![Pierre Habouzit](/assets/img/avatar_default.png)
While toying with perf, I've noticed that perf record can easily enter a busy loop when doing something as silly as: $ perf record -A ls Yeah, do_read here really wants to read a known size, not being able to should die(), not busy-loop ;) That was the cause for the bug. Signed-off-by: Pierre Habouzit <pierre.habouzit@intersec.com> Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Paul Mackerras <paulus@samba.org> Signed-off-by: Ingo Molnar <mingo@elte.hu>
246 lines
4.5 KiB
C
246 lines
4.5 KiB
C
#include <sys/types.h>
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#include <unistd.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include "util.h"
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#include "header.h"
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/*
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*
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*/
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struct perf_header_attr *perf_header_attr__new(struct perf_counter_attr *attr)
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{
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struct perf_header_attr *self = malloc(sizeof(*self));
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if (!self)
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die("nomem");
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self->attr = *attr;
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self->ids = 0;
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self->size = 1;
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self->id = malloc(sizeof(u64));
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if (!self->id)
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die("nomem");
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return self;
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}
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void perf_header_attr__add_id(struct perf_header_attr *self, u64 id)
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{
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int pos = self->ids;
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self->ids++;
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if (self->ids > self->size) {
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self->size *= 2;
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self->id = realloc(self->id, self->size * sizeof(u64));
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if (!self->id)
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die("nomem");
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}
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self->id[pos] = id;
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}
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/*
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*
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*/
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struct perf_header *perf_header__new(void)
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{
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struct perf_header *self = malloc(sizeof(*self));
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if (!self)
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die("nomem");
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self->frozen = 0;
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self->attrs = 0;
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self->size = 1;
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self->attr = malloc(sizeof(void *));
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if (!self->attr)
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die("nomem");
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self->data_offset = 0;
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self->data_size = 0;
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return self;
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}
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void perf_header__add_attr(struct perf_header *self,
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struct perf_header_attr *attr)
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{
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int pos = self->attrs;
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if (self->frozen)
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die("frozen");
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self->attrs++;
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if (self->attrs > self->size) {
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self->size *= 2;
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self->attr = realloc(self->attr, self->size * sizeof(void *));
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if (!self->attr)
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die("nomem");
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}
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self->attr[pos] = attr;
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}
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static const char *__perf_magic = "PERFFILE";
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#define PERF_MAGIC (*(u64 *)__perf_magic)
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struct perf_file_section {
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u64 offset;
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u64 size;
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};
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struct perf_file_attr {
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struct perf_counter_attr attr;
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struct perf_file_section ids;
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};
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struct perf_file_header {
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u64 magic;
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u64 size;
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u64 attr_size;
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struct perf_file_section attrs;
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struct perf_file_section data;
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};
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static void do_write(int fd, void *buf, size_t size)
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{
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while (size) {
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int ret = write(fd, buf, size);
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if (ret < 0)
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die("failed to write");
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size -= ret;
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buf += ret;
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}
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}
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void perf_header__write(struct perf_header *self, int fd)
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{
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struct perf_file_header f_header;
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struct perf_file_attr f_attr;
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struct perf_header_attr *attr;
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int i;
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lseek(fd, sizeof(f_header), SEEK_SET);
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for (i = 0; i < self->attrs; i++) {
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attr = self->attr[i];
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attr->id_offset = lseek(fd, 0, SEEK_CUR);
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do_write(fd, attr->id, attr->ids * sizeof(u64));
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}
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self->attr_offset = lseek(fd, 0, SEEK_CUR);
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for (i = 0; i < self->attrs; i++) {
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attr = self->attr[i];
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f_attr = (struct perf_file_attr){
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.attr = attr->attr,
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.ids = {
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.offset = attr->id_offset,
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.size = attr->ids * sizeof(u64),
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}
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};
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do_write(fd, &f_attr, sizeof(f_attr));
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}
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self->data_offset = lseek(fd, 0, SEEK_CUR);
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f_header = (struct perf_file_header){
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.magic = PERF_MAGIC,
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.size = sizeof(f_header),
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.attr_size = sizeof(f_attr),
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.attrs = {
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.offset = self->attr_offset,
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.size = self->attrs * sizeof(f_attr),
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},
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.data = {
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.offset = self->data_offset,
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.size = self->data_size,
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},
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};
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lseek(fd, 0, SEEK_SET);
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do_write(fd, &f_header, sizeof(f_header));
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lseek(fd, self->data_offset + self->data_size, SEEK_SET);
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self->frozen = 1;
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}
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static void do_read(int fd, void *buf, size_t size)
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{
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while (size) {
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int ret = read(fd, buf, size);
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if (ret < 0)
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die("failed to read");
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if (ret == 0)
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die("failed to read: missing data");
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size -= ret;
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buf += ret;
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}
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}
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struct perf_header *perf_header__read(int fd)
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{
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struct perf_header *self = perf_header__new();
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struct perf_file_header f_header;
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struct perf_file_attr f_attr;
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u64 f_id;
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int nr_attrs, nr_ids, i, j;
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lseek(fd, 0, SEEK_SET);
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do_read(fd, &f_header, sizeof(f_header));
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if (f_header.magic != PERF_MAGIC ||
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f_header.size != sizeof(f_header) ||
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f_header.attr_size != sizeof(f_attr))
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die("incompatible file format");
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nr_attrs = f_header.attrs.size / sizeof(f_attr);
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lseek(fd, f_header.attrs.offset, SEEK_SET);
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for (i = 0; i < nr_attrs; i++) {
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struct perf_header_attr *attr;
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off_t tmp;
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do_read(fd, &f_attr, sizeof(f_attr));
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tmp = lseek(fd, 0, SEEK_CUR);
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attr = perf_header_attr__new(&f_attr.attr);
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nr_ids = f_attr.ids.size / sizeof(u64);
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lseek(fd, f_attr.ids.offset, SEEK_SET);
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for (j = 0; j < nr_ids; j++) {
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do_read(fd, &f_id, sizeof(f_id));
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perf_header_attr__add_id(attr, f_id);
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}
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perf_header__add_attr(self, attr);
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lseek(fd, tmp, SEEK_SET);
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}
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self->data_offset = f_header.data.offset;
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self->data_size = f_header.data.size;
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lseek(fd, self->data_offset + self->data_size, SEEK_SET);
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self->frozen = 1;
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return self;
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}
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