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x86 and arm64 can both support direct access of event counters in userspace. The access sequence is less than trivial and currently exists in perf test code (tools/perf/arch/x86/tests/rdpmc.c) with copies in projects such as PAPI and libpfm4. In order to support userspace access, an event must be mmapped first with perf_evsel__mmap(). Then subsequent calls to perf_evsel__read() will use the fast path (assuming the arch supports it). Committer notes: Added a '__maybe_unused' attribute to the read_perf_counter() argument to fix the build on arches other than x86_64 and arm. Committer testing: Building and running the libperf tests in verbose mode (V=1) now shows those "loop = N, count = N" extra lines, testing user space counter access. # make V=1 -C tools/lib/perf tests make: Entering directory '/home/acme/git/perf/tools/lib/perf' make -f /home/acme/git/perf/tools/build/Makefile.build dir=. obj=libperf make -C /home/acme/git/perf/tools/lib/api/ O= libapi.a make -f /home/acme/git/perf/tools/build/Makefile.build dir=./fd obj=libapi make -f /home/acme/git/perf/tools/build/Makefile.build dir=./fs obj=libapi make -C tests gcc -I/home/acme/git/perf/tools/lib/perf/include -I/home/acme/git/perf/tools/include -I/home/acme/git/perf/tools/lib -g -Wall -o test-cpumap-a test-cpumap.c ../libperf.a /home/acme/git/perf/tools/lib/api/libapi.a gcc -I/home/acme/git/perf/tools/lib/perf/include -I/home/acme/git/perf/tools/include -I/home/acme/git/perf/tools/lib -g -Wall -o test-threadmap-a test-threadmap.c ../libperf.a /home/acme/git/perf/tools/lib/api/libapi.a gcc -I/home/acme/git/perf/tools/lib/perf/include -I/home/acme/git/perf/tools/include -I/home/acme/git/perf/tools/lib -g -Wall -o test-evlist-a test-evlist.c ../libperf.a /home/acme/git/perf/tools/lib/api/libapi.a gcc -I/home/acme/git/perf/tools/lib/perf/include -I/home/acme/git/perf/tools/include -I/home/acme/git/perf/tools/lib -g -Wall -o test-evsel-a test-evsel.c ../libperf.a /home/acme/git/perf/tools/lib/api/libapi.a gcc -I/home/acme/git/perf/tools/lib/perf/include -I/home/acme/git/perf/tools/include -I/home/acme/git/perf/tools/lib -g -Wall -L.. -o test-cpumap-so test-cpumap.c /home/acme/git/perf/tools/lib/api/libapi.a -lperf gcc -I/home/acme/git/perf/tools/lib/perf/include -I/home/acme/git/perf/tools/include -I/home/acme/git/perf/tools/lib -g -Wall -L.. -o test-threadmap-so test-threadmap.c /home/acme/git/perf/tools/lib/api/libapi.a -lperf gcc -I/home/acme/git/perf/tools/lib/perf/include -I/home/acme/git/perf/tools/include -I/home/acme/git/perf/tools/lib -g -Wall -L.. -o test-evlist-so test-evlist.c /home/acme/git/perf/tools/lib/api/libapi.a -lperf gcc -I/home/acme/git/perf/tools/lib/perf/include -I/home/acme/git/perf/tools/include -I/home/acme/git/perf/tools/lib -g -Wall -L.. -o test-evsel-so test-evsel.c /home/acme/git/perf/tools/lib/api/libapi.a -lperf make -C tests run running static: - running test-cpumap.c...OK - running test-threadmap.c...OK - running test-evlist.c...OK - running test-evsel.c... loop = 65536, count = 333926 loop = 131072, count = 655781 loop = 262144, count = 1311141 loop = 524288, count = 2630126 loop = 1048576, count = 5256955 loop = 65536, count = 524594 loop = 131072, count = 1058916 loop = 262144, count = 2097458 loop = 524288, count = 4205429 loop = 1048576, count = 8406606 OK running dynamic: - running test-cpumap.c...OK - running test-threadmap.c...OK - running test-evlist.c...OK - running test-evsel.c... loop = 65536, count = 328102 loop = 131072, count = 655782 loop = 262144, count = 1317494 loop = 524288, count = 2627851 loop = 1048576, count = 5255187 loop = 65536, count = 524601 loop = 131072, count = 1048923 loop = 262144, count = 2107917 loop = 524288, count = 4194606 loop = 1048576, count = 8409322 OK make: Leaving directory '/home/acme/git/perf/tools/lib/perf' # Signed-off-by: Rob Herring <robh@kernel.org> Acked-by: Jiri Olsa <jolsa@redhat.com> Acked-by: Namhyung Kim <namhyung@kernel.org> Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Itaru Kitayama <itaru.kitayama@gmail.com> Cc: Mark Rutland <mark.rutland@arm.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Will Deacon <will@kernel.org> Link: http://lore.kernel.org/lkml/20210414155412.3697605-4-robh@kernel.org Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
58 lines
1.4 KiB
C
58 lines
1.4 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
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#ifndef __LIBPERF_INTERNAL_MMAP_H
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#define __LIBPERF_INTERNAL_MMAP_H
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#include <linux/compiler.h>
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#include <linux/refcount.h>
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#include <linux/types.h>
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#include <stdbool.h>
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/* perf sample has 16 bits size limit */
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#define PERF_SAMPLE_MAX_SIZE (1 << 16)
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struct perf_mmap;
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struct perf_counts_values;
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typedef void (*libperf_unmap_cb_t)(struct perf_mmap *map);
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/**
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* struct perf_mmap - perf's ring buffer mmap details
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*
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* @refcnt - e.g. code using PERF_EVENT_IOC_SET_OUTPUT to share this
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*/
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struct perf_mmap {
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void *base;
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int mask;
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int fd;
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int cpu;
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refcount_t refcnt;
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u64 prev;
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u64 start;
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u64 end;
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bool overwrite;
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u64 flush;
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libperf_unmap_cb_t unmap_cb;
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char event_copy[PERF_SAMPLE_MAX_SIZE] __aligned(8);
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struct perf_mmap *next;
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};
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struct perf_mmap_param {
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int prot;
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int mask;
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};
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size_t perf_mmap__mmap_len(struct perf_mmap *map);
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void perf_mmap__init(struct perf_mmap *map, struct perf_mmap *prev,
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bool overwrite, libperf_unmap_cb_t unmap_cb);
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int perf_mmap__mmap(struct perf_mmap *map, struct perf_mmap_param *mp,
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int fd, int cpu);
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void perf_mmap__munmap(struct perf_mmap *map);
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void perf_mmap__get(struct perf_mmap *map);
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void perf_mmap__put(struct perf_mmap *map);
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u64 perf_mmap__read_head(struct perf_mmap *map);
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int perf_mmap__read_self(struct perf_mmap *map, struct perf_counts_values *count);
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#endif /* __LIBPERF_INTERNAL_MMAP_H */
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