This patch modifies perf_probe_msr() by allowing passing of
struct perf_msr array where some entries are not populated, i.e.,
they have either an msr address of 0 or no attribute_group pointer.
This helps with certain call paths, e.g., RAPL.
In case the grp is NULL, the default sysfs visibility rule
applies which is to make the group visible. Without the patch,
you would get a kernel crash with a NULL group.
Signed-off-by: Stephane Eranian <eranian@google.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/20200527224659.206129-5-eranian@google.com
Adding perf_msr_probe function to provide interface for
checking up on MSR register and set the related attribute
group visibility.
User defines following struct for each MSR register:
struct perf_msr {
u64 msr;
struct attribute_group *grp;
bool (*test)(int idx, void *data);
bool no_check;
};
Where:
msr - is the MSR address
attrs - is attribute groups array to add if the check passed
test - is test function pointer
no_check - is bool that bypass the check and adds the
attribute without any test
The array of struct perf_msr is passed into:
perf_msr_probe(struct perf_msr *msr, int cnt, bool zero, void *data)
Together with:
cnt - which is the number of struct msr array elements
data - which is user pointer passed to the test function
zero - allow counters that returns zero on rdmsr
The perf_msr_probe will executed test code, read the MSR and
check the value is != 0. If all these tests pass, related
attribute group is kept visible.
Also adding PMU_EVENT_GROUP macro helper to define attribute
group for single attribute. It will be used in following patches.
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Kan <kan.liang@linux.intel.com>
Cc: Liang
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vince Weaver <vincent.weaver@maine.edu>
Link: https://lkml.kernel.org/r/20190616140358.27799-2-jolsa@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
