diff options
author | Laurent Pinchart <laurent.pinchart@ideasonboard.com> | 2021-09-24 05:05:51 +0300 |
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committer | Laurent Pinchart <laurent.pinchart@ideasonboard.com> | 2021-10-15 05:05:25 +0300 |
commit | a7c7f58d599573250276199faec5108e5fb0ed74 (patch) | |
tree | 0688d1e12d8a0076c05b8f9561e07f2c4dbdaae5 /src/libcamera/base/backtrace.cpp | |
parent | f8d76fe79b6137d3996f951568b29a615bb3c415 (diff) |
libcamera: base: backtrace: Use libunwind when available
libunwind is an alternative to glibc's backtrace() to extract a
backtrace. Use it when available to extend backtrace support to more
platforms.
Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Kieran Bingham <kieran.bingham@ideasonboard.com>
Diffstat (limited to 'src/libcamera/base/backtrace.cpp')
-rw-r--r-- | src/libcamera/base/backtrace.cpp | 67 |
1 files changed, 64 insertions, 3 deletions
diff --git a/src/libcamera/base/backtrace.cpp b/src/libcamera/base/backtrace.cpp index 79e4a31f..0aafc6a3 100644 --- a/src/libcamera/base/backtrace.cpp +++ b/src/libcamera/base/backtrace.cpp @@ -18,6 +18,15 @@ #include <unistd.h> #endif +#if HAVE_UNWIND +/* + * Disable support for remote unwinding to enable a more optimized + * implementation. + */ +#define UNW_LOCAL_ONLY +#include <libunwind.h> +#endif + #include <sstream> #include <libcamera/base/span.h> @@ -147,16 +156,65 @@ std::string DwflParser::stackEntry(const void *ip) */ Backtrace::Backtrace() { + /* Try libunwind first and fall back to backtrace() if it fails. */ + if (unwindTrace()) + return; + + backtraceTrace(); +} + +/* + * Avoid inlining to make sure that the Backtrace constructor adds exactly two + * calls to the stack, which are later skipped in toString(). + */ +__attribute__((__noinline__)) +bool Backtrace::backtraceTrace() +{ #if HAVE_BACKTRACE backtrace_.resize(32); int num_entries = backtrace(backtrace_.data(), backtrace_.size()); if (num_entries < 0) { backtrace_.clear(); - return; + return false; } backtrace_.resize(num_entries); + + return true; +#else + return false; +#endif +} + +__attribute__((__noinline__)) +bool Backtrace::unwindTrace() +{ +#if HAVE_UNWIND + unw_context_t uc; + int ret = unw_getcontext(&uc); + if (ret) + return false; + + unw_cursor_t cursor; + ret = unw_init_local(&cursor, &uc); + if (ret) + return false; + + do { + unw_word_t ip; + ret = unw_get_reg(&cursor, UNW_REG_IP, &ip); + if (ret) { + backtrace_.push_back(nullptr); + continue; + } + + backtrace_.push_back(reinterpret_cast<void *>(ip)); + } while (unw_step(&cursor) > 0); + + return true; +#else + return false; #endif } @@ -181,8 +239,11 @@ Backtrace::Backtrace() */ std::string Backtrace::toString(unsigned int skipLevels) const { - /* Skip the first entry, corresponding to the Backtrace construction. */ - skipLevels += 1; + /* + * Skip the first two entries, corresponding to the Backtrace + * construction. + */ + skipLevels += 2; if (backtrace_.size() <= skipLevels) return std::string(); |