michael@0: // Copyright (c) 2010 Google Inc.
michael@0: // All rights reserved.
michael@0: //
michael@0: // Redistribution and use in source and binary forms, with or without
michael@0: // modification, are permitted provided that the following conditions are
michael@0: // met:
michael@0: //
michael@0: //     * Redistributions of source code must retain the above copyright
michael@0: // notice, this list of conditions and the following disclaimer.
michael@0: //     * Redistributions in binary form must reproduce the above
michael@0: // copyright notice, this list of conditions and the following disclaimer
michael@0: // in the documentation and/or other materials provided with the
michael@0: // distribution.
michael@0: //     * Neither the name of Google Inc. nor the names of its
michael@0: // contributors may be used to endorse or promote products derived from
michael@0: // this software without specific prior written permission.
michael@0: //
michael@0: // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
michael@0: // "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
michael@0: // LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
michael@0: // A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
michael@0: // OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
michael@0: // SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
michael@0: // LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
michael@0: // DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
michael@0: // THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
michael@0: // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
michael@0: // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
michael@0: 
michael@0: // stackwalker_arm.cc: arm-specific stackwalker.
michael@0: //
michael@0: // See stackwalker_arm.h for documentation.
michael@0: //
michael@0: // Author: Mark Mentovai, Ted Mielczarek, Jim Blandy
michael@0: 
michael@0: #include <vector>
michael@0: 
michael@0: #include "common/scoped_ptr.h"
michael@0: #include "google_breakpad/processor/call_stack.h"
michael@0: #include "google_breakpad/processor/memory_region.h"
michael@0: #include "google_breakpad/processor/source_line_resolver_interface.h"
michael@0: #include "google_breakpad/processor/stack_frame_cpu.h"
michael@0: #include "processor/cfi_frame_info.h"
michael@0: #include "common/logging.h"
michael@0: #include "processor/stackwalker_arm.h"
michael@0: 
michael@0: namespace google_breakpad {
michael@0: 
michael@0: 
michael@0: StackwalkerARM::StackwalkerARM(const SystemInfo* system_info,
michael@0:                                const MDRawContextARM* context,
michael@0:                                int fp_register,
michael@0:                                MemoryRegion* memory,
michael@0:                                const CodeModules* modules,
michael@0:                                StackFrameSymbolizer* resolver_helper)
michael@0:     : Stackwalker(system_info, memory, modules, resolver_helper),
michael@0:       context_(context), fp_register_(fp_register),
michael@0:       context_frame_validity_(StackFrameARM::CONTEXT_VALID_ALL) { }
michael@0: 
michael@0: 
michael@0: StackFrame* StackwalkerARM::GetContextFrame() {
michael@0:   if (!context_) {
michael@0:     BPLOG(ERROR) << "Can't get context frame without context";
michael@0:     return NULL;
michael@0:   }
michael@0: 
michael@0:   StackFrameARM* frame = new StackFrameARM();
michael@0: 
michael@0:   // The instruction pointer is stored directly in a register (r15), so pull it
michael@0:   // straight out of the CPU context structure.
michael@0:   frame->context = *context_;
michael@0:   frame->context_validity = context_frame_validity_;
michael@0:   frame->trust = StackFrame::FRAME_TRUST_CONTEXT;
michael@0:   frame->instruction = frame->context.iregs[MD_CONTEXT_ARM_REG_PC];
michael@0: 
michael@0:   return frame;
michael@0: }
michael@0: 
michael@0: StackFrameARM* StackwalkerARM::GetCallerByCFIFrameInfo(
michael@0:     const vector<StackFrame*> &frames,
michael@0:     CFIFrameInfo* cfi_frame_info) {
michael@0:   StackFrameARM* last_frame = static_cast<StackFrameARM*>(frames.back());
michael@0: 
michael@0:   static const UniqueString *register_names[] = {
michael@0:     ToUniqueString("r0"),  ToUniqueString("r1"),
michael@0:     ToUniqueString("r2"),  ToUniqueString("r3"),
michael@0:     ToUniqueString("r4"),  ToUniqueString("r5"),
michael@0:     ToUniqueString("r6"),  ToUniqueString("r7"),
michael@0:     ToUniqueString("r8"),  ToUniqueString("r9"),
michael@0:     ToUniqueString("r10"), ToUniqueString("r11"),
michael@0:     ToUniqueString("r12"), ToUniqueString("sp"),
michael@0:     ToUniqueString("lr"),  ToUniqueString("pc"),
michael@0:     ToUniqueString("f0"),  ToUniqueString("f1"),
michael@0:     ToUniqueString("f2"),  ToUniqueString("f3"),
michael@0:     ToUniqueString("f4"),  ToUniqueString("f5"),
michael@0:     ToUniqueString("f6"),  ToUniqueString("f7"),
michael@0:     ToUniqueString("fps"), ToUniqueString("cpsr"),
michael@0:     NULL
michael@0:   };
michael@0: 
michael@0:   // Populate a dictionary with the valid register values in last_frame.
