From 0a636257d433df77242d8809efb62c216d60723a Mon Sep 17 00:00:00 2001
From: "ted.mielczarek@gmail.com"
<ted.mielczarek@gmail.com@4c0a9323-5329-0410-9bdc-e9ce6186880e>
Date: Tue, 4 Dec 2012 19:30:31 +0000
Subject: Allow StackwalkerARM to scan much farther to find the caller of the
context frame R=jimb at https://breakpad.appspot.com/501002/
git-svn-id: http://google-breakpad.googlecode.com/svn/trunk@1086 4c0a9323-5329-0410-9bdc-e9ce6186880e
---
src/processor/stackwalker.cc | 1 +
src/processor/stackwalker_arm.cc | 9 ++++-
src/processor/stackwalker_arm_unittest.cc | 57 +++++++++++++++++++++++++++++++
3 files changed, 66 insertions(+), 1 deletion(-)
(limited to 'src/processor')
diff --git a/src/processor/stackwalker.cc b/src/processor/stackwalker.cc
index 762c47f5..16880441 100644
--- a/src/processor/stackwalker.cc
+++ b/src/processor/stackwalker.cc
@@ -55,6 +55,7 @@
namespace google_breakpad {
+const int Stackwalker::kRASearchWords = 30;
u_int32_t Stackwalker::max_frames_ = 1024;
Stackwalker::Stackwalker(const SystemInfo* system_info,
diff --git a/src/processor/stackwalker_arm.cc b/src/processor/stackwalker_arm.cc
index 2535cd0f..da07fbcf 100644
--- a/src/processor/stackwalker_arm.cc
+++ b/src/processor/stackwalker_arm.cc
@@ -166,7 +166,14 @@ StackFrameARM* StackwalkerARM::GetCallerByStackScan(
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)) {
+ // When searching for the caller of the context frame,
+ // allow the scanner to look farther down the stack.
+ const int kRASearchWords = frames.size() == 1 ?
+ Stackwalker::kRASearchWords * 4 :
+ Stackwalker::kRASearchWords;
+
+ if (!ScanForReturnAddress(last_sp, &caller_sp, &caller_pc,
+ kRASearchWords)) {
// No plausible return address was found.
return NULL;
}
diff --git a/src/processor/stackwalker_arm_unittest.cc b/src/processor/stackwalker_arm_unittest.cc
index 4c2ca047..a86729fd 100644
--- a/src/processor/stackwalker_arm_unittest.cc
+++ b/src/processor/stackwalker_arm_unittest.cc
@@ -306,6 +306,63 @@ TEST_F(GetCallerFrame, ScanWithFunctionSymbols) {
EXPECT_EQ(0x50000100U, frame1->function_base);
}
+TEST_F(GetCallerFrame, ScanFirstFrame) {
+ // If the stackwalker resorts to stack scanning, it will scan much
+ // farther to find the caller of the context frame.
+ stack_section.start() = 0x80000000;
+ u_int32_t return_address1 = 0x50000100;
+ u_int32_t return_address2 = 0x50000900;
+ Label frame1_sp, frame2_sp;
+ stack_section
+ // frame 0
+ .Append(32, 0) // space
+
+ .D32(0x40090000) // junk that's not
+ .D32(0x60000000) // a return address
+
+ .Append(96, 0) // more space
+
+ .D32(return_address1) // actual return address
+ // frame 1
+ .Mark(&frame1_sp)
+ .Append(32, 0) // space
+
+ .D32(0xF0000000) // more junk
+ .D32(0x0000000D)
+
+ .Append(96, 0) // more space
+
+ .D32(return_address2) // actual return address
+ // (won't be found)
+ // frame 2
+ .Mark(&frame2_sp)
+ .Append(32, 0); // end of stack
+ RegionFromSection();
+
+ raw_context.iregs[MD_CONTEXT_ARM_REG_PC] = 0x40005510;
+ raw_context.iregs[MD_CONTEXT_ARM_REG_SP] = stack_section.start().Value();
+
+ StackFrameSymbolizer frame_symbolizer(&supplier, &resolver);
+ StackwalkerARM walker(&system_info, &raw_context, -1, &stack_region, &modules,
+ &frame_symbolizer);
+ ASSERT_TRUE(walker.Walk(&call_stack));
+ frames = call_stack.frames();
+ ASSERT_EQ(2U, frames->size());
+
+ StackFrameARM *frame0 = static_cast<StackFrameARM *>(frames->at(0));
+ EXPECT_EQ(StackFrame::FRAME_TRUST_CONTEXT, frame0->trust);
+ ASSERT_EQ(StackFrameARM::CONTEXT_VALID_ALL, frame0->context_validity);
+ EXPECT_EQ(0, memcmp(&raw_context, &frame0->context, sizeof(raw_context)));
+
+ StackFrameARM *frame1 = static_cast<StackFrameARM *>(frames->at(1));
+ EXPECT_EQ(StackFrame::FRAME_TRUST_SCAN, frame1->trust);
+ ASSERT_EQ((StackFrameARM::CONTEXT_VALID_PC |
+ StackFrameARM::CONTEXT_VALID_SP),
+ frame1->context_validity);
+ EXPECT_EQ(return_address1, frame1->context.iregs[MD_CONTEXT_ARM_REG_PC]);
+ EXPECT_EQ(frame1_sp.Value(), frame1->context.iregs[MD_CONTEXT_ARM_REG_SP]);
+}
+
struct CFIFixture: public StackwalkerARMFixture {
CFIFixture() {
// Provide a bunch of STACK CFI records; we'll walk to the caller
--
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