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ddegazioddegazio
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Use mach_vm_remap instead of mach_vm_map to set up permanent mapping for g_config
https://bugs.webkit.org/show_bug.cgi?id=290066 rdar://147347736 Reviewed by Mark Lam. Uses mach_vm_remap to set up permanent mapping for g_config, preventing a possible issue where g_config values that were set up prior to WTF initialization would be zeroed out. * Source/WTF/wtf/WTFConfig.cpp: (WTF::setPermissionsOfConfigPage): (WTF::Config::initialize): Canonical link: https://commits.webkit.org/292440@main
1 parent 11716e6 commit 153af86

3 files changed

Lines changed: 8 additions & 26 deletions

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‎Source/JavaScriptCore/jit/ExecutableAllocator.cpp‎

Lines changed: 1 addition & 23 deletions
Original file line numberDiff line numberDiff line change
@@ -65,29 +65,7 @@ WTF_ALLOW_UNSAFE_BUFFER_USAGE_END
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#include <fcntl.h>
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#include <mach/mach.h>
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#include <mach/mach_time.h>
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extern "C" {
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/* Routine mach_vm_remap */
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#ifdef mig_external
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mig_external
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#else
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extern
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#endif /* mig_external */
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kern_return_t mach_vm_remap
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(
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vm_map_t target_task,
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mach_vm_address_t *target_address,
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mach_vm_size_t size,
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mach_vm_offset_t mask,
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int flags,
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vm_map_t src_task,
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mach_vm_address_t src_address,
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boolean_t copy,
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vm_prot_t *cur_protection,
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vm_prot_t *max_protection,
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vm_inherit_t inheritance
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);
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}
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#include <wtf/spi/cocoa/MachVMSPI.h>
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#endif
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#if USE(INLINE_JIT_PERMISSIONS_API)

‎Source/WTF/wtf/WTFConfig.cpp‎

Lines changed: 5 additions & 3 deletions
Original file line numberDiff line numberDiff line change
@@ -73,9 +73,13 @@ void setPermissionsOfConfigPage()
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std::call_once(onceFlag, [] {
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mach_vm_address_t addr = std::bit_cast<uintptr_t>(static_cast<void*>(WebConfig::g_config));
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auto flags = VM_FLAGS_FIXED | VM_FLAGS_OVERWRITE | VM_FLAGS_PERMANENT;
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auto prot = VM_PROT_READ | VM_PROT_WRITE;
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auto attemptVMMapping = [&] {
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return mach_vm_map(mach_task_self(), &addr, ConfigSizeToProtect, pageSize() - 1, flags, MEMORY_OBJECT_NULL, 0, false, VM_PROT_READ | VM_PROT_WRITE, VM_PROT_READ | VM_PROT_WRITE, VM_INHERIT_DEFAULT);
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// We use remap instead of map here to avoid zeroing the config,
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// since WebKit components like bmalloc can potentially use the
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// config prior to WTF initialization.
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return mach_vm_remap(mach_task_self(), &addr, ConfigSizeToProtect, pageSize() - 1, flags, mach_task_self(), addr, false, &prot, &prot, VM_INHERIT_DEFAULT);
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};
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auto result = attemptVMMapping();
@@ -120,8 +124,6 @@ void Config::initialize()
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SignalHandlers::initialize();
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uint8_t* reservedConfigBytes = reinterpret_cast_ptr<uint8_t*>(WebConfig::g_config + WebConfig::reservedSlotsForExecutableAllocator);
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reservedConfigBytes[WebConfig::ReservedByteForAllocationProfiling] = 0;
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reservedConfigBytes[WebConfig::ReservedByteForAllocationProfilingMode] = 0;
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#if USE(APPLE_INTERNAL_SDK)
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WTF_INITIALIZE_ADDITIONAL_CONFIG();

‎Source/WTF/wtf/spi/cocoa/MachVMSPI.h‎

Lines changed: 2 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -39,6 +39,8 @@ kern_return_t mach_vm_allocate(vm_map_t target, mach_vm_address_t*, mach_vm_size
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kern_return_t mach_vm_deallocate(vm_map_t target, mach_vm_address_t, mach_vm_size_t);
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kern_return_t mach_vm_map(vm_map_t targetTask, mach_vm_address_t*, mach_vm_size_t, mach_vm_offset_t mask, int flags,
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mem_entry_name_port_t, memory_object_offset_t, boolean_t copy, vm_prot_t currentProtection, vm_prot_t maximumProtection, vm_inherit_t);
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kern_return_t mach_vm_remap(vm_map_t targetTask, mach_vm_address_t*, mach_vm_size_t, mach_vm_offset_t mask, int flags,
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vm_map_t srcTask, mach_vm_address_t srcAddress, boolean_t copy, vm_prot_t* currentProtection, vm_prot_t* maximumProtection, vm_inherit_t);
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kern_return_t mach_vm_protect(vm_map_t targetTask, mach_vm_address_t, mach_vm_size_t, boolean_t setMaximum, vm_prot_t newProtection);
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kern_return_t mach_vm_region(vm_map_t targetTask, mach_vm_address_t*, mach_vm_size_t*, vm_region_flavor_t, vm_region_info_t,
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mach_msg_type_number_t* infoCount, mach_port_t* objectName);

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