[<prev] [next>] [thread-next>] [day] [month] [year] [list]
Message-ID: <ZuB8Q3NQej-gB6Tz@x1>
Date: Tue, 10 Sep 2024 14:05:07 -0300
From: arnaldo.melo@...il.com
To: Ian Rogers <irogers@...gle.com>
Cc: Alan Maguire <alan.maguire@...cle.com>,
Adrian Hunter <adrian.hunter@...el.com>,
Howard Chu <howardchu95@...il.com>, Jiri Olsa <jolsa@...nel.org>,
Kan Liang <kan.liang@...ux.intel.com>,
Namhyung Kim <namhyung@...nel.org>,
Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
linux-perf-users@...r.kernel.org
Subject: [PATCH 1/1] perf trace: If a syscall arg is marked as 'const',
assume it is coming _from_ userspace
We need to decide where to copy syscall arg contents, if at the
syscalls:sys_entry hook, meaning is something that is coming from
user to kernel space, or if it is a response, i.e. if it is something
the _kernel_ is filling in and thus going to userspace.
Since we have 'const' used in those syscalls, and unsure about this
being consistent, doing:
root@...ber:~# echo $(grep const /sys/kernel/tracing/events/syscalls/sys_enter_*/format | grep struct | cut -c47- | cut -d'/' -f1)
clock_nanosleep clock_settime epoll_pwait2 futex io_pgetevents landlock_create_ruleset listmount mq_getsetattr mq_notify mq_timedreceive mq_timedsend preadv2 preadv prlimit64 process_madvise process_vm_readv process_vm_readv process_vm_writev process_vm_writev pwritev2 pwritev readv rt_sigaction rt_sigtimedwait semtimedop statmount timerfd_settime timer_settime vmsplice writev
root@...ber:~#
Seems to indicate that we can use that for the ones that have the
'const' to mark it as coming from user space, do it.
Most notable/frequent syscall that now gets BTF pretty printed in a
system wide 'perf trace' session is:
root@...ber:~# perf trace
21.160 ( ): MediaSu~isor #/1028597 futex(uaddr: 0x7f49e1dfe964, op: WAIT_BITSET|PRIVATE_FLAG, utime: (struct __kernel_timespec){.tv_sec = (__kernel_time64_t)50290,.tv_nsec = (long long int)810362837,}, val3: MATCH_ANY) ...
21.166 ( 0.000 ms): RemVidChild/6995 futex(uaddr: 0x7f49fcc7fa00, op: WAKE|PRIVATE_FLAG, val: 1) = 0
21.169 ( 0.001 ms): RemVidChild/6995 sendmsg(fd: 25<socket:[78915]>, msg: 0x7f49e9af9da0, flags: DONTWAIT) = 280
21.172 ( 0.289 ms): RemVidChild/6995 futex(uaddr: 0x7f49fcc7fa58, op: WAIT_BITSET|PRIVATE_FLAG|CLOCK_REALTIME, val3: MATCH_ANY) = 0
21.463 ( 0.000 ms): RemVidChild/6995 futex(uaddr: 0x7f49fcc7fa00, op: WAKE|PRIVATE_FLAG, val: 1) = 0
21.467 ( 0.001 ms): RemVidChild/6995 futex(uaddr: 0x7f49e28bb964, op: WAKE|PRIVATE_FLAG, val: 1) = 1
21.160 ( 0.314 ms): MediaSu~isor #/1028597 ... [continued]: futex()) = 0
21.469 ( ): RemVidChild/6995 futex(uaddr: 0x7f49fcc7fa5c, op: WAIT_BITSET|PRIVATE_FLAG|CLOCK_REALTIME, val3: MATCH_ANY) ...
21.475 ( 0.000 ms): MediaSu~isor #/1028597 futex(uaddr: 0x7f49d0223040, op: WAKE|PRIVATE_FLAG, val: 1) = 0
21.478 ( 0.001 ms): MediaSu~isor #/1028597 futex(uaddr: 0x7f49e26ac964, op: WAKE|PRIVATE_FLAG, val: 1) = 1
^Croot@...ber:~#
root@...ber:~# cat /sys/kernel/tracing/events/syscalls/sys_enter_futex/format
name: sys_enter_futex
ID: 454
format:
field:unsigned short common_type; offset:0; size:2; signed:0;
field:unsigned char common_flags; offset:2; size:1; signed:0;
field:unsigned char common_preempt_count; offset:3; size:1; signed:0;
field:int common_pid; offset:4; size:4; signed:1;
field:int __syscall_nr; offset:8; size:4; signed:1;
field:u32 * uaddr; offset:16; size:8; signed:0;
field:int op; offset:24; size:8; signed:0;
field:u32 val; offset:32; size:8; signed:0;
field:const struct __kernel_timespec * utime; offset:40; size:8; signed:0;
field:u32 * uaddr2; offset:48; size:8; signed:0;
field:u32 val3; offset:56; size:8; signed:0;
print fmt: "uaddr: 0x%08lx, op: 0x%08lx, val: 0x%08lx, utime: 0x%08lx, uaddr2: 0x%08lx, val3: 0x%08lx", ((unsigned long)(REC->uaddr)), ((unsigned long)(REC->op)), ((unsigned long)(REC->val)), ((unsigned long)(REC->utime)), ((unsigned long)(REC->uaddr2)), ((unsigned long)(REC->val3))
root@...ber:~#
Suggested-by: Ian Rogers <irogers@...gle.com>
Cc: Adrian Hunter <adrian.hunter@...el.com>
Cc: Alan Maguire <alan.maguire@...cle.com>
Cc: Howard Chu <howardchu95@...il.com>
Cc: Jiri Olsa <jolsa@...nel.org>
Cc: Kan Liang <kan.liang@...ux.intel.com>
Cc: Namhyung Kim <namhyung@...nel.org>
Signed-off-by: Arnaldo Carvalho de Melo <acme@...hat.com>
---
tools/perf/builtin-trace.c | 5 ++++-
1 file changed, 4 insertions(+), 1 deletion(-)
diff --git a/tools/perf/builtin-trace.c b/tools/perf/builtin-trace.c
index 83eb15b72333edd9..e26baf1256d5bb56 100644
--- a/tools/perf/builtin-trace.c
+++ b/tools/perf/builtin-trace.c
@@ -2001,11 +2001,14 @@ syscall_arg_fmt__init_array(struct syscall_arg_fmt *arg, struct tep_format_field
len = strlen(field->name);
+ // As far as heuristics (or intention) goes this seems to hold true, and makes sense!
+ if ((field->flags & TEP_FIELD_IS_POINTER) && strstarts(field->type, "const "))
+ arg->from_user = true;
+
if (strcmp(field->type, "const char *") == 0 &&
((len >= 4 && strcmp(field->name + len - 4, "name") == 0) ||
strstr(field->name, "path") != NULL)) {
arg->scnprintf = SCA_FILENAME;
- arg->from_user = true;
} else if ((field->flags & TEP_FIELD_IS_POINTER) || strstr(field->name, "addr"))
arg->scnprintf = SCA_PTR;
else if (strcmp(field->type, "pid_t") == 0)
--
2.46.0
Powered by blists - more mailing lists