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//===-- sanitizer_procmaps_mac.cpp ----------------------------------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
//
// Information about the process mappings (Mac-specific parts).
//===----------------------------------------------------------------------===//
#include "sanitizer_platform.h"
#if SANITIZER_MAC
#include "sanitizer_common.h"
#include "sanitizer_placement_new.h"
#include "sanitizer_procmaps.h"
#include <mach-o/dyld.h>
#include <mach-o/loader.h>
#include <mach/mach.h>
// These are not available in older macOS SDKs.
#ifndef CPU_SUBTYPE_X86_64_H
#define CPU_SUBTYPE_X86_64_H ((cpu_subtype_t)8) /* Haswell */
#endif
#ifndef CPU_SUBTYPE_ARM_V7S
#define CPU_SUBTYPE_ARM_V7S ((cpu_subtype_t)11) /* Swift */
#endif
#ifndef CPU_SUBTYPE_ARM_V7K
#define CPU_SUBTYPE_ARM_V7K ((cpu_subtype_t)12)
#endif
#ifndef CPU_TYPE_ARM64
#define CPU_TYPE_ARM64 (CPU_TYPE_ARM | CPU_ARCH_ABI64)
#endif
namespace __sanitizer {
// Contains information used to iterate through sections.
struct MemoryMappedSegmentData {
char name[kMaxSegName];
uptr nsects;
const char *current_load_cmd_addr;
u32 lc_type;
uptr base_virt_addr;
uptr addr_mask;
};
template <typename Section>
static void NextSectionLoad(LoadedModule *module, MemoryMappedSegmentData *data,
bool isWritable) {
const Section *sc = (const Section *)data->current_load_cmd_addr;
data->current_load_cmd_addr += sizeof(Section);
uptr sec_start = (sc->addr & data->addr_mask) + data->base_virt_addr;
uptr sec_end = sec_start + sc->size;
module->addAddressRange(sec_start, sec_end, /*executable=*/false, isWritable,
sc->sectname);
}
void MemoryMappedSegment::AddAddressRanges(LoadedModule *module) {
// Don't iterate over sections when the caller hasn't set up the
// data pointer, when there are no sections, or when the segment
// is executable. Avoid iterating over executable sections because
// it will confuse libignore, and because the extra granularity
// of information is not needed by any sanitizers.
if (!data_ || !data_->nsects || IsExecutable()) {
module->addAddressRange(start, end, IsExecutable(), IsWritable(),
data_ ? data_->name : nullptr);
return;
}
do {
if (data_->lc_type == LC_SEGMENT) {
NextSectionLoad<struct section>(module, data_, IsWritable());
#ifdef MH_MAGIC_64
} else if (data_->lc_type == LC_SEGMENT_64) {
NextSectionLoad<struct section_64>(module, data_, IsWritable());
#endif
}
} while (--data_->nsects);
}
MemoryMappingLayout::MemoryMappingLayout(bool cache_enabled) {
Reset();
}
MemoryMappingLayout::~MemoryMappingLayout() {
}
bool MemoryMappingLayout::Error() const {
return false;
}
// More information about Mach-O headers can be found in mach-o/loader.h
// Each Mach-O image has a header (mach_header or mach_header_64) starting with
// a magic number, and a list of linker load commands directly following the
// header.
// A load command is at least two 32-bit words: the command type and the
// command size in bytes. We're interested only in segment load commands
// (LC_SEGMENT and LC_SEGMENT_64), which tell that a part of the file is mapped
// into the task's address space.
// The |vmaddr|, |vmsize| and |fileoff| fields of segment_command or
// segment_command_64 correspond to the memory address, memory size and the
// file offset of the current memory segment.
// Because these fields are taken from the images as is, one needs to add
// _dyld_get_image_vmaddr_slide() to get the actual addresses at runtime.
void MemoryMappingLayout::Reset() {
// Count down from the top.
// TODO(glider): as per man 3 dyld, iterating over the headers with
// _dyld_image_count is thread-unsafe. We need to register callbacks for
// adding and removing images which will invalidate the MemoryMappingLayout
// state.
data_.current_image = _dyld_image_count();
data_.current_load_cmd_count = -1;
data_.current_load_cmd_addr = 0;
data_.current_magic = 0;
data_.current_filetype = 0;
data_.current_arch = kModuleArchUnknown;
internal_memset(data_.current_uuid, 0, kModuleUUIDSize);
}
// The dyld load address should be unchanged throughout process execution,
// and it is expensive to compute once many libraries have been loaded,
// so cache it here and do not reset.
static mach_header *dyld_hdr = 0;
static const char kDyldPath[] = "/usr/lib/dyld";
static const int kDyldImageIdx = -1;
// static
void MemoryMappingLayout::CacheMemoryMappings() {
// No-op on Mac for now.
