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perf trace: Add BPF augmenter to perf_event_open()'s 'struct perf_event_attr' arg

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Using BPF for that, doing a cleverish reuse of perf_event_attr__fprintf(),
that really needs to be turned into __snprintf(), etc.

But since the plan is to go the BTF way probably use libbpf's
btf_dump__dump_type_data().

Example:

[root@quaco ~]# perf trace -e ~acme/git/perf/tools/perf/examples/bpf/augmented_raw_syscalls.c,perf_event_open --max-events 10 perf stat --quiet sleep 0.001
fg
     0.000 perf_event_open(attr_uptr: { type: 1, size: 128, config: 0x1, sample_type: IDENTIFIER, read_format: TOTAL_TIME_ENABLED|TOTAL_TIME_RUNNING, disabled: 1, inherit: 1, enable_on_exec: 1, exclude_guest: 1 }, pid: 258859 (perf), cpu: -1, group_fd: -1, flags: FD_CLOEXEC) = 3
     0.067 perf_event_open(attr_uptr: { type: 1, size: 128, config: 0x3, sample_type: IDENTIFIER, read_format: TOTAL_TIME_ENABLED|TOTAL_TIME_RUNNING, disabled: 1, inherit: 1, enable_on_exec: 1, exclude_guest: 1 }, pid: 258859 (perf), cpu: -1, group_fd: -1, flags: FD_CLOEXEC) = 4
     0.120 perf_event_open(attr_uptr: { type: 1, size: 128, config: 0x4, sample_type: IDENTIFIER, read_format: TOTAL_TIME_ENABLED|TOTAL_TIME_RUNNING, disabled: 1, inherit: 1, enable_on_exec: 1, exclude_guest: 1 }, pid: 258859 (perf), cpu: -1, group_fd: -1, flags: FD_CLOEXEC) = 5
     0.172 perf_event_open(attr_uptr: { type: 1, size: 128, config: 0x2, sample_type: IDENTIFIER, read_format: TOTAL_TIME_ENABLED|TOTAL_TIME_RUNNING, disabled: 1, inherit: 1, enable_on_exec: 1, exclude_guest: 1 }, pid: 258859 (perf), cpu: -1, group_fd: -1, flags: FD_CLOEXEC) = 7
     0.190 perf_event_open(attr_uptr: { size: 128, sample_type: IDENTIFIER, read_format: TOTAL_TIME_ENABLED|TOTAL_TIME_RUNNING, disabled: 1, inherit: 1, enable_on_exec: 1, exclude_guest: 1 }, pid: 258859 (perf), cpu: -1, group_fd: -1, flags: FD_CLOEXEC) = 8
     0.199 perf_event_open(attr_uptr: { size: 128, config: 0x1, sample_type: IDENTIFIER, read_format: TOTAL_TIME_ENABLED|TOTAL_TIME_RUNNING, disabled: 1, inherit: 1, enable_on_exec: 1, exclude_guest: 1 }, pid: 258859 (perf), cpu: -1, group_fd: -1, flags: FD_CLOEXEC) = 9
     0.204 perf_event_open(attr_uptr: { size: 128, config: 0x4, sample_type: IDENTIFIER, read_format: TOTAL_TIME_ENABLED|TOTAL_TIME_RUNNING, disabled: 1, inherit: 1, enable_on_exec: 1, exclude_guest: 1 }, pid: 258859 (perf), cpu: -1, group_fd: -1, flags: FD_CLOEXEC) = 10
     0.210 perf_event_open(attr_uptr: { size: 128, config: 0x5, sample_type: IDENTIFIER, read_format: TOTAL_TIME_ENABLED|TOTAL_TIME_RUNNING, disabled: 1, inherit: 1, enable_on_exec: 1, exclude_guest: 1 }, pid: 258859 (perf), cpu: -1, group_fd: -1, flags: FD_CLOEXEC) = 11
[root@quaco ~]#

Suggested-by: Ian Rogers <irogers@google.com>
Tested-by: Ian Rogers <irogers@google.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Link: https://lore.kernel.org/r/Y2V2Tpu+2vzJyon2@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
This commit is contained in:
Arnaldo Carvalho de Melo 2022-11-04 16:44:52 -03:00
parent b018899e62
commit a9cd6c6766
3 changed files with 90 additions and 1 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

