On Fri, Jul 26, 2024 at 8:48 PM Tony Ambardar tony.ambardar@gmail.com wrote:
On Thu, Jul 25, 2024 at 01:22:37PM -0700, Andrii Nakryiko wrote:
On Thu, Jul 25, 2024 at 3:39 AM Tony Ambardar tony.ambardar@gmail.com wrote:
From: Tony Ambardar tony.ambardar@gmail.com
Use backtrace functions only with glibc and otherwise provide stubs in test_progs.c. This avoids 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@gmail.com
tools/testing/selftests/bpf/test_progs.c | 9 ++++++++- 1 file changed, 8 insertions(+), 1 deletion(-)
diff --git a/tools/testing/selftests/bpf/test_progs.c b/tools/testing/selftests/bpf/test_progs.c index 60c5ec0f6abf..f6cfc6a8e8f0 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 +18,14 @@ #include <bpf/btf.h> #include "json_writer.h"
+#ifdef __GLIBC__ +#include <execinfo.h> /* backtrace */ +#else +#define backtrace(...) (0) +#define backtrace_symbols_fd(bt, sz, fd) \
dprintf(fd, "<backtrace not supported>\n", bt, sz)+#endif
First, let's define backtrace() and backtrace_symbols_fd() as proper functions, not a macro?
And second, what if we then make those functions __weak, so they provide default implementations if libc doesn't provide those functions?
This parts seems unavoidable, though:
#ifdef __GLIBC__ #include <execinfo.h> #endif
I agree that would be cleaner, will work on a v2 with this.
v2 looks good, thanks
Out of curiosity, I saw that tools/build includes feature-detection code (incl backtrace) and wondered if selftests/bpf ever used this facility?
I don't remember, tbh, it might have at some point in the past.
static bool verbose(void) { return env.verbosity > VERBOSE_NONE; -- 2.34.1