perf trace: Mark the 'rseq' arg in the rseq syscall as coming from user space

With that it uses the generic BTF based pretty printer:

  root@number:~# grep -w rseq /sys/kernel/tracing/events/syscalls/sys_enter_rseq/format
  	field:struct rseq * rseq;	offset:16;	size:8;	signed:0;
  print fmt: "rseq: 0x%08lx, rseq_len: 0x%08lx, flags: 0x%08lx, sig: 0x%08lx", ((unsigned long)(REC->rseq)), ((unsigned long)(REC->rseq_len)), ((unsigned long)(REC->flags)), ((unsigned long)(REC->sig))
  root@number:~#

Before:

  root@number:~# perf trace -e rseq
       0.000 ( 0.017 ms): Isolated Web C/1195452 rseq(rseq: 0x7ff0ecfe6fe0, rseq_len: 32, sig: 1392848979)             = 0
      74.018 ( 0.006 ms): :1195453/1195453 rseq(rseq: 0x7f2af20fffe0, rseq_len: 32, sig: 1392848979)             = 0
    1817.220 ( 0.009 ms): Isolated Web C/1195454 rseq(rseq: 0x7f5c9ec7dfe0, rseq_len: 32, sig: 1392848979)             = 0
    2515.526 ( 0.034 ms): :1195455/1195455 rseq(rseq: 0x7f61503fffe0, rseq_len: 32, sig: 1392848979)             = 0
  ^Croot@number:~#

After:

  root@number:~# perf trace -e rseq
       0.000 ( 0.019 ms): Isolated Web C/1197258 rseq(rseq: (struct rseq){.cpu_id_start = (__u32)4,.cpu_id = (__u32)4,.mm_cid = (__u32)5,}, rseq_len: 32, sig: 1392848979) = 0
    1663.835 ( 0.019 ms): Isolated Web C/1197259 rseq(rseq: (struct rseq){.cpu_id_start = (__u32)24,.cpu_id = (__u32)24,.mm_cid = (__u32)2,}, rseq_len: 32, sig: 1392848979) = 0
    4750.444 ( 0.018 ms): Isolated Web C/1197260 rseq(rseq: (struct rseq){.cpu_id_start = (__u32)8,.cpu_id = (__u32)8,.mm_cid = (__u32)4,}, rseq_len: 32, sig: 1392848979) = 0
    4994.132 ( 0.018 ms): Isolated Web C/1197261 rseq(rseq: (struct rseq){.cpu_id_start = (__u32)10,.cpu_id = (__u32)10,.mm_cid = (__u32)1,}, rseq_len: 32, sig: 1392848979) = 0
    4997.578 ( 0.011 ms): Isolated Web C/1197263 rseq(rseq: (struct rseq){.cpu_id_start = (__u32)16,.cpu_id = (__u32)16,.mm_cid = (__u32)4,}, rseq_len: 32, sig: 1392848979) = 0
    4997.462 ( 0.014 ms): Isolated Web C/1197262 rseq(rseq: (struct rseq){.cpu_id_start = (__u32)17,.cpu_id = (__u32)17,.mm_cid = (__u32)3,}, rseq_len: 32, sig: 1392848979) = 0
  ^Croot@number:~#

We'll probably need to come up with some way for using the BTF info to
synthesize a test that then gets used and captures the output of the
'perf trace' output to check if the arguments are the ones synthesized,
randomically, for now, lets make do manually:

  root@number:~# cat ~acme/c/rseq.c
  #include <sys/syscall.h>     /* Definition of SYS_* constants */
  #include <linux/rseq.h>
  #include <errno.h>
  #include <string.h>
  #include <unistd.h>
  #include <stdint.h>
  #include <stdio.h>