}
void MemoryMappingLayout::LoadFromCache() {
// No-op on Mac for now.
}
// _dyld_get_image_header() and related APIs don't report dyld itself.
// We work around this by manually recursing through the memory map
// until we hit a Mach header matching dyld instead. These recurse
// calls are expensive, but the first memory map generation occurs
// early in the process, when dyld is one of the only images loaded,
// so it will be hit after only a few iterations.
static mach_header *get_dyld_image_header() {
unsigned depth = 1;
vm_size_t size = 0;
vm_address_t address = 0;
kern_return_t err = KERN_SUCCESS;
mach_msg_type_number_t count = VM_REGION_SUBMAP_INFO_COUNT_64;
while (true) {
struct vm_region_submap_info_64 info;
err = vm_region_recurse_64(mach_task_self(), &address, &size, &depth,
(vm_region_info_t)&info, &count);
if (err != KERN_SUCCESS) return nullptr;
if (size >= sizeof(mach_header) && info.protection & kProtectionRead) {
mach_header *hdr = (mach_header *)address;
if ((hdr->magic == MH_MAGIC || hdr->magic == MH_MAGIC_64) &&
hdr->filetype == MH_DYLINKER) {
return hdr;
}
}
address += size;
}
}
const mach_header *get_dyld_hdr() {
if (!dyld_hdr) dyld_hdr = get_dyld_image_header();
return dyld_hdr;
}
// Next and NextSegmentLoad were inspired by base/sysinfo.cc in
// Google Perftools, https://github.com/gperftools/gperftools.
// NextSegmentLoad scans the current image for the next segment load command
// and returns the start and end addresses and file offset of the corresponding
// segment.
// Note that the segment addresses are not necessarily sorted.
template <u32 kLCSegment, typename SegmentCommand>
static bool NextSegmentLoad(MemoryMappedSegment *segment,
MemoryMappedSegmentData *seg_data,
MemoryMappingLayoutData *layout_data) {
const char *lc = layout_data->current_load_cmd_addr;
layout_data->current_load_cmd_addr += ((const load_command *)lc)->cmdsize;
if (((const load_command *)lc)->cmd == kLCSegment) {
const SegmentCommand* sc = (const SegmentCommand *)lc;
uptr base_virt_addr, addr_mask;
if (layout_data->current_image == kDyldImageIdx) {
base_virt_addr = (uptr)get_dyld_hdr();
// vmaddr is masked with 0xfffff because on macOS versions < 10.12,
// it contains an absolute address rather than an offset for dyld.
// To make matters even more complicated, this absolute address
// isn't actually the absolute segment address, but the offset portion
// of the address is accurate when combined with the dyld base address,
// and the mask will give just this offset.
addr_mask = 0xfffff;
} else {
base_virt_addr =
(uptr)_dyld_get_image_vmaddr_slide(layout_data->current_image);
addr_mask = ~0;
}
segment->start = (sc->vmaddr & addr_mask) + base_virt_addr;
segment->end = segment->start + sc->vmsize;
// Most callers don't need section information, so only fill this struct
// when required.
if (seg_data) {
seg_data->nsects = sc->nsects;
seg_data->current_load_cmd_addr =
(const char *)lc + sizeof(SegmentCommand);
seg_data->lc_type = kLCSegment;
seg_data->base_virt_addr = base_virt_addr;
seg_data->addr_mask = addr_mask;
internal_strncpy(seg_data->name, sc->segname,
ARRAY_SIZE(seg_data->name));
}
// Return the initial protection.
