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Subject[PATCH 02/44] perf evlist: Add support for mmapping an AUX area buffer
Date
This patch supports the addition to the kernel
of AUX area buffers that can be mmapped separately
from the perf-events buffer.

The AUX buffer can be configured to contain
hardware-produced trace information. The first
implementation will support Intel BTS and Intel PT.

One auxtrace buffer is mmapped per perf-events buffer.
If the requested auxtrace buffer size is zero, which
it will be until further support is added, then
no auxtrace mmapping is attempted.

Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
---
tools/perf/util/Build | 1 +
tools/perf/util/auxtrace.c | 113 +++++++++++++++++++++++++++++++++++++++++++
tools/perf/util/auxtrace.h | 117 +++++++++++++++++++++++++++++++++++++++++++++
tools/perf/util/evlist.c | 61 +++++++++++++++++++++--
tools/perf/util/evlist.h | 5 ++
5 files changed, 294 insertions(+), 3 deletions(-)
create mode 100644 tools/perf/util/auxtrace.c
create mode 100644 tools/perf/util/auxtrace.h

diff --git a/tools/perf/util/Build b/tools/perf/util/Build
index 797490a..b6c3f39 100644
--- a/tools/perf/util/Build
+++ b/tools/perf/util/Build
@@ -74,6 +74,7 @@ libperf-y += data.o
libperf-$(CONFIG_X86) += tsc.o
libperf-y += cloexec.o
libperf-y += thread-stack.o
+libperf-y += auxtrace.o

