Move map data into backtrace data proper.
The backtrace structure used to include a pointer to a backtrace_map_t
that represented the map data for a particular pc. This introduced a
race condition where the pointer could be discarded, but the backtrace
structure still contained a pointer to garbage memory. Now all of the map
information is right in the structure.
Bug: 19028453
Change-Id: If7088a73f3c6bf1f3bc8cdd2bb4b62e7cab831c0
diff --git a/include/backtrace/Backtrace.h b/include/backtrace/Backtrace.h
index e07d322..e2d718b 100644
--- a/include/backtrace/Backtrace.h
+++ b/include/backtrace/Backtrace.h
@@ -39,7 +39,7 @@
uintptr_t pc; // The absolute pc.
uintptr_t sp; // The top of the stack.
size_t stack_size; // The size of the stack, zero indicate an unknown stack size.
- const backtrace_map_t* map; // The map associated with the given pc.
+ backtrace_map_t map; // The map associated with the given pc.
std::string func_name; // The function name associated with this pc, NULL if not found.
uintptr_t func_offset; // pc relative to the start of the function, only valid if func_name is not NULL.
};
@@ -78,8 +78,8 @@
// If the string is empty, then no valid function name was found.
virtual std::string GetFunctionName(uintptr_t pc, uintptr_t* offset);
- // Find the map associated with the given pc.
- virtual const backtrace_map_t* FindMap(uintptr_t pc);
+ // Fill in the map data associated with the given pc.
+ virtual void FillInMap(uintptr_t pc, backtrace_map_t* map);
// Read the data at a specific address.
virtual bool ReadWord(uintptr_t ptr, word_t* out_value) = 0;
diff --git a/include/backtrace/BacktraceMap.h b/include/backtrace/BacktraceMap.h
index 4ed23a8..da96307 100644
--- a/include/backtrace/BacktraceMap.h
+++ b/include/backtrace/BacktraceMap.h
@@ -33,6 +33,8 @@
#include <string>
struct backtrace_map_t {
+ backtrace_map_t(): start(0), end(0), flags(0) {}
+
uintptr_t start;
uintptr_t end;
int flags;
@@ -48,15 +50,16 @@
virtual ~BacktraceMap();
- // Get the map data structure for the given address.
- virtual const backtrace_map_t* Find(uintptr_t addr);
+ // Fill in the map data structure for the given address.
+ virtual void FillIn(uintptr_t addr, backtrace_map_t* map);
// The flags returned are the same flags as used by the mmap call.
// The values are PROT_*.
int GetFlags(uintptr_t pc) {
- const backtrace_map_t* map = Find(pc);
- if (map) {
- return map->flags;
+ backtrace_map_t map;
+ FillIn(pc, &map);
+ if (IsValid(map)) {
+ return map.flags;
}
return PROT_NONE;
}
@@ -75,6 +78,10 @@
virtual bool Build();
+ static inline bool IsValid(const backtrace_map_t& map) {
+ return map.end > 0;
+ }
+
protected:
BacktraceMap(pid_t pid);