Fix handling of load bias values.
It turns out that for the dwarf information, if a FDE indicates it's pc
relative, then pc has to be incremented by the load bias. If not, then
it should not be incremented.
Previously, the code always subtracted load bias values from pcs, and assumed
that all fdes were incremented by load bias values. The new code actually
reads the fdes and adjusted the pcs in the fde and in the eh frame hdr so
that load bias values are already handled properly.
In addition, add dumping of arm exidx values in unwind_reg_info. This allowed
verifying that the debug frame in those elf files was being handled properly.
Added a new unit test that only has a debug frame that has a non-zero load
bias and has fde entries that do not have pc relative encoding.
Fix a couple of other small bugs.
Bug: 109824792
Test: All libbacktrace/libunwindstack unit tests pass.
Test: Ran ART 137-cfi test and 004-ThreadStress.
Test: Verify that displaying the fde start and end pc actually match the
Test: real data for fde that have pc relative set, and that don't.
Test: Verified that the unwind information for arm exidx matches the
Test: debug frame data.
Change-Id: I707555286b5cb05df9f25489e8c5ede753cfe0fb
diff --git a/libunwindstack/ElfInterfaceArm.cpp b/libunwindstack/ElfInterfaceArm.cpp
index f93baeb..9b61599 100644
--- a/libunwindstack/ElfInterfaceArm.cpp
+++ b/libunwindstack/ElfInterfaceArm.cpp
@@ -26,6 +26,14 @@
namespace unwindstack {
+bool ElfInterfaceArm::Init(uint64_t* load_bias) {
+ if (!ElfInterface32::Init(load_bias)) {
+ return false;
+ }
+ load_bias_ = *load_bias;
+ return true;
+}
+
bool ElfInterfaceArm::FindEntry(uint32_t pc, uint64_t* entry_offset) {
if (start_offset_ == 0 || total_entries_ == 0) {
last_error_.code = ERROR_UNWIND_INFO;
@@ -96,24 +104,22 @@
return true;
}
-bool ElfInterfaceArm::Step(uint64_t pc, uint64_t load_bias, Regs* regs, Memory* process_memory,
- bool* finished) {
+bool ElfInterfaceArm::Step(uint64_t pc, Regs* regs, Memory* process_memory, bool* finished) {
// Dwarf unwind information is precise about whether a pc is covered or not,
// but arm unwind information only has ranges of pc. In order to avoid
// incorrectly doing a bad unwind using arm unwind information for a
// different function, always try and unwind with the dwarf information first.
- return ElfInterface32::Step(pc, load_bias, regs, process_memory, finished) ||
- StepExidx(pc, load_bias, regs, process_memory, finished);
+ return ElfInterface32::Step(pc, regs, process_memory, finished) ||
+ StepExidx(pc, regs, process_memory, finished);
}
-bool ElfInterfaceArm::StepExidx(uint64_t pc, uint64_t load_bias, Regs* regs, Memory* process_memory,
- bool* finished) {
+bool ElfInterfaceArm::StepExidx(uint64_t pc, Regs* regs, Memory* process_memory, bool* finished) {
// Adjust the load bias to get the real relative pc.
- if (pc < load_bias) {
+ if (pc < load_bias_) {
last_error_.code = ERROR_UNWIND_INFO;
return false;
}
- pc -= load_bias;
+ pc -= load_bias_;
RegsArm* regs_arm = reinterpret_cast<RegsArm*>(regs);
uint64_t entry_offset;
@@ -167,13 +173,12 @@
return return_value;
}
-bool ElfInterfaceArm::GetFunctionName(uint64_t addr, uint64_t load_bias, std::string* name,
- uint64_t* offset) {
+bool ElfInterfaceArm::GetFunctionName(uint64_t addr, std::string* name, uint64_t* offset) {
// For ARM, thumb function symbols have bit 0 set, but the address passed
// in here might not have this bit set and result in a failure to find
// the thumb function names. Adjust the address and offset to account
// for this possible case.
- if (ElfInterface32::GetFunctionName(addr | 1, load_bias, name, offset)) {
+ if (ElfInterface32::GetFunctionName(addr | 1, name, offset)) {
*offset &= ~1;
return true;
}