libbacktraceoffline: choose correct debug section for a given address.
1. In /system/lib/libart.so, the ranges of functions covered by .eh_frame
and .ARM.exidx overlap with each other. Currently, we don't check .eh_frame
if the address is in the ranges of functions covered by .ARM.exidx. It leads
to a wrong unwinding result. So change the logic to first try .eh_frame and
.debug_frame, if it fails, then try .ARM.exidx.
2. Add test for Item 1.
Bug: http://b/35251937
Test: run backtrace_test.
Change-Id: Ic412705617c300bc69b4ece178cc2e1bb3eb765b
diff --git a/libbacktrace/BacktraceOffline.cpp b/libbacktrace/BacktraceOffline.cpp
index 5e54328..53ea796 100644
--- a/libbacktrace/BacktraceOffline.cpp
+++ b/libbacktrace/BacktraceOffline.cpp
@@ -21,6 +21,7 @@
#include <dwarf.h>
}
+#include <pthread.h>
#include <stdint.h>
#include <stdio.h>
#include <string.h>
@@ -282,39 +283,14 @@
// vaddr in the elf file.
uint64_t ip_vaddr = ip - map.start + debug_frame->min_vaddr;
- if (debug_frame->has_arm_exidx) {
- auto& func_vaddrs = debug_frame->arm_exidx.func_vaddr_array;
- if (ip_vaddr >= func_vaddrs[0] && ip_vaddr < debug_frame->text_end_vaddr) {
- // Use binary search to find the correct function.
- auto it = std::upper_bound(func_vaddrs.begin(), func_vaddrs.end(),
- static_cast<uint32_t>(ip_vaddr));
- if (it != func_vaddrs.begin()) {
- --it;
- // Found the exidx entry.
- size_t index = it - func_vaddrs.begin();
- proc_info->format = UNW_INFO_FORMAT_ARM_EXIDX;
- proc_info->unwind_info = reinterpret_cast<void*>(
- static_cast<uintptr_t>(index * sizeof(ArmIdxEntry) +
- debug_frame->arm_exidx.exidx_vaddr +
- debug_frame->min_vaddr));
-
- // Prepare arm_exidx space and arm_extab space.
- arm_exidx_space_.start = debug_frame->min_vaddr + debug_frame->arm_exidx.exidx_vaddr;
- arm_exidx_space_.end = arm_exidx_space_.start +
- debug_frame->arm_exidx.exidx_data.size() * sizeof(ArmIdxEntry);
- arm_exidx_space_.data = reinterpret_cast<const uint8_t*>(
- debug_frame->arm_exidx.exidx_data.data());
-
- arm_extab_space_.start = debug_frame->min_vaddr + debug_frame->arm_exidx.extab_vaddr;
- arm_extab_space_.end = arm_extab_space_.start +
- debug_frame->arm_exidx.extab_data.size();
- arm_extab_space_.data = debug_frame->arm_exidx.extab_data.data();
- return true;
- }
- }
- }
-
+ // The unwind info can come from .ARM.exidx or .eh_frame, or .debug_frame/.gnu_debugdata.
+ // First check .eh_frame/.debug_frame, then check .ARM.exidx. Because .eh_frame/.debug_frame has
+ // function range for each entry, by matching ip address with the function range, we know exactly
+ // whether the ip address hits an entry. But .ARM.exidx doesn't have function range for each
+ // entry, it thinks that an ip address hits an entry when (entry.addr <= ip < next_entry.addr).
+ // To prevent ip addresses hit in .eh_frame/.debug_frame being regarded as addresses hit in
+ // .ARM.exidx, we need to check .eh_frame/.debug_frame first.
if (debug_frame->has_eh_frame) {
if (ip_vaddr >= debug_frame->eh_frame.min_func_vaddr &&
ip_vaddr < debug_frame->text_end_vaddr) {
@@ -323,7 +299,6 @@
eh_frame_hdr_space_.end =
eh_frame_hdr_space_.start + debug_frame->eh_frame.hdr_data.size();
eh_frame_hdr_space_.data = debug_frame->eh_frame.hdr_data.data();
-
eh_frame_space_.start = ip - ip_vaddr + debug_frame->eh_frame.vaddr;
eh_frame_space_.end = eh_frame_space_.start + debug_frame->eh_frame.data.size();
eh_frame_space_.data = debug_frame->eh_frame.data.data();
@@ -345,7 +320,6 @@
}
}
}
-
if (debug_frame->has_debug_frame || debug_frame->has_gnu_debugdata) {
unw_dyn_info_t di;
unw_word_t segbase = map.start - map.offset;
@@ -359,6 +333,40 @@
}
}
}
+
+ if (debug_frame->has_arm_exidx) {
+ auto& func_vaddrs = debug_frame->arm_exidx.func_vaddr_array;
+ if (ip_vaddr >= func_vaddrs[0] && ip_vaddr < debug_frame->text_end_vaddr) {
+ // Use binary search to find the correct function.
+ auto it = std::upper_bound(func_vaddrs.begin(), func_vaddrs.end(),
+ static_cast<uint32_t>(ip_vaddr));
+ if (it != func_vaddrs.begin()) {
+ --it;
+ // Found the exidx entry.
+ size_t index = it - func_vaddrs.begin();
+ proc_info->start_ip = *it;
+ proc_info->format = UNW_INFO_FORMAT_ARM_EXIDX;
+ proc_info->unwind_info = reinterpret_cast<void*>(
+ static_cast<uintptr_t>(index * sizeof(ArmIdxEntry) +
+ debug_frame->arm_exidx.exidx_vaddr +
+ debug_frame->min_vaddr));
+ eh_frame_hdr_space_.Clear();
+ eh_frame_space_.Clear();
+ // Prepare arm_exidx space and arm_extab space.
+ arm_exidx_space_.start = debug_frame->min_vaddr + debug_frame->arm_exidx.exidx_vaddr;
+ arm_exidx_space_.end = arm_exidx_space_.start +
+ debug_frame->arm_exidx.exidx_data.size() * sizeof(ArmIdxEntry);
+ arm_exidx_space_.data = reinterpret_cast<const uint8_t*>(
+ debug_frame->arm_exidx.exidx_data.data());
+
+ arm_extab_space_.start = debug_frame->min_vaddr + debug_frame->arm_exidx.extab_vaddr;
+ arm_extab_space_.end = arm_extab_space_.start +
+ debug_frame->arm_exidx.extab_data.size();
+ arm_extab_space_.data = debug_frame->arm_exidx.extab_data.data();
+ return true;
+ }
+ }
+ }
return false;
}
@@ -560,7 +568,7 @@
}
DebugFrameInfo* debug_frame = ReadDebugFrameFromFile(filename);
if (cache_file_) {
- g_debug_frames.emplace(filename, std::unique_ptr<DebugFrameInfo>(debug_frame));
+ g_debug_frames.emplace(filename, std::unique_ptr<DebugFrameInfo>(debug_frame));
}
return debug_frame;
}