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perf trace: Add trace__bpf_sys_enter_beauty_map() to prepare for fetching data in BPF

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Set up beauty_map, load it to BPF, in such format: if argument No.3 is a
struct of size 32 bytes (of syscall number 114) beauty_map[114][2] = 32;

if argument No.3 is a string (of syscall number 114) beauty_map[114][2] =
1;

if argument No.3 is a buffer, its size is indicated by argument No.4 (of
syscall number 114) beauty_map[114][2] = -4; /* -1 ~ -6, we'll read this
buffer size in BPF  */

Committer notes:

Moved syscall_arg_fmt__cache_btf_struct() from a ifdef
HAVE_LIBBPF_SUPPORT to closer to where it is used, that is ifdef'ed on
HAVE_BPF_SKEL and thus breaks the build when building with
BUILD_BPF_SKEL=0, as detected using 'make -C tools/perf build-test'.

Also add 'struct beauty_map_enter' to tools/perf/util/bpf_skel/augmented_raw_syscalls.bpf.c
as we're using it in this patch, otherwise we get this while trying to
build at this point in the original patch series:

  builtin-trace.c: In function ‘trace__init_syscalls_bpf_prog_array_maps’:
  builtin-trace.c:3725:58: error: ‘struct <anonymous>’ has no member named ‘beauty_map_enter’
   3725 |         int beauty_map_fd = bpf_map__fd(trace->skel->maps.beauty_map_enter);
        |

We also have to take into account syscall_arg_fmt.from_user when telling
the kernel what to copy in the sys_enter generic collector, we don't
want to collect bogus data in buffers that will only be available to us
at sys_exit time, i.e. after the kernel has filled it, so leave this for
when we have such a sys_exit based collector.

Committer testing:

Not wired up yet, so all continues to work, using the existing BPF
collector and userspace beautifiers that are augmentation aware:

  root@number:~# rm -f 987654 ; touch 123456 ; perf trace -e rename* mv 123456 987654
       0.000 ( 0.031 ms): mv/20888 renameat2(olddfd: CWD, oldname: "123456", newdfd: CWD, newname: "987654", flags: NOREPLACE) = 0
  root@number:~# perf trace -e connect,sendto ping -c 1 www.google.com
       0.000 ( 0.014 ms): ping/20892 connect(fd: 5, uservaddr: { .family: LOCAL, path: /run/systemd/resolve/io.systemd.Resolve }, addrlen: 42) = 0
       0.040 ( 0.003 ms): ping/20892 sendto(fd: 5, buff: 0x560b4ff17980, len: 97, flags: DONTWAIT|NOSIGNAL) = 97
       0.480 ( 0.017 ms): ping/20892 sendto(fd: 5, buff: 0x7ffd82d07150, len: 20, addr: { .family: NETLINK }, addr_len: 0xc) = 20
       0.526 ( 0.014 ms): ping/20892 connect(fd: 5, uservaddr: { .family: INET6, port: 0, addr: 2800:3f0:4004:810::2004 }, addrlen: 28) = 0
       0.542 ( 0.002 ms): ping/20892 connect(fd: 5, uservaddr: { .family: UNSPEC }, addrlen: 16)           = 0
       0.544 ( 0.004 ms): ping/20892 connect(fd: 5, uservaddr: { .family: INET, port: 0, addr: 142.251.135.100 }, addrlen: 16) = 0
       0.559 ( 0.002 ms): ping/20892 connect(fd: 5, uservaddr: { .family: INET, port: 1025, addr: 142.251.135.100 }, addrlen: 16PING www.google.com (142.251.135.100) 56(84) bytes of data.
  ) = 0
       0.589 ( 0.058 ms): ping/20892 sendto(fd: 3, buff: 0x560b4ff11ac0, len: 64, addr: { .family: INET, port: 0, addr: 142.251.135.100 }, addr_len: 0x10) = 64
      45.250 ( 0.029 ms): ping/20892 connect(fd: 5, uservaddr: { .family: LOCAL, path: /run/systemd/resolve/io.systemd.Resolve }, addrlen: 42) = 0
      45.344 ( 0.012 ms): ping/20892 sendto(fd: 5, buff: 0x560b4ff19340, len: 111, flags: DONTWAIT|NOSIGNAL) = 111
  64 bytes from rio09s08-in-f4.1e100.net (142.251.135.100): icmp_seq=1 ttl=49 time=44.4 ms

  --- www.google.com ping statistics ---
  1 packets transmitted, 1 received, 0% packet loss, time 0ms
  rtt min/avg/max/mdev = 44.361/44.361/44.361/0.000 ms
  root@number:~#

Signed-off-by: Howard Chu <howardchu95@gmail.com>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Ian Rogers <irogers@google.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Kan Liang <kan.liang@linux.intel.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Link: https://lore.kernel.org/r/20240815013626.935097-4-howardchu95@gmail.com
Link: https://lore.kernel.org/r/20240824163322.60796-3-howardchu95@gmail.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
This commit is contained in:
Howard Chu 2024-08-25 00:33:16 +08:00 committed by Arnaldo Carvalho de Melo
parent d92f490cba
commit 7f40306728
2 changed files with 117 additions and 0 deletions
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110
tools/perf/builtin-trace.c
View File

