diff options
Diffstat (limited to 'src/processor/stackwalker_riscv64.cc')
| -rw-r--r-- | src/processor/stackwalker_riscv64.cc | 535 |
1 files changed, 535 insertions, 0 deletions
diff --git a/src/processor/stackwalker_riscv64.cc b/src/processor/stackwalker_riscv64.cc new file mode 100644 index 00000000..d97bad63 --- /dev/null +++ b/src/processor/stackwalker_riscv64.cc @@ -0,0 +1,535 @@ +// Copyright 2013 Google LLC +// +// Redistribution and use in source and binary forms, with or without +// modification, are permitted provided that the following conditions are +// met: +// +// * Redistributions of source code must retain the above copyright +// notice, this list of conditions and the following disclaimer. +// * Redistributions in binary form must reproduce the above +// copyright notice, this list of conditions and the following disclaimer +// in the documentation and/or other materials provided with the +// distribution. +// * Neither the name of Google LLC nor the names of its +// contributors may be used to endorse or promote products derived from +// this software without specific prior written permission. +// +// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS +// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT +// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR +// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT +// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, +// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT +// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, +// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY +// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT +// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE +// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. + +/* stackwalker_riscv64.cc: riscv64-specific stackwalker. + * + * See stackwalker_riscv64.h for documentation. + * + * Author: Iacopo Colonnelli + */ + +#include "common/scoped_ptr.h" +#include "google_breakpad/processor/call_stack.h" +#include "google_breakpad/processor/code_modules.h" +#include "google_breakpad/processor/memory_region.h" +#include "google_breakpad/processor/stack_frame_cpu.h" +#include "google_breakpad/processor/system_info.h" +#include "processor/cfi_frame_info.h" +#include "processor/logging.h" +#include "processor/stackwalker_riscv64.h" + +namespace google_breakpad { + +StackwalkerRISCV64::StackwalkerRISCV64(const SystemInfo* system_info, + const MDRawContextRISCV64* context, + MemoryRegion* memory, + const CodeModules* modules, + StackFrameSymbolizer* resolver_helper) + : Stackwalker(system_info, memory, modules, resolver_helper), + context_(context), + context_frame_validity_(StackFrameRISCV::CONTEXT_VALID_ALL) { +} + + +StackFrame* StackwalkerRISCV64::GetContextFrame() { + if (!context_) { + BPLOG(ERROR) << "Can't get context frame without context"; + return NULL; + } + + StackFrameRISCV64* frame = new StackFrameRISCV64(); + + frame->context = *context_; + frame->context_validity = context_frame_validity_; + frame->trust = StackFrame::FRAME_TRUST_CONTEXT; + frame->instruction = frame->context.pc; + + return frame; +} + +StackFrameRISCV64* StackwalkerRISCV64::GetCallerByCFIFrameInfo( + const vector<StackFrame*>& frames, + CFIFrameInfo* cfi_frame_info) { + StackFrameRISCV64* last_frame = + static_cast<StackFrameRISCV64*>(frames.back()); + + // Populate a dictionary with the valid register values in last_frame. + CFIFrameInfo::RegisterValueMap<uint64_t> callee_registers; + if (last_frame->context_validity & StackFrameRISCV64::CONTEXT_VALID_PC) + callee_registers["pc"] = last_frame->context.pc; + if (last_frame->context_validity & StackFrameRISCV64::CONTEXT_VALID_RA) + callee_registers["ra"] = last_frame->context.ra; + if (last_frame->context_validity & StackFrameRISCV64::CONTEXT_VALID_SP) + callee_registers["sp"] = last_frame->context.sp; + if (last_frame->context_validity & StackFrameRISCV64::CONTEXT_VALID_GP) + callee_registers["gp"] = last_frame->context.gp; + if (last_frame->context_validity & StackFrameRISCV64::CONTEXT_VALID_TP) + callee_registers["tp"] = last_frame->context.tp; + if (last_frame->context_validity & StackFrameRISCV64::CONTEXT_VALID_T0) + callee_registers["t0"] = last_frame->context.t0; + if (last_frame->context_validity & StackFrameRISCV64::CONTEXT_VALID_T1) + callee_registers["t1"] = last_frame->context.t1; + if (last_frame->context_validity & StackFrameRISCV64::CONTEXT_VALID_T2) + callee_registers["t2"] = last_frame->context.t2; + if (last_frame->context_validity & StackFrameRISCV64::CONTEXT_VALID_S0) + callee_registers["s0"] = last_frame->context.s0; + if (last_frame->context_validity & StackFrameRISCV64::CONTEXT_VALID_S1) + callee_registers["s1"] = last_frame->context.s1; + if (last_frame->context_validity & StackFrameRISCV64::CONTEXT_VALID_A0) + callee_registers["a0"] = last_frame->context.a0; + if (last_frame->context_validity & StackFrameRISCV64::CONTEXT_VALID_A1) + callee_registers["a1"] = last_frame->context.a1; + if (last_frame->context_validity & StackFrameRISCV64::CONTEXT_VALID_A2) + callee_registers["a2"] = last_frame->context.a2; + if (last_frame->context_validity & StackFrameRISCV64::CONTEXT_VALID_A3) + callee_registers["a3"] = last_frame->context.a3; + if (last_frame->context_validity & StackFrameRISCV64::CONTEXT_VALID_A4) + callee_registers["a4"] = last_frame->context.a4; + if (last_frame->context_validity & StackFrameRISCV64::CONTEXT_VALID_A5) + callee_registers["a5"] = last_frame->context.a5; + if (last_frame->context_validity & StackFrameRISCV64::CONTEXT_VALID_A6) + callee_registers["a6"] = last_frame->context.a6; + if (last_frame->context_validity & StackFrameRISCV64::CONTEXT_VALID_A7) + callee_registers["a7"] = last_frame->context.a7; + if (last_frame->context_validity & StackFrameRISCV64::CONTEXT_VALID_S2) + callee_registers["s2"] = last_frame->context.s2; + if (last_frame->context_validity & StackFrameRISCV64::CONTEXT_VALID_S3) + callee_registers["s3"] = last_frame->context.s3; + if (last_frame->context_validity & StackFrameRISCV64::CONTEXT_VALID_S4) + callee_registers["s4"] = last_frame->context.s4; + if (last_frame->context_validity & StackFrameRISCV64::CONTEXT_VALID_S5) + callee_registers["s5"] = last_frame->context.s5; + if (last_frame->context_validity & StackFrameRISCV64::CONTEXT_VALID_S6) + callee_registers["s6"] = last_frame->context.s6; + if (last_frame->context_validity & StackFrameRISCV64::CONTEXT_VALID_S7) + callee_registers["s7"] = last_frame->context.s7; + if (last_frame->context_validity & StackFrameRISCV64::CONTEXT_VALID_S8) + callee_registers["s8"] = last_frame->context.s8; + if (last_frame->context_validity & StackFrameRISCV64::CONTEXT_VALID_S9) + callee_registers["s9"] = last_frame->context.s9; + if (last_frame->context_validity & StackFrameRISCV64::CONTEXT_VALID_S10) + callee_registers["s10"] = last_frame->context.s10; + if (last_frame->context_validity & StackFrameRISCV64::CONTEXT_VALID_S11) + callee_registers["s11"] = last_frame->context.s11; + if (last_frame->context_validity & StackFrameRISCV64::CONTEXT_VALID_T3) + callee_registers["t3"] = last_frame->context.t3; + if (last_frame->context_validity & StackFrameRISCV64::CONTEXT_VALID_T4) + callee_registers["t4"] = last_frame->context.t4; + if (last_frame->context_validity & StackFrameRISCV64::CONTEXT_VALID_T5) + callee_registers["t5"] = last_frame->context.t5; + if (last_frame->context_validity & StackFrameRISCV64::CONTEXT_VALID_T6) + callee_registers["t6"] = last_frame->context.t6; + + // Use the STACK CFI data to recover the caller's register values. + CFIFrameInfo::RegisterValueMap<uint64_t> caller_registers; + if (!cfi_frame_info->FindCallerRegs(callee_registers, *memory_, + &caller_registers)) { + return NULL; + } + + // Construct a new stack frame given the values the CFI recovered. + CFIFrameInfo::RegisterValueMap<uint64_t>::iterator entry; + scoped_ptr<StackFrameRISCV64> frame(new StackFrameRISCV64()); + entry = caller_registers.find("pc"); + if (entry != caller_registers.end()) { + frame->context_validity |= StackFrameRISCV64::CONTEXT_VALID_PC; + frame->context.pc = entry->second; + } else{ + // If the CFI doesn't recover the PC explicitly, then use .ra. + entry = caller_registers.find(".ra"); + if (entry != caller_registers.end()) { + frame->context_validity |= StackFrameRISCV64::CONTEXT_VALID_PC; + frame->context.pc = entry->second; + } + } + entry = caller_registers.find("ra"); + if (entry != caller_registers.end()) { + frame->context_validity |= StackFrameRISCV64::CONTEXT_VALID_RA; + frame->context.ra = entry->second; + } + entry = caller_registers.find("sp"); + if (entry != caller_registers.end()) { + frame->context_validity |= StackFrameRISCV64::CONTEXT_VALID_SP; + frame->context.sp = entry->second; + } else { + // If the CFI doesn't recover the SP explicitly, then use .cfa. + entry = caller_registers.find(".cfa"); + if (entry != caller_registers.end()) { + frame->context_validity |= StackFrameRISCV64::CONTEXT_VALID_SP; + frame->context.sp = entry->second; + } + } + entry = caller_registers.find("gp"); + if (entry != caller_registers.end()) { + frame->context_validity |= StackFrameRISCV64::CONTEXT_VALID_GP; + frame->context.gp = entry->second; + } + entry = caller_registers.find("tp"); + if (entry != caller_registers.end()) { + frame->context_validity |= StackFrameRISCV64::CONTEXT_VALID_TP; + frame->context.tp = entry->second; + } + entry = caller_registers.find("t0"); + if (entry != caller_registers.end()) { + frame->context_validity |= StackFrameRISCV64::CONTEXT_VALID_T0; + frame->context.t0 = entry->second; + } + entry = caller_registers.find("t1"); + if (entry != caller_registers.end()) { + frame->context_validity |= StackFrameRISCV64::CONTEXT_VALID_T1; + frame->context.t1 = entry->second; + } + entry = caller_registers.find("t2"); + if (entry != caller_registers.end()) { + frame->context_validity |= StackFrameRISCV64::CONTEXT_VALID_T2; + frame->context.t2 = entry->second; + } + entry = caller_registers.find("s0"); + if (entry != caller_registers.end()) { + frame->context_validity |= StackFrameRISCV64::CONTEXT_VALID_S0; + frame->context.s0 = entry->second; + } else if (last_frame->context_validity & + StackFrameRISCV64::CONTEXT_VALID_S0) { + // Since the register is callee-saves, assume the callee + // has not yet changed it. + frame->context_validity |= StackFrameRISCV64::CONTEXT_VALID_S0; + frame->context.s0 = last_frame->context.s0; + } + entry = caller_registers.find("s1"); + if (entry != caller_registers.end()) { + frame->context_validity |= StackFrameRISCV64::CONTEXT_VALID_S1; + frame->context.s1 = entry->second; + } else if (last_frame->context_validity & + StackFrameRISCV64::CONTEXT_VALID_S1) { + // Since the register is callee-saves, assume the callee + // has not yet changed it. + frame->context_validity |= StackFrameRISCV64::CONTEXT_VALID_S1; + frame->context.s1 = last_frame->context.s1; + } + entry = caller_registers.find("a0"); + if (entry != caller_registers.end()) { + frame->context_validity |= StackFrameRISCV64::CONTEXT_VALID_A0; + frame->context.a0 = entry->second; + } + entry = caller_registers.find("a1"); + if (entry != caller_registers.end()) { + frame->context_validity |= StackFrameRISCV64::CONTEXT_VALID_A1; + frame->context.a1 = entry->second; + } + entry = caller_registers.find("a2"); + if (entry != caller_registers.end()) { + frame->context_validity |= StackFrameRISCV64::CONTEXT_VALID_A2; + frame->context.a2 = entry->second; + } + entry = caller_registers.find("a3"); + if (entry != caller_registers.end()) { + frame->context_validity |= StackFrameRISCV64::CONTEXT_VALID_A3; + frame->context.a3 = entry->second; + } + entry = caller_registers.find("a4"); + if (entry != caller_registers.end()) { + frame->context_validity |= StackFrameRISCV64::CONTEXT_VALID_A4; + frame->context.a4 = entry->second; + } + entry = caller_registers.find("a5"); + if (entry != caller_registers.end()) { + frame->context_validity |= StackFrameRISCV64::CONTEXT_VALID_A5; + frame->context.a5 = entry->second; + } + entry = caller_registers.find("a6"); + if (entry != caller_registers.end()) { + frame->context_validity |= StackFrameRISCV64::CONTEXT_VALID_A6; + frame->context.a6 = entry->second; + } + entry = caller_registers.find("a7"); + if (entry != caller_registers.end()) { + frame->context_validity |= StackFrameRISCV64::CONTEXT_VALID_A7; + frame->context.a7 = entry->second; + } + entry = caller_registers.find("s2"); + if (entry != caller_registers.end()) { + frame->context_validity |= StackFrameRISCV64::CONTEXT_VALID_S2; + frame->context.s2 = entry->second; + } else if (last_frame->context_validity & + StackFrameRISCV64::CONTEXT_VALID_S2) { + // Since the register is callee-saves, assume the callee + // has not yet changed it. + frame->context_validity |= StackFrameRISCV64::CONTEXT_VALID_S2; + frame->context.s2 = last_frame->context.s2; + } + entry = caller_registers.find("s3"); + if (entry != caller_registers.end()) { + frame->context_validity |= StackFrameRISCV64::CONTEXT_VALID_S3; + frame->context.s3 = entry->second; + } else if (last_frame->context_validity & + StackFrameRISCV64::CONTEXT_VALID_S3) { + // Since the register is callee-saves, assume the callee + // has not yet changed it. + frame->context_validity |= StackFrameRISCV64::CONTEXT_VALID_S3; + frame->context.s3 = last_frame->context.s3; + } + entry = caller_registers.find("s4"); + if (entry != caller_registers.end()) { + frame->context_validity |= StackFrameRISCV64::CONTEXT_VALID_S4; + frame->context.s4 = entry->second; + } else if (last_frame->context_validity & + StackFrameRISCV64::CONTEXT_VALID_S4) { + // Since the register is callee-saves, assume the callee + // has not yet changed it. + frame->context_validity |= StackFrameRISCV64::CONTEXT_VALID_S4; + frame->context.s4 = last_frame->context.s4; + } + entry = caller_registers.find("s5"); + if (entry != caller_registers.end()) { + frame->context_validity |= StackFrameRISCV64::CONTEXT_VALID_S5; + frame->context.s5 = entry->second; + } else if (last_frame->context_validity & + StackFrameRISCV64::CONTEXT_VALID_S5) { + // Since the register is callee-saves, assume the callee + // has not yet changed it. + frame->context_validity |= StackFrameRISCV64::CONTEXT_VALID_S5; + frame->context.s5 = last_frame->context.s5; + } + entry = caller_registers.find("s6"); + if (entry != caller_registers.end()) { + frame->context_validity |= StackFrameRISCV64::CONTEXT_VALID_S6; + frame->context.s6 = entry->second; + } else if (last_frame->context_validity & + StackFrameRISCV64::CONTEXT_VALID_S6) { + // Since the register is callee-saves, assume the callee + // has not yet changed it. + frame->context_validity |= StackFrameRISCV64::CONTEXT_VALID_S6; + frame->context.s6 = last_frame->context.s6; + } + entry = caller_registers.find("s7"); + if (entry != caller_registers.end()) { + frame->context_validity |= StackFrameRISCV64::CONTEXT_VALID_S7; + frame->context.s7 = entry->second; + } else if (last_frame->context_validity & + StackFrameRISCV64::CONTEXT_VALID_S7) { + // Since the register is callee-saves, assume the callee + // has not yet changed it. + frame->context_validity |= StackFrameRISCV64::CONTEXT_VALID_S7; + frame->context.s7 = last_frame->context.s7; + } + entry = caller_registers.find("s8"); + if (entry != caller_registers.end()) { + frame->context_validity |= StackFrameRISCV64::CONTEXT_VALID_S8; + frame->context.s8 = entry->second; + } else if (last_frame->context_validity & + StackFrameRISCV64::CONTEXT_VALID_S8) { + // Since the register is callee-saves, assume the callee + // has not yet changed it. + frame->context_validity |= StackFrameRISCV64::CONTEXT_VALID_S8; + frame->context.s8 = last_frame->context.s8; + } + entry = caller_registers.find("s9"); + if (entry != caller_registers.end()) { + frame->context_validity |= StackFrameRISCV64::CONTEXT_VALID_S9; + frame->context.s9 = entry->second; + } else if (last_frame->context_validity & + StackFrameRISCV64::CONTEXT_VALID_S9) { + // Since the register is callee-saves, assume the callee + // has not yet changed it. + frame->context_validity |= StackFrameRISCV64::CONTEXT_VALID_S9; + frame->context.s9 = last_frame->context.s9; + } + entry = caller_registers.find("s10"); + if (entry != caller_registers.end()) { + frame->context_validity |= StackFrameRISCV64::CONTEXT_VALID_S10; + frame->context.s10 = entry->second; + } else if (last_frame->context_validity & + StackFrameRISCV64::CONTEXT_VALID_S10) { + // Since the register is callee-saves, assume the callee + // has not yet changed it. + frame->context_validity |= StackFrameRISCV64::CONTEXT_VALID_S10; + frame->context.s10 = last_frame->context.s10; + } + entry = caller_registers.find("s11"); + if (entry != caller_registers.end()) { + frame->context_validity |= StackFrameRISCV64::CONTEXT_VALID_S11; + frame->context.s11 = entry->second; + } else if (last_frame->context_validity & + StackFrameRISCV64::CONTEXT_VALID_S11) { + // Since the register is callee-saves, assume the callee + // has not yet changed it. + frame->context_validity |= StackFrameRISCV64::CONTEXT_VALID_S11; + frame->context.s11 = last_frame->context.s11; + } + entry = caller_registers.find("t3"); + if (entry != caller_registers.end()) { + frame->context_validity |= StackFrameRISCV64::CONTEXT_VALID_T3; + frame->context.t3 = entry->second; + } + entry = caller_registers.find("t4"); + if (entry != caller_registers.end()) { + frame->context_validity |= StackFrameRISCV64::CONTEXT_VALID_T4; + frame->context.t4 = entry->second; + } + entry = caller_registers.find("t5"); + if (entry != caller_registers.end()) { + frame->context_validity |= StackFrameRISCV64::CONTEXT_VALID_T5; + frame->context.t5 = entry->second; + } + entry = caller_registers.find("t6"); + if (entry != caller_registers.end()) { + frame->context_validity |= StackFrameRISCV64::CONTEXT_VALID_T6; + frame->context.t6 = entry->second; + } + + // If we didn't recover the PC and the SP, then the frame isn't very useful. + static const uint64_t essentials = (StackFrameRISCV64::CONTEXT_VALID_SP + | StackFrameRISCV64::CONTEXT_VALID_PC); + if ((frame->context_validity & essentials) != essentials) + return NULL; + + frame->trust = StackFrame::FRAME_TRUST_CFI; + return frame.release(); +} + +StackFrameRISCV64* StackwalkerRISCV64::GetCallerByStackScan( + const vector<StackFrame*>& frames) { + StackFrameRISCV64* last_frame = + static_cast<StackFrameRISCV64*>(frames.back()); + uint64_t last_sp = last_frame->context.sp; + uint64_t caller_sp, caller_pc; + + if (!ScanForReturnAddress(last_sp, &caller_sp, &caller_pc, + last_frame->trust == StackFrame::FRAME_TRUST_CONTEXT)) { + // No plausible return