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perf mmap: Move perf_mmap and methods to separate mmap.[ch] files
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To better organize the sources, and we may end up even using it
directly, without evlists and evsels.

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Wang Nan <wangnan0@huawei.com>
Link: http://lkml.kernel.org/n/tip-oiqrm7grflurnnzo2ovfnslg@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
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Arnaldo Carvalho de Melo committed Oct 23, 2017
1 parent ead81ee commit 1695849
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Showing 6 changed files with 349 additions and 323 deletions.
1 change: 1 addition & 0 deletions tools/perf/util/Build
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Original file line number Diff line number Diff line change
Expand Up @@ -13,6 +13,7 @@ libperf-y += find_bit.o
libperf-y += kallsyms.o
libperf-y += levenshtein.o
libperf-y += llvm-utils.o
libperf-y += mmap.o
libperf-y += memswap.o
libperf-y += parse-events.o
libperf-y += perf_regs.o
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248 changes: 0 additions & 248 deletions tools/perf/util/evlist.c
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Original file line number Diff line number Diff line change
Expand Up @@ -33,9 +33,6 @@
#include <linux/log2.h>
#include <linux/err.h>

static void perf_mmap__munmap(struct perf_mmap *map);
static void perf_mmap__put(struct perf_mmap *map);

#define FD(e, x, y) (*(int *)xyarray__entry(e->fd, x, y))
#define SID(e, x, y) xyarray__entry(e->sample_id, x, y)

Expand Down Expand Up @@ -704,129 +701,6 @@ static int perf_evlist__resume(struct perf_evlist *evlist)
return perf_evlist__set_paused(evlist, false);
}

/* When check_messup is true, 'end' must points to a good entry */
static union perf_event *
perf_mmap__read(struct perf_mmap *md, bool check_messup, u64 start,
u64 end, u64 *prev)
{
unsigned char *data = md->base + page_size;
union perf_event *event = NULL;
int diff = end - start;

if (check_messup) {
/*
* If we're further behind than half the buffer, there's a chance
* the writer will bite our tail and mess up the samples under us.
*
* If we somehow ended up ahead of the 'end', we got messed up.
*
* In either case, truncate and restart at 'end'.
*/
if (diff > md->mask / 2 || diff < 0) {
fprintf(stderr, "WARNING: failed to keep up with mmap data.\n");

/*
* 'end' points to a known good entry, start there.
*/
start = end;
diff = 0;
}
}

if (diff >= (int)sizeof(event->header)) {
size_t size;

event = (union perf_event *)&data[start & md->mask];
size = event->header.size;

if (size < sizeof(event->header) || diff < (int)size) {
event = NULL;
goto broken_event;
}

/*
* Event straddles the mmap boundary -- header should always
* be inside due to u64 alignment of output.
*/
if ((start & md->mask) + size != ((start + size) & md->mask)) {
unsigned int offset = start;
unsigned int len = min(sizeof(*event), size), cpy;
void *dst = md->event_copy;

do {
cpy = min(md->mask + 1 - (offset & md->mask), len);
memcpy(dst, &data[offset & md->mask], cpy);
offset += cpy;
dst += cpy;
len -= cpy;
} while (len);

event = (union perf_event *) md->event_copy;
}

start += size;
}

broken_event:
if (prev)
*prev = start;

return event;
}

union perf_event *perf_mmap__read_forward(struct perf_mmap *md, bool check_messup)
{
u64 head;
u64 old = md->prev;

/*
* Check if event was unmapped due to a POLLHUP/POLLERR.
*/
if (!refcount_read(&md->refcnt))
return NULL;

head = perf_mmap__read_head(md);

return perf_mmap__read(md, check_messup, old, head, &md->prev);
}

union perf_event *
perf_mmap__read_backward(struct perf_mmap *md)
{
u64 head, end;
u64 start = md->prev;

/*
* Check if event was unmapped due to a POLLHUP/POLLERR.
*/
if (!refcount_read(&md->refcnt))
return NULL;

head = perf_mmap__read_head(md);
if (!head)
return NULL;

