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Subject[PATCH 07/28] perf trace: Consider syscall aliases too
Date
From: Arnaldo Carvalho de Melo <acme@redhat.com>

When trying to trace the 'umount' syscall on x86_64 I noticed that it
was failing:

# trace -e umount umount /mnt
event syntax error: 'umount'
\___ parser error
Run 'perf list' for a list of valid events

Usage: perf trace [<options>] [<command>]
or: perf trace [<options>] -- <command> [<options>]
or: perf trace record [<options>] [<command>]
or: perf trace record [<options>] -- <command> [<options>]

-e, --event <event> event/syscall selector. use 'perf list' to list available events
#

This is because in the x86-64 we have it just as 'umount2':

$ grep umount arch/x86/entry/syscalls/syscall_64.tbl
166 common umount2 __x64_sys_umount
$

So if the syscall name fails, try fallbacking to looking at the aliases
we have in the syscall_fmts table to then re-lookup, now:

# trace -e umount umount -f /mnt
umount: /mnt: not mounted.
1.759 ( 0.004 ms): umount/18365 umount2(name: 0x55fbfcbc4480, flags: 1) = -1 EINVAL Invalid argument
#

Time to beautify the flags arg :-)

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Benjamin Peterson <benjamin@python.org>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Wang Nan <wangnan0@huawei.com>
Link: https://lkml.kernel.org/n/tip-ukweodgzbmjd25lfkgryeft1@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
---
tools/perf/builtin-trace.c | 22 +++++++++++++++++++++-
1 file changed, 21 insertions(+), 1 deletion(-)

diff --git a/tools/perf/builtin-trace.c b/tools/perf/builtin-trace.c
index 76c14c0129fc..db8711061ca3 100644
--- a/tools/perf/builtin-trace.c
+++ b/tools/perf/builtin-trace.c
@@ -862,6 +862,18 @@ static struct syscall_fmt *syscall_fmt__find(const char *name)
return bsearch(name, syscall_fmts, nmemb, sizeof(struct syscall_fmt), syscall_fmt__cmp);
}

+static struct syscall_fmt *syscall_fmt__find_by_alias(const char *alias)
+{
+ int i, nmemb = ARRAY_SIZE(syscall_fmts);
+
+ for (i = 0; i < nmemb; ++i) {
+ if (syscall_fmts[i].alias && strcmp(syscall_fmts[i].alias, alias) == 0)
+ return &syscall_fmts[i];
+ }
+
+ return NULL;
+}
+
/*
* is_exit: is this "exit" or "exit_group"?
* is_open: is this "open" or "openat"? To associate the fd returned in sys_exit with the pathname in sys_enter.
@@ -3195,6 +3207,7 @@ static int trace__parse_events_option(const struct option *opt, const char *str,
int len = strlen(str) + 1, err = -1, list, idx;
char *strace_groups_dir = system_path(STRACE_GROUPS_DIR);
char group_name[PATH_MAX];
+ struct syscall_fmt *fmt;

if (strace_groups_dir == NULL)
return -1;
@@ -3212,12 +3225,19 @@ static int trace__parse_events_option(const struct option *opt, const char *str,
if (syscalltbl__id(trace->sctbl, s) >= 0 ||
syscalltbl__strglobmatch_first(trace->sctbl, s, &idx) >= 0) {
list = 1;
+ goto do_concat;
+ }
+
+ fmt = syscall_fmt__find_by_alias(s);
+ if (fmt != NULL) {
+ list = 1;
+ s = fmt->name;
} else {
path__join(group_name, sizeof(group_name), strace_groups_dir, s);
if (access(group_name, R_OK) == 0)
list = 1;
}
-
+do_concat:
if (lists[list]) {
sprintf(lists[list] + strlen(lists[list]), ",%s", s);
} else {
--
2.14.4
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