libperf-$(CONFIG_LIBELF) += symbol-elf.o
libperf-$(CONFIG_LIBELF) += probe-event.o
diff --git a/tools/perf/util/auxtrace.c b/tools/perf/util/auxtrace.c
new file mode 100644
index 0000000..dedb646
--- /dev/null
+++ b/tools/perf/util/auxtrace.c
@@ -0,0 +1,113 @@
+/*
+ * auxtrace.c: AUX area trace support
+ * Copyright (c) 2013-2015, Intel Corporation.
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms and conditions of the GNU General Public License,
+ * version 2, as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
+ * more details.
+ *
+ */
+
+#include <sys/types.h>
+#include <sys/mman.h>
+#include <stdbool.h>
+
+#include <linux/kernel.h>
+#include <linux/perf_event.h>
+#include <linux/types.h>
+#include <linux/bitops.h>
+#include <linux/log2.h>
+
+#include "../perf.h"
+#include "util.h"
+#include "evlist.h"
+#include "cpumap.h"
+#include "thread_map.h"
+#include "asm/bug.h"
+#include "auxtrace.h"
+
+int auxtrace_mmap__mmap(struct auxtrace_mmap *mm,
+ struct auxtrace_mmap_params *mp,
+ void *userpg, int fd)
+{
+ struct perf_event_mmap_page *pc = userpg;
+
+#if BITS_PER_LONG != 64 && !defined(HAVE_SYNC_COMPARE_AND_SWAP_SUPPORT)
+ pr_err("Cannot use AUX area tracing mmaps\n");
+ return -1;
+#endif
+
+ WARN_ONCE(mm->base, "Uninitialized auxtrace_mmap\n");
+
+ mm->userpg = userpg;
+ mm->mask = mp->mask;
+ mm->len = mp->len;
+ mm->prev = 0;
+ mm->idx = mp->idx;
+ mm->tid = mp->tid;
+ mm->cpu = mp->cpu;
+
+ if (!mp->len) {
+ mm->base = NULL;
+ return 0;
+ }
+
+ pc->aux_offset = mp->offset;
+ pc->aux_size = mp->len;
+
+ mm->base = mmap(NULL, mp->len, mp->prot, MAP_SHARED, fd, mp->offset);
+ if (mm->base == MAP_FAILED) {
+ pr_debug2("failed to mmap AUX area\n");
+ mm->base = NULL;
+ return -1;
+ }
+
+ return 0;
+}
+
+void auxtrace_mmap__munmap(struct auxtrace_mmap *mm)
+{
+ if (mm->base) {
+ munmap(mm->base, mm->len);
+ mm->base = NULL;
+ }
+}
+
+void auxtrace_mmap_params__init(struct auxtrace_mmap_params *mp,
+ off_t auxtrace_offset,
+ unsigned int auxtrace_pages,
+ bool auxtrace_overwrite)
+{
+ if (auxtrace_pages) {
+ mp->offset = auxtrace_offset;
+ mp->len = auxtrace_pages * (size_t)page_size;
+ mp->mask = is_power_of_2(mp->len) ? mp->len - 1 : 0;
+ mp->prot = PROT_READ | (auxtrace_overwrite ? 0 : PROT_WRITE);
+ pr_debug2("AUX area mmap length %zu\n", mp->len);
+ } else {
+ mp->len = 0;
+ }
+}
+
+void auxtrace_mmap_params__set_idx(struct auxtrace_mmap_params *mp,
+ struct perf_evlist *evlist, int idx,
+ bool per_cpu)
+{
+ mp->idx = idx;
+
+ if (per_cpu) {
+ mp->cpu = evlist->cpus->map[idx];
+ if (evlist->threads)
+ mp->tid = evlist->threads->map[0];
+ else
+ mp->tid = -1;
+ } else {
+ mp->cpu = -1;
+ mp->tid = evlist->threads->map[idx];
+ }
+}
diff --git a/tools/perf/util/auxtrace.h b/tools/perf/util/auxtrace.h
new file mode 100644
index 0000000..2071b36
--- /dev/null
+++ b/tools/perf/util/auxtrace.h
@@ -0,0 +1,117 @@
+/*
+ * auxtrace.h: AUX area trace support
+ * Copyright (c) 2013-2015, Intel Corporation.
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms and conditions of the GNU General Public License,
+ * version 2, as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
+ * more details.
+ *
+ */
+
+#ifndef __PERF_AUXTRACE_H
+#define __PERF_AUXTRACE_H
+
+#include <sys/types.h>
+#include <stdbool.h>
+
+#include <linux/perf_event.h>
+#include <linux/types.h>
+
+#include "../perf.h"
+
+struct perf_evlist;
+
+/**
+ * struct auxtrace_mmap - records an mmap of the auxtrace buffer.
+ * @base: address of mapped area
+ * @userpg: pointer to buffer's perf_event_mmap_page
+ * @mask: %0 if @len is not a power of two, otherwise (@len - %1)
+ * @len: size of mapped area
+ * @prev: previous aux_head
+ * @idx: index of this mmap
+ * @tid: tid for a per-thread mmap (also set if there is only 1 tid on a per-cpu
+ * mmap) otherwise %0
+ * @cpu: cpu number for a per-cpu mmap otherwise %-1
+ */
+struct auxtrace_mmap {
+ void *base;
+ void *userpg;
+ size_t mask;
+ size_t len;
+ u64 prev;
+ int idx;
+ pid_t tid;
+ int cpu;
+};
+
+/**
+ * struct auxtrace_mmap_params - parameters to set up struct auxtrace_mmap.
+ * @mask: %0 if @len is not a power of two, otherwise (@len - %1)
+ * @offset: file offset of mapped area
+ * @len: size of mapped area
+ * @prot: mmap memory protection
+ * @idx: index of this mmap
+ * @tid: tid for a per-thread mmap (also set if there is only 1 tid on a per-cpu
+ * mmap) otherwise %0
+ * @cpu: cpu number for a per-cpu mmap otherwise %-1
+ */
+struct auxtrace_mmap_params {
+ size_t mask;
+ off_t offset;
+ size_t len;
+ int prot;
+ int idx;
+ pid_t tid;
+ int cpu;
+};
+
+static inline u64 auxtrace_mmap__read_head(struct auxtrace_mmap *mm)
+{
+ struct perf_event_mmap_page *pc = mm->userpg;
+#if BITS_PER_LONG == 64 || !defined(HAVE_SYNC_COMPARE_AND_SWAP_SUPPORT)
+ u64 head = ACCESS_ONCE(pc->aux_head);
+#else
+ u64 head = __sync_val_compare_and_swap(&pc->aux_head, 0, 0);
+#endif
+
+ /* Ensure all reads are done after we read the head */
+ rmb();
+ return head;
+}
+
+static inline void auxtrace_mmap__write_tail(struct auxtrace_mmap *mm, u64 tail)
+{
+ struct perf_event_mmap_page *pc = mm->userpg;
+#if BITS_PER_LONG != 64 && defined(HAVE_SYNC_COMPARE_AND_SWAP_SUPPORT)
+ u64 old_tail;
+#endif
+
+ /* Ensure all reads are done before we write the tail out */
+ mb();
+#if BITS_PER_LONG == 64 || !defined(HAVE_SYNC_COMPARE_AND_SWAP_SUPPORT)
+ pc->aux_tail = tail;
+#else
+ do {
+ old_tail = __sync_val_compare_and_swap(&pc->aux_tail, 0, 0);
+ } while (!__sync_bool_compare_and_swap(&pc->aux_tail, old_tail, tail));
+#endif
+}
+
+int auxtrace_mmap__mmap(struct auxtrace_mmap *mm,
+ struct auxtrace_mmap_params *mp,
+ void *userpg, int fd);
+void auxtrace_mmap__munmap(struct auxtrace_mmap *mm);
+void auxtrace_mmap_params__init(struct auxtrace_mmap_params *mp,
+ off_t auxtrace_offset,
+ unsigned int auxtrace_pages,
+ bool auxtrace_overwrite);
+void auxtrace_mmap_params__set_idx(struct auxtrace_mmap_params *mp,
+ struct perf_evlist *evlist, int idx,
+ bool per_cpu);
+
+#endif
diff --git a/tools/perf/util/evlist.c b/tools/perf/util/evlist.c
index 76ef7ee..a588e01 100644
--- a/tools/perf/util/evlist.c
+++ b/tools/perf/util/evlist.c
@@ -725,6 +725,34 @@ void perf_evlist__mmap_consume(struct perf_evlist *evlist, int idx)
perf_evlist__mmap_put(evlist, idx);
}

