The following commit has been merged into the perf/urgent branch of tip:
Commit-ID: 1873f1547dde65c687de143938581347a9312207
Gitweb: https://git.kernel.org/tip/1873f1547dde65c687de143938581347a9312207
Author: Thomas Richter <tmricht@xxxxxxxxxxxxx>
AuthorDate: Mon, 20 Jan 2020 14:20:10 +01:00
Committer: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
CommitterDate: Fri, 31 Jan 2020 09:33:58 +01:00
perf probe: Add ustring support for perf probe command
Kernel commit 88903c464321 ("tracing/probe: Add ustring type for user-space string")
adds support for user-space strings when type 'ustring' is specified.
Here is an example using sysfs command line interface
for kprobes:
Function to probe:
struct filename *
getname_flags(const char __user *filename, int flags, int *empty)
Setup:
# cd /sys/kernel/debug/tracing/
# echo 'p:tmr1 getname_flags +0(%r2):ustring' > kprobe_events
# cat events/kprobes/tmr1/format | fgrep print
print fmt: "(%lx) arg1=\"%s\"", REC->__probe_ip, REC->arg1
# echo 1 > events/kprobes/tmr1/enable
# touch /tmp/111
# echo 0 > events/kprobes/tmr1/enable
# cat trace|fgrep /tmp/111
touch-5846 [005] d..2 255520.717960: tmr1:\
(getname_flags+0x0/0x400) arg1="/tmp/111"
Doing the same with the perf tool fails.
Using type 'string' succeeds:
# perf probe "vfs_getname=getname_flags:72 pathname=filename:string"
Added new event:
probe:vfs_getname (on getname_flags:72 with pathname=filename:string)
....
# perf probe -d probe:vfs_getname
Removed event: probe:vfs_getname
However using type 'ustring' fails (output before):
# perf probe "vfs_getname=getname_flags:72 pathname=filename:ustring"
Failed to write event: Invalid argument
Error: Failed to add events.
#
Fix this by adding type 'ustring' in function
convert_variable_type().
Using ustring succeeds (output after):
# ./perf probe "vfs_getname=getname_flags:72 pathname=filename:ustring"
Added new event:
probe:vfs_getname (on getname_flags:72 with pathname=filename:ustring)
You can now use it in all perf tools, such as:
perf record -e probe:vfs_getname -aR sleep 1
#
Note: This issue also exists on x86, it is not s390 specific.
Signed-off-by: Thomas Richter <tmricht@xxxxxxxxxxxxx>
Cc: Heiko Carstens <heiko.carstens@xxxxxxxxxx>
Cc: Vasily Gorbik <gor@xxxxxxxxxxxxx>
Cc: sumanthk@xxxxxxxxxxxxx
Link: http://lore.kernel.org/lkml/20200120132011.64698-2-tmricht@xxxxxxxxxxxxx
Signed-off-by: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
---
tools/perf/util/probe-finder.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/tools/perf/util/probe-finder.c b/tools/perf/util/probe-finder.c
index c470c49..1c817ad 100644
--- a/tools/perf/util/probe-finder.c
+++ b/tools/perf/util/probe-finder.c
@@ -303,7 +303,8 @@ static int convert_variable_type(Dwarf_Die *vr_die,
char prefix;
/* TODO: check all types */
- if (cast && strcmp(cast, "string") != 0 && strcmp(cast, "x") != 0 &&
+ if (cast && strcmp(cast, "string") != 0 && strcmp(cast, "ustring") &&
+ strcmp(cast, "x") != 0 &&
strcmp(cast, "s") != 0 && strcmp(cast, "u") != 0) {
/* Non string type is OK */
/* and respect signedness/hexadecimal cast */
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