linux-stable/tools/perf/util/jitdump.c
Arnaldo Carvalho de Melo ef2c3e76d9 perf jit: Avoid returning garbage for a ret variable
When the loop body isn't executed at all, then the 'ret' local variable,
that is uninitialized will be used as the return value.

This triggers this error on Alpine Linux:

    CC	   /tmp/build/perf/util/demangle-java.o
    CC	   /tmp/build/perf/util/demangle-rust.o
    CC       /tmp/build/perf/util/jitdump.o
    CC       /tmp/build/perf/util/genelf.o
  util/jitdump.c: In function 'jit_process':
  util/jitdump.c:622:3: error: 'ret' may be used uninitialized in this function [-Werror=maybe-uninitialized]
     fprintf(stderr, "injected: %s (%d)\n", path, ret);
     ^
  util/jitdump.c:584:6: note: 'ret' was declared here
    int ret;
        ^
    FLEX     /tmp/build/perf/util/parse-events-flex.c

  / $ gcc -v
  Using built-in specs.
  COLLECT_GCC=gcc
  COLLECT_LTO_WRAPPER=/usr/libexec/gcc/x86_64-alpine-linux-musl/5.3.0/lto-wrapper
  Target: x86_64-alpine-linux-musl
  Configured with: /home/buildozer/aports/main/gcc/src/gcc-5.3.0/configure --prefix=/usr --mandir=/usr/share/man --infodir=/usr/share/info
  +--build=x86_64-alpine-linux-musl --host=x86_64-alpine-linux-musl --target=x86_64-alpine-linux-musl --with-pkgversion='Alpine 5.3.0' --enable-checking=release
  +--disable-fixed-point --disable-libstdcxx-pch --disable-multilib --disable-nls --disable-werror --disable-symvers --enable-__cxa_atexit --enable-esp
  +--enable-cloog-backend --enable-languages=c,c++,objc,java,fortran,ada --disable-libssp --disable-libmudflap --disable-libsanitizer --enable-shared
  +--enable-threads --enable-tls --with-system-zlib
  Thread model: posix
  gcc version 5.3.0 (Alpine 5.3.0)

But this so far got under the radar, not causing any build problem, till the
"perf jit: enable jitdump support without dwarf" gets applied, when the above
problem takes place, some combination of inlining or whatever, the problem
is real, so fix it by initializing the variable to zero.

Cc: Anton Blanchard <anton@ozlabs.org>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Maciej Debski <maciejd@google.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Link: https://lkml.kernel.org/r/20161013200437.GA12815@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
2016-10-24 11:07:36 -03:00

727 lines
16 KiB
C

#include <sys/sysmacros.h>
#include <sys/types.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <fcntl.h>
#include <unistd.h>
#include <inttypes.h>
#include <byteswap.h>
#include <sys/stat.h>
#include <sys/mman.h>
#include "util.h"
#include "event.h"
#include "debug.h"
#include "evlist.h"
#include "symbol.h"
#include "strlist.h"
#include <elf.h>
#include "tsc.h"
#include "session.h"
#include "jit.h"
#include "jitdump.h"
#include "genelf.h"
#include "../builtin.h"
struct jit_buf_desc {
struct perf_data_file *output;
struct perf_session *session;
struct machine *machine;
union jr_entry *entry;
void *buf;
uint64_t sample_type;
size_t bufsize;
FILE *in;
bool needs_bswap; /* handles cross-endianess */
bool use_arch_timestamp;
void *debug_data;
size_t nr_debug_entries;
uint32_t code_load_count;
u64 bytes_written;
struct rb_root code_root;
char dir[PATH_MAX];
};
struct debug_line_info {
unsigned long vma;
unsigned int lineno;
/* The filename format is unspecified, absolute path, relative etc. */
char const filename[0];
};
struct jit_tool {