+int __weak auxtrace_mmap__mmap(struct auxtrace_mmap *mm __maybe_unused,
+ struct auxtrace_mmap_params *mp __maybe_unused,
+ void *userpg __maybe_unused,
+ int fd __maybe_unused)
+{
+ return 0;
+}
+
+void __weak auxtrace_mmap__munmap(struct auxtrace_mmap *mm __maybe_unused)
+{
+}
+
+void __weak auxtrace_mmap_params__init(
+ struct auxtrace_mmap_params *mp __maybe_unused,
+ off_t auxtrace_offset __maybe_unused,
+ unsigned int auxtrace_pages __maybe_unused,
+ bool auxtrace_overwrite __maybe_unused)
+{
+}
+
+void __weak auxtrace_mmap_params__set_idx(
+ struct auxtrace_mmap_params *mp __maybe_unused,
+ struct perf_evlist *evlist __maybe_unused,
+ int idx __maybe_unused,
+ bool per_cpu __maybe_unused)
+{
+}
+
static void __perf_evlist__munmap(struct perf_evlist *evlist, int idx)
{
if (evlist->mmap[idx].base != NULL) {
@@ -732,6 +760,7 @@ static void __perf_evlist__munmap(struct perf_evlist *evlist, int idx)
evlist->mmap[idx].base = NULL;
evlist->mmap[idx].refcnt = 0;
}
+ auxtrace_mmap__munmap(&evlist->mmap[idx].auxtrace_mmap);
}

void perf_evlist__munmap(struct perf_evlist *evlist)
@@ -759,6 +788,7 @@ static int perf_evlist__alloc_mmap(struct perf_evlist *evlist)
struct mmap_params {
int prot;
int mask;
+ struct auxtrace_mmap_params auxtrace_mp;
};

static int __perf_evlist__mmap(struct perf_evlist *evlist, int idx,
@@ -789,6 +819,10 @@ static int __perf_evlist__mmap(struct perf_evlist *evlist, int idx,
return -1;
}

+ if (auxtrace_mmap__mmap(&evlist->mmap[idx].auxtrace_mmap,
+ &mp->auxtrace_mp, evlist->mmap[idx].base, fd))
+ return -1;
+
return 0;
}

@@ -853,6 +887,9 @@ static int perf_evlist__mmap_per_cpu(struct perf_evlist *evlist,
for (cpu = 0; cpu < nr_cpus; cpu++) {
int output = -1;

