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Date: Wed, 14 Apr 2021 11:07:37 -0500
From: Rob Herring <robh@...nel.org>
To: Peter Zijlstra <peterz@...radead.org>,
Ingo Molnar <mingo@...hat.com>,
Arnaldo Carvalho de Melo <acme@...nel.org>,
Jiri Olsa <jolsa@...hat.com>
Cc: linux-kernel@...r.kernel.org, Will Deacon <will@...nel.org>,
Catalin Marinas <catalin.marinas@....com>,
Mark Rutland <mark.rutland@....com>,
Namhyung Kim <namhyung@...nel.org>,
Itaru Kitayama <itaru.kitayama@...il.com>
Subject: [PATCH v8 2/4] libperf: Add evsel mmap support
In order to support usersapce access, an event must be mmapped. While
there's already mmap support for evlist, the usecase is a bit different
than the self monitoring with userspace access. So let's add new
perf_evsel__mmap()/perf_evsel_munmap() functions to mmap/munmap an
evsel. This allows implementing userspace access as a fastpath for
perf_evsel__read().
The mmapped address is returned by perf_evsel__mmap_base() which
primarily for users/tests to check if userspace access is enabled.
Signed-off-by: Rob Herring <robh@...nel.org>
---
v8:
- Add perf_evsel__munmap()
- munmap in event of an error in perf_evsel__mmap()
- Ensure repeated calls to perf_evsel__mmap return error
v7:
- Add NULL fd check to perf_evsel__mmap
v6:
- split mmap struct into it's own xyarray
v5:
- Create an mmap for every underlying event opened. Due to this, we
need a different way to get the mmap ptr, so perf_evsel__mmap_base()
is introduced.
v4:
- Change perf_evsel__mmap size to pages instead of bytes
v3:
- New patch split out from user access patch
---
tools/lib/perf/Documentation/libperf.txt | 3 +
tools/lib/perf/evsel.c | 76 ++++++++++++++++++++++++
tools/lib/perf/include/internal/evsel.h | 1 +
tools/lib/perf/include/perf/evsel.h | 3 +
tools/lib/perf/libperf.map | 3 +
5 files changed, 86 insertions(+)
diff --git a/tools/lib/perf/Documentation/libperf.txt b/tools/lib/perf/Documentation/libperf.txt
index 0c74c30ed23a..63ae5e0195ce 100644
--- a/tools/lib/perf/Documentation/libperf.txt
+++ b/tools/lib/perf/Documentation/libperf.txt
@@ -136,6 +136,9 @@ SYNOPSIS
struct perf_thread_map *threads);
void perf_evsel__close(struct perf_evsel *evsel);
void perf_evsel__close_cpu(struct perf_evsel *evsel, int cpu);
+ int perf_evsel__mmap(struct perf_evsel *evsel, int pages);
+ void perf_evsel__munmap(struct perf_evsel *evsel);
+ void *perf_evsel__mmap_base(struct perf_evsel *evsel, int cpu, int thread);
int perf_evsel__read(struct perf_evsel *evsel, int cpu, int thread,
struct perf_counts_values *count);
int perf_evsel__enable(struct perf_evsel *evsel);
diff --git a/tools/lib/perf/evsel.c b/tools/lib/perf/evsel.c
index 4dc06289f4c7..cd203998e875 100644
--- a/tools/lib/perf/evsel.c
+++ b/tools/lib/perf/evsel.c
@@ -11,10 +11,12 @@
#include <stdlib.h>
#include <internal/xyarray.h>
#include <internal/cpumap.h>
+#include <internal/mmap.h>
#include <internal/threadmap.h>
#include <internal/lib.h>
#include <linux/string.h>
#include <sys/ioctl.h>
+#include <sys/mman.h>
void perf_evsel__init(struct perf_evsel *evsel, struct perf_event_attr *attr)
{
@@ -38,6 +40,7 @@ void perf_evsel__delete(struct perf_evsel *evsel)
}
#define FD(e, x, y) (*(int *) xyarray__entry(e->fd, x, y))
+#define MMAP(e, x, y) (e->mmap ? ((struct perf_mmap *) xyarray__entry(e->mmap, x, y)) : NULL)
int perf_evsel__alloc_fd(struct perf_evsel *evsel, int ncpus, int nthreads)
{
@@ -55,6 +58,13 @@ int perf_evsel__alloc_fd(struct perf_evsel *evsel, int ncpus, int nthreads)
return evsel->fd != NULL ? 0 : -ENOMEM;
}
+static int perf_evsel__alloc_mmap(struct perf_evsel *evsel, int ncpus, int nthreads)
+{
