[PATCH v2 4/7] KVM: selftests: Add backtrace fallback

[Aqib Faruqui <aqibaf@amazon.com>]

The backtrace() function is a GNU extension available in glibc but may
not be present in non-glibc libraries. KVM selftests use backtrace() for
error reporting and debugging.

Add conditional inclusion of execinfo.h only for glibc builds and
provide a weak stub implementation of backtrace() that returns 0 (stack
trace empty) for non-glibc systems.

Signed-off-by: Aqib Faruqui <aqibaf@amazon.com>
---
 tools/testing/selftests/kvm/lib/assert.c | 10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

diff --git a/tools/testing/selftests/kvm/lib/assert.c b/tools/testing/selftests/kvm/lib/assert.c
index b49690658..c9778dc6c 100644
--- a/tools/testing/selftests/kvm/lib/assert.c
+++ b/tools/testing/selftests/kvm/lib/assert.c
@@ -6,11 +6,19 @@
  */
 #include "test_util.h"
 
-#include <execinfo.h>
 #include <sys/syscall.h>
 
+#ifdef __GLIBC__
+#include <execinfo.h> /* backtrace */
+#endif
+
 #include "kselftest.h"
 
+int __attribute__((weak)) backtrace(void **buffer, int size)
+{
+	return 0;
+}
+
 /* Dumps the current stack trace to stderr. */
 static void __attribute__((noinline)) test_dump_stack(void);
 static void test_dump_stack(void)
-- 
2.47.3