@ -120,6 +120,7 @@ struct syscall_arg_fmt {
bool show_zero;
#ifdef HAVE_LIBBPF_SUPPORT
const struct btf_type *type;
int type_id; /* used in btf_dump */
#endif
};
@ -3462,6 +3463,23 @@ out_enomem:
}
#ifdef HAVE_BPF_SKEL
static int syscall_arg_fmt__cache_btf_struct(struct syscall_arg_fmt *arg_fmt, struct btf *btf, char *type)
{
int id;
if (arg_fmt->type != NULL)
return -1;
id = btf__find_by_name(btf, type);
if (id < 0)
return -1;
arg_fmt->type = btf__type_by_id(btf, id);
arg_fmt->type_id = id;
return 0;
}
static struct bpf_program *trace__find_bpf_program_by_title(struct trace *trace, const char *name)
{
struct bpf_program *pos, *prog = NULL;
@ -3537,6 +3555,87 @@ static int trace__bpf_prog_sys_exit_fd(struct trace *trace, int id)
return sc ? bpf_program__fd(sc->bpf_prog.sys_exit) : bpf_program__fd(trace->skel->progs.syscall_unaugmented);
}
static int trace__bpf_sys_enter_beauty_map(struct trace *trace, int key, unsigned int *beauty_array)
{
struct tep_format_field *field;
struct syscall *sc = trace__syscall_info(trace, NULL, key);
const struct btf_type *bt;
char *struct_offset, *tmp, name[32];
bool can_augment = false;
int i, cnt;
if (sc == NULL)
return -1;
trace__load_vmlinux_btf(trace);
if (trace->btf == NULL)
return -1;
for (i = 0, field = sc->args; field; ++i, field = field->next) {
struct_offset = strstr(field->type, "struct ");
// XXX We're only collecting pointer payloads _from_ user space
if (!sc->arg_fmt[i].from_user)
continue;
if (field->flags & TEP_FIELD_IS_POINTER && struct_offset) { /* struct */
struct_offset += 7;
/* for 'struct foo *', we only want 'foo' */
for (tmp = struct_offset, cnt = 0; *tmp != ' ' && *tmp != '\0'; ++tmp, ++cnt) {
}
strncpy(name, struct_offset, cnt);
name[cnt] = '\0';
/* cache struct's btf_type and type_id */
if (syscall_arg_fmt__cache_btf_struct(&sc->arg_fmt[i], trace->btf, name))
continue;
bt = sc->arg_fmt[i].type;
beauty_array[i] = bt->size;
can_augment = true;
} else if (field->flags & TEP_FIELD_IS_POINTER && /* string */
strcmp(field->type, "const char *") == 0 &&
(strstr(field->name, "name") ||
strstr(field->name, "path") ||
strstr(field->name, "file") ||
strstr(field->name, "root") ||
strstr(field->name, "key") ||
strstr(field->name, "special") ||
strstr(field->name, "type") ||
strstr(field->name, "description"))) {
beauty_array[i] = 1;
can_augment = true;
} else if (field->flags & TEP_FIELD_IS_POINTER && /* buffer */
strstr(field->type, "char *") &&
(strstr(field->name, "buf") ||
strstr(field->name, "val") ||
strstr(field->name, "msg"))) {
int j;
struct tep_format_field *field_tmp;
/* find the size of the buffer that appears in pairs with buf */
for (j = 0, field_tmp = sc->args; field_tmp; ++j, field_tmp = field_tmp->next) {
if (!(field_tmp->flags & TEP_FIELD_IS_POINTER) && /* only integers */
(strstr(field_tmp->name, "count") ||
strstr(field_tmp->name, "siz") || /* size, bufsiz */
(strstr(field_tmp->name, "len") && strcmp(field_tmp->name, "filename")))) {
/* filename's got 'len' in it, we don't want that */
beauty_array[i] = -(j + 1);
can_augment = true;
break;
}
}
}
}
if (can_augment)
return 0;
return -1;
}
static struct bpf_program *trace__find_usable_bpf_prog_entry(struct trace *trace, struct syscall *sc)
{
struct tep_format_field *field, *candidate_field;
@ -3641,7 +3740,9 @@ static int trace__init_syscalls_bpf_prog_array_maps(struct trace *trace)
{
int map_enter_fd = bpf_map__fd(trace->skel->maps.syscalls_sys_enter);
int map_exit_fd = bpf_map__fd(trace->skel->maps.syscalls_sys_exit);
int beauty_map_fd = bpf_map__fd(trace->skel->maps.beauty_map_enter);
int err = 0;
unsigned int beauty_array[6];
for (int i = 0; i < trace->sctbl->syscalls.nr_entries; ++i) {
int prog_fd, key = syscalltbl__id_at_idx(trace->sctbl, i);
@ -3660,6 +3761,15 @@ static int trace__init_syscalls_bpf_prog_array_maps(struct trace *trace)
err = bpf_map_update_elem(map_exit_fd, &key, &prog_fd, BPF_ANY);
if (err)
break;
/* use beauty_map to tell BPF how many bytes to collect, set beauty_map's value here */
memset(beauty_array, 0, sizeof(beauty_array));
err = trace__bpf_sys_enter_beauty_map(trace, key, (unsigned int *)beauty_array);
if (err)
continue;
err = bpf_map_update_elem(beauty_map_fd, &key, beauty_array, BPF_ANY);
if (err)
break;
}
/*

7
tools/perf/util/bpf_skel/augmented_raw_syscalls.bpf.c
View File

@ -124,6 +124,13 @@ struct augmented_args_tmp {
__uint(max_entries, 1);
} augmented_args_tmp SEC(".maps");
struct beauty_map_enter {
__uint(type, BPF_MAP_TYPE_HASH);
__type(key, int);
__type(value, __u32[6]);
__uint(max_entries, 512);
} beauty_map_enter SEC(".maps");
static inline struct augmented_args_payload *augmented_args_payload(void)
{
int key = 0;