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authorDaniel Baumann <daniel.baumann@progress-linux.org>2024-04-19 00:47:55 +0000
committerDaniel Baumann <daniel.baumann@progress-linux.org>2024-04-19 00:47:55 +0000
commit26a029d407be480d791972afb5975cf62c9360a6 (patch)
treef435a8308119effd964b339f76abb83a57c29483 /js/src/jit/AutoWritableJitCode.h
parentInitial commit. (diff)
downloadfirefox-26a029d407be480d791972afb5975cf62c9360a6.tar.xz
firefox-26a029d407be480d791972afb5975cf62c9360a6.zip
Adding upstream version 124.0.1.upstream/124.0.1
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
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+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*-
+ * vim: set ts=8 sts=2 et sw=2 tw=80:
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef jit_AutoWritableJitCode_h
+#define jit_AutoWritableJitCode_h
+
+#include "mozilla/Assertions.h"
+#include "mozilla/Attributes.h"
+#include "mozilla/ScopeExit.h"
+#include "mozilla/TimeStamp.h"
+
+#include <stddef.h>
+
+#include "jit/ExecutableAllocator.h"
+#include "jit/JitCode.h"
+#include "jit/JitOptions.h"
+#include "jit/ProcessExecutableMemory.h"
+#include "vm/JSContext.h"
+#include "vm/Realm.h"
+#include "vm/Runtime.h"
+
+namespace js::jit {
+
+// This class ensures JIT code is executable on its destruction. Creators
+// must call makeWritable(), and not attempt to write to the buffer if it fails.
+//
+// AutoWritableJitCodeFallible may only fail to make code writable; it cannot
+// fail to make JIT code executable (because the creating code has no chance to
+// recover from a failed destructor).
+class MOZ_RAII AutoWritableJitCodeFallible {
+ JSRuntime* rt_;
+ void* addr_;
+ size_t size_;
+ AutoMarkJitCodeWritableForThread writableForThread_;
+
+ public:
+ AutoWritableJitCodeFallible(JSRuntime* rt, void* addr, size_t size)
+ : rt_(rt), addr_(addr), size_(size) {
+ rt_->toggleAutoWritableJitCodeActive(true);
+ }
+
+ AutoWritableJitCodeFallible(void* addr, size_t size)
+ : AutoWritableJitCodeFallible(TlsContext.get()->runtime(), addr, size) {}
+
+ explicit AutoWritableJitCodeFallible(JitCode* code)
+ : AutoWritableJitCodeFallible(code->runtimeFromMainThread(), code->raw(),
+ code->bufferSize()) {}
+
+ [[nodiscard]] bool makeWritable() {
+ return ExecutableAllocator::makeWritable(addr_, size_);
+ }
+
+ ~AutoWritableJitCodeFallible() {
+ // Taking TimeStamps frequently can be expensive, and there's no point
+ // measuring this if write protection is disabled.
+ const bool measuringTime = JitOptions.writeProtectCode;
+ const mozilla::TimeStamp startTime =
+ measuringTime ? mozilla::TimeStamp::Now() : mozilla::TimeStamp();
+ auto timer = mozilla::MakeScopeExit([&] {
+ if (measuringTime) {
+ if (Realm* realm = rt_->mainContextFromOwnThread()->realm()) {
+ realm->timers.protectTime += mozilla::TimeStamp::Now() - startTime;
+ }
+ }
+ });
+
+ if (!ExecutableAllocator::makeExecutableAndFlushICache(addr_, size_)) {
+ MOZ_CRASH();
+ }
+ rt_->toggleAutoWritableJitCodeActive(false);
+ }
+};
+
+// Infallible variant of AutoWritableJitCodeFallible, ensures writable during
+// construction
+class MOZ_RAII AutoWritableJitCode : private AutoWritableJitCodeFallible {
+ public:
+ AutoWritableJitCode(JSRuntime* rt, void* addr, size_t size)
+ : AutoWritableJitCodeFallible(rt, addr, size) {
+ AutoEnterOOMUnsafeRegion oomUnsafe;
+ if (!makeWritable()) {
+ oomUnsafe.crash("Failed to mmap. Likely no mappings available.");
+ }
+ }
+
+ AutoWritableJitCode(void* addr, size_t size)
+ : AutoWritableJitCode(TlsContext.get()->runtime(), addr, size) {}
+
+ explicit AutoWritableJitCode(JitCode* code)
+ : AutoWritableJitCode(code->runtimeFromMainThread(), code->raw(),
+ code->bufferSize()) {}
+};
+
+} // namespace js::jit
+
+#endif /* jit_AutoWritableJitCode_h */