[TSan] Improve handling of stack pointer mangling in {set,long}jmp, pt.3

[yln]

Summary

Remove unnecessary computation of mangled SP for x86_64 architecture.

[dvyukov]

Looks good (if it does not break anything :))

compiler-rt/trunk/lib/tsan/rtl/tsan_interceptors.cc

if (buf->sp == sp) {
       return;
     }
   }
   Printf("ThreadSanitizer: can't find longjmp buf\n");
   CHECK(0);
 }
 
 // FIXME: put everything below into a common extern "C" block?
-extern "C" void __tsan_setjmp(uptr sp, uptr mangled_sp) {
+extern "C" void __tsan_setjmp(uptr sp) {
   cur_thread_init();
   SetJmp(cur_thread(), sp);
 }
 
 #if SANITIZER_MAC
 TSAN_INTERCEPTOR(int, setjmp, void *env);
 TSAN_INTERCEPTOR(int, _setjmp, void *env);
 TSAN_INTERCEPTOR(int, sigsetjmp, void *env);

compiler-rt/trunk/lib/tsan/rtl/tsan_rtl_amd64.S

 ASM_TYPE_FUNCTION(ASM_SYMBOL_INTERCEPTOR(setjmp))
 ASM_SYMBOL_INTERCEPTOR(setjmp):
 #endif
   CFI_STARTPROC
   // save env parameter
   push %rdi
   CFI_ADJUST_CFA_OFFSET(8)
   CFI_REL_OFFSET(%rdi, 0)
-  // obtain %rsp
+  // obtain SP, store in %rdi, first argument to `void __tsan_setjmp(uptr sp)`
 #if defined(__FreeBSD__) || defined(__NetBSD__)
   lea 8(%rsp), %rdi
-  mov %rdi, %rsi
-#elif defined(__APPLE__)
+#elif defined(__linux__) || defined(__APPLE__)
   lea 16(%rsp), %rdi
-  mov %rdi, %rsi
-  xorq ___tsan_darwin_setjmp_xor_key(%rip), %rsi
-#elif defined(__linux__)
-  lea 16(%rsp), %rdi
-  mov %rdi, %rsi
-  xor %fs:0x30, %rsi  // magic mangling of rsp (see libc setjmp)
-  rol $0x11, %rsi
 #else
 # error "Unknown platform"
 #endif
   // call tsan interceptor
   call ASM_SYMBOL(__tsan_setjmp)
   // restore env parameter
   pop %rdi
   CFI_ADJUST_CFA_OFFSET(-8)

 .globl ASM_SYMBOL_INTERCEPTOR(_setjmp)
 ASM_TYPE_FUNCTION(ASM_SYMBOL_INTERCEPTOR(_setjmp))
 ASM_SYMBOL_INTERCEPTOR(_setjmp):
   CFI_STARTPROC
   // save env parameter
   push %rdi
   CFI_ADJUST_CFA_OFFSET(8)
   CFI_REL_OFFSET(%rdi, 0)
-  // obtain %rsp
+  // obtain SP, store in %rdi, first argument to `void __tsan_setjmp(uptr sp)`
 #if defined(__FreeBSD__) || defined(__NetBSD__)
   lea 8(%rsp), %rdi
-  mov %rdi, %rsi
-#elif defined(__APPLE__)
-  lea 16(%rsp), %rdi
-  mov %rdi, %rsi
-  xorq ___tsan_darwin_setjmp_xor_key(%rip), %rsi
-#elif defined(__linux__)
+#elif defined(__linux__) || defined(__APPLE__)
   lea 16(%rsp), %rdi
-  mov %rdi, %rsi
-  xor %fs:0x30, %rsi  // magic mangling of rsp (see libc setjmp)
-  rol $0x11, %rsi
 #else
 # error "Unknown platform"
 #endif
   // call tsan interceptor
   call ASM_SYMBOL(__tsan_setjmp)
   // restore env parameter
   pop %rdi
   CFI_ADJUST_CFA_OFFSET(-8)
#endif
   CFI_REL_OFFSET(%rdi, 0)
   // save savesigs parameter
   push %rsi
   CFI_ADJUST_CFA_OFFSET(8)
   CFI_REL_OFFSET(%rsi, 0)
   // align stack frame
   sub $8, %rsp
   CFI_ADJUST_CFA_OFFSET(8)
-  // obtain %rsp
+  // obtain SP, store in %rdi, first argument to `void __tsan_setjmp(uptr sp)`
 #if defined(__FreeBSD__) || defined(__NetBSD__)
   lea 24(%rsp), %rdi
-  mov %rdi, %rsi
-#elif defined(__APPLE__)
-  lea 32(%rsp), %rdi
-  mov %rdi, %rsi
-  xorq ___tsan_darwin_setjmp_xor_key(%rip), %rsi
-#elif defined(__linux__)
+#elif defined(__linux__) || defined(__APPLE__)
   lea 32(%rsp), %rdi
-  mov %rdi, %rsi
-  xor %fs:0x30, %rsi  // magic mangling of rsp (see libc setjmp)
-  rol $0x11, %rsi
 #else
 # error "Unknown platform"
 #endif
   // call tsan interceptor
   call ASM_SYMBOL(__tsan_setjmp)
   // unalign stack frame
   add $8, %rsp
   CFI_ADJUST_CFA_OFFSET(-8)
ASM_SYMBOL_INTERCEPTOR(__sigsetjmp):
   CFI_REL_OFFSET(%rdi, 0)
   // save savesigs parameter
   push %rsi
   CFI_ADJUST_CFA_OFFSET(8)
   CFI_REL_OFFSET(%rsi, 0)
   // align stack frame
   sub $8, %rsp
   CFI_ADJUST_CFA_OFFSET(8)
-  // obtain %rsp
+  // obtain SP, store in %rdi, first argument to `void __tsan_setjmp(uptr sp)`
 #if defined(__FreeBSD__)
   lea 24(%rsp), %rdi
-  mov %rdi, %rsi
 #else
   lea 32(%rsp), %rdi
-  mov %rdi, %rsi
-  xor %fs:0x30, %rsi  // magic mangling of rsp (see libc setjmp)
-  rol $0x11, %rsi
 #endif
   // call tsan interceptor
   call ASM_SYMBOL(__tsan_setjmp)
   // unalign stack frame
   add $8, %rsp
   CFI_ADJUST_CFA_OFFSET(-8)
   // restore savesigs parameter
   pop %rsi