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* Enhance native stack dumps.Jeff Brown2012-06-081-2/+8
| | | | | | | | | | | | | | | | | | | | | | | | | Provides a new mechanism for dumpstate (while running as root) to request that debuggerd dump the stacks of native processes that we care about in bug reports. In this mode, the backtrace is formatted to look similar to a Dalvik backtrace. Moved the tombstone generating code into a separate file to make it easier to maintain. Fixed a bug where sometimes the stack traces would be incomplete because we were not waiting for each thread to stop after issuing PTRACE_ATTACH, only the main thread. So sometimes we were missing traces for some threads. Refactored the logging code to prevent accidentally writing data to logcat when explicitly dumping a tombstone or backtrace from the console. Only root or system server can request to dump backtraces but only root can dump tombstones. Bug: 6615693 Change-Id: Ib3edcc16f9f3a687e414e3f2d250d9500566123b
* Improve stack unwinder robustness.Jeff Brown2011-11-041-1/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Keep track of whether memory maps are readable. Use the information in try_get_word to try to avoid accidentally dereferencing an invalid pointer within the current process. (Note that I haven't ever seen that happen during normal unwinding, but it pays to be a little more careful.) Refactored try_get_word a little to make it easier to pass it the needed state for validation checks by way of a little memory_t struct. Improved how the memory map for the current process is cached. This is important because we need up to date information about readable maps. Use a 5 second cache expiration. Improved the PC -> LR fallback logic in the unwinder so we can eke out an extra frame sometimes. Fixed a bug reading ELF program headers. The phnum & phentsize fields are half-words. We were incorrectly interpreting phnum as a whole word. Used android_atomic_* operations carefully in the unwinder to prevent possible memory races between the dumper and the dumpee. This was highly unlikely (or even impossible due to the presence of other barriers along the way) but the code is clearer now about its invariants. Fixed a bug in debuggerd where the pid was being passed to have its stack dump taken instead of the tid, resulting in short stacks because ptrace couldn't read the data if pid != tid. Did a full sweep to ensure that we use pid / tid correctly everywhere. Ported old code from debuggerd to rewind the program counter back one instruction so that it points to the branch instruction itself instead of the return address. Change-Id: Icc4eb08320052975a4ae7f0f5f0ac9308a2d33d7
* Use libcorkscrew in debuggerd.Jeff Brown2011-10-221-0/+25
Change-Id: I5e3645a39d96c808f87075b49111d0262a19a0c8