[asan] For iOS/AArch64, if the dynamic shadow doesn't fit, restrict the VM space
On iOS/AArch64, the address space is very limited and has a dynamic maximum address based on the configuration of the device. We're already using a dynamic shadow, and we find a large-enough "gap" in the VM where we place the shadow memory. In some cases and some device configuration, we might not be able to find a large-enough gap: E.g. if the main executable is linked against a large number of libraries that are not part of the system, these libraries can fragment the address space, and this happens before ASan starts initializing. This patch has a solution, where we have a "backup plan" when we cannot find a large-enough gap: We will restrict the address space (via MmapFixedNoAccess) to a limit, for which the shadow limit will fit. Differential Revision: https://reviews.llvm.org/D35098 llvm-svn: 307865
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@ -75,6 +75,7 @@ void NORETURN ShowStatsAndAbort();
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void ReplaceSystemMalloc();
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void ReplaceSystemMalloc();
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// asan_linux.cc / asan_mac.cc / asan_win.cc
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// asan_linux.cc / asan_mac.cc / asan_win.cc
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uptr FindDynamicShadowStart();
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void *AsanDoesNotSupportStaticLinkage();
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void *AsanDoesNotSupportStaticLinkage();
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void AsanCheckDynamicRTPrereqs();
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void AsanCheckDynamicRTPrereqs();
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void AsanCheckIncompatibleRT();
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void AsanCheckIncompatibleRT();
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@ -77,6 +77,11 @@ void *AsanDoesNotSupportStaticLinkage() {
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return &_DYNAMIC; // defined in link.h
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return &_DYNAMIC; // defined in link.h
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}
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}
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uptr FindDynamicShadowStart() {
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UNREACHABLE("FindDynamicShadowStart is not available");
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return 0;
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}
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void AsanApplyToGlobals(globals_op_fptr op, const void *needle) {
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void AsanApplyToGlobals(globals_op_fptr op, const void *needle) {
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UNIMPLEMENTED();
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UNIMPLEMENTED();
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}
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}
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@ -55,6 +55,29 @@ void *AsanDoesNotSupportStaticLinkage() {
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return 0;
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return 0;
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}
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}
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uptr FindDynamicShadowStart() {
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uptr granularity = GetMmapGranularity();
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uptr alignment = 8 * granularity;
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uptr left_padding = granularity;
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uptr space_size = kHighShadowEnd + left_padding;
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uptr largest_gap_found = 0;
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uptr shadow_start = FindAvailableMemoryRange(space_size, alignment,
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granularity, &largest_gap_found);
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// If the shadow doesn't fit, restrict the address space to make it fit.
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if (shadow_start == 0) {
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uptr new_max_vm = RoundDownTo(largest_gap_found << SHADOW_SCALE, alignment);
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RestrictMemoryToMaxAddress(new_max_vm);
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kHighMemEnd = new_max_vm - 1;
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space_size = kHighShadowEnd + left_padding;
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shadow_start =
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FindAvailableMemoryRange(space_size, alignment, granularity, nullptr);
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}
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CHECK_NE((uptr)0, shadow_start);
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CHECK(IsAligned(shadow_start, alignment));
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return shadow_start;
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}
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// No-op. Mac does not support static linkage anyway.
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// No-op. Mac does not support static linkage anyway.
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void AsanCheckDynamicRTPrereqs() {}
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void AsanCheckDynamicRTPrereqs() {}
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@ -438,15 +438,7 @@ static void InitializeShadowMemory() {
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if (shadow_start == kDefaultShadowSentinel) {
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if (shadow_start == kDefaultShadowSentinel) {
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__asan_shadow_memory_dynamic_address = 0;
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__asan_shadow_memory_dynamic_address = 0;
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CHECK_EQ(0, kLowShadowBeg);
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CHECK_EQ(0, kLowShadowBeg);
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shadow_start = FindDynamicShadowStart();
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uptr granularity = GetMmapGranularity();
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uptr alignment = 8 * granularity;
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uptr left_padding = granularity;
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uptr space_size = kHighShadowEnd + left_padding;
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shadow_start = FindAvailableMemoryRange(space_size, alignment, granularity);
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CHECK_NE((uptr)0, shadow_start);
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CHECK(IsAligned(shadow_start, alignment));
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}
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}
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// Update the shadow memory address (potentially) used by instrumentation.
