perf trace: Pretty print struct data

Change the arg->augmented.args to arg->augmented.args->value to skip the
header for customized pretty printers, since we collect data in BPF
using the general augment_sys_enter(), which always adds the header.

Use btf_dump API to pretty print augmented struct pointer.

Prefer existed pretty-printer than btf general pretty-printer.

set compact = true and skip_names = true, so that no newline character
and argument name are printed.

Committer notes:

Simplified the btf_dump_snprintf callback to avoid using multiple
buffers, as discussed in the thread accessible via the Link tag below.

Also made it do:

dump_data_opts.skip_names = !arg->trace->show_arg_names;

I.e. show the type and struct field names according to that tunable, we
probably need another tunable just for this, but for now if the user
wants to see syscall names in addition to its value, it makes sense to
see the struct field names according to that tunable.

Committer testing:

The following have explicitely set beautifiers (SCA_FILENAME,
SCA_SOCKADDR and SCA_PERF_ATTR), SCA_FILENAME is here just because we
have been wiring up the "renameat2" ("renameat" until recently), so it
doesn't use the introduced generic fallback (btf_struct_scnprintf(), see
the definition of SCA_PERF_ATTR, SCA_SOCKADDR to see the more feature
rich beautifiers, that are not using BTF):

root@number:~# rm -f 987654 ; touch 123456 ; perf trace -e rename* mv 123456 987654
0.000 ( 0.039 ms): mv/258478 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/258481 connect(fd: 5, uservaddr: { .family: LOCAL, path: /run/systemd/resolve/io.systemd.Resolve }, addrlen: 42) = 0
0.040 ( 0.003 ms): ping/258481 sendto(fd: 5, buff: 0x55bc317a6980, len: 97, flags: DONTWAIT|NOSIGNAL) = 97
18.742 ( 0.020 ms): ping/258481 sendto(fd: 5, buff: 0x7ffc04768df0, len: 20, addr: { .family: NETLINK }, addr_len: 0xc) = 20
PING www.google.com (142.251.129.68) 56(84) bytes of data.
18.783 ( 0.012 ms): ping/258481 connect(fd: 5, uservaddr: { .family: INET6, port: 0, addr: 2800:3f0:4004:810::2004 }, addrlen: 28) = 0
18.797 ( 0.001 ms): ping/258481 connect(fd: 5, uservaddr: { .family: UNSPEC }, addrlen: 16) = 0
18.800 ( 0.004 ms): ping/258481 connect(fd: 5, uservaddr: { .family: INET, port: 0, addr: 142.251.129.68 }, addrlen: 16) = 0
18.815 ( 0.002 ms): ping/258481 connect(fd: 5, uservaddr: { .family: INET, port: 1025, addr: 142.251.129.68 }, addrlen: 16) = 0
18.862 ( 0.023 ms): ping/258481 sendto(fd: 3, buff: 0x55bc317a0ac0, len: 64, addr: { .family: INET, port: 0, addr: 142.251.129.68 }, addr_len: 0x10) = 64
63.330 ( 0.038 ms): ping/258481 connect(fd: 5, uservaddr: { .family: LOCAL, path: /run/systemd/resolve/io.systemd.Resolve }, addrlen: 42) = 0
63.435 ( 0.010 ms): ping/258481 sendto(fd: 5, buff: 0x55bc317a8340, len: 110, flags: DONTWAIT|NOSIGNAL) = 110
64 bytes from rio07s07-in-f4.1e100.net (142.251.129.68): icmp_seq=1 ttl=49 time=44.2 ms

