[Mesa-dev] [PATCH 2/2] gallium/util: libunwind support

[Rob Clark]

It's kinda sad that (a) we don't have debug_backtrace support on !X86
and that (b) we re-invent our own crude backtrace support in the first
place.  If available, use libunwind instead.  The backtrace format is
based on what xserver and weston use, since it is nice not to have to
figure out a different format.

Signed-off-by: Rob Clark <robdclark at gmail.com>
---
 configure.ac                               | 24 ++++++++
 src/gallium/Automake.inc                   |  1 +
 src/gallium/auxiliary/util/u_debug_stack.c | 91 ++++++++++++++++++++++++++++++
 src/gallium/auxiliary/util/u_debug_stack.h | 15 ++++-
 4 files changed, 129 insertions(+), 2 deletions(-)

diff --git a/configure.ac b/configure.ac
index a99684b..5046acb 100644
--- a/configure.ac
+++ b/configure.ac
@@ -1025,6 +1025,30 @@ AC_SUBST([LLVM_LIBS])
 AC_SUBST([LLVM_LDFLAGS])
 AC_SUBST([LLVM_INCLUDEDIR])
 
+dnl
+dnl libunwind
+dnl
+AC_ARG_ENABLE([libunwind],
+    [AS_HELP_STRING([--enable-libunwind],
+            [Use libunwind for backtracing (default: auto)])],
+        [LIBUNWIND="$enableval"],
+        [LIBUNWIND="auto"])
+
+PKG_CHECK_MODULES(LIBUNWIND, libunwind, [HAVE_LIBUNWIND=yes], [HAVE_LIBUNWIND=no])
+if test "x$LIBUNWIND" = "xauto"; then
+    LIBUNWIND="$HAVE_LIBUNWIND"
+fi
+
+if test "x$LIBUNWIND" = "xyes"; then
+    if test "x$HAVE_LIBUNWIND" != "xyes"; then
+        AC_MSG_ERROR([libunwind requested but not installed.])
+    fi
+    AC_DEFINE(HAVE_LIBUNWIND, 1, [Have libunwind support])
+fi
+
+AM_CONDITIONAL(HAVE_LIBUNWIND, [test "x$LIBUNWIND" = xyes])
+
+
 dnl Options for APIs
 AC_ARG_ENABLE([opengl],
     [AS_HELP_STRING([--disable-opengl],
diff --git a/src/gallium/Automake.inc b/src/gallium/Automake.inc
index a01fa54..48b5a44 100644
--- a/src/gallium/Automake.inc
+++ b/src/gallium/Automake.inc
@@ -46,6 +46,7 @@ GALLIUM_TARGET_CFLAGS = \
 
 GALLIUM_COMMON_LIB_DEPS = \
 	-lm \
+	$(LIBUNWIND_LIBS) \
 	$(LIBSENSORS_LIBS) \
 	$(CLOCK_LIB) \
 	$(PTHREAD_LIBS) \
diff --git a/src/gallium/auxiliary/util/u_debug_stack.c b/src/gallium/auxiliary/util/u_debug_stack.c
index f941234..cf05f13 100644
--- a/src/gallium/auxiliary/util/u_debug_stack.c
+++ b/src/gallium/auxiliary/util/u_debug_stack.c
@@ -36,6 +36,95 @@
 #include "u_debug_symbol.h"
 #include "u_debug_stack.h"
 
+#if defined(HAVE_LIBUNWIND)
+
+#ifndef _GNU_SOURCE
+#define _GNU_SOURCE
+#endif
+#include <dlfcn.h>
+
+void
+debug_backtrace_capture(struct debug_stack_frame *backtrace,
+                        unsigned start_frame,
+                        unsigned nr_frames)
+{
+   unw_cursor_t cursor;
+   unw_context_t context;
+   unw_proc_info_t pip;
+   unsigned i = 0;
+   int ret;
+
+   pip.unwind_info = NULL;
+
+   unw_getcontext(&context);
+   unw_init_local(&cursor, &context);
+
+   while ((start_frame > 0) && (unw_step(&cursor) > 0))
+      start_frame--;
+
+   while (unw_step(&cursor) > 0) {
+      char procname[256];
+      const char *filename;
+      unw_word_t off;
+      Dl_info dlinfo;
+
+      unw_get_proc_info(&cursor, &pip);
+
+      ret = unw_get_proc_name(&cursor, procname, 256, &off);
+      if (ret && ret != -UNW_ENOMEM) {
+         procname[0] = '?';
+         procname[1] = 0;
+      }
+
+       if (dladdr((void *)(uintptr_t)(pip.start_ip + off), &dlinfo) && dlinfo.dli_fname &&
+               *dlinfo.dli_fname)
+           filename = dlinfo.dli_fname;
+       else
+           filename = "?";
+
+      snprintf(backtrace[i].buf, sizeof(backtrace[i].buf),
+            "%u: %s (%s%s+0x%x) [%p]", i, filename, procname,
+            ret == -UNW_ENOMEM ? "..." : "", (int)off,
+            (void *)(uintptr_t)(pip.start_ip + off));
+
+      i++;
+   }
+
+   while (i < nr_frames) {
+      backtrace[i].buf[0] = '\0';
+      i++;
+   }
+}
+
+void
+debug_backtrace_dump(const struct debug_stack_frame *backtrace,
+                     unsigned nr_frames)
+{
+   unsigned i;
+
+   for (i = 0; i < nr_frames; ++i) {
+      if (backtrace[i].buf[0] == '\0')
+         break;
+      debug_printf("\t%s\n", backtrace[i].buf);
+   }
+}
+
+void
+debug_backtrace_print(FILE *f,
+                      const struct debug_stack_frame *backtrace,
+                      unsigned nr_frames)
+{
+   unsigned i;
+
+   for (i = 0; i < nr_frames; ++i) {
+      if (backtrace[i].buf[0] == '\0')
+         break;
+      fprintf(f, "\t%s\n", backtrace[i].buf);
+   }
+}
+
+#else /* ! HAVE_LIBUNWIND */
+
 #if defined(PIPE_OS_WINDOWS)
 #include <windows.h>
 #endif
@@ -179,3 +268,5 @@ debug_backtrace_print(FILE *f,
          fprintf(f, "%s\n", symbol);
    }
 }
+
+#endif /* HAVE_LIBUNWIND */
diff --git a/src/gallium/auxiliary/util/u_debug_stack.h b/src/gallium/auxiliary/util/u_debug_stack.h
index 04eba08..0effcbe 100644
--- a/src/gallium/auxiliary/util/u_debug_stack.h
+++ b/src/gallium/auxiliary/util/u_debug_stack.h
@@ -30,6 +30,11 @@
 
 #include <stdio.h>
 
+#ifdef HAVE_LIBUNWIND
+#define UNW_LOCAL_ONLY
+#include <libunwind.h>
+#endif
+
 /**
  * @file
  * Stack backtracing.
@@ -46,15 +51,21 @@ extern "C" {
 /**
  * Represent a frame from a stack backtrace.
  *
- * XXX: Do not change this.
+#if defined(PIPE_OS_WINDOWS) && !defined(HAVE_LIBUNWIND)
+ * XXX: Do not change this. (passed to Windows' CaptureStackBackTrace())
+#endif
  *
  * TODO: This should be refactored as a void * typedef.
  */
 struct debug_stack_frame 
 {
+#ifdef HAVE_LIBUNWIND
+   char buf[128];
+#else
    const void *function;
+#endif
 };
-   
+
 
 void
 debug_backtrace_capture(struct debug_stack_frame *backtrace,
-- 
2.9.3