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// Update the shadow memory address (potentially) used by instrumentation.
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__asan_shadow_memory_dynamic_address = shadow_start;
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__asan_shadow_memory_dynamic_address = shadow_start;
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@ -217,6 +217,18 @@ void *AsanDoesNotSupportStaticLinkage() {
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return 0;
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return 0;
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}
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}
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uptr FindDynamicShadowStart() {
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uptr granularity = GetMmapGranularity();
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uptr alignment = 8 * granularity;
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uptr left_padding = granularity;
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uptr space_size = kHighShadowEnd + left_padding;
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uptr shadow_start =
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FindAvailableMemoryRange(space_size, alignment, granularity, nullptr);
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CHECK_NE((uptr)0, shadow_start);
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CHECK(IsAligned(shadow_start, alignment));
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return shadow_start;
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}
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void AsanCheckDynamicRTPrereqs() {}
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void AsanCheckDynamicRTPrereqs() {}
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void AsanCheckIncompatibleRT() {}
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void AsanCheckIncompatibleRT() {}
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@ -58,6 +58,7 @@ set(SANITIZER_LIBCDEP_SOURCES
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sanitizer_coverage_libcdep_new.cc
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sanitizer_coverage_libcdep_new.cc
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sanitizer_coverage_win_sections.cc
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sanitizer_coverage_win_sections.cc
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sanitizer_linux_libcdep.cc
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sanitizer_linux_libcdep.cc
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sanitizer_mac_libcdep.cc
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sanitizer_posix_libcdep.cc
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sanitizer_posix_libcdep.cc
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sanitizer_stacktrace_libcdep.cc
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sanitizer_stacktrace_libcdep.cc
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sanitizer_stoptheworld_linux_libcdep.cc
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sanitizer_stoptheworld_linux_libcdep.cc
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@ -107,7 +107,8 @@ bool MprotectNoAccess(uptr addr, uptr size);
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bool MprotectReadOnly(uptr addr, uptr size);
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bool MprotectReadOnly(uptr addr, uptr size);
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// Find an available address space.
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// Find an available address space.
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uptr FindAvailableMemoryRange(uptr size, uptr alignment, uptr left_padding);
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uptr FindAvailableMemoryRange(uptr size, uptr alignment, uptr left_padding,
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uptr *largest_gap_found);
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// Used to check if we can map shadow memory to a fixed location.
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// Used to check if we can map shadow memory to a fixed location.