struct perf_tool tool;
struct perf_data_file output;
struct perf_data_file input;
u64 bytes_written;
};
#define hmax(a, b) ((a) > (b) ? (a) : (b))
#define get_jit_tool(t) (container_of(tool, struct jit_tool, tool))
static int
jit_emit_elf(char *filename,
const char *sym,
uint64_t code_addr,
const void *code,
int csize,
void *debug,
int nr_debug_entries)
{
int ret, fd;
if (verbose > 0)
fprintf(stderr, "write ELF image %s\n", filename);
fd = open(filename, O_CREAT|O_TRUNC|O_WRONLY, 0644);
if (fd == -1) {
pr_warning("cannot create jit ELF %s: %s\n", filename, strerror(errno));
return -1;
}
ret = jit_write_elf(fd, code_addr, sym, (const void *)code, csize, debug, nr_debug_entries);
close(fd);
if (ret)
unlink(filename);
return ret;
}
static void
jit_close(struct jit_buf_desc *jd)
{
if (!(jd && jd->in))
return;
funlockfile(jd->in);
fclose(jd->in);
jd->in = NULL;
}
static int
jit_validate_events(struct perf_session *session)
{
struct perf_evsel *evsel;
/*
* check that all events use CLOCK_MONOTONIC
*/
evlist__for_each_entry(session->evlist, evsel) {
if (evsel->attr.use_clockid == 0 || evsel->attr.clockid != CLOCK_MONOTONIC)
return -1;
}
return 0;
}
static int
jit_open(struct jit_buf_desc *jd, const char *name)
{
struct jitheader header;
struct jr_prefix *prefix;
ssize_t bs, bsz = 0;
void *n, *buf = NULL;
int ret, retval = -1;
jd->in = fopen(name, "r");
if (!jd->in)
return -1;
bsz = hmax(sizeof(header), sizeof(*prefix));
buf = malloc(bsz);
if (!buf)
goto error;
/*
* protect from writer modifying the file while we are reading it
*/
flockfile(jd->in);
ret = fread(buf, sizeof(header), 1, jd->in);
if (ret != 1)
goto error;
memcpy(&header, buf, sizeof(header));
if (header.magic != JITHEADER_MAGIC) {
if (header.magic != JITHEADER_MAGIC_SW)
goto error;
jd->needs_bswap = true;
}
if (jd->needs_bswap) {
header.version = bswap_32(header.version);
header.total_size = bswap_32(header.total_size);
header.pid = bswap_32(header.pid);
header.elf_mach = bswap_32(header.elf_mach);
header.timestamp = bswap_64(header.timestamp);
header.flags = bswap_64(header.flags);
}
jd->use_arch_timestamp = header.flags & JITDUMP_FLAGS_ARCH_TIMESTAMP;
if (verbose > 2)
pr_debug("version=%u\nhdr.size=%u\nts=0x%llx\npid=%d\nelf_mach=%d\nuse_arch_timestamp=%d\n",
header.version,
header.total_size,
(unsigned long long)header.timestamp,
header.pid,
header.elf_mach,
jd->use_arch_timestamp);
if (header.flags & JITDUMP_FLAGS_RESERVED) {
pr_err("jitdump file contains invalid or unsupported flags 0x%llx\n",
(unsigned long long)header.flags & JITDUMP_FLAGS_RESERVED);
goto error;
}
if (jd->use_arch_timestamp && !jd->session->time_conv.time_mult) {
pr_err("jitdump file uses arch timestamps but there is no timestamp conversion\n");
goto error;
}
/*
* validate event is using the correct clockid
*/
if (!jd->use_arch_timestamp && jit_validate_events(jd->session)) {
pr_err("error, jitted code must be sampled with perf record -k 1\n");
goto error;
}
bs = header.total_size - sizeof(header);
if (bs > bsz) {
n = realloc(buf, bs);
if (!n)
goto error;
bsz = bs;
buf = n;
/* read extra we do not know about */
ret = fread(buf, bs - bsz, 1, jd->in);
if (ret != 1)
goto error;
}
/*
* keep dirname for generating files and mmap records
*/
strcpy(jd->dir, name);
dirname(jd->dir);
return 0;
error:
funlockfile(jd->in);
fclose(jd->in);
return retval;
}
static union jr_entry *
jit_get_next_entry(struct jit_buf_desc *jd)
