[PATCH v2 1/2] perf: Fix user attribute access in kprobes

[Sumanth Korikkar <sumanthk@xxxxxxxxxxxxx>]

Issue:
perf probe -a 'do_sched_setscheduler  pid policy
param->sched_priority@user' did not work before.

Fix:
Make (perf probe -a 'do_sched_setscheduler  pid policy
param->sched_priority@user') output equivalent to ftrace
('p:probe/do_sched_setscheduler _text+517384 pid=%r2:s32 policy=%r3:s32
sched_priority=+u0(%r4):s32' > kprobe_events)

Other:
1. Right now, __match_glob() does not handle [u]<offset>. For now, use
  *u]<offset>.
2. @user attribute was introduced in commit 1e032f7cfa14 ("perf-probe:
   Add user memory access attribute support")

Test:
1. perf probe -a 'do_sched_setscheduler  pid policy
   param->sched_priority@user'

2 ./perf script
   sched 305669 [000] 1614458.838675: perf_bpf_probe:func: (2904e508)
   pid=261614 policy=2 sched_priority=1

3. cat /sys/kernel/debug/tracing/trace
   <...>-309956 [006] .... 1616098.093957: 0: prio: 1

Signed-off-by: Sumanth Korikkar <sumanthk@xxxxxxxxxxxxx>
Reviewed-by: Thomas Richter <tmricht@xxxxxxxxxxxxx>
Acked-by: Masami Hiramatsu <mhiramat@xxxxxxxxxx>
---
 tools/perf/util/probe-event.c | 7 +++++--
 tools/perf/util/probe-file.c  | 2 +-
 2 files changed, 6 insertions(+), 3 deletions(-)

diff --git a/tools/perf/util/probe-event.c b/tools/perf/util/probe-event.c
index a08f373d3305..df713a5d1e26 100644
--- a/tools/perf/util/probe-event.c
+++ b/tools/perf/util/probe-event.c
@@ -1575,7 +1575,7 @@ static int parse_perf_probe_arg(char *str, struct perf_probe_arg *arg)
 	}
 
 	tmp = strchr(str, '@');
-	if (tmp && tmp != str && strcmp(tmp + 1, "user")) { /* user attr */
+	if (tmp && tmp != str && !strcmp(tmp + 1, "user")) { /* user attr */
 		if (!user_access_is_supported()) {
 			semantic_error("ftrace does not support user access\n");
 			return -EINVAL;
@@ -1995,7 +1995,10 @@ static int __synthesize_probe_trace_arg_ref(struct probe_trace_arg_ref *ref,
 		if (depth < 0)
 			return depth;
 	}
-	err = strbuf_addf(buf, "%+ld(", ref->offset);
+	if (ref->user_access)
+		err = strbuf_addf(buf, "%s%ld(", "+u", ref->offset);
+	else
+		err = strbuf_addf(buf, "%+ld(", ref->offset);
 	return (err < 0) ? err : depth;
 }
 
diff --git a/tools/perf/util/probe-file.c b/tools/perf/util/probe-file.c
index 8c852948513e..064b63a6a3f3 100644
--- a/tools/perf/util/probe-file.c
+++ b/tools/perf/util/probe-file.c
@@ -1044,7 +1044,7 @@ static struct {
 	DEFINE_TYPE(FTRACE_README_PROBE_TYPE_X, "*type: * x8/16/32/64,*"),
 	DEFINE_TYPE(FTRACE_README_KRETPROBE_OFFSET, "*place (kretprobe): *"),
 	DEFINE_TYPE(FTRACE_README_UPROBE_REF_CTR, "*ref_ctr_offset*"),
-	DEFINE_TYPE(FTRACE_README_USER_ACCESS, "*[u]<offset>*"),
+	DEFINE_TYPE(FTRACE_README_USER_ACCESS, "*u]<offset>*"),
 	DEFINE_TYPE(FTRACE_README_MULTIPROBE_EVENT, "*Create/append/*"),
 	DEFINE_TYPE(FTRACE_README_IMMEDIATE_VALUE, "*\\imm-value,*"),
 };
-- 
2.17.1