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bool MemoryRangeIsAvailable(uptr range_start, uptr range_end);
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bool MemoryRangeIsAvailable(uptr range_start, uptr range_end);
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@ -1671,7 +1671,8 @@ void CheckNoDeepBind(const char *filename, int flag) {
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#endif
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#endif
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}
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}
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uptr FindAvailableMemoryRange(uptr size, uptr alignment, uptr left_padding) {
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uptr FindAvailableMemoryRange(uptr size, uptr alignment, uptr left_padding,
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uptr *largest_gap_found) {
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UNREACHABLE("FindAvailableMemoryRange is not available");
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UNREACHABLE("FindAvailableMemoryRange is not available");
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return 0;
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return 0;
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}
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}
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@ -840,7 +840,8 @@ uptr GetMaxVirtualAddress() {
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uptr FindAvailableMemoryRange(uptr shadow_size,
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uptr FindAvailableMemoryRange(uptr shadow_size,
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uptr alignment,
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uptr alignment,
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uptr left_padding) {
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uptr left_padding,
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uptr *largest_gap_found) {
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typedef vm_region_submap_short_info_data_64_t RegionInfo;
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typedef vm_region_submap_short_info_data_64_t RegionInfo;
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enum { kRegionInfoSize = VM_REGION_SUBMAP_SHORT_INFO_COUNT_64 };
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enum { kRegionInfoSize = VM_REGION_SUBMAP_SHORT_INFO_COUNT_64 };
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// Start searching for available memory region past PAGEZERO, which is
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// Start searching for available memory region past PAGEZERO, which is
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@ -851,6 +852,7 @@ uptr FindAvailableMemoryRange(uptr shadow_size,
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mach_vm_address_t address = start_address;
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mach_vm_address_t address = start_address;
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mach_vm_address_t free_begin = start_address;
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mach_vm_address_t free_begin = start_address;
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kern_return_t kr = KERN_SUCCESS;
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kern_return_t kr = KERN_SUCCESS;
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if (largest_gap_found) *largest_gap_found = 0;
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while (kr == KERN_SUCCESS) {
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while (kr == KERN_SUCCESS) {
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mach_vm_size_t vmsize = 0;
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mach_vm_size_t vmsize = 0;
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natural_t depth = 0;
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natural_t depth = 0;
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(vm_region_info_t)&vminfo, &count);
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(vm_region_info_t)&vminfo, &count);
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if (free_begin != address) {
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if (free_begin != address) {
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// We found a free region [free_begin..address-1].
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// We found a free region [free_begin..address-1].
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uptr shadow_address = RoundUpTo((uptr)free_begin + left_padding,
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uptr gap_start = RoundUpTo((uptr)free_begin + left_padding, alignment);
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alignment);
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uptr gap_end = RoundDownTo((uptr)address, alignment);
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if (shadow_address + shadow_size < (uptr)address) {
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uptr gap_size = gap_end > gap_start ? gap_end - gap_start : 0;
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return shadow_address;
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if (shadow_size < gap_size) {
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return gap_start;
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}
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if (largest_gap_found && *largest_gap_found < gap_size) {
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*largest_gap_found = gap_size;
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}
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}
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}
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}
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// Move to the next region.
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// Move to the next region.
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@ -36,6 +36,8 @@ MacosVersion GetMacosVersion();
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char **GetEnviron();
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char **GetEnviron();
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void RestrictMemoryToMaxAddress(uptr max_address);
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} // namespace __sanitizer
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} // namespace __sanitizer
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extern "C" {
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extern "C" {
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@ -0,0 +1,30 @@
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//===-- sanitizer_mac_libcdep.cc ------------------------------------------===//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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//
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// This file is shared between various sanitizers' runtime libraries and
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// implements OSX-specific functions.
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//===----------------------------------------------------------------------===//
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#include "sanitizer_platform.h"
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#if SANITIZER_MAC
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#include "sanitizer_mac.h"
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#include <sys/mman.h>
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namespace __sanitizer {
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void RestrictMemoryToMaxAddress(uptr max_address) {
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uptr size_to_mmap = GetMaxVirtualAddress() + 1 - max_address;
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void *res = MmapFixedNoAccess(max_address, size_to_mmap, "high gap");
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CHECK(res != MAP_FAILED);
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}
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} // namespace __sanitizer
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#endif // SANITIZER_MAC
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// FIXME: add madvise-analog when we move to 64-bits.
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// FIXME: add madvise-analog when we move to 64-bits.
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}
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}
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uptr FindAvailableMemoryRange(uptr size, uptr alignment, uptr left_padding) {
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uptr FindAvailableMemoryRange(uptr size, uptr alignment, uptr left_padding,
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uptr *largest_gap_found) {
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uptr address = 0;
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uptr address = 0;
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while (true) {
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while (true) {
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MEMORY_BASIC_INFORMATION info;
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MEMORY_BASIC_INFORMATION info;
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