// Copyright (c) 2013 Google Inc.
// All rights reserved.
//
// 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 Inc. 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_arm64.cc: arm64-specific stackwalker.
//
// See stackwalker_arm64.h for documentation.
//
// Author: Mark Mentovai, Ted Mielczarek, Jim Blandy, Colin Blundell
#include <vector>
#include "common/scoped_ptr.h"
#include "google_breakpad/processor/call_stack.h"
#include "google_breakpad/processor/memory_region.h"
#include "google_breakpad/processor/source_line_resolver_interface.h"
#include "google_breakpad/processor/stack_frame_cpu.h"
#include "processor/cfi_frame_info.h"
#include "processor/logging.h"
#include "processor/stackwalker_arm64.h"
namespace google_breakpad {
StackwalkerARM64::StackwalkerARM64(const SystemInfo* system_info,
const MDRawContextARM64* context,
MemoryRegion* memory,
const CodeModules* modules,
StackFrameSymbolizer* resolver_helper)
: Stackwalker(system_info, memory, modules, resolver_helper),
context_(context),
context_frame_validity_(StackFrameARM64::CONTEXT_VALID_ALL) { }
StackFrame* StackwalkerARM64::GetContextFrame() {
if (!context_) {
BPLOG(ERROR) << "Can't get context frame without context";
return NULL;
}
StackFrameARM64* frame = new StackFrameARM64();
// The instruction pointer is stored directly in a register (x32), so pull it
// straight out of the CPU context structure.
frame->context = *context_;
frame->context_validity = context_frame_validity_;
frame->trust = StackFrame::FRAME_TRUST_CONTEXT;
frame->instruction = frame->context.iregs[MD_CONTEXT_ARM64_REG_PC];
return frame;
}
StackFrameARM64* StackwalkerARM64::GetCallerByCFIFrameInfo(
const vector<StackFrame*> &frames,
CFIFrameInfo* cfi_frame_info) {
StackFrameARM64* last_frame = static_cast<StackFrameARM64*>(frames.back());
static const char* register_names[] = {
"x0", "x1", "x2", "x3", "x4", "x5", "x6", "x7",
"x8", "x9", "x10", "x11", "x12", "x13", "x14", "x15",
"x16", "x17", "x18", "x19", "x20", "x21", "x22", "x23",
"x24", "x25", "x26", "x27", "x28", "x29", "x30", "sp",
"pc", NULL
};
// Populate a dictionary with the valid register values in last_frame.
CFIFrameInfo::RegisterValueMap<uint64_t> callee_registers;
for (int i = 0; register_names[i]; i++) {
if (last_frame->context_validity & StackFrameARM64::RegisterValidFlag(i))
callee_registers[register_names[i]] = last_frame->context.iregs[i];
}
// 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.
scoped_ptr<StackFrameARM64> frame(new StackFrameARM64());
for (int i = 0; register_names[i]; i++) {
CFIFrameInfo::RegisterValueMap<uint64_t>::iterator entry =
caller_registers.find(register_names[i]);
if (entry != caller_registers.end()) {
// We recovered the value of this register; fill the context with the
// value from caller_registers.
frame->context_validity |= StackFrameARM64::RegisterValidFlag(i);
frame->context.iregs[i] = entry->second;
} else if (19 <= i && i <= 29 && (last_frame->context_validity &
StackFrameARM64::RegisterValidFlag(i))) {
// If the STACK CFI data doesn't mention some callee-saves register, and
// it is valid in the callee, assume the callee has not yet changed it.
// Registers r19 through r29 are callee-saves, according to the Procedure
// Call Standard for the ARM AARCH64 Architecture, which the Linux ABI
// follows.
frame->context_validity |= StackFrameARM64::RegisterValidFlag(i);
frame->context.iregs[i] = last_frame->context.iregs[i];
}
}
// If the CFI doesn't recover the PC explicitly, then use .ra.
if (!(frame->context_validity & StackFrameARM64::CONTEXT_VALID_PC)) {
CFIFrameInfo::RegisterValueMap<uint64_t>::iterator entry =
caller_registers.find(".ra");
if (entry != caller_registers.end()) {
frame->context_validity |= StackFrameARM64::CONTEXT_VALID_PC;
frame->context.iregs[MD_CONTEXT_ARM64_REG_PC] = entry->second;
}
}
// If the CFI doesn't recover the SP explicitly, then use .cfa.
