[glibc/fw/unwind-link] m68k: Implement backtrace on top of <unwind-link.h>

[Florian Weimer <fw@sourceware.org>]

https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=80188847b5e4cb93bf70aa61fa15946c50c4b7aa

commit 80188847b5e4cb93bf70aa61fa15946c50c4b7aa
Author: Florian Weimer <fweimer@redhat.com>
Date:   Mon Feb 10 16:01:29 2020 +0100

    m68k: Implement backtrace on top of <unwind-link.h>

Diff:
---
 sysdeps/m68k/backtrace.c | 82 +++++++++++-------------------------------------
 1 file changed, 18 insertions(+), 64 deletions(-)

diff --git a/sysdeps/m68k/backtrace.c b/sysdeps/m68k/backtrace.c
index 6020aca..c586a14 100644
--- a/sysdeps/m68k/backtrace.c
+++ b/sysdeps/m68k/backtrace.c
@@ -16,52 +16,18 @@
    License along with the GNU C Library; if not, see
    <https://www.gnu.org/licenses/>.  */
 
-#include <libc-lock.h>
-#include <dlfcn.h>
 #include <execinfo.h>
 #include <stdlib.h>
-#include <unwind.h>
+#include <unwind-link.h>
 
 struct trace_arg
 {
   void **array;
+  struct unwind_link *unwind_link;
   int cnt, size;
   void *lastfp, *lastsp;
 };
 
-#ifdef SHARED
-static _Unwind_Reason_Code (*unwind_backtrace) (_Unwind_Trace_Fn, void *);
-static _Unwind_Ptr (*unwind_getip) (struct _Unwind_Context *);
-static _Unwind_Ptr (*unwind_getcfa) (struct _Unwind_Context *);
-static _Unwind_Ptr (*unwind_getgr) (struct _Unwind_Context *, int);
-static void *libgcc_handle;
-
-static void
-init (void)
-{
-  libgcc_handle = __libc_dlopen ("libgcc_s.so.2");
-
-  if (libgcc_handle == NULL)
-    return;
-
-  unwind_backtrace = __libc_dlsym (libgcc_handle, "_Unwind_Backtrace");
-  unwind_getip = __libc_dlsym (libgcc_handle, "_Unwind_GetIP");
-  unwind_getcfa = __libc_dlsym (libgcc_handle, "_Unwind_GetCFA");
-  unwind_getgr = __libc_dlsym (libgcc_handle, "_Unwind_GetGR");
-  if (unwind_getip == NULL || unwind_getgr == NULL || unwind_getcfa == NULL)
-    {
-      unwind_backtrace = NULL;
-      __libc_dlclose (libgcc_handle);
-      libgcc_handle = NULL;
-    }
-}
-#else
-# define unwind_backtrace _Unwind_Backtrace
-# define unwind_getip _Unwind_GetIP
-# define unwind_getcfa _Unwind_GetCFA
-# define unwind_getgr _Unwind_GetGR
-#endif
-
 static _Unwind_Reason_Code
 backtrace_helper (struct _Unwind_Context *ctx, void *a)
 {
@@ -70,13 +36,16 @@ backtrace_helper (struct _Unwind_Context *ctx, void *a)
   /* We are first called with address in the __backtrace function.
      Skip it.  */
   if (arg->cnt != -1)
-    arg->array[arg->cnt] = (void *) unwind_getip (ctx);
+    arg->array[arg->cnt]
+      = (void *) UNWIND_LINK_PTR (arg->unwind_link, _Unwind_GetIP) (ctx);
   if (++arg->cnt == arg->size)
     return _URC_END_OF_STACK;
 
   /* %fp is DWARF2 register 14 on M68K.  */
-  arg->lastfp = (void *) unwind_getgr (ctx, 14);
-  arg->lastsp = (void *) unwind_getcfa (ctx);
+  arg->lastfp
+    = (void *) UNWIND_LINK_PTR (arg->unwind_link, _Unwind_GetGR) (ctx, 14);
+  arg->lastsp
+    = (void *) UNWIND_LINK_PTR (arg->unwind_link, _Unwind_GetCFA) (ctx);
   return _URC_NO_REASON;
 }
 
@@ -110,20 +79,19 @@ struct layout
 int
 __backtrace (void **array, int size)
 {
-  struct trace_arg arg = { .array = array, .size = size, .cnt = -1 };
-
-  if (size <= 0)
-    return 0;
-
-#ifdef SHARED
-  __libc_once_define (static, once);
+  struct trace_arg arg =
+    {
+     .array = array,
+     .unwind_link = __libc_unwind_link_get (),
+     .size = size,
+     .cnt = -1,
+    };
 
-  __libc_once (once, init);
-  if (unwind_backtrace == NULL)
+  if (size <= 0 || arg.unwind_link == NULL)
     return 0;
-#endif
 
-  unwind_backtrace (backtrace_helper, &arg);
+  UNWIND_LINK_PTR (arg.unwind_link, _Unwind_Backtrace)
+    (backtrace_helper, &arg);
 
   if (arg.cnt > 1 && arg.array[arg.cnt - 1] == NULL)
     --arg.cnt;
@@ -146,17 +114,3 @@ __backtrace (void **array, int size)
 }
 weak_alias (__backtrace, backtrace)
 libc_hidden_def (__backtrace)
-
-
-#ifdef SHARED
-/* Free all resources if necessary.  */
-libc_freeres_fn (free_mem)
-{
-  unwind_backtrace = NULL;
-  if (libgcc_handle != NULL)
-    {
-      __libc_dlclose (libgcc_handle);
-      libgcc_handle = NULL;
-    }
-}
-#endif