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// Copyright (c) 2010 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_arm.cc: arm-specific stackwalker.
//
// See stackwalker_arm.h for documentation.
//
// Author: Mark Mentovai, Ted Mielczarek, Jim Blandy
#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/scoped_ptr.h"
#include "processor/stackwalker_arm.h"
namespace google_breakpad {
StackwalkerARM::StackwalkerARM(const SystemInfo *system_info,
const MDRawContextARM *context,
MemoryRegion *memory,
const CodeModules *modules,
SymbolSupplier *supplier,
SourceLineResolverInterface *resolver)
: Stackwalker(system_info, memory, modules, supplier, resolver),
context_(context),
context_frame_validity_(StackFrameARM::CONTEXT_VALID_ALL) { }
StackFrame* StackwalkerARM::GetContextFrame() {
if (!context_ || !memory_) {
BPLOG(ERROR) << "Can't get context frame without context or memory";
return NULL;
}
StackFrameARM *frame = new StackFrameARM();
// The instruction pointer is stored directly in a register (r15), 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[15];
return frame;
}
StackFrameARM *StackwalkerARM::GetCallerByCFIFrameInfo(
const vector<StackFrame *> &frames,
CFIFrameInfo *cfi_frame_info) {
StackFrameARM *last_frame = static_cast<StackFrameARM *>(frames.back());
static const char *register_names[] = {
"r0", "r1", "r2", "r3", "r4", "r5", "r6", "r7",
"r8", "r9", "r10", "r11", "r12", "sp", "lr", "pc",
"f0", "f1", "f2", "f3", "f4", "f5", "f6", "f7",
"fps", "cpsr",
NULL
};
// Populate a dictionary with the valid register values in last_frame.
CFIFrameInfo::RegisterValueMap<u_int32_t> callee_registers;
for (int i = 0; register_names[i]; i++)
if (last_frame->context_validity & StackFrameARM::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<u_int32_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<StackFrameARM> frame(new StackFrameARM());
for (int i = 0; register_names[i]; i++) {
CFIFrameInfo::RegisterValueMap<u_int32_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 |= StackFrameARM::RegisterValidFlag(i);
frame->context.iregs[i] = entry->second;
} else if (4 <= i && i <= 11 && (last_frame->context_validity &
StackFrameARM::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 r4 through r11 are callee-saves, according to the Procedure
// Call Standard for the ARM Architecture, which the Linux ABI follows.
frame->context_validity |= StackFrameARM::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 & StackFrameARM::CONTEXT_VALID_PC)) {
CFIFrameInfo::RegisterValueMap<u_int32_t>::iterator entry =
caller_registers.find(".ra");
if (entry != caller_registers.end()) {
frame->context_validity |= StackFrameARM::CONTEXT_VALID_PC;
frame->context.iregs[MD_CONTEXT_ARM_REG_PC] = entry->second;
}
}
// If the CFI doesn't recover the SP explicitly, then use .cfa.
if (! (frame->context_validity & StackFrameARM::CONTEXT_VALID_SP)) {
CFIFrameInfo::RegisterValueMap<u_int32_t>::iterator entry =
caller_registers.find(".cfa");
if (entry != caller_registers.end()) {
frame->context_validity |= StackFrameARM::CONTEXT_VALID_SP;
frame->context.iregs[MD_CONTEXT_ARM_REG_SP] = entry->second;
}
}
// If we didn't recover the PC and the SP, then the frame isn't very useful.
static const int essentials = (StackFrameARM::CONTEXT_VALID_SP
| StackFrameARM::CONTEXT_VALID_PC);
if ((frame->context_validity & essentials) != essentials)
return NULL;
frame->trust = StackFrame::FRAME_TRUST_CFI;
return frame.release();
}
StackFrameARM *StackwalkerARM::GetCallerByStackScan(
const vector<StackFrame *> &frames) {
StackFrameARM *last_frame = static_cast<StackFrameARM *>(frames.back());
u_int32_t last_sp = last_frame->context.iregs[MD_CONTEXT_ARM_REG_SP];
u_int32_t caller_sp, caller_pc;
if (!ScanForReturnAddress(last_sp, &caller_sp, &caller_pc)) {
// 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 += 4;
// Create a new stack frame (ownership will be transferred to the caller)
// and fill it in.
StackFrameARM *frame = new StackFrameARM();
frame->trust = StackFrame::FRAME_TRUST_SCAN;
frame->context = last_frame->context;
frame->context.iregs[MD_CONTEXT_ARM_REG_PC] = caller_pc;
frame->context.iregs[MD_CONTEXT_ARM_REG_SP] = caller_sp;
frame->context_validity = StackFrameARM::CONTEXT_VALID_PC |
StackFrameARM::CONTEXT_VALID_SP;
return frame;
}
StackFrame* StackwalkerARM::GetCallerFrame(const CallStack *stack) {
if (!memory_ || !stack) {
BPLOG(ERROR) << "Can't get caller frame without memory or stack";
return NULL;
}
const vector<StackFrame *> &frames = *stack->frames();
StackFrameARM *last_frame = static_cast<StackFrameARM *>(frames.back());
scoped_ptr<StackFrameARM> frame;
// See if there is DWARF call frame information covering this address.
scoped_ptr<CFIFrameInfo> cfi_frame_info(
resolver_ ? resolver_->FindCFIFrameInfo(last_frame) : NULL);
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 stack scanning.
if (!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_ARM_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_ARM_REG_SP]
< last_frame->context.iregs[MD_CONTEXT_ARM_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. Set new_frame->instruction to one less than the PC. This won't
// reference the beginning of the call instruction, but it's at least
// within it, which is sufficient to get the source line information to
// match up with the line that contains the function call. Callers that
// require the exact return address value may access
// frame->context.iregs[MD_CONTEXT_ARM_REG_PC].
frame->instruction = frame->context.iregs[MD_CONTEXT_ARM_REG_PC] - 1;
return frame.release();
}
} // namespace google_breakpad
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