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Fix JIT stub veneers being reused after an OPcache restart on AArch64 #24273

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Fix JIT stub veneers being reused after an OPcache restart on AArch64 #24273

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7 changes: 5 additions & 2 deletions ext/opcache/jit/zend_jit.c
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Original file line number Diff line number Diff line change
Expand Up @@ -3702,8 +3702,8 @@ void zend_jit_startup(void *buf, size_t size, bool reattached)
*dasm_ptr = (void**)*dasm_ptr + sizeof(zend_jit_stubs) / sizeof(zend_jit_stubs[0]);
#elif defined(IR_TARGET_AARCH64)
zend_jit_stub_handlers = dasm_buf;
*dasm_ptr = (void**)*dasm_ptr + (sizeof(zend_jit_stubs) / sizeof(zend_jit_stubs[0])) * 2;
memset(zend_jit_stub_handlers, 0, (sizeof(zend_jit_stubs) / sizeof(zend_jit_stubs[0])) * 2 * sizeof(void*));
*dasm_ptr = (void**)*dasm_ptr + (sizeof(zend_jit_stubs) / sizeof(zend_jit_stubs[0])) * 3;
memset(zend_jit_stub_handlers, 0, (sizeof(zend_jit_stubs) / sizeof(zend_jit_stubs[0])) * 3 * sizeof(void*));
#endif
*dasm_ptr = (void*)ZEND_MM_ALIGNED_SIZE_EX(((size_t)(*dasm_ptr)), 16);
zend_jit_protect();
Expand Down Expand Up @@ -3889,6 +3889,9 @@ void zend_jit_restart(void)

/* restore JIT buffer pos */
dasm_ptr[0] = dasm_ptr[1];
#if defined(IR_TARGET_AARCH64)
zend_jit_restore_stub_handlers();
#endif

zend_jit_trace_restart();

Expand Down
21 changes: 21 additions & 0 deletions ext/opcache/jit/zend_jit_ir.c
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Original file line number Diff line number Diff line change
Expand Up @@ -449,6 +449,24 @@ static void zend_jit_commit_veneers(void)
}
}
}

/* zend_jit_commit_veneers() replaces the address of a stub by the address of a veneer emitted
* after it. zend_jit_restart() rewinds the buffer below such veneers, so it restores the
* original addresses, kept after the pending veneers. */
static void zend_jit_save_stub_handlers(void)
{
int count = sizeof(zend_jit_stubs) / sizeof(zend_jit_stubs[0]);

memcpy(zend_jit_stub_handlers + count * 2, zend_jit_stub_handlers, count * sizeof(void*));
}

static void zend_jit_restore_stub_handlers(void)
{
int count = sizeof(zend_jit_stubs) / sizeof(zend_jit_stubs[0]);

memcpy(zend_jit_stub_handlers, zend_jit_stub_handlers + count * 2, count * sizeof(void*));
memset(zend_jit_stub_handlers + count, 0, count * sizeof(void*));
}
#endif

static bool zend_jit_prefer_const_addr_load(zend_jit_ctx *jit, uintptr_t addr)
Expand Down Expand Up @@ -2969,6 +2987,9 @@ static void zend_jit_setup_stubs(void)
}
zend_jit_free_ctx(&jit);
}
#if defined(IR_TARGET_AARCH64)
zend_jit_save_stub_handlers();
#endif
}

#define REGISTER_HELPER(n) \
Expand Down
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