6.18-stable review patch. If anyone has any objections, please let me know.
------------------
From: Namhyung Kim namhyung@kernel.org
[ Upstream commit 553d18c98a896094b99a01765b9698b204183d49 ]
On some machines, it caused troubles when it tried to find kernel symbols. I think it's because kernel modules and kallsyms are messed up during load and split.
Basically we want to make sure the kernel map is loaded and the code has it in the lock_contention_read(). But recently we added more lookups in the lock_contention_prepare() which is called before _read().
Also the kernel map (kallsyms) may not be the first one in the group like on ARM. Let's use machine__kernel_map() rather than just loading the first map.
Reviewed-by: Ian Rogers irogers@google.com Fixes: 688d2e8de231c54e ("perf lock contention: Add -l/--lock-addr option") Signed-off-by: Namhyung Kim namhyung@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org --- tools/perf/util/bpf_lock_contention.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-)
diff --git a/tools/perf/util/bpf_lock_contention.c b/tools/perf/util/bpf_lock_contention.c index 60b81d586323f..7b5671f13c535 100644 --- a/tools/perf/util/bpf_lock_contention.c +++ b/tools/perf/util/bpf_lock_contention.c @@ -184,6 +184,9 @@ int lock_contention_prepare(struct lock_contention *con) struct evlist *evlist = con->evlist; struct target *target = con->target;
+ /* make sure it loads the kernel map before lookup */ + map__load(machine__kernel_map(con->machine)); + skel = lock_contention_bpf__open(); if (!skel) { pr_err("Failed to open lock-contention BPF skeleton\n"); @@ -749,9 +752,6 @@ int lock_contention_read(struct lock_contention *con) bpf_prog_test_run_opts(prog_fd, &opts); }
- /* make sure it loads the kernel map */ - maps__load_first(machine->kmaps); - prev_key = NULL; while (!bpf_map_get_next_key(fd, prev_key, &key)) { s64 ls_key;