  /* Provide own rseq stub because glibc doesn't */
  __attribute__((weak))
  int sys_rseq(struct rseq *rseq, __u32 rseq_len, int flags, __u32 sig)
  {
  	return syscall(SYS_rseq, rseq, rseq_len, flags, sig);
  }

  int main(int argc, char *argv[])
  {
  	struct rseq rseq = {
  		.cpu_id_start = 12,
  		.cpu_id = 34,
  		.rseq_cs = 56,
  		.flags = 78,
  		.node_id = 90,
  		.mm_cid = 12,
  	};
  	int err = sys_rseq(&rseq, sizeof(rseq), 98765, 0xdeadbeaf);

  	printf("sys_rseq({ .cpu_id_start = 12, .cpu_id = 34, .rseq_cs = 56, .flags = 78, .node_id = 90, .mm_cid = 12, }, %d, 0) = %d (%s)\n", sizeof(rseq), err, strerror(errno));
  	return err;
  }
  root@number:~# perf trace -e rseq ~acme/c/rseq
  sys_rseq({ .cpu_id_start = 12, .cpu_id = 34, .rseq_cs = 56, .flags = 78, .node_id = 90, .mm_cid = 12, }, 32, 0) = -1 (Invalid argument)
       0.000 ( 0.003 ms): rseq/1200640 rseq(rseq: (struct rseq){}, rseq_len: 32, sig: 1392848979)            =
       0.064 ( 0.001 ms): rseq/1200640 rseq(rseq: (struct rseq){.cpu_id_start = (__u32)12,.cpu_id = (__u32)34,.rseq_cs = (__u64)56,.flags = (__u32)78,.node_id = (__u32)90,.mm_cid = (__u32)12,}, rseq_len: 32, flags: 98765, sig: 3735928495) = -1 EINVAL (Invalid argument)
  root@number:~#root@number:~# cat ~acme/c/rseq.c
  #include <sys/syscall.h>     /* Definition of SYS_* constants */
  #include <linux/rseq.h>
  #include <errno.h>
  #include <string.h>
  #include <unistd.h>
  #include <stdint.h>
  #include <stdio.h>

  /* Provide own rseq stub because glibc doesn't */
  __attribute__((weak))
  int sys_rseq(struct rseq *rseq, __u32 rseq_len, int flags, __u32 sig)
  {
  	return syscall(SYS_rseq, rseq, rseq_len, flags, sig);
  }

  int main(int argc, char *argv[])
  {
  	struct rseq rseq = {
  		.cpu_id_start = 12,
  		.cpu_id = 34,
  		.rseq_cs = 56,
  		.flags = 78,
  		.node_id = 90,
  		.mm_cid = 12,
  	};
  	int err = sys_rseq(&rseq, sizeof(rseq), 98765, 0xdeadbeaf);

  	printf("sys_rseq({ .cpu_id_start = 12, .cpu_id = 34, .rseq_cs = 56, .flags = 78, .node_id = 90, .mm_cid = 12, }, %d, 0) = %d (%s)\n", sizeof(rseq), err, strerror(errno));
  	return err;
  }
  root@number:~# perf trace -e rseq ~acme/c/rseq
  sys_rseq({ .cpu_id_start = 12, .cpu_id = 34, .rseq_cs = 56, .flags = 78, .node_id = 90, .mm_cid = 12, }, 32, 0) = -1 (Invalid argument)
       0.000 ( 0.003 ms): rseq/1200640 rseq(rseq: (struct rseq){}, rseq_len: 32, sig: 1392848979)            =
       0.064 ( 0.001 ms): rseq/1200640 rseq(rseq: (struct rseq){.cpu_id_start = (__u32)12,.cpu_id = (__u32)34,.rseq_cs = (__u64)56,.flags = (__u32)78,.node_id = (__u32)90,.mm_cid = (__u32)12,}, rseq_len: 32, flags: 98765, sig: 3735928495) = -1 EINVAL (Invalid argument)
  root@number:~#

Interesting, glibc seems to be using rseq here, as in addition to the
totally fake one this test case uses, we have this one, around these
other syscalls:

