[llvm-dev] Attempt to modify memory sanitizer for support of X86
Kostya Serebryany via llvm-dev
llvm-dev at lists.llvm.org
Fri Jun 17 10:13:15 PDT 2016
+eugenis (the msan co-author and current maintainer)
I don't remember any hard blockers for 32-bit msan.
Soft blockers are:
* extra work and extra maintenance
* too little address space, hard to fit any non-trivial application.
You may start looking at /proc/<PID>/maps to see what is the memory region
you
are failing on and how it is related to kMemoryLayout.
Just curious, why are you trying to do this?
--kcc
On Fri, Jun 17, 2016 at 8:02 AM, Pusl, Stefan via llvm-dev <
llvm-dev at lists.llvm.org> wrote:
> Hello,
>
>
>
> I’m quite new to LLVM, but I’m interested in memory sanitizer. The petty
> thing is, that 32bit addressing on Linux is not supported. Thus I tried to
> take the latest version of the software and to modify it, using Ubuntu
> 16.04 as operating system. Given the example
>
>
>
> *example.c:*
>
> *#include <stdio.h>*
>
> *#include <stdlib.h>*
>
>
>
> *int main(int argc, char **argv) {*
>
> * int *a = (int *)malloc(10*sizeof(10));*
>
> * a[5] = 0;*
>
> * if (a[argc])*
>
> * printf("xx\n");*
>
> * return 0;*
>
> *}*
>
>
>
> which I compiled with the command
>
>
>
> *clang -fsanitize=memory -m32 -fPIE -pie -fno-omit-frame-pointer -g
> -Wl,-Map,example32.map example.c -oexample32.out*
>
>
>
> I get now a segmentation fault during the execution:
>
>
>
> *(gdb) r*
>
> *Starting program: /home/pusl/code/example32.out *
>
> *[Thread debugging using libthread_db enabled]*
>
> *Using host libthread_db library
> "/lib/x86_64-linux-gnu/libthread_db.so.1".*
>
>
>
> *Program received signal SIGSEGV, Segmentation fault.*
>
> *0x565e14f9 in main (argc=1448445640, argv=0xf7f1d3dc) at example.c:4*
>
>
>
>
>
> I tried to figure out the issue, but as a newcomer to LLVM I don’t have
> any further idea now to get nearer to the root cause. Any new idea is
> welcome.
>
>
>
> I changed 5 files. The diffs are:
>
>
>
> - *cmake/config-ix.cmake*:
>
> *diff --git a/cmake/config-ix.cmake b/cmake/config-ix.cmake*
>
> *index 04e33a0..d02e319 100644*
>
> *--- a/cmake/config-ix.cmake*
>
> *+++ b/cmake/config-ix.cmake*
>
> *@@ -149,7 +149,7 @@ set(ALL_ASAN_SUPPORTED_ARCH ${X86} ${X86_64} ${ARM32}
> ${ARM64}*
>
> * ${MIPS32} ${MIPS64} ${PPC64})*
>
> *set(ALL_DFSAN_SUPPORTED_ARCH ${X86_64} ${MIPS64} ${ARM64})*
>
> *set(ALL_LSAN_SUPPORTED_ARCH ${X86_64} ${MIPS64} ${ARM64})*
>
> *-set(ALL_MSAN_SUPPORTED_ARCH ${X86_64} ${MIPS64} ${ARM64})*
>
> *+set(ALL_MSAN_SUPPORTED_ARCH ${X86} ${X86_64} ${MIPS64} ${ARM64})*
>
