From: Arnaldo Carvalho de Melo acme@redhat.com
[ Upstream commit 7a1ac110c22eb726684c837544a2d42c33e07be7 ]
Since commit 18e7a45af91a ("perf/x86: Reject non sampling events with precise_ip") returns -EINVAL for sys_perf_event_open() with an attribute with (attr.precise_ip > 0 && attr.sample_period == 0), just like is done in the routine used to probe the max precise level when no events were passed to 'perf record' or 'perf top', i.e.:
perf_evsel__new_cycles() perf_event_attr__set_max_precise_ip()
The x86 code, in x86_pmu_hw_config(), which is called all the way from sys_perf_event_open() did, starting with the aforementioned commit:
/* There's no sense in having PEBS for non sampling events: */ if (!is_sampling_event(event)) return -EINVAL;
Which makes it fail for cycles:ppp, cycles:pp and cycles:p, always using just the non precise cycles variant.
To make sure that this is the case, I tested it, before this patch, with:
# perf probe -L x86_pmu_hw_config <x86_pmu_hw_config@/home/acme/git/linux/arch/x86/events/core.c:0> 0 int x86_pmu_hw_config(struct perf_event *event) 1 { 2 if (event->attr.precise_ip) { <SNIP> 17 if (event->attr.precise_ip > precise) 18 return -EOPNOTSUPP;
/* There's no sense in having PEBS for non sampling events: */ 21 if (!is_sampling_event(event)) 22 return -EINVAL; } <SNIP> # perf probe x86_pmu_hw_config:22 Added new events: probe:x86_pmu_hw_config (on x86_pmu_hw_config:22) probe:x86_pmu_hw_config_1 (on x86_pmu_hw_config:22)
You can now use it in all perf tools, such as:
perf record -e probe:x86_pmu_hw_config_1 -aR sleep 1
# perf trace -e perf_event_open,probe:x86_pmu_hwconfig*/max-stack=16/ perf record usleep 1 0.000 ( 0.015 ms): perf/4150 perf_event_open(attr_uptr: 0x7ffebc8ba110, cpu: -1, group_fd: -1 ) ... 0.015 ( ): probe:x86_pmu_hw_config:(ffffffff9c0065e1)) x86_pmu_hw_config ([kernel.kallsyms]) hsw_hw_config ([kernel.kallsyms]) x86_pmu_event_init ([kernel.kallsyms]) perf_try_init_event ([kernel.kallsyms]) perf_event_alloc ([kernel.kallsyms]) SYSC_perf_event_open ([kernel.kallsyms]) sys_perf_event_open ([kernel.kallsyms]) do_syscall_64 ([kernel.kallsyms]) return_from_SYSCALL_64 ([kernel.kallsyms]) syscall (/usr/lib64/libc-2.24.so) perf_event_attr__set_max_precise_ip (/home/acme/bin/perf) perf_evsel__new_cycles (/home/acme/bin/perf) perf_evlist__add_default (/home/acme/bin/perf) cmd_record (/home/acme/bin/perf) run_builtin (/home/acme/bin/perf) handle_internal_command (/home/acme/bin/perf) 0.000 ( 0.021 ms): perf/4150 ... [continued]: perf_event_open()) = -1 EINVAL Invalid argument 0.023 ( 0.002 ms): perf/4150 perf_event_open(attr_uptr: 0x7ffebc8ba110, cpu: -1, group_fd: -1 ) ... 0.025 ( ): probe:x86_pmu_hw_config:(ffffffff9c0065e1)) x86_pmu_hw_config ([kernel.kallsyms]) hsw_hw_config ([kernel.kallsyms]) x86_pmu_event_init ([kernel.kallsyms]) perf_try_init_event ([kernel.kallsyms]) perf_event_alloc ([kernel.kallsyms]) SYSC_perf_event_open ([kernel.kallsyms]) sys_perf_event_open ([kernel.kallsyms]) do_syscall_64 ([kernel.kallsyms]) return_from_SYSCALL_64 ([kernel.kallsyms]) syscall (/usr/lib64/libc-2.24.so) perf_event_attr__set_max_precise_ip (/home/acme/bin/perf) perf_evsel__new_cycles (/home/acme/bin/perf) perf_evlist__add_default (/home/acme/bin/perf) cmd_record (/home/acme/bin/perf) run_builtin (/home/acme/bin/perf) handle_internal_command (/home/acme/bin/perf) 0.023 ( 0.004 ms): perf/4150 ... [continued]: perf_event_open()) = -1 EINVAL Invalid argument 0.028 ( 0.002 ms): perf/4150 perf_event_open(attr_uptr: 0x7ffebc8ba110, cpu: -1, group_fd: -1 ) ... 