segment->protection = sc->initprot;
segment->offset = (layout_data->current_filetype ==
/*MH_EXECUTE*/ 0x2)
? sc->vmaddr
: sc->fileoff;
if (segment->filename) {
const char *src = (layout_data->current_image == kDyldImageIdx)
? kDyldPath
: _dyld_get_image_name(layout_data->current_image);
internal_strncpy(segment->filename, src, segment->filename_size);
}
segment->arch = layout_data->current_arch;
internal_memcpy(segment->uuid, layout_data->current_uuid, kModuleUUIDSize);
return true;
}
return false;
}
ModuleArch ModuleArchFromCpuType(cpu_type_t cputype, cpu_subtype_t cpusubtype) {
cpusubtype = cpusubtype & ~CPU_SUBTYPE_MASK;
switch (cputype) {
case CPU_TYPE_I386:
return kModuleArchI386;
case CPU_TYPE_X86_64:
if (cpusubtype == CPU_SUBTYPE_X86_64_ALL) return kModuleArchX86_64;
if (cpusubtype == CPU_SUBTYPE_X86_64_H) return kModuleArchX86_64H;
CHECK(0 && "Invalid subtype of x86_64");
return kModuleArchUnknown;
case CPU_TYPE_ARM:
if (cpusubtype == CPU_SUBTYPE_ARM_V6) return kModuleArchARMV6;
if (cpusubtype == CPU_SUBTYPE_ARM_V7) return kModuleArchARMV7;
if (cpusubtype == CPU_SUBTYPE_ARM_V7S) return kModuleArchARMV7S;
if (cpusubtype == CPU_SUBTYPE_ARM_V7K) return kModuleArchARMV7K;
CHECK(0 && "Invalid subtype of ARM");
return kModuleArchUnknown;
case CPU_TYPE_ARM64:
return kModuleArchARM64;
default:
CHECK(0 && "Invalid CPU type");
return kModuleArchUnknown;
}
}
static const load_command *NextCommand(const load_command *lc) {
return (const load_command *)((const char *)lc + lc->cmdsize);
}
static void FindUUID(const load_command *first_lc, u8 *uuid_output) {
for (const load_command *lc = first_lc; lc->cmd != 0; lc = NextCommand(lc)) {
if (lc->cmd != LC_UUID) continue;
const uuid_command *uuid_lc = (const uuid_command *)lc;
const uint8_t *uuid = &uuid_lc->uuid[0];
internal_memcpy(uuid_output, uuid, kModuleUUIDSize);
return;
}
}
static bool IsModuleInstrumented(const load_command *first_lc) {
for (const load_command *lc = first_lc; lc->cmd != 0; lc = NextCommand(lc)) {
if (lc->cmd != LC_LOAD_DYLIB) continue;
const dylib_command *dylib_lc = (const dylib_command *)lc;
uint32_t dylib_name_offset = dylib_lc->dylib.name.offset;
const char *dylib_name = ((const char *)dylib_lc) + dylib_name_offset;
dylib_name = StripModuleName(dylib_name);
if (dylib_name != 0 && (internal_strstr(dylib_name, "libclang_rt."))) {
return true;
}
}
return false;
}
bool MemoryMappingLayout::Next(MemoryMappedSegment *segment) {
for (; data_.current_image >= kDyldImageIdx; data_.current_image--) {
const mach_header *hdr = (data_.current_image == kDyldImageIdx)
? get_dyld_hdr()
: _dyld_get_image_header(data_.current_image);
if (!hdr) continue;
if (data_.current_load_cmd_count < 0) {
// Set up for this image;
data_.current_load_cmd_count = hdr->ncmds;
data_.current_magic = hdr->magic;
data_.current_filetype = hdr->filetype;
data_.current_arch = ModuleArchFromCpuType(hdr->cputype, hdr->cpusubtype);
switch (data_.current_magic) {
#ifdef MH_MAGIC_64
case MH_MAGIC_64: {
data_.current_load_cmd_addr =
(const char *)hdr + sizeof(mach_header_64);
break;
}
#endif
case MH_MAGIC: {
data_.current_load_cmd_addr = (const char *)hdr + sizeof(mach_header);
break;
}
default: {
continue;
}
}
FindUUID((const load_command *)data_.current_load_cmd_addr,
data_.current_uuid);
data_.current_instrumented = IsModuleInstrumented(
(const load_command *)data_.current_load_cmd_addr);
}
for (; data_.current_load_cmd_count >= 0; data_.current_load_cmd_count--) {
switch (data_.current_magic) {
// data_.current_magic may be only one of MH_MAGIC, MH_MAGIC_64.
#ifdef MH_MAGIC_64
case MH_MAGIC_64: {
if (NextSegmentLoad<LC_SEGMENT_64, struct segment_command_64>(
segment, segment->data_, &data_))
return true;
break;
}
#endif
case MH_MAGIC: {
if (NextSegmentLoad<LC_SEGMENT, struct segment_command>(
segment, segment->data_, &data_))
return true;
break;
}
}
}
// If we get here, no more load_cmd's in this image talk about
// segments. Go on to the next image.
}
return false;
}
void MemoryMappingLayout::DumpListOfModules(
InternalMmapVectorNoCtor<LoadedModule> *modules) {
Reset();
InternalMmapVector<char> module_name(kMaxPathLength);
MemoryMappedSegment segment(module_name.data(), module_name.size());
MemoryMappedSegmentData data;
segment.data_ = &data;
while (Next(&segment)) {
if (segment.filename[0] == '\0') continue;
LoadedModule *cur_module = nullptr;
if (!modules->empty() &&
0 == internal_strcmp(segment.filename, modules->back().full_name())) {
cur_module = &modules->back();
} else {
modules->push_back(LoadedModule());
cur_module = &modules->back();
cur_module->set(segment.filename, segment.start, segment.arch,
segment.uuid, data_.current_instrumented);
}
segment.AddAddressRanges(cur_module);
}
}
} // namespace __sanitizer
#endif // SANITIZER_MAC