3
tools/perf/builtin-trace.c
View file

@ -1053,7 +1053,8 @@ static struct syscall_fmt syscall_fmts[] = {
.arg = { [0] = { .scnprintf = SCA_FDAT, /* dfd */ },
[2] = { .scnprintf = SCA_OPEN_FLAGS, /* flags */ }, }, },
{ .name = "perf_event_open",
.arg = { [2] = { .scnprintf = SCA_INT, /* cpu */ },
.arg = { [0] = { .scnprintf = SCA_PERF_ATTR, /* attr */ },
[2] = { .scnprintf = SCA_INT, /* cpu */ },
[3] = { .scnprintf = SCA_FD, /* group_fd */ },
[4] = { .scnprintf = SCA_PERF_FLAGS, /* flags */ }, }, },
{ .name = "pipe2",

44
tools/perf/examples/bpf/augmented_raw_syscalls.c
View file

@ -129,6 +129,7 @@ struct augmented_args_payload {
struct augmented_arg arg, arg2;
};
struct sockaddr_storage saddr;
char __data[sizeof(struct augmented_arg)];
};
};
@ -293,6 +294,49 @@ int sys_enter_renameat(struct syscall_enter_args *args)
return augmented__output(args, augmented_args, len);
}
#define PERF_ATTR_SIZE_VER0 64 /* sizeof first published struct */
// we need just the start, get the size to then copy it
struct perf_event_attr_size {
__u32 type;
/*
* Size of the attr structure, for fwd/bwd compat.
*/
__u32 size;
};
SEC("!syscalls:sys_enter_perf_event_open")
int sys_enter_perf_event_open(struct syscall_enter_args *args)
{
struct augmented_args_payload *augmented_args = augmented_args_payload();
const struct perf_event_attr_size *attr = (const struct perf_event_attr_size *)args->args[0], *attr_read;
unsigned int len = sizeof(augmented_args->args);
if (augmented_args == NULL)
goto failure;
if (bpf_probe_read(&augmented_args->__data, sizeof(*attr), attr) < 0)
goto failure;
attr_read = (const struct perf_event_attr_size *)augmented_args->__data;
__u32 size = attr_read->size;
if (!size)
size = PERF_ATTR_SIZE_VER0;
if (size > sizeof(augmented_args->__data))
goto failure;
// Now that we read attr->size and tested it against the size limits, read it completely
if (bpf_probe_read(&augmented_args->__data, size, attr) < 0)
goto failure;
return augmented__output(args, augmented_args, len + size);
failure:
return 1; /* Failure: don't filter */
}
static pid_t getpid(void)
{
return bpf_get_current_pid_tgid();

44
tools/perf/trace/beauty/perf_event_open.c
View file

@ -44,3 +44,47 @@ static size_t syscall_arg__scnprintf_perf_flags(char *bf, size_t size,
}
#define SCA_PERF_FLAGS syscall_arg__scnprintf_perf_flags
struct attr_fprintf_args {
size_t size, printed;
char *bf;
bool first;
};
static int attr__fprintf(FILE *fp __maybe_unused, const char *name, const char *val, void *priv)
{
struct attr_fprintf_args *args = priv;
size_t printed = scnprintf(args->bf + args->printed , args->size - args->printed, "%s%s: %s", args->first ? "" : ", ", name, val);
args->first = false;
args->printed += printed;
return printed;
}
static size_t perf_event_attr___scnprintf(struct perf_event_attr *attr, char *bf, size_t size, bool show_zeros __maybe_unused)
{
struct attr_fprintf_args args = {
.printed = scnprintf(bf, size, "{ "),
.size = size,
.first = true,
.bf = bf,
};
perf_event_attr__fprintf(stdout, attr, attr__fprintf, &args);
return args.printed + scnprintf(bf + args.printed, size - args.printed, " }");
}
static size_t syscall_arg__scnprintf_augmented_perf_event_attr(struct syscall_arg *arg, char *bf, size_t size)
{
return perf_event_attr___scnprintf((void *)arg->augmented.args, bf, size, arg->trace->show_zeros);
}
static size_t syscall_arg__scnprintf_perf_event_attr(char *bf, size_t size, struct syscall_arg *arg)
{
if (arg->augmented.args)
return syscall_arg__scnprintf_augmented_perf_event_attr(arg, bf, size);
return scnprintf(bf, size, "%#lx", arg->val);
}
#define SCA_PERF_ATTR syscall_arg__scnprintf_perf_event_attr