michael@0:   CFIFrameInfo::RegisterValueMap<uint32_t> callee_registers;
michael@0:   for (int i = 0; register_names[i]; i++)
michael@0:     if (last_frame->context_validity & StackFrameARM::RegisterValidFlag(i))
michael@0:       callee_registers.set(register_names[i], last_frame->context.iregs[i]);
michael@0: 
michael@0:   // Use the STACK CFI data to recover the caller's register values.
michael@0:   CFIFrameInfo::RegisterValueMap<uint32_t> caller_registers;
michael@0:   if (!cfi_frame_info->FindCallerRegs(callee_registers, *memory_,
michael@0:                                       &caller_registers))
michael@0:     return NULL;
michael@0: 
michael@0:   // Construct a new stack frame given the values the CFI recovered.
michael@0:   scoped_ptr<StackFrameARM> frame(new StackFrameARM());
michael@0:   for (int i = 0; register_names[i]; i++) {
michael@0:     bool found = false;
michael@0:     uint32_t v = caller_registers.get(&found, register_names[i]);
michael@0:     if (found) {
michael@0:       // We recovered the value of this register; fill the context with the
michael@0:       // value from caller_registers.
michael@0:       frame->context_validity |= StackFrameARM::RegisterValidFlag(i);
michael@0:       frame->context.iregs[i] = v;
michael@0:     } else if (4 <= i && i <= 11 && (last_frame->context_validity &
michael@0:                                      StackFrameARM::RegisterValidFlag(i))) {
michael@0:       // If the STACK CFI data doesn't mention some callee-saves register, and
michael@0:       // it is valid in the callee, assume the callee has not yet changed it.
michael@0:       // Registers r4 through r11 are callee-saves, according to the Procedure
michael@0:       // Call Standard for the ARM Architecture, which the Linux ABI follows.
michael@0:       frame->context_validity |= StackFrameARM::RegisterValidFlag(i);
michael@0:       frame->context.iregs[i] = last_frame->context.iregs[i];
michael@0:     }
michael@0:   }
michael@0:   // If the CFI doesn't recover the PC explicitly, then use .ra.
michael@0:   if (!(frame->context_validity & StackFrameARM::CONTEXT_VALID_PC)) {
michael@0:     bool found = false;
michael@0:     uint32_t v = caller_registers.get(&found, ustr__ZDra());
michael@0:     if (found) {
michael@0:       if (fp_register_ == -1) {
michael@0:         frame->context_validity |= StackFrameARM::CONTEXT_VALID_PC;
michael@0:         frame->context.iregs[MD_CONTEXT_ARM_REG_PC] = v;
michael@0:       } else {
michael@0:         // The CFI updated the link register and not the program counter.
michael@0:         // Handle getting the program counter from the link register.
michael@0:         frame->context_validity |= StackFrameARM::CONTEXT_VALID_PC;
michael@0:         frame->context_validity |= StackFrameARM::CONTEXT_VALID_LR;
michael@0:         frame->context.iregs[MD_CONTEXT_ARM_REG_LR] = v;
michael@0:         frame->context.iregs[MD_CONTEXT_ARM_REG_PC] =
michael@0:             last_frame->context.iregs[MD_CONTEXT_ARM_REG_LR];
michael@0:       }
michael@0:     }
michael@0:   }
michael@0:   // If the CFI doesn't recover the SP explicitly, then use .cfa.