0.030 ( ): probe:x86_pmu_hw_config:(ffffffff9c0065e1)) x86_pmu_hw_config ([kernel.kallsyms]) hsw_hw_config ([kernel.kallsyms]) x86_pmu_event_init ([kernel.kallsyms]) perf_try_init_event ([kernel.kallsyms]) perf_event_alloc ([kernel.kallsyms]) SYSC_perf_event_open ([kernel.kallsyms]) sys_perf_event_open ([kernel.kallsyms]) do_syscall_64 ([kernel.kallsyms]) return_from_SYSCALL_64 ([kernel.kallsyms]) syscall (/usr/lib64/libc-2.24.so) perf_event_attr__set_max_precise_ip (/home/acme/bin/perf) perf_evsel__new_cycles (/home/acme/bin/perf) perf_evlist__add_default (/home/acme/bin/perf) cmd_record (/home/acme/bin/perf) run_builtin (/home/acme/bin/perf) handle_internal_command (/home/acme/bin/perf) 0.028 ( 0.004 ms): perf/4150 ... [continued]: perf_event_open()) = -1 EINVAL Invalid argument 41.018 ( 0.012 ms): perf/4150 perf_event_open(attr_uptr: 0x7ffebc8b5dd0, pid: -1, group_fd: -1, flags: FD_CLOEXEC) = 4 41.065 ( 0.011 ms): perf/4150 perf_event_open(attr_uptr: 0x3c7db78, pid: -1, group_fd: -1, flags: FD_CLOEXEC) = 4 41.080 ( 0.006 ms): perf/4150 perf_event_open(attr_uptr: 0x3c7db78, pid: -1, group_fd: -1, flags: FD_CLOEXEC) = 4 41.103 ( 0.010 ms): perf/4150 perf_event_open(attr_uptr: 0x3c4e748, pid: 4151 (perf), group_fd: -1, flags: FD_CLOEXEC) = 4 41.115 ( 0.006 ms): perf/4150 perf_event_open(attr_uptr: 0x3c4e748, pid: 4151 (perf), cpu: 1, group_fd: -1, flags: FD_CLOEXEC) = 5 41.122 ( 0.004 ms): perf/4150 perf_event_open(attr_uptr: 0x3c4e748, pid: 4151 (perf), cpu: 2, group_fd: -1, flags: FD_CLOEXEC) = 6 41.128 ( 0.008 ms): perf/4150 perf_event_open(attr_uptr: 0x3c4e748, pid: 4151 (perf), cpu: 3, group_fd: -1, flags: FD_CLOEXEC) = 8 [ perf record: Woken up 1 times to write data ] [ perf record: Captured and wrote 0.017 MB perf.data (2 samples) ] #
I.e. that return -EINVAL in x86_pmu_hw_config() is hit three times.
So fix it by just setting attr.sample_period
Now, after this patch:
# perf trace --max-stack=2 -e perf_event_open,probe:x86_pmu_hw_config* perf record usleep 1 [ perf record: Woken up 1 times to write data ] 0.000 ( 0.017 ms): perf/8469 perf_event_open(attr_uptr: 0x7ffe36c27d10, pid: -1, cpu: 3, group_fd: -1, flags: FD_CLOEXEC) = 4 syscall (/usr/lib64/libc-2.24.so) perf_event_open_cloexec_flag (/home/acme/bin/perf) 0.050 ( 0.031 ms): perf/8469 perf_event_open(attr_uptr: 0x24ebb78, pid: -1, group_fd: -1, flags: FD_CLOEXEC) = 4 syscall (/usr/lib64/libc-2.24.so) perf_evlist__config (/home/acme/bin/perf) 0.092 ( 0.040 ms): perf/8469 perf_event_open(attr_uptr: 0x24ebb78, pid: -1, group_fd: -1, flags: FD_CLOEXEC) = 4 syscall (/usr/lib64/libc-2.24.so) perf_evlist__config (/home/acme/bin/perf) 0.143 ( 0.007 ms): perf/8469 perf_event_open(attr_uptr: 0x24bc748, cpu: -1, group_fd: -1 ) = 4 syscall (/usr/lib64/libc-2.24.so) perf_event_attr__set_max_precise_ip (/home/acme/bin/perf) 0.161 ( 0.007 ms): perf/8469 perf_event_open(attr_uptr: 0x24bc748, pid: 8470 (perf), group_fd: -1, flags: FD_CLOEXEC) = 4 syscall (/usr/lib64/libc-2.24.so) perf_evsel__open (/home/acme/bin/perf) 0.171 ( 0.005 ms): perf/8469 perf_event_open(attr_uptr: 0x24bc748, pid: 8470 (perf), cpu: 1, group_fd: -1, flags: FD_CLOEXEC) = 5 syscall (/usr/lib64/libc-2.24.so) perf_evsel__open (/home/acme/bin/perf) 0.180 ( 0.007 ms): perf/8469 perf_event_open(attr_uptr: 0x24bc748, pid: 8470 (perf), cpu: 2, group_fd: -1, flags: FD_CLOEXEC) = 6 syscall (/usr/lib64/libc-2.24.so) perf_evsel__open (/home/acme/bin/perf) 0.190 ( 0.005 ms): perf/8469 perf_event_open(attr_uptr: 0x24bc748, pid: 8470 (perf), cpu: 3, group_fd: -1, flags: FD_CLOEXEC) = 8 syscall (/usr/lib64/libc-2.24.so) perf_evsel__open (/home/acme/bin/perf) [ perf record: Captured and wrote 0.017 MB perf.data (7 samples) ] #
The probe one called from perf_event_attr__set_max_precise_ip() works the first time, with attr.precise_ip = 3, wit hthe next ones being the per cpu ones for the cycles:ppp event.
