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-rw-r--r--src/processor/stackwalker_amd64.cc37
-rw-r--r--src/processor/stackwalker_amd64_unittest.cc87
2 files changed, 110 insertions, 14 deletions
diff --git a/src/processor/stackwalker_amd64.cc b/src/processor/stackwalker_amd64.cc
index fd9ccdf3..5a9ddb19 100644
--- a/src/processor/stackwalker_amd64.cc
+++ b/src/processor/stackwalker_amd64.cc
@@ -146,18 +146,13 @@ StackFrameAMD64 *StackwalkerAMD64::GetCallerByStackScan(
const vector<StackFrame *> &frames) {
StackFrameAMD64 *last_frame = static_cast<StackFrameAMD64 *>(frames.back());
u_int64_t last_rsp = last_frame->context.rsp;
- u_int64_t caller_rsp, caller_rip;
-
- if (!ScanForReturnAddress(last_rsp, &caller_rsp, &caller_rip)) {
+ u_int64_t caller_rip_address, caller_rip;
+
+ if (!ScanForReturnAddress(last_rsp, &caller_rip_address, &caller_rip)) {
// No plausible return address was found.
return NULL;
}
- // ScanForReturnAddress found a reasonable return address. Advance
- // %rsp to the location above the one where the return address was
- // found.
- caller_rsp += 8;
-
// Create a new stack frame (ownership will be transferred to the caller)
// and fill it in.
StackFrameAMD64 *frame = new StackFrameAMD64();
@@ -165,10 +160,34 @@ StackFrameAMD64 *StackwalkerAMD64::GetCallerByStackScan(
frame->trust = StackFrame::FRAME_TRUST_SCAN;
frame->context = last_frame->context;
frame->context.rip = caller_rip;
- frame->context.rsp = caller_rsp;
+ // The caller's %rsp is directly underneath the return address pushed by
+ // the call.
+ frame->context.rsp = caller_rip_address + 8;
frame->context_validity = StackFrameAMD64::CONTEXT_VALID_RIP |
StackFrameAMD64::CONTEXT_VALID_RSP;
+ // Other unwinders give up if they don't have an %rbp value, so see if we
+ // can pass some plausible value on.
+ if (last_frame->context_validity & StackFrameAMD64::CONTEXT_VALID_RBP) {
+ // Functions typically push their caller's %rbp immediately upon entry,
+ // and then set %rbp to point to that. So if the callee's %rbp is
+ // pointing to the first word below the alleged return address, presume
+ // that the caller's %rbp is saved there.
+ if (caller_rip_address - 8 == last_frame->context.rbp) {
+ u_int64_t caller_rbp = 0;
+ if (memory_->GetMemoryAtAddress(last_frame->context.rbp, &caller_rbp) &&
+ caller_rbp > caller_rip_address) {
+ frame->context.rbp = caller_rbp;
+ frame->context_validity |= StackFrameAMD64::CONTEXT_VALID_RBP;
+ }
+ } else if (last_frame->context.rbp >= caller_rip_address + 8) {
+ // If the callee's %rbp is plausible as a value for the caller's
+ // %rbp, presume that the callee left it unchanged.
+ frame->context.rbp = last_frame->context.rbp;
+ frame->context_validity |= StackFrameAMD64::CONTEXT_VALID_RBP;
+ }
+ }
+
return frame;
}
diff --git a/src/processor/stackwalker_amd64_unittest.cc b/src/processor/stackwalker_amd64_unittest.cc
index 0cb5fd57..a107bee8 100644
--- a/src/processor/stackwalker_amd64_unittest.cc
+++ b/src/processor/stackwalker_amd64_unittest.cc
@@ -182,7 +182,7 @@ TEST_F(GetCallerFrame, ScanWithoutSymbols) {
stack_section.start() = 0x8000000080000000ULL;
u_int64_t return_address1 = 0x50000000b0000100ULL;
u_int64_t return_address2 = 0x50000000b0000900ULL;
- Label frame1_sp, frame2_sp;
+ Label frame1_sp, frame2_sp, frame1_rbp;
stack_section
// frame 0
.Append(16, 0) // space
@@ -198,6 +198,11 @@ TEST_F(GetCallerFrame, ScanWithoutSymbols) {
.D64(0x40000000b0000000ULL) // more junk
.D64(0x50000000d0000000ULL)
+ .Mark(&frame1_rbp)
+ .D64(stack_section.start()) // This is in the right place to be
+ // a saved rbp, but it's bogus, so
+ // we shouldn't report it.
