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Improve dlopen() on Apple Silicon

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- Introduce MAP_JIT which is zero on other platforms
- Invent __jit_begin() and __jit_end() which wrap Apple's APIs
- Runtime dispatch to sys_icache_invalidate() in __clear_cache()
This commit is contained in:
Justine Tunney 2023-11-17 02:33:14 -08:00
parent 7a9e176ecf
commit 529cb4817c
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GPG key ID: BE714B4575D6E328
20 changed files with 120 additions and 117 deletions
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19
libc/dlopen/dlopen.c
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@ -424,12 +424,12 @@ static char *dlerror_set(const char *str) {
return dlerror_buf;
}
static char *foreign_alloc_block(void) {
static dontinline char *foreign_alloc_block(void) {
char *p = 0;
size_t sz = 65536;
if (!IsWindows()) {
p = __sys_mmap(0, sz, PROT_READ | PROT_WRITE | PROT_EXEC,
MAP_PRIVATE | MAP_ANONYMOUS, -1, 0, 0);
MAP_PRIVATE | MAP_ANONYMOUS | MAP_JIT, -1, 0, 0);
if (p == MAP_FAILED) {
p = 0;
}
@ -448,7 +448,7 @@ static char *foreign_alloc_block(void) {
return p;
}
static void *foreign_alloc(size_t n) {
static dontinline void *foreign_alloc(size_t n) {
void *res;
static char *block;
static pthread_mutex_t lock = PTHREAD_MUTEX_INITIALIZER;
@ -520,11 +520,14 @@ static void *foreign_thunk_sysv(void *func) {
*p++ = 0xff;
*p++ = 0xe2;
#elif defined(__aarch64__)
if (!(p = code = foreign_alloc(36))) return 0; // 16 + 16 + 4 = 36
p = movimm(p, 5, (uintptr_t)func);
p = movimm(p, 10, (uintptr_t)foreign_tramp);
*(uint32_t *)p = 0xd61f0140; // br x10
__clear_cache(code, p + 4);
__jit_begin();
if ((p = code = foreign_alloc(36))) {
p = movimm(p, 5, (uintptr_t)func);
p = movimm(p, 10, (uintptr_t)foreign_tramp);
*(uint32_t *)p = 0xd61f0140; // br x10
__clear_cache(code, p + 4);
}
__jit_end();
#else
#error "unsupported architecture"
#endif