michael@0:   if (!(frame->context_validity & StackFrameARM::CONTEXT_VALID_SP)) {
michael@0:     bool found = false;
michael@0:     uint32_t v = caller_registers.get(&found, ustr__ZDcfa());
michael@0:     if (found) {
michael@0:       frame->context_validity |= StackFrameARM::CONTEXT_VALID_SP;
michael@0:       frame->context.iregs[MD_CONTEXT_ARM_REG_SP] = v;
michael@0:     }
michael@0:   }
michael@0: 
michael@0:   // If we didn't recover the PC and the SP, then the frame isn't very useful.
michael@0:   static const int essentials = (StackFrameARM::CONTEXT_VALID_SP
michael@0:                                  | StackFrameARM::CONTEXT_VALID_PC);
michael@0:   if ((frame->context_validity & essentials) != essentials)
michael@0:     return NULL;
michael@0: 
michael@0:   frame->trust = StackFrame::FRAME_TRUST_CFI;
michael@0:   return frame.release();
michael@0: }
michael@0: 
michael@0: StackFrameARM* StackwalkerARM::GetCallerByStackScan(
michael@0:     const vector<StackFrame*> &frames) {
michael@0:   StackFrameARM* last_frame = static_cast<StackFrameARM*>(frames.back());
michael@0:   uint32_t last_sp = last_frame->context.iregs[MD_CONTEXT_ARM_REG_SP];
michael@0:   uint32_t caller_sp, caller_pc;
michael@0: 
michael@0:   // When searching for the caller of the context frame,
michael@0:   // allow the scanner to look farther down the stack.
michael@0:   const int kRASearchWords = frames.size() == 1 ?
michael@0:     Stackwalker::kRASearchWords * 4 :
michael@0:     Stackwalker::kRASearchWords;
michael@0: 
michael@0:   if (!ScanForReturnAddress(last_sp, &caller_sp, &caller_pc,
michael@0:                             kRASearchWords)) {
michael@0:     // No plausible return address was found.
michael@0:     return NULL;
michael@0:   }
michael@0: 
michael@0:   // ScanForReturnAddress found a reasonable return address. Advance
michael@0:   // %sp to the location above the one where the return address was
michael@0:   // found.
michael@0:   caller_sp += 4;
michael@0: 
michael@0:   // Create a new stack frame (ownership will be transferred to the caller)
michael@0:   // and fill it in.
michael@0:   StackFrameARM* frame = new StackFrameARM();
michael@0: 
michael@0:   frame->trust = StackFrame::FRAME_TRUST_SCAN;
michael@0:   frame->context = last_frame->context;
michael@0:   frame->context.iregs[MD_CONTEXT_ARM_REG_PC] = caller_pc;
michael@0:   frame->context.iregs[MD_CONTEXT_ARM_REG_SP] = caller_sp;
michael@0:   frame->context_validity = StackFrameARM::CONTEXT_VALID_PC |
michael@0:                             StackFrameARM::CONTEXT_VALID_SP;
michael@0: 
michael@0:   return frame;
michael@0: }
michael@0: 
michael@0: StackFrameARM* StackwalkerARM::GetCallerByFramePointer(
michael@0:     const vector<StackFrame*> &frames) {
michael@0:   StackFrameARM* last_frame = static_cast<StackFrameARM*>(frames.back());
michael@0: 
michael@0:   if (!(last_frame->context_validity &
michael@0:         StackFrameARM::RegisterValidFlag(fp_register_))) {
michael@0:     return NULL;
michael@0:   }
michael@0: 
michael@0:   uint32_t last_fp = last_frame->context.iregs[fp_register_];
michael@0: 
michael@0:   uint32_t caller_fp = 0;
michael@0:   if (last_fp && !memory_->GetMemoryAtAddress(last_fp, &caller_fp)) {
michael@0:     BPLOG(ERROR) << "Unable to read caller_fp from last_fp: 0x"
michael@0:                  << std::hex << last_fp;
michael@0:     return NULL;
michael@0:   }
michael@0: 
michael@0:   uint32_t caller_lr = 0;
michael@0:   if (last_fp && !memory_->GetMemoryAtAddress(last_fp + 4, &caller_lr)) {
michael@0:     BPLOG(ERROR) << "Unable to read caller_lr from last_fp + 4: 0x"
michael@0:                  << std::hex << (last_fp + 4);
michael@0:     return NULL;
michael@0:   }
michael@0: 
michael@0:   uint32_t caller_sp = last_fp ? last_fp + 8 :
michael@0:       last_frame->context.iregs[MD_CONTEXT_ARM_REG_SP];
michael@0: 
michael@0:   // Create a new stack frame (ownership will be transferred to the caller)
michael@0:   // and fill it in.
