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Bug 1883457 - Part 2: Use be_memory_inline_jit_restrict_* APIs for JIT on iOS, r=jandem

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This change enables the JS_USE_APPLE_FAST_WX option for iOS, but uses the
BrowserEngineKit APIs rather than the pthread_jit APIs which are available on
macOS. It is unclear to me if there are other differences with these APIs which
would need to be handled beyond what has been written so far, as this is just a
naive substitution.

Given these functions are explicitly "inline", it may be desirable at some
point to refactor the code to allow the calls to be made inline within
ProcessExecutableMemory.h, however that was left out-of-scope.

Differential Revision: https://phabricator.services.mozilla.com/D203499
This commit is contained in:
Nika Layzell 2024-03-25 17:12:53 +00:00
parent 5c6cb3e502
commit d574456eec
3 changed files with 20 additions and 6 deletions
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11
js/moz.configure
View File

@ -591,13 +591,14 @@ set_define("MOZ_AARCH64_JSCVT", aarch64_jscvt)
@depends(target)
def has_pthread_jit_write_protect_np(target):
return target.os == "OSX" and target.cpu == "aarch64"
def has_apple_fast_wx(target):
return target.kernel == "Darwin" and target.cpu == "aarch64"
# On Apple Silicon we use MAP_JIT with pthread_jit_write_protect_np to implement
# JIT code write protection.
set_define("JS_USE_APPLE_FAST_WX", True, when=has_pthread_jit_write_protect_np)
# On Apple Silicon macOS we use MAP_JIT with pthread_jit_write_protect_np to
# implement JIT code write protection, while on iOS we use MAP_JIT with
# be_memory_inline_jit_restrict_*.
set_define("JS_USE_APPLE_FAST_WX", True, when=has_apple_fast_wx)
# CTypes

3
js/src/jit/JitOptions.cpp
View File

@ -447,7 +447,8 @@ void DefaultJitOptions::resetNormalIonWarmUpThreshold() {
void DefaultJitOptions::maybeSetWriteProtectCode(bool val) {
#ifdef JS_USE_APPLE_FAST_WX
// On Apple Silicon we always use pthread_jit_write_protect_np.
// On Apple Silicon we always use pthread_jit_write_protect_np, or
// be_memory_inline_jit_restrict_*.
MOZ_ASSERT(!writeProtectCode);
#else
writeProtectCode = val;

12
js/src/jit/ProcessExecutableMemory.cpp
View File

@ -46,6 +46,10 @@
# include <valgrind/valgrind.h>
#endif
#if defined(XP_IOS)
# include <BrowserEngineCore/BEMemory.h>
#endif
using namespace js;
using namespace js::jit;
@ -990,11 +994,19 @@ bool js::jit::ReprotectRegion(void* start, size_t size,
#ifdef JS_USE_APPLE_FAST_WX
void js::jit::AutoMarkJitCodeWritableForThread::markExecutable(
bool executable) {
# if defined(XP_IOS)
if (executable) {
be_memory_inline_jit_restrict_rwx_to_rx_with_witness();
} else {
be_memory_inline_jit_restrict_rwx_to_rw_with_witness();
}
# else
if (__builtin_available(macOS 11.0, *)) {
pthread_jit_write_protect_np(executable);
} else {
MOZ_CRASH("pthread_jit_write_protect_np must be available");
}
# endif
}
#endif