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Differential D128936 Diff 441481 compiler-rt/lib/sanitizer_common/sanitizer_procmaps_mac.cpp

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compiler-rt/lib/sanitizer_common/sanitizer_procmaps_mac.cpp

//===-- sanitizer_procmaps_mac.cpp ----------------------------------------===// //===-- sanitizer_procmaps_mac.cpp ----------------------------------------===//
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// //
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information. // See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
// //
//===----------------------------------------------------------------------===// //===----------------------------------------------------------------------===//
// //
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void MemoryMappingLayout::CacheMemoryMappings() { void MemoryMappingLayout::CacheMemoryMappings() {
// No-op on Mac for now. // No-op on Mac for now.
} }
void MemoryMappingLayout::LoadFromCache() { void MemoryMappingLayout::LoadFromCache() {
// No-op on Mac for now. // No-op on Mac for now.
} }
static bool IsDyldHdr(const mach_header *hdr) {
return (hdr->magic == MH_MAGIC || hdr->magic == MH_MAGIC_64) &&
hdr->filetype == MH_DYLINKER;
}
// _dyld_get_image_header() and related APIs don't report dyld itself. // _dyld_get_image_header() and related APIs don't report dyld itself.
// We work around this by manually recursing through the memory map // We work around this by manually recursing through the memory map
// until we hit a Mach header matching dyld instead. These recurse // until we hit a Mach header matching dyld instead. These recurse
// calls are expensive, but the first memory map generation occurs // calls are expensive, but the first memory map generation occurs
// early in the process, when dyld is one of the only images loaded, // early in the process, when dyld is one of the only images loaded,
// so it will be hit after only a few iterations. // so it will be hit after only a few iterations. These assumptions don't hold
static mach_header *get_dyld_image_header() { // on macOS 13+ anymore (dyld itself has moved into the shared cache).
static mach_header *GetDyldImageHeaderViaVMRegion() {
vm_address_t address = 0; vm_address_t address = 0;
while (true) { while (true) {
vm_size_t size = 0; vm_size_t size = 0;
unsigned depth = 1; unsigned depth = 1;
struct vm_region_submap_info_64 info; struct vm_region_submap_info_64 info;
mach_msg_type_number_t count = VM_REGION_SUBMAP_INFO_COUNT_64; mach_msg_type_number_t count = VM_REGION_SUBMAP_INFO_COUNT_64;
kern_return_t err = kern_return_t err =
vm_region_recurse_64(mach_task_self(), &address, &size, &depth, vm_region_recurse_64(mach_task_self(), &address, &size, &depth,
(vm_region_info_t)&info, &count); (vm_region_info_t)&info, &count);
if (err != KERN_SUCCESS) return nullptr; if (err != KERN_SUCCESS) return nullptr;
if (size >= sizeof(mach_header) && info.protection & kProtectionRead) { if (size >= sizeof(mach_header) && info.protection & kProtectionRead) {
mach_header *hdr = (mach_header *)address; mach_header *hdr = (mach_header *)address;
if ((hdr->magic == MH_MAGIC || hdr->magic == MH_MAGIC_64) && if (IsDyldHdr(hdr)) {
hdr->filetype == MH_DYLINKER) {
return hdr; return hdr;
} }
} }
address += size; address += size;
} }
} }
extern "C" {
struct dyld_shared_cache_dylib_text_info {
uint64_t version; // current version 2
// following fields all exist in version 1
uint64_t loadAddressUnslid;
uint64_t textSegmentSize;
uuid_t dylibUuid;
const char *path; // pointer invalid at end of iterations
// following fields all exist in version 2
uint64_t textSegmentOffset; // offset from start of cache
};
typedef struct dyld_shared_cache_dylib_text_info
dyld_shared_cache_dylib_text_info;
extern bool _dyld_get_shared_cache_uuid(uuid_t uuid);
extern const void *_dyld_get_shared_cache_range(size_t *length);
extern int dyld_shared_cache_iterate_text(
const uuid_t cacheUuid,
void (^callback)(const dyld_shared_cache_dylib_text_info *info));
} // extern "C"
static mach_header *GetDyldImageHeaderViaSharedCache() {
uuid_t uuid;
bool hasCache = _dyld_get_shared_cache_uuid(uuid);
if (!hasCache)
return nullptr;
size_t cacheLength;
__block uptr cacheStart = (uptr)_dyld_get_shared_cache_range(&cacheLength);
CHECK(cacheStart && cacheLength);
__block mach_header *dyld_hdr = nullptr;
int res = dyld_shared_cache_iterate_text(
uuid, ^(const dyld_shared_cache_dylib_text_info *info) {
mach_header *hdr =
(mach_header *)(cacheStart + info->textSegmentOffset);
if (IsDyldHdr(hdr))
dyld_hdr = hdr;
});
CHECK_EQ(res, 0);
return dyld_hdr;
}
const mach_header *get_dyld_hdr() { const mach_header *get_dyld_hdr() {
if (!dyld_hdr) dyld_hdr = get_dyld_image_header(); if (!dyld_hdr) {
// On macOS 13+, dyld itself has moved into the shared cache. Looking it up
// via vm_region_recurse_64() causes spins/hangs/crashes.
bool dyldInSharedCache = GetMacosAlignedVersion() >= MacosVersion(13, 0);
if (dyldInSharedCache) {
dyld_hdr = GetDyldImageHeaderViaSharedCache();
}
if (!dyld_hdr) {
if (dyldInSharedCache) {
Printf(
"Failed to lookup the dyld image header in the shared cache on "
"macOS 13+ (or no shared cache in use). Falling back to "
"vm_region_recurse_64() to lookup the dyld image header.\n");
}
dyld_hdr = GetDyldImageHeaderViaVMRegion();
}
CHECK(dyld_hdr);
}
return dyld_hdr; return dyld_hdr;
} }
// Next and NextSegmentLoad were inspired by base/sysinfo.cc in // Next and NextSegmentLoad were inspired by base/sysinfo.cc in
// Google Perftools, https://github.com/gperftools/gperftools. // Google Perftools, https://github.com/gperftools/gperftools.
// NextSegmentLoad scans the current image for the next segment load command // NextSegmentLoad scans the current image for the next segment load command
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