/*
* 'head' pointer starts from 0. Kernel minus sizeof(record) form
* it each time when kernel writes to it, so in fact 'head' is
* negative. 'end' pointer is made manually by adding the size of
* the ring buffer to 'head' pointer, means the validate data can
* read is the whole ring buffer. If 'end' is positive, the ring
* buffer has not fully filled, so we must adjust 'end' to 0.
*
* However, since both 'head' and 'end' is unsigned, we can't
* simply compare 'end' against 0. Here we compare '-head' and
* the size of the ring buffer, where -head is the number of bytes
* kernel write to the ring buffer.
*/
if (-head < (u64)(md->mask + 1))
end = 0;
else
end = head + md->mask + 1;

return perf_mmap__read(md, false, start, end, &md->prev);
}

union perf_event *perf_evlist__mmap_read_forward(struct perf_evlist *evlist, int idx)
{
struct perf_mmap *md = &evlist->mmap[idx];
Expand Down Expand Up @@ -857,96 +731,16 @@ union perf_event *perf_evlist__mmap_read(struct perf_evlist *evlist, int idx)
return perf_evlist__mmap_read_forward(evlist, idx);
}

void perf_mmap__read_catchup(struct perf_mmap *md)
{
u64 head;

if (!refcount_read(&md->refcnt))
return;

head = perf_mmap__read_head(md);
md->prev = head;
}

void perf_evlist__mmap_read_catchup(struct perf_evlist *evlist, int idx)
{
perf_mmap__read_catchup(&evlist->mmap[idx]);
}

static bool perf_mmap__empty(struct perf_mmap *md)
{
return perf_mmap__read_head(md) == md->prev && !md->auxtrace_mmap.base;
}

static void perf_mmap__get(struct perf_mmap *map)
{
refcount_inc(&map->refcnt);
}

static void perf_mmap__put(struct perf_mmap *md)
{
BUG_ON(md->base && refcount_read(&md->refcnt) == 0);

if (refcount_dec_and_test(&md->refcnt))
perf_mmap__munmap(md);
}

void perf_mmap__consume(struct perf_mmap *md, bool overwrite)
{
if (!overwrite) {
u64 old = md->prev;

perf_mmap__write_tail(md, old);
}

if (refcount_read(&md->refcnt) == 1 && perf_mmap__empty(md))
perf_mmap__put(md);
}

void perf_evlist__mmap_consume(struct perf_evlist *evlist, int idx)
{
perf_mmap__consume(&evlist->mmap[idx], evlist->overwrite);
}

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_mmap__munmap(struct perf_mmap *map)
{
if (map->base != NULL) {
munmap(map->base, perf_mmap__mmap_len(map));
map->base = NULL;
map->fd = -1;
refcount_set(&map->refcnt, 0);
}
auxtrace_mmap__munmap(&map->auxtrace_mmap);
}

static void perf_evlist__munmap_nofree(struct perf_evlist *evlist)
{
int i;
Expand Down Expand Up @@ -995,48 +789,6 @@ static struct perf_mmap *perf_evlist__alloc_mmap(struct perf_evlist *evlist)
return map;
}

struct mmap_params {
int prot;
int mask;
struct auxtrace_mmap_params auxtrace_mp;
};

static int perf_mmap__mmap(struct perf_mmap *map,
struct mmap_params *mp, int fd)
{
/*
* The last one will be done at perf_evlist__mmap_consume(), so that we
* make sure we don't prevent tools from consuming every last event in
* the ring buffer.
*
* I.e. we can get the POLLHUP meaning that the fd doesn't exist
* anymore, but the last events for it are still in the ring buffer,
* waiting to be consumed.
*
* Tools can chose to ignore this at their own discretion, but the
* evlist layer can't just drop it when filtering events in
* perf_evlist__filter_pollfd().
*/
refcount_set(&map->refcnt, 2);
map->prev = 0;
map->mask = mp->mask;
map->base = mmap(NULL, perf_mmap__mmap_len(map), mp->prot,
MAP_SHARED, fd, 0);
if (map->base == MAP_FAILED) {
pr_debug2("failed to mmap perf event ring buffer, error %d\n",
errno);
map->base = NULL;
return -1;
}
map->fd = fd;

if (auxtrace_mmap__mmap(&map->auxtrace_mmap,
&mp->auxtrace_mp, map->base, fd))
return -1;

return 0;
}

static bool
perf_evlist__should_poll(struct perf_evlist *evlist __maybe_unused,
struct perf_evsel *evsel)
Expand Down
76 changes: 1 addition & 75 deletions tools/perf/util/evlist.h
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Original file line number Diff line number Diff line change
Expand Up @@ -11,8 +11,8 @@
#include "../perf.h"
#include "event.h"
#include "evsel.h"
#include "mmap.h"
#include "util.h"
#include "auxtrace.h"
#include <signal.h>
#include <unistd.h>