+ evsel->mmap = xyarray__new(ncpus, nthreads, sizeof(struct perf_mmap));
+
+ return evsel->mmap != NULL ? 0 : -ENOMEM;
+}
+
static int
sys_perf_event_open(struct perf_event_attr *attr,
pid_t pid, int cpu, int group_fd,
@@ -156,6 +166,72 @@ void perf_evsel__close_cpu(struct perf_evsel *evsel, int cpu)
perf_evsel__close_fd_cpu(evsel, cpu);
}
+void perf_evsel__munmap(struct perf_evsel *evsel)
+{
+ int cpu, thread;
+
+ if (evsel->fd == NULL || evsel->mmap == NULL)
+ return;
+
+ for (cpu = 0; cpu < xyarray__max_x(evsel->fd); cpu++) {
+ for (thread = 0; thread < xyarray__max_y(evsel->fd); thread++) {
+ int fd = FD(evsel, cpu, thread);
+ struct perf_mmap *map = MMAP(evsel, cpu, thread);
+
+ if (fd < 0)
+ continue;
+
+ perf_mmap__munmap(map);
+ }
+ }
+
+ xyarray__delete(evsel->mmap);
+ evsel->mmap = NULL;
+}
+
+int perf_evsel__mmap(struct perf_evsel *evsel, int pages)
+{
+ int ret, cpu, thread;
+ struct perf_mmap_param mp = {
+ .prot = PROT_READ | PROT_WRITE,
+ .mask = (pages * page_size) - 1,
+ };
+
+ if (evsel->fd == NULL || evsel->mmap)
+ return -EINVAL;
+
+ if (perf_evsel__alloc_mmap(evsel, xyarray__max_x(evsel->fd), xyarray__max_y(evsel->fd)) < 0)
+ return -ENOMEM;
+
+ for (cpu = 0; cpu < xyarray__max_x(evsel->fd); cpu++) {
+ for (thread = 0; thread < xyarray__max_y(evsel->fd); thread++) {
+ int fd = FD(evsel, cpu, thread);
+ struct perf_mmap *map = MMAP(evsel, cpu, thread);
+
+ if (fd < 0)
+ continue;
+
+ perf_mmap__init(map, NULL, false, NULL);
+
+ ret = perf_mmap__mmap(map, &mp, fd, cpu);
+ if (ret) {
+ perf_evsel__munmap(evsel);
+ return ret;
+ }
+ }
+ }
+
+ return 0;
+}
+
+void *perf_evsel__mmap_base(struct perf_evsel *evsel, int cpu, int thread)
+{
+ if (FD(evsel, cpu, thread) < 0 || MMAP(evsel, cpu, thread) == NULL)
+ return NULL;
+
+ return MMAP(evsel, cpu, thread)->base;
+}
+
int perf_evsel__read_size(struct perf_evsel *evsel)
{
u64 read_format = evsel->attr.read_format;
diff --git a/tools/lib/perf/include/internal/evsel.h b/tools/lib/perf/include/internal/evsel.h
index 1ffd083b235e..1c067d088bc6 100644
--- a/tools/lib/perf/include/internal/evsel.h
+++ b/tools/lib/perf/include/internal/evsel.h
@@ -41,6 +41,7 @@ struct perf_evsel {
struct perf_cpu_map *own_cpus;
struct perf_thread_map *threads;
struct xyarray *fd;
+ struct xyarray *mmap;
struct xyarray *sample_id;
u64 *id;
u32 ids;
diff --git a/tools/lib/perf/include/perf/evsel.h b/tools/lib/perf/include/perf/evsel.h
index c82ec39a4ad0..60eae25076d3 100644
--- a/tools/lib/perf/include/perf/evsel.h
+++ b/tools/lib/perf/include/perf/evsel.h
@@ -27,6 +27,9 @@ LIBPERF_API int perf_evsel__open(struct perf_evsel *evsel, struct perf_cpu_map *
struct perf_thread_map *threads);
LIBPERF_API void perf_evsel__close(struct perf_evsel *evsel);
LIBPERF_API void perf_evsel__close_cpu(struct perf_evsel *evsel, int cpu);
+LIBPERF_API int perf_evsel__mmap(struct perf_evsel *evsel, int pages);
+LIBPERF_API void perf_evsel__munmap(struct perf_evsel *evsel);
+LIBPERF_API void *perf_evsel__mmap_base(struct perf_evsel *evsel, int cpu, int thread);
LIBPERF_API int perf_evsel__read(struct perf_evsel *evsel, int cpu, int thread,
struct perf_counts_values *count);
LIBPERF_API int perf_evsel__enable(struct perf_evsel *evsel);
diff --git a/tools/lib/perf/libperf.map b/tools/lib/perf/libperf.map
index 7be1af8a546c..c0c7ceb11060 100644
--- a/tools/lib/perf/libperf.map
+++ b/tools/lib/perf/libperf.map
@@ -23,6 +23,9 @@ LIBPERF_0.0.1 {
perf_evsel__disable;
perf_evsel__open;
perf_evsel__close;
+ perf_evsel__mmap;
+ perf_evsel__munmap;
+ perf_evsel__mmap_base;
perf_evsel__read;
perf_evsel__cpus;
perf_evsel__threads;
--
2.27.0
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