6.6-stable review patch. If anyone has any objections, please let me know.
------------------
From: Kajol Jain kjain@linux.ibm.com
[ Upstream commit d7c9ae8d5d1be0c4156d1e20e4369a77b711a4cc ]
The perf test named "kernel lock contention analysis test" fails in powerpc system with below error:
[command]# ./perf test 81 -vv 81: kernel lock contention analysis test : --- start --- test child forked, pid 2140 Testing perf lock record and perf lock contention Testing perf lock contention --use-bpf [Skip] No BPF support Testing perf lock record and perf lock contention at the same time Testing perf lock contention --threads Testing perf lock contention --lock-addr Testing perf lock contention --type-filter (w/ spinlock) Testing perf lock contention --lock-filter (w/ tasklist_lock) Testing perf lock contention --callstack-filter (w/ unix_stream) [Fail] Recorded result should have a lock from unix_stream: test child finished with -1 ---- end ---- kernel lock contention analysis test: FAILED!
The test is failing because we get an address entry with 0 in perf lock samples for powerpc, and code for lock contention option "--callstack-filter" will not check further entries after address 0.
Below are some of the samples from test generated perf.data file, which have 0 address in the 2nd entry of callstack: -------- sched-messaging 3409 [001] 7152.904029: lock:contention_begin: 0xc00000c80904ef00 (flags=SPIN) c0000000001e926c __traceiter_contention_begin+0x6c ([kernel.kallsyms]) 0 [unknown] ([unknown]) c000000000f8a178 native_queued_spin_lock_slowpath+0x1f8 ([kernel.kallsyms]) c000000000f89f44 _raw_spin_lock_irqsave+0x84 ([kernel.kallsyms]) c0000000001d9fd0 prepare_to_wait+0x50 ([kernel.kallsyms]) c000000000c80f50 sock_alloc_send_pskb+0x1b0 ([kernel.kallsyms]) c000000000e82298 unix_stream_sendmsg+0x2b8 ([kernel.kallsyms]) c000000000c78980 sock_sendmsg+0x80 ([kernel.kallsyms])
sched-messaging 3408 [005] 7152.904036: lock:contention_begin: 0xc00000c80904ef00 (flags=SPIN) c0000000001e926c __traceiter_contention_begin+0x6c ([kernel.kallsyms]) 0 [unknown] ([unknown]) c000000000f8a178 native_queued_spin_lock_slowpath+0x1f8 ([kernel.kallsyms]) c000000000f89f44 _raw_spin_lock_irqsave+0x84 ([kernel.kallsyms]) c0000000001d9fd0 prepare_to_wait+0x50 ([kernel.kallsyms]) c000000000c80f50 sock_alloc_send_pskb+0x1b0 ([kernel.kallsyms]) c000000000e82298 unix_stream_sendmsg+0x2b8 ([kernel.kallsyms]) c000000000c78980 sock_sendmsg+0x80 ([kernel.kallsyms]) --------
Based on commit 20002ded4d93 ("perf_counter: powerpc: Add callchain support"), incase of powerpc, the callchain saved by kernel always includes first three entries as the NIP (next instruction pointer), LR (link register), and the contents of LR save area in the second stack frame. In certain scenarios its possible to have invalid kernel instruction addresses in either of LR or the second stack frame's LR. In that case, kernel will store the address as zer0. Hence, its possible to have 2nd or 3rd callstack entry as 0.
As per the current code in match_callstack_filter function, we skip the callstack check incase we get 0 address. And hence the test case is failing in powerpc.
Fix this issue by updating the check in match_callstack_filter function, to not skip callstack check if the 2nd or 3rd entry have 0 address for powerpc.
Result in powerpc after patch changes:
[command]# ./perf test 81 -vv 81: kernel lock contention analysis test : --- start --- test child forked, pid 4570 Testing perf lock record and perf lock contention Testing perf lock contention --use-bpf [Skip] No BPF support Testing perf lock record and perf lock contention at the same time Testing perf lock contention --threads Testing perf lock contention --lock-addr Testing perf lock contention --type-filter (w/ spinlock) Testing perf lock contention --lock-filter (w/ tasklist_lock) [Skip] Could not find 'tasklist_lock' Testing perf lock contention --callstack-filter (w/ unix_stream) Testing perf lock contention --callstack-filter with task aggregation Testing perf lock contention CSV output [Skip] No BPF support test child finished with 0 ---- end ---- kernel lock contention analysis test: Ok
Fixes: ebab291641be ("perf lock contention: Support filters for different aggregation") Reported-by: Disha Goel disgoel@linux.vnet.ibm.com Tested-by: Disha Goel disgoel@linux.ibm.com Signed-off-by: Kajol Jain kjain@linux.ibm.com Cc: maddy@linux.ibm.com Cc: atrajeev@linux.vnet.ibm.com Link: https://lore.kernel.org/r/20231003092113.252380-1-kjain@linux.ibm.com Signed-off-by: Namhyung Kim namhyung@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org --- tools/perf/builtin-lock.c | 17 ++++++++++++++++- 1 file changed, 16 insertions(+), 1 deletion(-)
diff --git a/tools/perf/builtin-lock.c b/tools/perf/builtin-lock.c index b141f21342740..0b4b4445c5207 100644 --- a/tools/perf/builtin-lock.c +++ b/tools/perf/builtin-lock.c @@ -524,6 +524,7 @@ bool match_callstack_filter(struct machine *machine, u64 *callstack) struct map *kmap; struct symbol *sym; u64 ip; + const char *arch = perf_env__arch(machine->env);
if (list_empty(&callstack_filters)) return true; @@ -531,7 +532,21 @@ bool match_callstack_filter(struct machine *machine, u64 *callstack) for (int i = 0; i < max_stack_depth; i++) { struct callstack_filter *filter;
- if (!callstack || !callstack[i]) + /* + * In powerpc, the callchain saved by kernel always includes + * first three entries as the NIP (next instruction pointer), + * LR (link register), and the contents of LR save area in the + * second stack frame. In certain scenarios its possible to have + * invalid kernel instruction addresses in either LR or the second + * stack frame's LR. In that case, kernel will store that address as + * zero. + * + * The below check will continue to look into callstack, + * incase first or second callstack index entry has 0 + * address for powerpc. + */ + if (!callstack || (!callstack[i] && (strcmp(arch, "powerpc") || + (i != 1 && i != 2)))) break;
ip = callstack[i];