */
}
lj_trace_err(J, LJ_TRERR_MCODEAL); /* Give up. OS probably ignores hints? */
return NULL;
}
#else
/* All 32 bit memory addresses are reachable by relative jumps on x86. */
#define mcode_alloc(J, sz, prot) mcode_alloc_at((J), 0, (sz), (prot))
#endif
/* -- MCode area management ----------------------------------------------- */
/* -- MCode area protection ----------------------------------------------- */
/* Define this ONLY if the page protection twiddling becomes a bottleneck. */
#ifdef LUAJIT_UNPROTECT_MCODE
@ -165,6 +125,11 @@ static void *mcode_alloc(jit_State *J, size_t sz, int prot)
#define MCPROT_GEN MCPROT_RWX
#define MCPROT_RUN MCPROT_RWX
static void mcode_protect(jit_State *J, int prot)
{
UNUSED(J); UNUSED(prot);
}
#else
/* This is the default behaviour and much safer:
@ -178,21 +143,60 @@ static void *mcode_alloc(jit_State *J, size_t sz, int prot)
#define MCPROT_GEN MCPROT_RW
#define MCPROT_RUN MCPROT_RX
#endif
/* Change protection of MCode area. */
static void mcode_protect(jit_State *J, int prot)
{
#ifdef LUAJIT_UNPROTECT_MCODE
UNUSED(J); UNUSED(prot);
#else
if (J->mcprot != prot) {
mcode_setprot(J->mcarea, J->szmcarea, prot);
J->mcprot = prot;
}
#endif
}
#endif
/* -- MCode area allocation ----------------------------------------------- */
#if LJ_64
/* Get memory within relative jump distance of our code in 64 bit mode. */
static void *mcode_alloc(jit_State *J, size_t sz)
{
/* Target an address in the static assembler code (64K aligned).
** Try addresses within a distance of target-1GB+1MB .. target+1GB-1MB.
*/
uintptr_t target = (uintptr_t)(void *)lj_vm_exit_handler & ~(uintptr_t)0xffff;
const uintptr_t range = (1u<<31) - (1u << 21);
/* First try a contiguous area below the last one. */
uintptr_t hint = (uintptr_t)J->mcarea - sz;
int i;
for (i = 0; i < 32; i++) { /* 32 attempts ought to be enough ... */
if (hint && hint < (uintptr_t)1<<47) {
void *p = mcode_alloc_at(J, hint, sz, MCPROT_GEN);
if (p && (uintptr_t)p < (uintptr_t)1<<47) {
if ((uintptr_t)p + sz - target < range || target - (uintptr_t)p < range)
return p;
mcode_free(J, p, sz); /* Free badly placed area. */
}
}
/* Next try probing pseudo-random addresses. */
do {
hint = (0x78fb ^ LJ_PRNG_BITS(J, 15)) << 16; /* 64K aligned. */
} while (!(hint + sz < range));
hint = target + hint - (range>>1);
}
lj_trace_err(J, LJ_TRERR_MCODEAL); /* Give up. OS probably ignores hints? */
return NULL;
}
#else
/* All 32 bit memory addresses are reachable by relative jumps on x86. */
#define mcode_alloc(J, sz) mcode_alloc_at((J), 0, (sz), MCPROT_GEN)
#endif
/* -- MCode area management ----------------------------------------------- */
/* Linked list of MCode areas. */
typedef struct MCLink {
MCode *next; /* Next area. */
@ -205,7 +209,7 @@ static void mcode_allocarea(jit_State *J)
MCode *oldarea = J->mcarea;
size_t sz = (size_t)J->param[JIT_P_sizemcode] << 10;
sz = (sz + LJ_PAGESIZE-1) & ~(size_t)(LJ_PAGESIZE - 1);
J->mcarea = (MCode *)mcode_alloc(J, sz, MCPROT_GEN);
J->mcarea = (MCode *)mcode_alloc(J, sz);
J->szmcarea = sz;
J->mcprot = MCPROT_GEN;
J->mctop = (MCode *)((char *)J->mcarea + J->szmcarea);