diff options
Diffstat (limited to 'src/processor/stackwalker_amd64.cc')
-rw-r--r-- | src/processor/stackwalker_amd64.cc | 54 |
1 files changed, 52 insertions, 2 deletions
diff --git a/src/processor/stackwalker_amd64.cc b/src/processor/stackwalker_amd64.cc index b2ffdb89..f252a33b 100644 --- a/src/processor/stackwalker_amd64.cc +++ b/src/processor/stackwalker_amd64.cc @@ -147,6 +147,52 @@ StackFrameAMD64* StackwalkerAMD64::GetCallerByCFIFrameInfo( return frame.release(); } +StackFrameAMD64* StackwalkerAMD64::GetCallerByFramePointerRecovery( + const vector<StackFrame*>& frames) { + StackFrameAMD64* last_frame = static_cast<StackFrameAMD64*>(frames.back()); + uint64_t last_rsp = last_frame->context.rsp; + uint64_t last_rbp = last_frame->context.rbp; + + // Assume the presence of a frame pointer. This is not mandated by the + // AMD64 ABI, c.f. section 3.2.2 footnote 7, though it is typical for + // compilers to still preserve the frame pointer and not treat %rbp as a + // general purpose register. + // + // With this assumption, the CALL instruction pushes the return address + // onto the stack and sets %rip to the procedure to enter. The procedure + // then establishes the stack frame with a prologue that PUSHes the current + // %rbp onto the stack, MOVes the current %rsp to %rbp, and then allocates + // space for any local variables. Using this procedure linking information, + // it is possible to locate frame information for the callee: + // + // %caller_rsp = *(%callee_rbp + 16) + // %caller_rip = *(%callee_rbp + 8) + // %caller_rbp = *(%callee_rbp) + + uint64_t caller_rip, caller_rbp; + if (memory_->GetMemoryAtAddress(last_rbp + 8, &caller_rip) && + memory_->GetMemoryAtAddress(last_rbp, &caller_rbp)) { + uint64_t caller_rsp = last_rbp + 16; + + // Simple sanity check that the stack is growing downwards as expected. + if (caller_rbp < last_rbp || caller_rsp < last_rsp) + return NULL; + + StackFrameAMD64* frame = new StackFrameAMD64(); + frame->trust = StackFrame::FRAME_TRUST_FP; + frame->context = last_frame->context; + frame->context.rip = caller_rip; + frame->context.rsp = caller_rsp; + frame->context.rbp = caller_rbp; + frame->context_validity = StackFrameAMD64::CONTEXT_VALID_RIP | + StackFrameAMD64::CONTEXT_VALID_RSP | + StackFrameAMD64::CONTEXT_VALID_RBP; + return frame; + } + + return NULL; +} + StackFrameAMD64* StackwalkerAMD64::GetCallerByStackScan( const vector<StackFrame*> &frames) { StackFrameAMD64* last_frame = static_cast<StackFrameAMD64*>(frames.back()); @@ -214,8 +260,12 @@ StackFrame* StackwalkerAMD64::GetCallerFrame(const CallStack* stack, if (cfi_frame_info.get()) new_frame.reset(GetCallerByCFIFrameInfo(frames, cfi_frame_info.get())); - // If CFI failed, or there wasn't CFI available, fall back - // to stack scanning. + // If CFI was not available or failed, try using frame pointer recovery. + if (!new_frame.get()) { + new_frame.reset(GetCallerByFramePointerRecovery(frames)); + } + + // If all else fails, fall back to stack scanning. if (stack_scan_allowed && !new_frame.get()) { new_frame.reset(GetCallerByStackScan(frames)); } |