perf bpf: Don't warn about unavailability of builtin clang, just fallback
tip-bot for Arnaldo Carvalho de Melo
merge botCommit-ID: 872523233d640c21ce13ea51269c5c031ebb2f78 Gitweb: https://git.kernel.org/tip/872523233d640c21ce13ea51269c5c031ebb2f78 Author: Arnaldo Carvalho de Melo <[email protected]> AuthorDate: Thu, 18 Jan 2018 13:07:00 -0300 Committer: Arnaldo Carvalho de Melo <[email protected]> CommitDate: Thu, 18 Jan 2018 13:07:00 -0300
perf bpf: Don't warn about unavailability of builtin clang, just fallback
When clang is not linked with 'perf' we should just add a debug message about that before doing the fallback to calling the external compiler.
I.e. just the "-95" warning below gets turned into a debug message:
# cat sys_enter_open.c #include "bpf.h"
SEC("syscalls:sys_enter_open")
int func(void *ctx)
{
struct {
char *ptr;
char path[256];
} filename = {
.ptr = *((char **)(ctx + 16)),
};
int len = bpf_probe_read_str(filename.path, sizeof(filename.path), filename.ptr);
if (len > 0) {
if (len == 1)
perf_event_output(ctx, &__bpf_stdout__, BPF_F_CURRENT_CPU, &filename, len + sizeof(filename.ptr));
else if (len < 256)
perf_event_output(ctx, &__bpf_stdout__, BPF_F_CURRENT_CPU, &filename, len + sizeof(filename.ptr));
}
return 0;
}
# trace -e open,sys_enter_open.c
bpf: builtin compilation failed: -95, try external compiler
0.000 ( ): __bpf_stdout__:@......./proc/self/task/11160/comm..)
0.014 ( 0.116 ms): qemu-system-x8/6721 open(filename: /proc/self/task/11160/comm, flags: RDWR) = 91
2335.411 ( ): __bpf_stdout__:FB..~.../etc/resolv.conf....)
2335.421 ( 0.030 ms): chronyd/883 open(filename: /etc/resolv.conf, flags: CLOEXEC) = 5
^C#Cc Adrian Hunter <[email protected]>
Cc David Ahern <[email protected]>
Cc Jiri Olsa <[email protected]>
Cc Namhyung Kim <[email protected]>
Cc Wang Nan <[email protected]>
Signed-off-by Arnaldo Carvalho de Melo <[email protected]>
--- tools/perf/util/bpf-loader.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
tools/perf/util/bpf-loader.c +1 -1
@@ -94,7 +94,7 @@ struct bpf_object *bpf__prepare_load(const char *filename, bool source) err =perf_clang__compile_bpf (filename, &obj_buf, &obj_buf_sz);perf_clang__cleanup ();if (err) { -pr_warning ("bpf: builtin compilation failed: %d, try external compiler\n" , err); +pr_debug ("bpf: builtin compilation failed: %d, try external compiler\n" , err); err =llvm__compile_bpf (filename, &obj_buf, &obj_buf_sz);if (err)return ERR_PTR (-BPF_LOADER_ERRNO__COMPILE );