--- www.google.com ping statistics ---
1 packets transmitted, 1 received, 0% packet loss, time 0ms
rtt min/avg/max/mdev = 44.158/44.158/44.158/0.000 ms
root@number:~# perf trace -e perf_event_open perf stat -e instructions,cache-misses,syscalls:sys_enter*sleep* sleep 1.23456789
0.000 ( 0.010 ms): :258487/258487 perf_event_open(attr_uptr: { type: 0 (PERF_TYPE_HARDWARE), config: 0xa00000000, disabled: 1, { bp_len, config2 }: 0x900000000, branch_sample_type: USER|COUNTERS, sample_regs_user: 0x3f1b7ffffffff, sample_stack_user: 258487, clockid: -599052088, sample_regs_intr: 0x60a000003eb, sample_max_stack: 14, sig_data: 120259084288 }, cpu: -1, group_fd: -1, flags: FD_CLOEXEC) = 3
0.016 ( 0.002 ms): :258487/258487 perf_event_open(attr_uptr: { type: 0 (PERF_TYPE_HARDWARE), config: 0x400000000, disabled: 1, { bp_len, config2 }: 0x900000000, branch_sample_type: USER|COUNTERS, sample_regs_user: 0x3f1b7ffffffff, sample_stack_user: 258487, clockid: -599044082, sample_regs_intr: 0x60a000003eb, sample_max_stack: 14, sig_data: 120259084288 }, cpu: -1, group_fd: -1, flags: FD_CLOEXEC) = 4
1.838 ( 0.006 ms): perf/258487 perf_event_open(attr_uptr: { type: 0 (PERF_TYPE_HARDWARE), size: 136, config: 0xa00000001, sample_type: IDENTIFIER, read_format: TOTAL_TIME_ENABLED|TOTAL_TIME_RUNNING, disabled: 1, inherit: 1, enable_on_exec: 1, exclude_guest: 1 }, pid: 258488 (perf), cpu: -1, group_fd: -1, flags: FD_CLOEXEC) = 5
1.846 ( 0.002 ms): perf/258487 perf_event_open(attr_uptr: { type: 0 (PERF_TYPE_HARDWARE), size: 136, config: 0x400000001, sample_type: IDENTIFIER, read_format: TOTAL_TIME_ENABLED|TOTAL_TIME_RUNNING, disabled: 1, inherit: 1, enable_on_exec: 1, exclude_guest: 1 }, pid: 258488 (perf), cpu: -1, group_fd: -1, flags: FD_CLOEXEC) = 6
1.849 ( 0.002 ms): perf/258487 perf_event_open(attr_uptr: { type: 0 (PERF_TYPE_HARDWARE), size: 136, config: 0xa00000003, sample_type: IDENTIFIER, read_format: TOTAL_TIME_ENABLED|TOTAL_TIME_RUNNING, disabled: 1, inherit: 1, enable_on_exec: 1, exclude_guest: 1 }, pid: 258488 (perf), cpu: -1, group_fd: -1, flags: FD_CLOEXEC) = 7
1.851 ( 0.002 ms): perf/258487 perf_event_open(attr_uptr: { type: 0 (PERF_TYPE_HARDWARE), size: 136, config: 0x400000003, sample_type: IDENTIFIER, read_format: TOTAL_TIME_ENABLED|TOTAL_TIME_RUNNING, disabled: 1, inherit: 1, enable_on_exec: 1, exclude_guest: 1 }, pid: 258488 (perf), cpu: -1, group_fd: -1, flags: FD_CLOEXEC) = 9
1.853 ( 0.600 ms): perf/258487 perf_event_open(attr_uptr: { type: 2 (tracepoint), size: 136, config: 0x190 (syscalls:sys_enter_nanosleep), sample_type: IDENTIFIER, read_format: TOTAL_TIME_ENABLED|TOTAL_TIME_RUNNING, disabled: 1, inherit: 1, enable_on_exec: 1, exclude_guest: 1 }, pid: 258488 (perf), cpu: -1, group_fd: -1, flags: FD_CLOEXEC) = 10
2.456 ( 0.016 ms): perf/258487 perf_event_open(attr_uptr: { type: 2 (tracepoint), size: 136, config: 0x196 (syscalls:sys_enter_clock_nanosleep), sample_type: IDENTIFIER, read_format: TOTAL_TIME_ENABLED|TOTAL_TIME_RUNNING, disabled: 1, inherit: 1, enable_on_exec: 1, exclude_guest: 1 }, pid: 258488 (perf), cpu: -1, group_fd: -1, flags: FD_CLOEXEC) = 11

Performance counter stats for 'sleep 1.23456789':

1,402,839 cpu_atom/instructions/
<not counted> cpu_core/instructions/ (0.00%)
11,066 cpu_atom/cache-misses/
<not counted> cpu_core/cache-misses/ (0.00%)
0 syscalls:sys_enter_nanosleep
1 syscalls:sys_enter_clock_nanosleep

1.236246714 seconds time elapsed

0.000000000 seconds user
0.001308000 seconds sys

root@number:~#

Now if we use it even for the ones we have a specific beautifier in
tools/perf/trace/beauty, i.e. use btf_struct_scnprintf() for all
structs, by adding the following patch:

@@ -2316,7 +2316,7 @@ static size_t syscall__scnprintf_args(struct syscall *sc, char *bf, size_t size,

default_scnprintf = sc->arg_fmt[arg.idx].scnprintf;

- if (default_scnprintf == NULL || default_scnprintf == SCA_PTR) {
+ if (1 || (default_scnprintf == NULL || default_scnprintf == SCA_PTR)) {
btf_printed = trace__btf_scnprintf(trace, &arg, bf + printed,
size - printed, val, field->type);
if (btf_printed) {