> *set(ALL_PROFILE_SUPPORTED_ARCH ${X86} ${X86_64} ${ARM32} ${ARM64}
> ${PPC64}*
>
> * ${MIPS32} ${MIPS64})*
>
> *set(ALL_TSAN_SUPPORTED_ARCH ${X86_64} ${MIPS64} ${ARM64} ${PPC64})*
>
>
>
> - *lib/msan/msan.h:*
>
> *diff --git a/lib/msan/msan.h b/lib/msan/msan.h*
>
> *index be74f6e..10b5b05 100644*
>
> *--- a/lib/msan/msan.h*
>
> *+++ b/lib/msan/msan.h*
>
> *@@ -147,6 +147,26 @@ const MappingDesc kMemoryLayout[] = {*
>
> *#define MEM_TO_SHADOW(mem) (LINEARIZE_MEM((mem)) + 0x100000000000ULL)*
>
> *#define SHADOW_TO_ORIGIN(shadow) (((uptr)(shadow)) + 0x280000000000)*
>
> *+#elif SANITIZER_LINUX && SANITIZER_WORDSIZE == 32*
>
> *+*
>
> *+const MappingDesc kMemoryLayout[] = {*
>
> *+ {0x00000000ULL, 0x10000000ULL, MappingDesc::APP, "app-1"},*
>
> *+ {0x10000000ULL, 0x20000000ULL, MappingDesc::SHADOW, "shadow-1"},*
>
> *+ {0x20000000ULL, 0x30000000ULL, MappingDesc::ORIGIN, "origin-1"},*
>
> *+ {0x30000000ULL, 0x50000000ULL, MappingDesc::INVALID, "invalid"},*
>
> *+ {0x50000000ULL, 0x60000000ULL, MappingDesc::APP, "app-2"},*
>
> *+ {0x60000000ULL, 0x70000000ULL, MappingDesc::SHADOW, "shadow-2"},*
>
> *+ {0x70000000ULL, 0x80000000ULL, MappingDesc::ORIGIN, "origin-2"}, *
>
> *+ {0x80000000ULL, 0x90000000ULL, MappingDesc::SHADOW, "shadow-3"},*
>
> *+ {0x90000000ULL, 0xa0000000ULL, MappingDesc::ORIGIN, "origin-3"},*
>
> *+ {0xa0000000ULL, 0xf0000000ULL, MappingDesc::INVALID, "invalid"},*
>
> *+ {0xf0000000ULL, 0xffffffffULL, MappingDesc::APP, "app-3"},*
>
> *+};*
>
> *+#define MOVE_MEM(mem) \*
>
> *+ ((uptr)(mem) & ~0x80000000ULL)*
>
> *+#define MEM_TO_SHADOW(mem) (MOVE_MEM((mem)) + 0x10000000ULL)*
>
> *+#define SHADOW_TO_ORIGIN(mem) (((uptr)(mem)) + 0x10000000ULL)*
>
> *+*
>
> *#elif SANITIZER_LINUX && SANITIZER_WORDSIZE == 64*
>
> * #ifdef MSAN_LINUX_X86_64_OLD_MAPPING*
>
>
>
> - *lib/msan/msan_allocator.cc:*
>
> *diff --git a/lib/msan/msan_allocator.cc b/lib/msan/msan_allocator.cc*
>
> *index b7d3947..dae6d72 100644*
>
> *--- a/lib/msan/msan_allocator.cc*
>
> *+++ b/lib/msan/msan_allocator.cc*
>
> *@@ -49,7 +49,15 @@ struct MsanMapUnmapCallback {*
>
> * typedef SizeClassAllocator32<0, SANITIZER_MMAP_RANGE_SIZE,
> sizeof(Metadata),*
>
> * SizeClassMap, kRegionSizeLog, ByteMap,*
>
> * MsanMapUnmapCallback> PrimaryAllocator;*
>
> *-*
>
> *+#elif defined (__i386__)*
>
> *+static const uptr kMaxAllowedMallocSize = 3UL << 30;*
>
> *+ static const uptr kRegionSizeLog = 20;*
>
> *+ static const uptr kNumRegions = SANITIZER_MMAP_RANGE_SIZE >>
> kRegionSizeLog;*
>
> *+ typedef FlatByteMap<kNumRegions> ByteMap;*
>
> *+ typedef CompactSizeClassMap SizeClassMap;*