+
.D64(return_address2) // actual return address
// frame 2
.Mark(&frame2_sp)
@@ -206,6 +211,7 @@ TEST_F(GetCallerFrame, ScanWithoutSymbols) {
RegionFromSection();
raw_context.rip = 0x40000000c0000200ULL;
+ raw_context.rbp = frame1_rbp.Value();
raw_context.rsp = stack_section.start().Value();
StackwalkerAMD64 walker(&system_info, &raw_context, &stack_region, &modules,
@@ -222,10 +228,12 @@ TEST_F(GetCallerFrame, ScanWithoutSymbols) {
StackFrameAMD64 *frame1 = static_cast<StackFrameAMD64 *>(frames->at(1));
EXPECT_EQ(StackFrame::FRAME_TRUST_SCAN, frame1->trust);
ASSERT_EQ((StackFrameAMD64::CONTEXT_VALID_RIP |
- StackFrameAMD64::CONTEXT_VALID_RSP),
+ StackFrameAMD64::CONTEXT_VALID_RSP |
+ StackFrameAMD64::CONTEXT_VALID_RBP),
frame1->context_validity);
EXPECT_EQ(return_address1, frame1->context.rip);
EXPECT_EQ(frame1_sp.Value(), frame1->context.rsp);
+ EXPECT_EQ(frame1_rbp.Value(), frame1->context.rbp);
StackFrameAMD64 *frame2 = static_cast<StackFrameAMD64 *>(frames->at(2));
EXPECT_EQ(StackFrame::FRAME_TRUST_SCAN, frame2->trust);
@@ -243,7 +251,7 @@ TEST_F(GetCallerFrame, ScanWithFunctionSymbols) {
// lies within a function's bounds.
stack_section.start() = 0x8000000080000000ULL;
u_int64_t return_address = 0x50000000b0000110ULL;
- Label frame1_sp;
+ Label frame1_sp, frame1_rbp;
stack_section
// frame 0
@@ -258,10 +266,12 @@ TEST_F(GetCallerFrame, ScanWithFunctionSymbols) {
.D64(return_address) // actual return address
// frame 1
.Mark(&frame1_sp)
- .Append(32, 0); // end of stack
+ .Append(32, 0) // end of stack
+ .Mark(&frame1_rbp);
RegionFromSection();
raw_context.rip = 0x40000000c0000200ULL;
+ raw_context.rbp = frame1_rbp.Value();
raw_context.rsp = stack_section.start().Value();
SetModuleSymbols(&module1,
@@ -286,14 +296,81 @@ TEST_F(GetCallerFrame, ScanWithFunctionSymbols) {
StackFrameAMD64 *frame1 = static_cast<StackFrameAMD64 *>(frames->at(1));
EXPECT_EQ(StackFrame::FRAME_TRUST_SCAN, frame1->trust);
ASSERT_EQ((StackFrameAMD64::CONTEXT_VALID_RIP |
- StackFrameAMD64::CONTEXT_VALID_RSP),
+ StackFrameAMD64::CONTEXT_VALID_RSP |
+ StackFrameAMD64::CONTEXT_VALID_RBP),
frame1->context_validity);
EXPECT_EQ(return_address, frame1->context.rip);
EXPECT_EQ(frame1_sp.Value(), frame1->context.rsp);
+ EXPECT_EQ(frame1_rbp.Value(), frame1->context.rbp);
EXPECT_EQ("echidna", frame1->function_name);
EXPECT_EQ(0x50000000b0000100ULL, frame1->function_base);
}
+TEST_F(GetCallerFrame, CallerPushedRBP) {
+ // Functions typically push their %rbp upon entry and set %rbp pointing
+ // there. If stackwalking finds a plausible address for the next frame's
+ // %rbp directly below the return address, assume that it is indeed the
+ // next frame's %rbp.