if (!(frame->context_validity & StackFrameARM64::CONTEXT_VALID_SP)) {
CFIFrameInfo::RegisterValueMap<uint64_t>::iterator entry =
caller_registers.find(".cfa");
if (entry != caller_registers.end()) {
frame->context_validity |= StackFrameARM64::CONTEXT_VALID_SP;
frame->context.iregs[MD_CONTEXT_ARM64_REG_SP] = entry->second;
}
}
// If we didn't recover the PC and the SP, then the frame isn't very useful.
static const uint64_t essentials = (StackFrameARM64::CONTEXT_VALID_SP
| StackFrameARM64::CONTEXT_VALID_PC);
if ((frame->context_validity & essentials) != essentials)
return NULL;
frame->trust = StackFrame::FRAME_TRUST_CFI;
return frame.release();
}
StackFrameARM64* StackwalkerARM64::GetCallerByStackScan(
const vector<StackFrame*> &frames) {
StackFrameARM64* last_frame = static_cast<StackFrameARM64*>(frames.back());
uint64_t last_sp = last_frame->context.iregs[MD_CONTEXT_ARM64_REG_SP];
uint64_t caller_sp, caller_pc;
if (!ScanForReturnAddress(last_sp, &caller_sp, &caller_pc,
frames.size() == 1 /* is_context_frame */)) {
// 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.
StackFrameARM64* frame = new StackFrameARM64();
frame->trust = StackFrame::FRAME_TRUST_SCAN;
frame->context = last_frame->context;
frame->context.iregs[MD_CONTEXT_ARM64_REG_PC] = caller_pc;
frame->context.iregs[MD_CONTEXT_ARM64_REG_SP] = caller_sp;
frame->context_validity = StackFrameARM64::CONTEXT_VALID_PC |
StackFrameARM64::CONTEXT_VALID_SP;
return frame;
}
StackFrameARM64* StackwalkerARM64::GetCallerByFramePointer(
const vector<StackFrame*> &frames) {
StackFrameARM64* last_frame = static_cast<StackFrameARM64*>(frames.back());
uint64_t last_fp = last_frame->context.iregs[MD_CONTEXT_ARM64_REG_FP];
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_lr = 0;
if (last_fp && !memory_->GetMemoryAtAddress(last_fp + 8, &caller_lr)) {
BPLOG(ERROR) << "Unable to read caller_lr from last_fp + 8: 0x"
<< std::hex << (last_fp + 8);
return NULL;
}
uint64_t caller_sp = last_fp ? last_fp + 16 :
last_frame->context.iregs[MD_CONTEXT_ARM64_REG_SP];
// Create a new stack frame (ownership will be transferred to the caller)
// and fill it in.
StackFrameARM64* frame = new StackFrameARM64();
frame->trust = StackFrame::FRAME_TRUST_FP;
frame->context = last_frame->context;
frame->context.iregs[MD_CONTEXT_ARM64_REG_FP] = caller_fp;
frame->context.iregs[MD_CONTEXT_ARM64_REG_SP] = caller_sp;
frame->context.iregs[MD_CONTEXT_ARM64_REG_PC] =
last_frame->context.iregs[MD_CONTEXT_ARM64_REG_LR];
frame->context.iregs[MD_CONTEXT_ARM64_REG_LR] = caller_lr;
frame->context_validity = StackFrameARM64::CONTEXT_VALID_PC |
StackFrameARM64::CONTEXT_VALID_LR |
StackFrameARM64::CONTEXT_VALID_FP |
StackFrameARM64::CONTEXT_VALID_SP;
return frame;
}
StackFrame* StackwalkerARM64::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();
StackFrameARM64* last_frame = static_cast<StackFrameARM64*>(frames.back());
scoped_ptr<StackFrameARM64> frame;
// See if there is DWARF call frame information covering this address.
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;
// An instruction address of zero marks the end of the stack.
if (frame->context.iregs[MD_CONTEXT_ARM64_REG_PC] == 0)
return NULL;
// If the new stack pointer is at a lower address than the old, then
// that's clearly incorrect. Treat this as end-of-stack to enforce
// progress and avoid infinite loops.
if (frame->context.iregs[MD_CONTEXT_ARM64_REG_SP]
< last_frame->context.iregs[MD_CONTEXT_ARM64_REG_SP])
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.
// ARM64 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.iregs[MD_CONTEXT_ARM64_REG_PC].
frame->instruction = frame->context.iregs[MD_CONTEXT_ARM64_REG_PC] - 4;
return frame.release();
}
} // namespace google_breakpad