michael@0:   StackFrameARM* frame = new StackFrameARM();
michael@0: 
michael@0:   frame->trust = StackFrame::FRAME_TRUST_FP;
michael@0:   frame->context = last_frame->context;
michael@0:   frame->context.iregs[fp_register_] = caller_fp;
michael@0:   frame->context.iregs[MD_CONTEXT_ARM_REG_SP] = caller_sp;
michael@0:   frame->context.iregs[MD_CONTEXT_ARM_REG_PC] =
michael@0:       last_frame->context.iregs[MD_CONTEXT_ARM_REG_LR];
michael@0:   frame->context.iregs[MD_CONTEXT_ARM_REG_LR] = caller_lr;
michael@0:   frame->context_validity = StackFrameARM::CONTEXT_VALID_PC |
michael@0:                             StackFrameARM::CONTEXT_VALID_LR |
michael@0:                             StackFrameARM::RegisterValidFlag(fp_register_) |
michael@0:                             StackFrameARM::CONTEXT_VALID_SP;
michael@0:   return frame;
michael@0: }
michael@0: 
michael@0: StackFrame* StackwalkerARM::GetCallerFrame(const CallStack* stack,
michael@0:                                            bool stack_scan_allowed) {
michael@0:   if (!memory_ || !stack) {
michael@0:     BPLOG(ERROR) << "Can't get caller frame without memory or stack";
michael@0:     return NULL;
michael@0:   }
michael@0: 
michael@0:   const vector<StackFrame*> &frames = *stack->frames();
michael@0:   StackFrameARM* last_frame = static_cast<StackFrameARM*>(frames.back());
michael@0:   scoped_ptr<StackFrameARM> frame;
michael@0: 
michael@0:   // See if there is DWARF call frame information covering this address.
michael@0:   scoped_ptr<CFIFrameInfo> cfi_frame_info(
michael@0:       frame_symbolizer_->FindCFIFrameInfo(last_frame));
michael@0:   if (cfi_frame_info.get())
michael@0:     frame.reset(GetCallerByCFIFrameInfo(frames, cfi_frame_info.get()));
michael@0: 
michael@0:   // If CFI failed, or there wasn't CFI available, fall back
michael@0:   // to frame pointer, if this is configured.
michael@0:   if (fp_register_ >= 0 && !frame.get())
michael@0:     frame.reset(GetCallerByFramePointer(frames));
michael@0: 
michael@0:   // If everuthing failed, fall back to stack scanning.
michael@0:   if (stack_scan_allowed && !frame.get())
michael@0:     frame.reset(GetCallerByStackScan(frames));
michael@0: 
michael@0:   // If nothing worked, tell the caller.
michael@0:   if (!frame.get())
michael@0:     return NULL;
michael@0: 
michael@0: 
michael@0:   // An instruction address of zero marks the end of the stack.
michael@0:   if (frame->context.iregs[MD_CONTEXT_ARM_REG_PC] == 0)
michael@0:     return NULL;
michael@0: 
michael@0:   // If the new stack pointer is at a lower address than the old, then
michael@0:   // that's clearly incorrect. Treat this as end-of-stack to enforce
michael@0:   // progress and avoid infinite loops.
michael@0:   if (frame->context.iregs[MD_CONTEXT_ARM_REG_SP]
michael@0:       < last_frame->context.iregs[MD_CONTEXT_ARM_REG_SP])
michael@0:     return NULL;
michael@0: 
michael@0:   // The new frame's context's PC is the return address, which is one
michael@0:   // instruction past the instruction that caused us to arrive at the
michael@0:   // callee. Set new_frame->instruction to one less than the PC. This won't
michael@0:   // reference the beginning of the call instruction, but it's at least
michael@0:   // within it, which is sufficient to get the source line information to
michael@0:   // match up with the line that contains the function call. Callers that
michael@0:   // require the exact return address value may access
michael@0:   // frame->context.iregs[MD_CONTEXT_ARM_REG_PC].
michael@0:   frame->instruction = frame->context.iregs[MD_CONTEXT_ARM_REG_PC] - 2;
michael@0: 
michael@0:   return frame.release();
michael@0: }
michael@0: 
michael@0: 
michael@0: }  // namespace google_breakpad