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    • Kajol Jain's avatar
      tools/perf: Update call stack check in builtin-lock.c · d7c9ae8d
      Kajol Jain authored
      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 20002ded ("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: ebab2916 ("perf lock contention: Support filters for different aggregation")
      Reported-by: default avatarDisha Goel <disgoel@linux.vnet.ibm.com>
      Tested-by: default avatarDisha Goel <disgoel@linux.ibm.com>
      Signed-off-by: default avatarKajol 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.comSigned-off-by: default avatarNamhyung Kim <namhyung@kernel.org>
      d7c9ae8d