+ stack_section.start() = 0x8000000080000000ULL;
+ u_int64_t return_address = 0x50000000b0000110ULL;
+ Label frame0_rbp, frame1_sp, frame1_rbp;
+
+ stack_section
+ // frame 0
+ .Append(16, 0) // space
+
+ .D64(0x40000000b0000000ULL) // junk that's not
+ .D64(0x50000000b0000000ULL) // a return address
+
+ .D64(0x40000000c0001000ULL) // a couple of plausible addresses
+ .D64(0x50000000b000aaaaULL) // that are not within functions
+
+ .Mark(&frame0_rbp)
+ .D64(frame1_rbp) // caller-pushed %rbp
+ .D64(return_address) // actual return address
+ // frame 1
+ .Mark(&frame1_sp)
+ .Append(32, 0) // body of frame1
+ .Mark(&frame1_rbp); // end of stack
+ RegionFromSection();
+
+ raw_context.rip = 0x40000000c0000200ULL;
+ raw_context.rbp = frame0_rbp.Value();
+ raw_context.rsp = stack_section.start().Value();
+
+ SetModuleSymbols(&module1,
+ // The youngest frame's function.
+ "FUNC 100 400 10 sasquatch\n");
+ SetModuleSymbols(&module2,
+ // The calling frame's function.
+ "FUNC 100 400 10 yeti\n");
+
+ StackwalkerAMD64 walker(&system_info, &raw_context, &stack_region, &modules,
+ &supplier, &resolver);
+ ASSERT_TRUE(walker.Walk(&call_stack));
+ frames = call_stack.frames();
+ ASSERT_EQ(2U, frames->size());
+
+ StackFrameAMD64 *frame0 = static_cast<StackFrameAMD64 *>(frames->at(0));
+ EXPECT_EQ(StackFrame::FRAME_TRUST_CONTEXT, frame0->trust);
+ ASSERT_EQ(StackFrameAMD64::CONTEXT_VALID_ALL, frame0->context_validity);
+ EXPECT_EQ(frame0_rbp.Value(), frame0->context.rbp);
+ EXPECT_EQ("sasquatch", frame0->function_name);
+ EXPECT_EQ(0x40000000c0000100ULL, frame0->function_base);
+
+ StackFrameAMD64 *frame1 = static_cast<StackFrameAMD64 *>(frames->at(1));
+ EXPECT_EQ(StackFrame::FRAME_TRUST_SCAN, frame1->trust);
+ ASSERT_EQ((StackFrameAMD64::CONTEXT_VALID_RIP |
+ StackFrameAMD64::CONTEXT_VALID_RSP |
+ StackFrameAMD64::CONTEXT_VALID_RBP),
+ frame1->context_validity);
+ EXPECT_EQ(return_address, frame1->context.rip);
+ EXPECT_EQ(frame1_sp.Value(), frame1->context.rsp);
+ EXPECT_EQ(frame1_rbp.Value(), frame1->context.rbp);
+ EXPECT_EQ("yeti", frame1->function_name);
+ EXPECT_EQ(0x50000000b0000100ULL, frame1->function_base);
+}
+
struct CFIFixture: public StackwalkerAMD64Fixture {
CFIFixture() {
// Provide a bunch of STACK CFI records; we'll walk to the caller
generated by cgit v1.2.1 (git 2.18.0) at 2024-12-01 23:56:17 +0000