+ auxtrace_mmap_params__set_idx(&mp->auxtrace_mp, evlist, cpu,
+ true);
+
for (thread = 0; thread < nr_threads; thread++) {
if (perf_evlist__mmap_per_evsel(evlist, cpu, mp, cpu,
thread, &output))
@@ -878,6 +915,9 @@ static int perf_evlist__mmap_per_thread(struct perf_evlist *evlist,
for (thread = 0; thread < nr_threads; thread++) {
int output = -1;

+ auxtrace_mmap_params__set_idx(&mp->auxtrace_mp, evlist, thread,
+ false);
+
if (perf_evlist__mmap_per_evsel(evlist, thread, mp, 0, thread,
&output))
goto out_unmap;
@@ -981,19 +1021,25 @@ int perf_evlist__parse_mmap_pages(const struct option *opt, const char *str,
}

/**
- * perf_evlist__mmap - Create mmaps to receive events.
+ * perf_evlist__mmap_ex - Create mmaps to receive events.
* @evlist: list of events
* @pages: map length in pages
* @overwrite: overwrite older events?
+ * @auxtrace_pages - auxtrace map length in pages
+ * @auxtrace_overwrite - overwrite older auxtrace data?
*
* If @overwrite is %false the user needs to signal event consumption using
* perf_mmap__write_tail(). Using perf_evlist__mmap_read() does this
* automatically.
*
+ * Similarly, if @auxtrace_overwrite is %false the user needs to signal data
+ * consumption using auxtrace_mmap__write_tail().
+ *
* Return: %0 on success, negative error code otherwise.
*/
-int perf_evlist__mmap(struct perf_evlist *evlist, unsigned int pages,
- bool overwrite)
+int perf_evlist__mmap_ex(struct perf_evlist *evlist, unsigned int pages,
+ bool overwrite, unsigned int auxtrace_pages,
+ bool auxtrace_overwrite)
{
struct perf_evsel *evsel;
const struct cpu_map *cpus = evlist->cpus;
@@ -1013,6 +1059,9 @@ int perf_evlist__mmap(struct perf_evlist *evlist, unsigned int pages,
pr_debug("mmap size %zuB\n", evlist->mmap_len);
mp.mask = evlist->mmap_len - page_size - 1;

+ auxtrace_mmap_params__init(&mp.auxtrace_mp, evlist->mmap_len,
+ auxtrace_pages, auxtrace_overwrite);
+
evlist__for_each(evlist, evsel) {
if ((evsel->attr.read_format & PERF_FORMAT_ID) &&
evsel->sample_id == NULL &&
@@ -1026,6 +1075,12 @@ int perf_evlist__mmap(struct perf_evlist *evlist, unsigned int pages,
return perf_evlist__mmap_per_cpu(evlist, &mp);
}

+int perf_evlist__mmap(struct perf_evlist *evlist, unsigned int pages,
+ bool overwrite)
+{
+ return perf_evlist__mmap_ex(evlist, pages, overwrite, 0, false);
+}
+
int perf_evlist__create_maps(struct perf_evlist *evlist, struct target *target)
{
evlist->threads = thread_map__new_str(target->pid, target->tid,
diff --git a/tools/perf/util/evlist.h b/tools/perf/util/evlist.h
index fb19c47..beed571 100644
--- a/tools/perf/util/evlist.h
+++ b/tools/perf/util/evlist.h
@@ -8,6 +8,7 @@
#include "event.h"
#include "evsel.h"
#include "util.h"
+#include "auxtrace.h"
#include <unistd.h>

struct pollfd;
@@ -28,6 +29,7 @@ struct perf_mmap {
int mask;
int refcnt;
unsigned int prev;
+ struct auxtrace_mmap auxtrace_mmap;
char event_copy[PERF_SAMPLE_MAX_SIZE] __attribute__((aligned(8)));
};

@@ -126,6 +128,9 @@ int perf_evlist__parse_mmap_pages(const struct option *opt,
const char *str,
int unset);

+int perf_evlist__mmap_ex(struct perf_evlist *evlist, unsigned int pages,
+ bool overwrite, unsigned int auxtrace_pages,
+ bool auxtrace_overwrite);
int perf_evlist__mmap(struct perf_evlist *evlist, unsigned int pages,
bool overwrite);
void perf_evlist__munmap(struct perf_evlist *evlist);
--
1.9.1


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