     0.175 ( 0.001 ms): rseq/1201095 set_tid_address(tidptr: 0x7f6def759a10)                               = 1201095 (rseq)
     0.177 ( 0.001 ms): rseq/1201095 set_robust_list(head: 0x7f6def759a20, len: 24)                        = 0
     0.178 ( 0.001 ms): rseq/1201095 rseq(rseq: (struct rseq){}, rseq_len: 32, sig: 1392848979)            =
     0.231 ( 0.005 ms): rseq/1201095 mprotect(start: 0x7f6def93f000, len: 16384, prot: READ)               = 0
     0.238 ( 0.003 ms): rseq/1201095 mprotect(start: 0x403000, len: 4096, prot: READ)                      = 0
     0.244 ( 0.004 ms): rseq/1201095 mprotect(start: 0x7f6def99c000, len: 8192, prot: READ)

Matches strace (well, not really as the strace in fedora:40 doesn't know
about rseq, printing just integer values in hex):

  set_robust_list(0x7fbc6acc7a20, 24)     = 0
  rseq(0x7fbc6acc8060, 0x20, 0, 0x53053053) = 0
  mprotect(0x7fbc6aead000, 16384, PROT_READ) = 0
  mprotect(0x403000, 4096, PROT_READ)     = 0
  mprotect(0x7fbc6af0a000, 8192, PROT_READ) = 0
  prlimit64(0, RLIMIT_STACK, NULL, {rlim_cur=8192*1024, rlim_max=RLIM64_INFINITY}) = 0
  munmap(0x7fbc6aebd000, 81563)           = 0
  rseq(0x7fff15bb9920, 0x20, 0x181cd, 0xdeadbeaf) = -1 EINVAL (Invalid argument)
  fstat(1, {st_mode=S_IFCHR|0620, st_rdev=makedev(0x88, 0x9), ...}) = 0
  getrandom("\xd0\x34\x97\x17\x61\xc2\x2b\x10", 8, GRND_NONBLOCK) = 8
  brk(NULL)                               = 0x18ff4000
  brk(0x19015000)                         = 0x19015000
  write(1, "sys_rseq({ .cpu_id_start = 12, ."..., 136sys_rseq({ .cpu_id_start = 12, .cpu_id = 34, .rseq_cs = 56, .flags = 78, .node_id = 90, .mm_cid = 12, }, 32, 0) = -1 (Invalid argument)
  ) = 136
  exit_group(-1)                          = ?
  +++ exited with 255 +++
  root@number:~#

And also the focus for the v6.13 should be to have a better, strace
like BTF pretty printer as one of the outputs we can get from the libbpf
BTF dumper.

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Alan Maguire <alan.maguire@oracle.com>
Cc: Howard Chu <howardchu95@gmail.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Kan Liang <kan.liang@linux.intel.com>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Link: https://lore.kernel.org/lkml/ZuH2K1LLt1pIDkbd@x1
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

1 files changed, 2 insertions, 0 deletions

diff --git a/tools/perf/builtin-trace.c b/tools/perf/builtin-trace.c
index 3b88ba50bb80..27084ae38bc4 100644
--- a/tools/perf/builtin-trace.c
+++ b/tools/perf/builtin-trace.c
@@ -1327,6 +1327,8 @@ static const struct syscall_fmt syscall_fmts[] = {
 	  .arg = { [0] = { .scnprintf = SCA_FDAT, /* olddirfd */ },
 		   [2] = { .scnprintf = SCA_FDAT, /* newdirfd */ },
 		   [4] = { .scnprintf = SCA_RENAMEAT2_FLAGS, /* flags */ }, }, },
+	{ .name	    = "rseq",	    .errpid = true,
+	  .arg = { [0] = { .from_user = true /* rseq */, }, }, },
 	{ .name	    = "rt_sigaction",
 	  .arg = { [0] = { .scnprintf = SCA_SIGNUM, /* sig */ }, }, },
 	{ .name	    = "rt_sigprocmask",