366efbff58
The event copy in the mmap is used to have storage to read an event. Not
all users of mmaps read the events, such as perf record. The amount of
buffer was also statically set to PERF_SAMPLE_MAX_SIZE rather than the
amount necessary from the header's event size.
Switch to a model where the event_copy is reallocated if too small to
the event's size. This adds the potential for the event to move, so if a
copy of the event pointer were stored it could be broken. All the
current users do:
while(event = perf_mmap__read_event()) { ... }
and so they would be broken due to the event being overwritten if they
had stored the pointer. Manual inspection and address sanitizer testing
also shows the event pointer not being stored.
Signed-off-by: Ian Rogers <irogers@google.com>
Acked-by: Namhyung Kim <namhyung@kernel.org>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Athira Jajeev <atrajeev@linux.vnet.ibm.com>
Cc: Changbin Du <changbin.du@huawei.com>
Cc: Colin Ian King <colin.i.king@gmail.com>
Cc: Dmitrii Dolgov <9erthalion6@gmail.com>
Cc: German Gomez <german.gomez@arm.com>
Cc: Guilherme Amadio <amadio@gentoo.org>
Cc: Huacai Chen <chenhuacai@kernel.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: James Clark <james.clark@arm.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: K Prateek Nayak <kprateek.nayak@amd.com>
Cc: Kajol Jain <kjain@linux.ibm.com>
Cc: Kan Liang <kan.liang@linux.intel.com>
Cc: Leo Yan <leo.yan@linaro.org>
Cc: Li Dong <lidong@vivo.com>
Cc: Liam Howlett <liam.howlett@oracle.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Cc: Miguel Ojeda <ojeda@kernel.org>
Cc: Ming Wang <wangming01@loongson.cn>
Cc: Nick Terrell <terrelln@fb.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ravi Bangoria <ravi.bangoria@amd.com>
Cc: Sandipan Das <sandipan.das@amd.com>
Cc: Sean Christopherson <seanjc@google.com>
Cc: Steinar H. Gunderson <sesse@google.com>
Cc: Vincent Whitchurch <vincent.whitchurch@axis.com>
Cc: Wenyu Liu <liuwenyu7@huawei.com>
Cc: Yang Jihong <yangjihong1@huawei.com>
Link: https://lore.kernel.org/r/20231127220902.1315692-3-irogers@google.com
[ Replace two lines with equivalent zfree(&map->event_copy) ]
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
61 lines
1.5 KiB
C
61 lines
1.5 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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#include <internal/cpumap.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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struct perf_cpu 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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void *event_copy;
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size_t event_copy_sz;
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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, struct perf_cpu 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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