We get:

root@number:~# perf trace -e connect,sendto ping -c 1 www.google.com
PING www.google.com (142.251.129.68) 56(84) bytes of data.
0.000 ( 0.015 ms): ping/283259 connect(fd: 5, uservaddr: (struct sockaddr){.sa_family = (sa_family_t)1,(union){.sa_data_min = (char[14])['/','r','u','n','/','s','y','s','t','e','m','d','/','r',],},}, addrlen: 42) = 0
0.046 ( 0.004 ms): ping/283259 sendto(fd: 5, buff: 0x559b008ae980, len: 97, flags: DONTWAIT|NOSIGNAL) = 97
0.353 ( 0.012 ms): ping/283259 sendto(fd: 5, buff: 0x7ffc01294960, len: 20, addr: (struct sockaddr){.sa_family = (sa_family_t)16,}, addr_len: 0xc) = 20
0.377 ( 0.006 ms): ping/283259 connect(fd: 5, uservaddr: (struct sockaddr){.sa_family = (sa_family_t)2,}, addrlen: 16) = 0
0.388 ( 0.010 ms): ping/283259 connect(fd: 5, uservaddr: (struct sockaddr){.sa_family = (sa_family_t)10,}, addrlen: 28) = 0
0.402 ( 0.001 ms): ping/283259 connect(fd: 5, uservaddr: (struct sockaddr){.sa_family = (sa_family_t)2,(union){.sa_data_min = (char[14])[4,1,142,251,129,'D',],},}, addrlen: 16) = 0
0.425 ( 0.045 ms): ping/283259 sendto(fd: 3, buff: 0x559b008a8ac0, len: 64, addr: (struct sockaddr){.sa_family = (sa_family_t)2,}, addr_len: 0x10) = 64
64 bytes from rio07s07-in-f4.1e100.net (142.251.129.68): icmp_seq=1 ttl=49 time=44.1 ms

--- www.google.com ping statistics ---
1 packets transmitted, 1 received, 0% packet loss, time 0ms
rtt min/avg/max/mdev = 44.113/44.113/44.113/0.000 ms
44.849 ( 0.038 ms): ping/283259 connect(fd: 5, uservaddr: (struct sockaddr){.sa_family = (sa_family_t)1,(union){.sa_data_min = (char[14])['/','r','u','n','/','s','y','s','t','e','m','d','/','r',],},}, addrlen: 42) = 0
44.927 ( 0.006 ms): ping/283259 sendto(fd: 5, buff: 0x559b008b03d0, len: 110, flags: DONTWAIT|NOSIGNAL) = 110
root@number:~#

Which looks sane, i.e.:

18.800 ( 0.004 ms): ping/258481 connect(fd: 5, uservaddr: { .family: INET, port: 0, addr: 142.251.129.68 }, addrlen: 16) = 0

Becomes:

0.402 ( 0.001 ms): ping/283259 connect(fd: 5, uservaddr: (struct sockaddr){.sa_family = (sa_family_t)2,(union){.sa_data_min = (char[14])[4,1,142,251,129,'D',],},}, addrlen: 16) = 0

And.

#define AF_UNIX 1 /* Unix domain sockets */
#define AF_LOCAL 1 /* POSIX name for AF_UNIX */
#define AF_INET 2 /* Internet IP Protocol */
<SNIP>
#define AF_INET6 10 /* IP version 6 */

And 'D' == 68, so the preexisting sockaddr BPF collector is working with
the new generic BTF pretty printer (btf_struct_scnprintf()), its just
that it doesn't know about 'struct sockaddr' besides what is in BTF,
i.e. its an array of bytes, not an IPv4 address that needs extra
massaging.

Ditto for the 'struct perf_event_attr' case:

1.851 ( 0.002 ms): perf/258487 perf_event_open(attr_uptr: { type: 0 (PERF_TYPE_HARDWARE), size: 136, config: 0x400000003, sample_type: IDENTIFIER, read_format: TOTAL_TIME_ENABLED|TOTAL_TIME_RUNNING, disabled: 1, inherit: 1, enable_on_exec: 1, exclude_guest: 1 }, pid: 258488 (perf), cpu: -1, group_fd: -1, flags: FD_CLOEXEC) = 9

Becomes:

2.081 ( 0.002 ms): :283304/283304 perf_event_open(attr_uptr: (struct perf_event_attr){.size = (__u32)136,.config = (__u64)17179869187,.sample_type = (__u64)65536,.read_format = (__u64)3,.disabled = (__u64)0x1,.inherit = (__u64)0x1,.enable_on_exec = (__u64)0x1,.exclude_guest = (__u64)0x1,}, pid: 283305 (sleep), cpu: -1, group_fd: -1, flags: FD_CLOEXEC) = 9

hex(17179869187) = 0x400000003, etc.

read_format: TOTAL_TIME_ENABLED|TOTAL_TIME_RUNNING is

enum perf_event_read_format {
PERF_FORMAT_TOTAL_TIME_ENABLED = 1U << 0,
PERF_FORMAT_TOTAL_TIME_RUNNING = 1U << 1,

and so on.