{
struct jr_prefix *prefix;
union jr_entry *jr;
void *addr;
size_t bs, size;
int id, ret;
if (!(jd && jd->in))
return NULL;
if (jd->buf == NULL) {
size_t sz = getpagesize();
if (sz < sizeof(*prefix))
sz = sizeof(*prefix);
jd->buf = malloc(sz);
if (jd->buf == NULL)
return NULL;
jd->bufsize = sz;
}
prefix = jd->buf;
/*
* file is still locked at this point
*/
ret = fread(prefix, sizeof(*prefix), 1, jd->in);
if (ret != 1)
return NULL;
if (jd->needs_bswap) {
prefix->id = bswap_32(prefix->id);
prefix->total_size = bswap_32(prefix->total_size);
prefix->timestamp = bswap_64(prefix->timestamp);
}
id = prefix->id;
size = prefix->total_size;
bs = (size_t)size;
if (bs < sizeof(*prefix))
return NULL;
if (id >= JIT_CODE_MAX) {
pr_warning("next_entry: unknown prefix %d, skipping\n", id);
return NULL;
}
if (bs > jd->bufsize) {
void *n;
n = realloc(jd->buf, bs);
if (!n)
return NULL;
jd->buf = n;
jd->bufsize = bs;
}
addr = ((void *)jd->buf) + sizeof(*prefix);
ret = fread(addr, bs - sizeof(*prefix), 1, jd->in);
if (ret != 1)
return NULL;
jr = (union jr_entry *)jd->buf;
switch(id) {
case JIT_CODE_DEBUG_INFO:
if (jd->needs_bswap) {
uint64_t n;
jr->info.code_addr = bswap_64(jr->info.code_addr);
jr->info.nr_entry = bswap_64(jr->info.nr_entry);
for (n = 0 ; n < jr->info.nr_entry; n++) {
jr->info.entries[n].addr = bswap_64(jr->info.entries[n].addr);
jr->info.entries[n].lineno = bswap_32(jr->info.entries[n].lineno);
jr->info.entries[n].discrim = bswap_32(jr->info.entries[n].discrim);
}
}
break;
case JIT_CODE_CLOSE:
break;
case JIT_CODE_LOAD:
if (jd->needs_bswap) {
jr->load.pid = bswap_32(jr->load.pid);
jr->load.tid = bswap_32(jr->load.tid);
jr->load.vma = bswap_64(jr->load.vma);
jr->load.code_addr = bswap_64(jr->load.code_addr);
jr->load.code_size = bswap_64(jr->load.code_size);
jr->load.code_index= bswap_64(jr->load.code_index);
}
jd->code_load_count++;
break;
case JIT_CODE_MOVE:
if (jd->needs_bswap) {
jr->move.pid = bswap_32(jr->move.pid);
jr->move.tid = bswap_32(jr->move.tid);
jr->move.vma = bswap_64(jr->move.vma);
jr->move.old_code_addr = bswap_64(jr->move.old_code_addr);
jr->move.new_code_addr = bswap_64(jr->move.new_code_addr);
jr->move.code_size = bswap_64(jr->move.code_size);
jr->move.code_index = bswap_64(jr->move.code_index);
}
break;
case JIT_CODE_MAX:
default:
return NULL;
}
return jr;
}
static int
jit_inject_event(struct jit_buf_desc *jd, union perf_event *event)
{
ssize_t size;
size = perf_data_file__write(jd->output, event, event->header.size);
if (size < 0)
return -1;
jd->bytes_written += size;
return 0;
}
static uint64_t convert_timestamp(struct jit_buf_desc *jd, uint64_t timestamp)
{
struct perf_tsc_conversion tc;
if (!jd->use_arch_timestamp)
return timestamp;
tc.time_shift = jd->session->time_conv.time_shift;
tc.time_mult = jd->session->time_conv.time_mult;
tc.time_zero = jd->session->time_conv.time_zero;
if (!tc.time_mult)
return 0;
return tsc_to_perf_time(timestamp, &tc);
}
static int jit_repipe_code_load(struct jit_buf_desc *jd, union jr_entry *jr)
{
struct perf_sample sample;
union perf_event *event;
struct perf_tool *tool = jd->session->tool;
uint64_t code, addr;
uintptr_t uaddr;
char *filename;
struct stat st;
size_t size;
u16 idr_size;
const char *sym;
uint32_t count;
int ret, csize;
pid_t pid, tid;
struct {
u32 pid, tid;
u64 time;
} *id;
pid = jr->load.pid;
tid = jr->load.tid;
csize = jr->load.code_size;
addr = jr->load.code_addr;
