If the kernel exposes a new perf_event_attr field in a format attr, perf
will return an error stating the specified PMU can't be found. For
example, a format attr with 'config3:0-63' causes an error as config3 is
unknown to perf. This causes a compatibility issue between a newer
kernel with older perf tool.
Before this change with a kernel adding 'config3' I get:
$ perf record -e arm_spe// -- true
event syntax error: 'arm_spe//'
\___ Cannot find PMU `arm_spe'. Missing kernel support?
Run 'perf list' for a list of valid events
Usage: perf record [<options>] [<command>]
or: perf record [<options>] -- <command> [<options>]
-e, --event <event> event selector. use 'perf list' to list
available events
After this change, I get:
$ perf record -e arm_spe// -- true
WARNING: 'arm_spe_0' format 'inv_event_filter' requires 'perf_event_attr::config3' which is not supported by this version of perf!
[ perf record: Woken up 2 times to write data ]
[ perf record: Captured and wrote 0.091 MB perf.data ]
To support unknown configN formats, rework the YACC implementation to
pass any config[0-9]+ format to perf_pmu__new_format() to handle with a
warning.
Reviewed-by: Namhyung Kim <namhyung@kernel.org>
Signed-off-by: Rob Herring <robh@kernel.org>
Tested-by: Leo Yan <leo.yan@linaro.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: James Clark <james.clark@arm.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/20220914-arm-perf-tool-spe1-2-v2-v4-1-83c098e6212e@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Adding pmu object which provides interface to pmu's sysfs
event format definition located at:
${sysfs_mount}/bus/event_source/devices/${pmu}/format
Following interface is exported:
struct perf_pmu* perf_pmu__find(char *name);
- this function returns pmu object, which is then
passed as a handle to other interface functions
int perf_pmu__config(struct perf_pmu *pmu, struct perf_event_attr *attr,
struct list_head *head_terms);
- this function configures perf_event_attr struct based
on pmu's format definitions and config terms data,
containined in head_terms list.
Parser generator is used to retrive the pmu's format definition.
The generated parser is part of the patch. Added makefile rule
'pmu-parser' to generate the parser code out of the bison/flex
sources.
Added builtin test 'Test perf pmu format parsing', which could
be run like:
perf test pmu
Acked-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Jiri Olsa <jolsa@redhat.com>
Link: http://lkml.kernel.org/n/tip-errz96u1668gj9wlop1zhpht@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