We need to work with the libbpf btf dump api to get one output that
matches the 'perf trace'/strace expectations/format, but having this in
this current form is already an improvement to 'perf trace', so lets
improve from what we have.

Signed-off-by: Howard Chu <[e-mail]>
Tested-by: Arnaldo Carvalho de Melo <[e-mail]>
Cc: Adrian Hunter <[e-mail]>
Cc: Ian Rogers <[e-mail]>
Cc: Jiri Olsa <[e-mail]>
Cc: Kan Liang <[e-mail]>
Cc: Namhyung Kim <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Arnaldo Carvalho de Melo <[e-mail]>

tools/perf/builtin-trace.c

···
 	return 0;
 }
 
+struct trace_btf_dump_snprintf_ctx {
+	char   *bf;
+	size_t printed, size;
+};
+
+static void trace__btf_dump_snprintf(void *vctx, const char *fmt, va_list args)
+{
+	struct trace_btf_dump_snprintf_ctx *ctx = vctx;
+
+	ctx->printed += vscnprintf(ctx->bf + ctx->printed, ctx->size - ctx->printed, fmt, args);
+}
+
+static size_t btf_struct_scnprintf(const struct btf_type *type, struct btf *btf, char *bf, size_t size, struct syscall_arg *arg)
+{
+	struct trace_btf_dump_snprintf_ctx ctx = {
+		.bf   = bf,
+		.size = size,
+	};
+	struct augmented_arg *augmented_arg = arg->augmented.args;
+	int type_id = arg->fmt->type_id, consumed;
+	struct btf_dump *btf_dump;
+
+	LIBBPF_OPTS(btf_dump_opts, dump_opts);
+	LIBBPF_OPTS(btf_dump_type_data_opts, dump_data_opts);
+
+	if (arg == NULL || arg->augmented.args == NULL)
+		return 0;
+
+	dump_data_opts.compact	  = true;
+	dump_data_opts.skip_names = !arg->trace->show_arg_names;
+
+	btf_dump = btf_dump__new(btf, trace__btf_dump_snprintf, &ctx, &dump_opts);
+	if (btf_dump == NULL)
+		return 0;
+
+	/* pretty print the struct data here */
+	if (btf_dump__dump_type_data(btf_dump, type_id, arg->augmented.args->value, type->size, &dump_data_opts) == 0)
+		return 0;
+
+	consumed = sizeof(*augmented_arg) + augmented_arg->size;
+	arg->augmented.args = ((void *)arg->augmented.args) + consumed;
+	arg->augmented.size -= consumed;
+
+	btf_dump__free(btf_dump);
+
+	return ctx.printed;
+}
+
 static size_t trace__btf_scnprintf(struct trace *trace, struct syscall_arg *arg, char *bf,
 				   size_t size, int val, char *type)
 {
···
 
 	if (btf_is_enum(arg_fmt->type))
 		return btf_enum_scnprintf(arg_fmt->type, trace->btf, bf, size, val);
+	else if (btf_is_struct(arg_fmt->type))
+		return btf_struct_scnprintf(arg_fmt->type, trace->btf, bf, size, arg);
 
 	return 0;
 }
···
 		.show_string_prefix = trace->show_string_prefix,
 	};
 	struct thread_trace *ttrace = thread__priv(thread);
+	void *default_scnprintf;
 
 	/*
 	 * Things like fcntl will set this in its 'cmd' formatter to pick the
···
 			if (trace->show_arg_names)
 				printed += scnprintf(bf + printed, size - printed, "%s: ", field->name);
 
-			btf_printed = trace__btf_scnprintf(trace, &arg, bf + printed,
-							   size - printed, val, field->type);
-			if (btf_printed) {
-				printed += btf_printed;
-				continue;
+			default_scnprintf = sc->arg_fmt[arg.idx].scnprintf;
+
+			if (default_scnprintf == NULL || default_scnprintf == SCA_PTR) {
+				btf_printed = trace__btf_scnprintf(trace, &arg, bf + printed,
+								   size - printed, val, field->type);
+				if (btf_printed) {
+					printed += btf_printed;
+					continue;
+				}
 			}
 
 			printed += syscall_arg_fmt__scnprintf_val(&sc->arg_fmt[arg.idx],