sym = (void *)((unsigned long)jr + sizeof(jr->load));
code = (unsigned long)jr + jr->load.p.total_size - csize;
count = jr->load.code_index;
idr_size = jd->machine->id_hdr_size;
event = calloc(1, sizeof(*event) + idr_size);
if (!event)
return -1;
filename = event->mmap2.filename;
size = snprintf(filename, PATH_MAX, "%s/jitted-%d-%u.so",
jd->dir,
pid,
count);
size++; /* for \0 */
size = PERF_ALIGN(size, sizeof(u64));
uaddr = (uintptr_t)code;
ret = jit_emit_elf(filename, sym, addr, (const void *)uaddr, csize, jd->debug_data, jd->nr_debug_entries);
if (jd->debug_data && jd->nr_debug_entries) {
free(jd->debug_data);
jd->debug_data = NULL;
jd->nr_debug_entries = 0;
}
if (ret) {
free(event);
return -1;
}
if (stat(filename, &st))
memset(&st, 0, sizeof(st));
event->mmap2.header.type = PERF_RECORD_MMAP2;
event->mmap2.header.misc = PERF_RECORD_MISC_USER;
event->mmap2.header.size = (sizeof(event->mmap2) -
(sizeof(event->mmap2.filename) - size) + idr_size);
event->mmap2.pgoff = GEN_ELF_TEXT_OFFSET;
event->mmap2.start = addr;
event->mmap2.len = csize;
event->mmap2.pid = pid;
event->mmap2.tid = tid;
event->mmap2.ino = st.st_ino;
event->mmap2.maj = major(st.st_dev);
event->mmap2.min = minor(st.st_dev);
event->mmap2.prot = st.st_mode;
event->mmap2.flags = MAP_SHARED;
event->mmap2.ino_generation = 1;
id = (void *)((unsigned long)event + event->mmap.header.size - idr_size);
if (jd->sample_type & PERF_SAMPLE_TID) {
id->pid = pid;
id->tid = tid;
}
if (jd->sample_type & PERF_SAMPLE_TIME)
id->time = convert_timestamp(jd, jr->load.p.timestamp);
/*
* create pseudo sample to induce dso hit increment
* use first address as sample address
*/
memset(&sample, 0, sizeof(sample));
sample.cpumode = PERF_RECORD_MISC_USER;
sample.pid = pid;
sample.tid = tid;
sample.time = id->time;
sample.ip = addr;
ret = perf_event__process_mmap2(tool, event, &sample, jd->machine);
if (ret)
return ret;
ret = jit_inject_event(jd, event);
/*
* mark dso as use to generate buildid in the header
*/
if (!ret)
build_id__mark_dso_hit(tool, event, &sample, NULL, jd->machine);
return ret;
}
static int jit_repipe_code_move(struct jit_buf_desc *jd, union jr_entry *jr)
{
struct perf_sample sample;
union perf_event *event;
struct perf_tool *tool = jd->session->tool;
char *filename;
size_t size;
struct stat st;
u16 idr_size;
int ret;
pid_t pid, tid;
struct {
u32 pid, tid;
u64 time;
} *id;
pid = jr->move.pid;
tid = jr->move.tid;
idr_size = jd->machine->id_hdr_size;
/*
* +16 to account for sample_id_all (hack)
*/
event = calloc(1, sizeof(*event) + 16);
if (!event)
return -1;
filename = event->mmap2.filename;
size = snprintf(filename, PATH_MAX, "%s/jitted-%d-%"PRIu64,
jd->dir,
pid,
jr->move.code_index);
size++; /* for \0 */
if (stat(filename, &st))
memset(&st, 0, sizeof(st));
size = PERF_ALIGN(size, sizeof(u64));
event->mmap2.header.type = PERF_RECORD_MMAP2;
event->mmap2.header.misc = PERF_RECORD_MISC_USER;
event->mmap2.header.size = (sizeof(event->mmap2) -
(sizeof(event->mmap2.filename) - size) + idr_size);
event->mmap2.pgoff = GEN_ELF_TEXT_OFFSET;
event->mmap2.start = jr->move.new_code_addr;
event->mmap2.len = jr->move.code_size;
event->mmap2.pid = pid;
event->mmap2.tid = tid;
event->mmap2.ino = st.st_ino;
event->mmap2.maj = major(st.st_dev);
event->mmap2.min = minor(st.st_dev);
event->mmap2.prot = st.st_mode;
event->mmap2.flags = MAP_SHARED;
event->mmap2.ino_generation = 1;