address was found. + return NULL; + } + + // ScanForReturnAddress found a reasonable return address. Advance + // sp to the location above the one where the return address was + // found. + caller_sp += 8; + + // Create a new stack frame (ownership will be transferred to the caller) + // and fill it in. + StackFrameRISCV64* frame = new StackFrameRISCV64(); + + frame->trust = StackFrame::FRAME_TRUST_SCAN; + frame->context = last_frame->context; + frame->context.pc = caller_pc; + frame->context.sp = caller_sp; + frame->context_validity = StackFrameRISCV64::CONTEXT_VALID_PC | + StackFrameRISCV64::CONTEXT_VALID_SP; + + return frame; +} + +StackFrameRISCV64* StackwalkerRISCV64::GetCallerByFramePointer( + const vector<StackFrame*>& frames) { + StackFrameRISCV64* last_frame = + static_cast<StackFrameRISCV64*>(frames.back()); + + uint64_t last_fp = last_frame->context.s0; + + uint64_t caller_fp = 0; + if (last_fp && !memory_->GetMemoryAtAddress(last_fp, &caller_fp)) { + BPLOG(ERROR) << "Unable to read caller_fp from last_fp: 0x" + << std::hex << last_fp; + return NULL; + } + + uint64_t caller_ra = 0; + if (last_fp && !memory_->GetMemoryAtAddress(last_fp + 8, &caller_ra)) { + BPLOG(ERROR) << "Unable to read caller_ra from last_fp + 8: 0x" + << std::hex << (last_fp + 8); + return NULL; + } + + uint64_t caller_sp = last_fp ? last_fp + 16 : last_frame->context.s0; + + // Create a new stack frame (ownership will be transferred to the caller) + // and fill it in. + StackFrameRISCV64* frame = new StackFrameRISCV64(); + + frame->trust = StackFrame::FRAME_TRUST_FP; + frame->context = last_frame->context; + frame->context.s0 = caller_fp; + frame->context.sp = caller_sp; + frame->context.pc = last_frame->context.ra; + frame->context.ra = caller_ra; + frame->context_validity = StackFrameRISCV64::CONTEXT_VALID_PC | + StackFrameRISCV64::CONTEXT_VALID_RA | + StackFrameRISCV64::CONTEXT_VALID_S0 | + StackFrameRISCV64::CONTEXT_VALID_SP; + return frame; +} + +StackFrame* StackwalkerRISCV64::GetCallerFrame(const CallStack* stack, + bool stack_scan_allowed) { + if (!memory_ || !stack) { + BPLOG(ERROR) << "Can't get caller frame without memory or stack"; + return NULL; + } + + const vector<StackFrame*>& frames = *stack->frames(); + StackFrameRISCV64* last_frame = + static_cast<StackFrameRISCV64*>(frames.back()); + scoped_ptr<StackFrameRISCV64> frame; + + // Try to recover caller information from CFI. + scoped_ptr<CFIFrameInfo> cfi_frame_info( + frame_symbolizer_->FindCFIFrameInfo(last_frame)); + if (cfi_frame_info.get()) + frame.reset(GetCallerByCFIFrameInfo(frames, cfi_frame_info.get())); + + // If CFI failed, or there wasn't CFI available, fall back to frame pointer. + if (!frame.get()) + frame.reset(GetCallerByFramePointer(frames)); + + // If everything failed, fall back to stack scanning. + if (stack_scan_allowed && !frame.get()) + frame.reset(GetCallerByStackScan(frames)); + + // If nothing worked, tell the caller. + if (!frame.get()) + return NULL; + + // Should we terminate the stack walk? (end-of-stack or broken invariant) + if (TerminateWalk(frame->context.pc, frame->context.sp, + last_frame->context.sp, + last_frame->trust == StackFrame::FRAME_TRUST_CONTEXT)) { + return NULL; + } + + // The new frame's context's PC is the return address, which is one + // instruction past the instruction that caused us to arrive at the callee. + // RISCV instructions have a uniform 4-byte encoding, so subtracting 4 off + // the return address gets back to the beginning of the call instruction. + // Callers that require the exact return address value may access + // frame->context.pc. + frame->instruction = frame->context.pc - 4; + + return frame.release(); +} + +} // namespace google_breakpad |