>
> *+ typedef SizeClassAllocator32<0, SANITIZER_MMAP_RANGE_SIZE,
> sizeof(Metadata),*
>
> *+ SizeClassMap, kRegionSizeLog, ByteMap,*
>
> *+ MsanMapUnmapCallback> PrimaryAllocator;*
>
> *#elif defined(__x86_64__)*
>
> *#if SANITIZER_LINUX && !defined(MSAN_LINUX_X86_64_OLD_MAPPING)*
>
> * static const uptr kAllocatorSpace = 0x700000000000ULL;*
>
>
>
> - *lib/msan/msan_linux.cc:*
>
> *diff --git a/lib/msan/msan_linux.cc b/lib/msan/msan_linux.cc*
>
> *index d6a9588..ca59564 100644*
>
> *--- a/lib/msan/msan_linux.cc*
>
> *+++ b/lib/msan/msan_linux.cc*
>
> *@@ -82,7 +82,7 @@ static void CheckMemoryLayoutSanity() {*
>
> * CHECK_LT(start, end);*
>
> * CHECK_EQ(prev_end, start);*
>
> * CHECK(addr_is_type(start, type));*
>
> *- CHECK(addr_is_type((start + end) / 2, type));*
>
> *+ CHECK(addr_is_type(start/2 + end/2, type));*
>
> * CHECK(addr_is_type(end - 1, type));*
>
> * if (type == MappingDesc::APP) {*
>
> * uptr addr = start;*
>
> *@@ -90,7 +90,7 @@ static void CheckMemoryLayoutSanity() {*
>
> * CHECK(MEM_IS_ORIGIN(MEM_TO_ORIGIN(addr)));*
>
> * CHECK_EQ(MEM_TO_ORIGIN(addr),
> SHADOW_TO_ORIGIN(MEM_TO_SHADOW(addr)));*
>
> *- addr = (start + end) / 2;*
>
> *+ addr = start/2 + end/2;*
>
> * CHECK(MEM_IS_SHADOW(MEM_TO_SHADOW(addr)));*
>
> * CHECK(MEM_IS_ORIGIN(MEM_TO_ORIGIN(addr)));*
>
> * CHECK_EQ(MEM_TO_ORIGIN(addr),
> SHADOW_TO_ORIGIN(MEM_TO_SHADOW(addr)));*
>
>
>
> - *lib/sanitizer_common/sanitizer_platform_interceptors.h:*
>
> *--- a/lib/sanitizer_common/sanitizer_platform_interceptors.h*
>
> *+++ b/lib/sanitizer_common/sanitizer_platform_interceptors.h*
>
> *@@ -211,7 +211,7 @@*
>
> * SI_FREEBSD || SI_MAC || SI_LINUX_NOT_ANDROID*
>
> *#define SANITIZER_INTERCEPT_ETHER_R SI_FREEBSD || SI_LINUX_NOT_ANDROID*
>
> *#define SANITIZER_INTERCEPT_SHMCTL \*
>
> *- ((SI_FREEBSD || SI_LINUX_NOT_ANDROID) && SANITIZER_WORDSIZE == 64)*
>
> *+ ((SI_FREEBSD || SI_LINUX_NOT_ANDROID) && (SANITIZER_WORDSIZE == 64 ||
> defined(__i386__)))*
>
> *#define SANITIZER_INTERCEPT_RANDOM_R SI_LINUX_NOT_ANDROID*
>
> *#define SANITIZER_INTERCEPT_PTHREAD_ATTR_GET SI_NOT_WINDOWS*
>
> *#define SANITIZER_INTERCEPT_PTHREAD_ATTR_GETINHERITSCHED \*
>
>
>
> Stefan Pusl
>
>
>
>
>
> Intel Deutschland GmbH
> Registered Address: Am Campeon 10-12, 85579 Neubiberg, Germany
> Tel: +49 89 99 8853-0, www.intel.de
> Managing Directors: Christin Eisenschmid, Christian Lamprechter
> Chairperson of the Supervisory Board: Nicole Lau
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>
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>
>
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