Patch "selftests/bpf: Fix compile if backtrace support missing in libc" has been added to the 6.10-stable tree

[Sasha Levin <sashal@xxxxxxxxxx>]

This is a note to let you know that I've just added the patch titled

    selftests/bpf: Fix compile if backtrace support missing in libc

to the 6.10-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     selftests-bpf-fix-compile-if-backtrace-support-missi.patch
and it can be found in the queue-6.10 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.



commit 67840aa7805965cebc400fab74088560b40f461f
Author: Tony Ambardar <tony.ambardar@xxxxxxxxx>
Date:   Mon Jul 29 02:24:22 2024 -0700

    selftests/bpf: Fix compile if backtrace support missing in libc
    
    [ Upstream commit c9a83e76b5a96801a2c7ea0a79ca77c356d8b38d ]
    
    Include GNU <execinfo.h> header only with glibc and provide weak, stubbed
    backtrace functions as a fallback in test_progs.c. This allows for non-GNU
    replacements while avoiding compile errors (e.g. with musl libc) like:
    
      test_progs.c:13:10: fatal error: execinfo.h: No such file or directory
         13 | #include <execinfo.h> /* backtrace */
            |          ^~~~~~~~~~~~
      test_progs.c: In function 'crash_handler':
      test_progs.c:1034:14: error: implicit declaration of function 'backtrace' [-Werror=implicit-function-declaration]
       1034 |         sz = backtrace(bt, ARRAY_SIZE(bt));
            |              ^~~~~~~~~
      test_progs.c:1045:9: error: implicit declaration of function 'backtrace_symbols_fd' [-Werror=implicit-function-declaration]
       1045 |         backtrace_symbols_fd(bt, sz, STDERR_FILENO);
            |         ^~~~~~~~~~~~~~~~~~~~
    
    Fixes: 9fb156bb82a3 ("selftests/bpf: Print backtrace on SIGSEGV in test_progs")
    Signed-off-by: Tony Ambardar <tony.ambardar@xxxxxxxxx>
    Signed-off-by: Andrii Nakryiko <andrii@xxxxxxxxxx>
    Link: https://lore.kernel.org/bpf/aa6dc8e23710cb457b278039d0081de7e7b4847d.1722244708.git.tony.ambardar@xxxxxxxxx
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

diff --git a/tools/testing/selftests/bpf/test_progs.c b/tools/testing/selftests/bpf/test_progs.c
index 60c5ec0f6abf6..d5d0cb4eb1975 100644
--- a/tools/testing/selftests/bpf/test_progs.c
+++ b/tools/testing/selftests/bpf/test_progs.c
@@ -10,7 +10,6 @@
 #include <sched.h>
 #include <signal.h>
 #include <string.h>
-#include <execinfo.h> /* backtrace */
 #include <sys/sysinfo.h> /* get_nprocs */
 #include <netinet/in.h>
 #include <sys/select.h>
@@ -19,6 +18,21 @@
 #include <bpf/btf.h>
 #include "json_writer.h"
 
+#ifdef __GLIBC__
+#include <execinfo.h> /* backtrace */
+#endif
+
+/* Default backtrace funcs if missing at link */
+__weak int backtrace(void **buffer, int size)
+{
+	return 0;
+}
+
+__weak void backtrace_symbols_fd(void *const *buffer, int size, int fd)
+{
+	dprintf(fd, "<backtrace not supported>\n");
+}
+
 static bool verbose(void)
 {
 	return env.verbosity > VERBOSE_NONE;