SanitizerCommon: fixes for unwinding & backtrace on SPARC

Summary:
This patch contains various fixes for the unwinding and backtrace machinery on the SPARC, which doesn't work correctly in various cases.  It was tested with GCC on SPARC/Solaris and SPARC/Linux.

Patch by Eric Botcazou.

Reviewers: #sanitizers, vitalybuka

Reviewed By: #sanitizers, vitalybuka

Subscribers: jrtc27, delcypher, vitalybuka, ro, jyknight, kubamracek, fedor.sergeev, jdoerfert, llvm-commits, #sanitizers

Tags: #sanitizers, #llvm

Differential Revision: https://reviews.llvm.org/D58431

llvm-svn: 355965

compiler-rt/lib/sanitizer_common/sanitizer_linux.cc

@@ -1821,10 +1821,20 @@ SignalContext::WriteFlag SignalContext::GetWriteFlag() const {
   u64 esr;
   if (!Aarch64GetESR(ucontext, &esr)) return UNKNOWN;
   return esr & ESR_ELx_WNR ? WRITE : READ;
-#elif SANITIZER_SOLARIS && defined(__sparc__)
+#elif defined(__sparc__)
   // Decode the instruction to determine the access type.
   // From OpenSolaris $SRC/uts/sun4/os/trap.c (get_accesstype).
+#if SANITIZER_SOLARIS
   uptr pc = ucontext->uc_mcontext.gregs[REG_PC];
+#else
+  // Historical BSDism here.
+  struct sigcontext *scontext = (struct sigcontext *)context;
+#if defined(__arch64__)
+  uptr pc = scontext->sigc_regs.tpc;
+#else
+  uptr pc = scontext->si_regs.pc;
+#endif
+#endif
   u32 instr = *(u32 *)pc;
   return (instr >> 21) & 1 ? WRITE: READ;
 #else
@@ -1915,28 +1925,27 @@ static void GetPcSpBp(void *context, uptr *pc, uptr *sp, uptr *bp) {
   // pointer, but GCC always uses r31 when we need a frame pointer.
   *bp = ucontext->uc_mcontext.regs->gpr[PT_R31];
 #elif defined(__sparc__)
-  ucontext_t *ucontext = (ucontext_t*)context;
-  uptr *stk_ptr;
-# if defined(__sparcv9) || defined (__arch64__)
-# ifndef MC_PC
-#  define MC_PC REG_PC
-# endif
-# ifndef MC_O6
-#  define MC_O6 REG_O6
+#if defined(__arch64__) || defined(__sparcv9)
+#define STACK_BIAS 2047
+#else
+#define STACK_BIAS 0
 # endif
 # if SANITIZER_SOLARIS
-#  define mc_gregs gregs
-# endif
-  *pc = ucontext->uc_mcontext.mc_gregs[MC_PC];
-  *sp = ucontext->uc_mcontext.mc_gregs[MC_O6];
-  stk_ptr = (uptr *) (*sp + 2047);
-  *bp = stk_ptr[15];
-# else
+  ucontext_t *ucontext = (ucontext_t *)context;
   *pc = ucontext->uc_mcontext.gregs[REG_PC];
-  *sp = ucontext->uc_mcontext.gregs[REG_O6];
-  stk_ptr = (uptr *) *sp;
-  *bp = stk_ptr[15];
+  *sp = ucontext->uc_mcontext.gregs[REG_O6] + STACK_BIAS;
+#else
+  // Historical BSDism here.
+  struct sigcontext *scontext = (struct sigcontext *)context;
+#if defined(__arch64__)
+  *pc = scontext->sigc_regs.tpc;
+  *sp = scontext->sigc_regs.u_regs[14] + STACK_BIAS;
+#else
+  *pc = scontext->si_regs.pc;
+  *sp = scontext->si_regs.u_regs[14];
+#endif
 # endif
+  *bp = (uptr)((uhwptr *)*sp)[14] + STACK_BIAS;
 #elif defined(__mips__)
   ucontext_t *ucontext = (ucontext_t*)context;
   *pc = ucontext->uc_mcontext.pc;

compiler-rt/lib/sanitizer_common/sanitizer_stacktrace.cc

@@ -17,10 +17,9 @@
 namespace __sanitizer {
 
 uptr StackTrace::GetNextInstructionPc(uptr pc) {
-#if defined(__mips__)
+#if defined(__sparc__) || defined(__mips__)
   return pc + 8;
-#elif defined(__powerpc__) || defined(__sparc__) || defined(__arm__) || \
-    defined(__aarch64__)
+#elif defined(__powerpc__) || defined(__arm__) || defined(__aarch64__)
   return pc + 4;
 #else
   return pc + 1;

compiler-rt/lib/sanitizer_common/sanitizer_stacktrace.h

@@ -20,7 +20,7 @@ struct BufferedStackTrace;
 
 static const u32 kStackTraceMax = 256;
 