Expand All @@ -24,55 +24,6 @@ struct record_opts;
#define PERF_EVLIST__HLIST_BITS 8
#define PERF_EVLIST__HLIST_SIZE (1 << PERF_EVLIST__HLIST_BITS)

/**
* struct perf_mmap - perf's ring buffer mmap details
*
* @refcnt - e.g. code using PERF_EVENT_IOC_SET_OUTPUT to share this
*/
struct perf_mmap {
void *base;
int mask;
int fd;
refcount_t refcnt;
u64 prev;
struct auxtrace_mmap auxtrace_mmap;
char event_copy[PERF_SAMPLE_MAX_SIZE] __aligned(8);
};

static inline size_t
perf_mmap__mmap_len(struct perf_mmap *map)
{
return map->mask + 1 + page_size;
}

/*
* State machine of bkw_mmap_state:
*
* .________________(forbid)_____________.
* | V
* NOTREADY --(0)--> RUNNING --(1)--> DATA_PENDING --(2)--> EMPTY
* ^ ^ | ^ |
* | |__(forbid)____/ |___(forbid)___/|
* | |
* \_________________(3)_______________/
*
* NOTREADY : Backward ring buffers are not ready
* RUNNING : Backward ring buffers are recording
* DATA_PENDING : We are required to collect data from backward ring buffers
* EMPTY : We have collected data from backward ring buffers.
*
* (0): Setup backward ring buffer
* (1): Pause ring buffers for reading
* (2): Read from ring buffers
* (3): Resume ring buffers for recording
*/
enum bkw_mmap_state {
BKW_MMAP_NOTREADY,
BKW_MMAP_RUNNING,
BKW_MMAP_DATA_PENDING,
BKW_MMAP_EMPTY,
};

struct perf_evlist {
struct list_head entries;
struct hlist_head heads[PERF_EVLIST__HLIST_SIZE];
Expand Down Expand Up @@ -177,12 +128,6 @@ struct perf_sample_id *perf_evlist__id2sid(struct perf_evlist *evlist, u64 id);

void perf_evlist__toggle_bkw_mmap(struct perf_evlist *evlist, enum bkw_mmap_state state);

union perf_event *perf_mmap__read_forward(struct perf_mmap *map, bool check_messup);
union perf_event *perf_mmap__read_backward(struct perf_mmap *map);

void perf_mmap__read_catchup(struct perf_mmap *md);
void perf_mmap__consume(struct perf_mmap *md, bool overwrite);

union perf_event *perf_evlist__mmap_read(struct perf_evlist *evlist, int idx);

union perf_event *perf_evlist__mmap_read_forward(struct perf_evlist *evlist,
Expand Down Expand Up @@ -286,25 +231,6 @@ size_t perf_evlist__fprintf(struct perf_evlist *evlist, FILE *fp);
int perf_evlist__strerror_open(struct perf_evlist *evlist, int err, char *buf, size_t size);
int perf_evlist__strerror_mmap(struct perf_evlist *evlist, int err, char *buf, size_t size);

static inline u64 perf_mmap__read_head(struct perf_mmap *mm)
{
struct perf_event_mmap_page *pc = mm->base;
u64 head = ACCESS_ONCE(pc->data_head);
rmb();
return head;
}

static inline void perf_mmap__write_tail(struct perf_mmap *md, u64 tail)
{
struct perf_event_mmap_page *pc = md->base;

/*
* ensure all reads are done before we write the tail out.
*/
mb();
pc->data_tail = tail;
}

bool perf_evlist__can_select_event(struct perf_evlist *evlist, const char *str);
void perf_evlist__to_front(struct perf_evlist *evlist,
struct perf_evsel *move_evsel);
Expand Down
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