id = (void *)((unsigned long)event + event->mmap.header.size - idr_size);
if (jd->sample_type & PERF_SAMPLE_TID) {
id->pid = pid;
id->tid = tid;
}
if (jd->sample_type & PERF_SAMPLE_TIME)
id->time = convert_timestamp(jd, jr->load.p.timestamp);
/*
* create pseudo sample to induce dso hit increment
* use first address as sample address
*/
memset(&sample, 0, sizeof(sample));
sample.cpumode = PERF_RECORD_MISC_USER;
sample.pid = pid;
sample.tid = tid;
sample.time = id->time;
sample.ip = jr->move.new_code_addr;
ret = perf_event__process_mmap2(tool, event, &sample, jd->machine);
if (ret)
return ret;
ret = jit_inject_event(jd, event);
if (!ret)
build_id__mark_dso_hit(tool, event, &sample, NULL, jd->machine);
return ret;
}
static int jit_repipe_debug_info(struct jit_buf_desc *jd, union jr_entry *jr)
{
void *data;
size_t sz;
if (!(jd && jr))
return -1;
sz = jr->prefix.total_size - sizeof(jr->info);
data = malloc(sz);
if (!data)
return -1;
memcpy(data, &jr->info.entries, sz);
jd->debug_data = data;
/*
* we must use nr_entry instead of size here because
* we cannot distinguish actual entry from padding otherwise
*/
jd->nr_debug_entries = jr->info.nr_entry;
return 0;
}
static int
jit_process_dump(struct jit_buf_desc *jd)
{
union jr_entry *jr;
int ret = 0;
while ((jr = jit_get_next_entry(jd))) {
switch(jr->prefix.id) {
case JIT_CODE_LOAD:
ret = jit_repipe_code_load(jd, jr);
break;
case JIT_CODE_MOVE:
ret = jit_repipe_code_move(jd, jr);
break;
case JIT_CODE_DEBUG_INFO:
ret = jit_repipe_debug_info(jd, jr);
break;
default:
ret = 0;
continue;
}
}
return ret;
}
static int
jit_inject(struct jit_buf_desc *jd, char *path)
{
int ret;
if (verbose > 0)
fprintf(stderr, "injecting: %s\n", path);
ret = jit_open(jd, path);
if (ret)
return -1;
ret = jit_process_dump(jd);
jit_close(jd);
if (verbose > 0)
fprintf(stderr, "injected: %s (%d)\n", path, ret);
return 0;
}
/*
* File must be with pattern .../jit-XXXX.dump
* where XXXX is the PID of the process which did the mmap()
* as captured in the RECORD_MMAP record
*/
static int
jit_detect(char *mmap_name, pid_t pid)
{
char *p;
char *end = NULL;
pid_t pid2;
if (verbose > 2)
fprintf(stderr, "jit marker trying : %s\n", mmap_name);
/*
* get file name
*/
p = strrchr(mmap_name, '/');
if (!p)
return -1;
/*
* match prefix
*/
if (strncmp(p, "/jit-", 5))
return -1;
/*
* skip prefix
*/
p += 5;
/*
* must be followed by a pid
*/
if (!isdigit(*p))
return -1;
pid2 = (int)strtol(p, &end, 10);
if (!end)
return -1;
/*
* pid does not match mmap pid
* pid==0 in system-wide mode (synthesized)
*/
if (pid && pid2 != pid)
return -1;
/*
* validate suffix
*/
if (strcmp(end, ".dump"))
return -1;
if (verbose > 0)
fprintf(stderr, "jit marker found: %s\n", mmap_name);
return 0;
}
int
jit_process(struct perf_session *session,
struct perf_data_file *output,
struct machine *machine,
char *filename,
pid_t pid,
u64 *nbytes)
{
struct perf_evsel *first;
struct jit_buf_desc jd;
int ret;
/*
* first, detect marker mmap (i.e., the jitdump mmap)
*/
if (jit_detect(filename, pid))
return 0;
memset(&jd, 0, sizeof(jd));
jd.session = session;
jd.output = output;
jd.machine = machine;
/*
* track sample_type to compute id_all layout
* perf sets the same sample type to all events as of now
*/
first = perf_evlist__first(session->evlist);
jd.sample_type = first->attr.sample_type;
*nbytes = 0;
ret = jit_inject(&jd, filename);
if (!ret) {
*nbytes = jd.bytes_written;
ret = 1;
}
return ret;
}