-#if defined(__sparc__) || (SANITIZER_LINUX && defined(__mips__))
+#if SANITIZER_LINUX && defined(__mips__)
 # define SANITIZER_CAN_FAST_UNWIND 0
 #elif SANITIZER_WINDOWS
 # define SANITIZER_CAN_FAST_UNWIND 0

compiler-rt/lib/sanitizer_common/sanitizer_stacktrace_sparc.cc

@@ -12,9 +12,13 @@
 // Implemention of fast stack unwinding for Sparc.
 //===----------------------------------------------------------------------===//
 
-// This file is ported to Sparc v8, but it should be easy to port to
-// Sparc v9.
-#if defined(__sparcv8__) || defined(__sparcv8) || defined(__sparc_v8__)
+#if defined(__sparc__)
+
+#if defined(__arch64__) || defined(__sparcv9)
+#define STACK_BIAS 2047
+#else
+#define STACK_BIAS 0
+#endif
 
 #include "sanitizer_common.h"
 #include "sanitizer_stacktrace.h"
@@ -26,34 +30,56 @@ void BufferedStackTrace::UnwindFast(uptr pc, uptr bp, uptr stack_top,
   // TODO(yln): add arg sanity check for stack_top/stack_bottom
   CHECK_GE(max_depth, 2);
   const uptr kPageSize = GetPageSizeCached();
+#if defined(__GNUC__)
+  // __builtin_return_address returns the address of the call instruction
+  // on the SPARC and not the return address, so we need to compensate.
+  trace_buffer[0] = GetNextInstructionPc(pc);
+#else
   trace_buffer[0] = pc;
+#endif
   size = 1;
   if (stack_top < 4096) return;  // Sanity check for stack top.
   // Flush register windows to memory
+#if defined(__sparc_v9__) || defined(__sparcv9__) || defined(__sparcv9)
+  asm volatile("flushw" ::: "memory");
+#else
   asm volatile("ta 3" ::: "memory");
-  uhwptr *frame = (uhwptr*)bp;
+#endif
+  // On the SPARC, the return address is not in the frame, it is in a
+  // register.  There is no way to access it off of the current frame
+  // pointer, but it can be accessed off the previous frame pointer by
+  // reading the value from the register window save area.
+  uptr prev_bp = GET_CURRENT_FRAME();
+  uptr next_bp = prev_bp;
+  unsigned int i = 0;
+  while (next_bp != bp && IsAligned(next_bp, sizeof(uhwptr)) && i++ < 8) {
+    prev_bp = next_bp;
+    next_bp = (uptr)((uhwptr *)next_bp)[14] + STACK_BIAS;
+  }
+  if (next_bp == bp)
+    bp = prev_bp;
   // Lowest possible address that makes sense as the next frame pointer.
   // Goes up as we walk the stack.
   uptr bottom = stack_bottom;
   // Avoid infinite loop when frame == frame[0] by using frame > prev_frame.
-  while (IsValidFrame((uptr)frame, stack_top, bottom) &&
-         IsAligned((uptr)frame, sizeof(*frame)) &&
+  while (IsValidFrame(bp, stack_top, bottom) && IsAligned(bp, sizeof(uhwptr)) &&
          size < max_depth) {
-    uhwptr pc1 = frame[15];
+    uhwptr pc1 = ((uhwptr *)bp)[15];
     // Let's assume that any pointer in the 0th page is invalid and
     // stop unwinding here.  If we're adding support for a platform
     // where this isn't true, we need to reconsider this check.
     if (pc1 < kPageSize)
       break;
     if (pc1 != pc) {
-      trace_buffer[size++] = (uptr) pc1;
+      // %o7 contains the address of the call instruction and not the
+      // return address, so we need to compensate.
+      trace_buffer[size++] = GetNextInstructionPc((uptr)pc1);
     }
-    bottom = (uptr)frame;
-    frame = (uhwptr*)frame[14];
+    bottom = bp;
+    bp = (uptr)((uhwptr *)bp)[14] + STACK_BIAS;
   }
 }
 
 }  // namespace __sanitizer
 
-#endif  // !defined(__sparcv8__) && !defined(__sparcv8) &&
-        // !defined(__sparc_v8__)
+#endif  // !defined(__sparc__)

compiler-rt/lib/sanitizer_common/sanitizer_unwind_linux_libcdep.cc

@@ -135,7 +135,13 @@ void BufferedStackTrace::UnwindSlow(uptr pc, u32 max_depth) {
   if (to_pop == 0 && size > 1)
     to_pop = 1;
   PopStackFrames(to_pop);
+#if defined(__GNUC__) && defined(__sparc__)
+  // __builtin_return_address returns the address of the call instruction
+  // on the SPARC and not the return address, so we need to compensate.
+  trace_buffer[0] = GetNextInstructionPc(pc);
+#else
   trace_buffer[0] = pc;
+#endif
 }
 
 void BufferedStackTrace::UnwindSlow(uptr pc, void *context, u32 max_depth) {