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[TSan] Improve handling of stack pointer mangling in {set,long}jmp, pt.8 

Refine longjmp key management.  For Linux, re-implement key retrieval in
C (instead of assembly).  Removal of `InitializeGuardPtr` and a final
round of cleanups will be done in the next commit.

Reviewed By: dvyukov

Differential Revision: https://reviews.llvm.org/D64092

llvm-svn: 365513
This commit is contained in:
Julian Lettner 2019-07-09 16:49:43 +00:00
parent b2d24bd540
commit 521f77e635
2 changed files with 51 additions and 10 deletions
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50
compiler-rt/lib/tsan/rtl/tsan_platform_linux.cc
View File

@ -68,12 +68,17 @@ void *__libc_stack_end = 0;
#endif
#if SANITIZER_LINUX && defined(__aarch64__)
void InitializeGuardPtr() __attribute__((visibility("hidden")));
__tsan::uptr InitializeGuardPtr() __attribute__((visibility("hidden")));
extern "C" __tsan::uptr _tsan_pointer_chk_guard;
#endif
namespace __tsan {
#if SANITIZER_LINUX && defined(__aarch64__)
static void InitializeLongjmpXorKey();
static uptr longjmp_xor_key;
#endif
#ifdef TSAN_RUNTIME_VMA
// Runtime detected VMA size.
uptr vmaSize;
@ -285,7 +290,25 @@ void InitializePlatform() {
reexec = true;
}
// Initialize the guard pointer used in {sig}{set,long}jump.
InitializeGuardPtr();
longjmp_xor_key = InitializeGuardPtr();
uptr old_value = longjmp_xor_key;
InitializeLongjmpXorKey();
CHECK_EQ(longjmp_xor_key, old_value);
// If the above check fails for you, please contact me (jlettner@apple.com)
// and let me know the values of the two differing keys. Please also set a
// breakpoint on `InitializeGuardPtr` and `InitializeLongjmpXorKey` and tell
// me the stack pointer (SP) values that go into the XOR operation (where we
// derive the key):
//
// InitializeLongjmpXorKey:
// uptr sp = (uptr)__builtin_frame_address(0);
//
// InitializeGuardPtr (in tsan_rtl_aarch64.S):
// mov x0, sp
// ...
// eor x0, x0, x1
//
// Then feel free to comment out the call to `InitializeLongjmpXorKey`.
#endif
if (reexec)
ReExec();
@ -353,9 +376,7 @@ static uptr UnmangleLongJmpSp(uptr mangled_sp) {
# endif
#elif defined(__aarch64__)
# if SANITIZER_LINUX
// TODO(yln): fix this
// return mangled_sp ^ _tsan_pointer_chk_guard;
return mangled_sp;
return mangled_sp ^ longjmp_xor_key;
# else
return mangled_sp;
# endif
@ -394,6 +415,25 @@ uptr ExtractLongJmpSp(uptr *env) {
return UnmangleLongJmpSp(mangled_sp);
}
#if SANITIZER_LINUX && defined(__aarch64__)
// GLIBC mangles the function pointers in jmp_buf (used in {set,long}*jmp
// functions) by XORing them with a random key. For AArch64 it is a global
// variable rather than a TCB one (as for x86_64/powerpc). We obtain the key by
// issuing a setjmp and XORing the SP pointer values to derive the key.
static void InitializeLongjmpXorKey() {
// 1. Call REAL(setjmp), which stores the mangled SP in env.
jump_buf env;
REAL(setjmp)(env);
// 2. Retrieve mangled/vanilla SP.
uptr mangled_sp = ((uptr *)&env)[LONG_JMP_SP_ENV_SLOT];
uptr sp = (uptr)__builtin_frame_address(0);
// 3. xor SPs to obtain key.
longjmp_xor_key = mangled_sp ^ sp;
}
#endif
void ImitateTlsWrite(ThreadState *thr, uptr tls_addr, uptr tls_size) {
// Check that the thr object is in tls;
const uptr thr_beg = (uptr)thr;

11
compiler-rt/lib/tsan/rtl/tsan_platform_mac.cc
View File

@ -238,8 +238,7 @@ void InitializePlatformEarly() {
#endif
}
static const uptr kPthreadSetjmpXorKeySlot = 0x7;
extern "C" uptr __tsan_darwin_setjmp_xor_key = 0;
static uptr longjmp_xor_key = 0;
void InitializePlatform() {
DisableCoreDumperIfNecessary();
@ -254,8 +253,9 @@ void InitializePlatform() {
#endif
if (GetMacosVersion() >= MACOS_VERSION_MOJAVE) {
__tsan_darwin_setjmp_xor_key =
(uptr)pthread_getspecific(kPthreadSetjmpXorKeySlot);
// Libsystem currently uses a process-global key; this might change.
const unsigned kTLSLongjmpXorKeySlot = 0x7;
longjmp_xor_key = (uptr)pthread_getspecific(kTLSLongjmpXorKeySlot);
}
}
@ -268,7 +268,8 @@ void InitializePlatform() {
uptr ExtractLongJmpSp(uptr *env) {
uptr mangled_sp = env[LONG_JMP_SP_ENV_SLOT];
return mangled_sp ^ __tsan_darwin_setjmp_xor_key;
uptr sp = mangled_sp ^ longjmp_xor_key;
return sp;
}
#if !SANITIZER_GO