And here is the text from a report and alternative proposed patch by Thomas-Mich Richter:
---
On s390 the counter and sampling facility do not support a precise IP skid level and sometimes returns EOPNOTSUPP when structure member precise_ip in struct perf_event_attr is not set to zero.
On s390 commnd 'perf record -- true' fails with error EOPNOTSUPP. This happens only when no events are specified on command line.
The functions called are ... --> perf_evlist__add_default --> perf_evsel__new_cycles --> perf_event_attr__set_max_precise_ip
The last function determines the value of structure member precise_ip by invoking the perf_event_open() system call and checking the return code. The first successful open is the value for precise_ip.
However the value is determined without setting member sample_period and indicates no sampling.
On s390 the counter facility and sampling facility are different. The above procedure determines a precise_ip value of 3 using the counter facility. Later it uses the sampling facility with a value of 3 and fails with EOPNOTSUPP.
---
v2: Older compilers (e.g. gcc 4.4.7) don't support referencing members of unnamed union members in the container struct initialization, so move from:
struct perf_event_attr attr = { ... .sample_period = 1, };
to right after it as:
struct perf_event_attr attr = { ... };
attr.sample_period = 1;
v3: We need to reset .sample_period to 0 to let the users of perf_evsel__new_cycles() to properly setup attr.sample_period or attr.sample_freq. Reported by Ingo Molnar.
Reported-and-Acked-by: Thomas-Mich Richter tmricht@linux.vnet.ibm.com Acked-by: Hendrik Brueckner brueckner@linux.vnet.ibm.com Acked-by: Jiri Olsa jolsa@redhat.com Cc: Adrian Hunter adrian.hunter@intel.com Cc: Alexander Shishkin alexander.shishkin@linux.intel.com Cc: David Ahern dsahern@gmail.com Cc: Namhyung Kim namhyung@kernel.org Cc: Peter Zijlstra peterz@infradead.org Cc: Wang Nan wangnan0@huawei.com Fixes: 18e7a45af91a ("perf/x86: Reject non sampling events with precise_ip") Link: http://lkml.kernel.org/n/tip-yv6nnkl7tzqocrm0hl3x7vf1@git.kernel.org Signed-off-by: Arnaldo Carvalho de Melo acme@redhat.com Signed-off-by: Sasha Levin sashal@kernel.org --- tools/perf/tests/task-exit.c | 2 +- tools/perf/util/evsel.c | 12 ++++++++++++ 2 files changed, 13 insertions(+), 1 deletion(-)
diff --git a/tools/perf/tests/task-exit.c b/tools/perf/tests/task-exit.c index 01a5ba2788c6..b0d005d295a9 100644 --- a/tools/perf/tests/task-exit.c +++ b/tools/perf/tests/task-exit.c @@ -82,7 +82,7 @@ int test__task_exit(int subtest __maybe_unused)
evsel = perf_evlist__first(evlist); evsel->attr.task = 1; - evsel->attr.sample_freq = 0; + evsel->attr.sample_freq = 1; evsel->attr.inherit = 0; evsel->attr.watermark = 0; evsel->attr.wakeup_events = 1; diff --git a/tools/perf/util/evsel.c b/tools/perf/util/evsel.c index 3be8c489884e..f7128c2a6386 100644 --- a/tools/perf/util/evsel.c +++ b/tools/perf/util/evsel.c @@ -263,8 +263,20 @@ struct perf_evsel *perf_evsel__new_cycles(void) struct perf_evsel *evsel;
event_attr_init(&attr); + /* + * Unnamed union member, not supported as struct member named + * initializer in older compilers such as gcc 4.4.7 + * + * Just for probing the precise_ip: + */ + attr.sample_period = 1;
perf_event_attr__set_max_precise_ip(&attr); + /* + * Now let the usual logic to set up the perf_event_attr defaults + * to kick in when we return and before perf_evsel__open() is called. + */ + attr.sample_period = 0;
evsel = perf_evsel__new(&attr); if (evsel == NULL)