path: root/tools
diff options
authorThomas Richter <tmricht@linux.ibm.com>2020-01-20 14:20:10 +0100
committerArnaldo Carvalho de Melo <acme@redhat.com>2020-01-31 09:33:58 +0100
commit1873f1547dde65c687de143938581347a9312207 (patch)
treefe96ee8c16e30ece45fd729aff63fb48a9be490b /tools
parentperf: Make perf able to build with latest libbfd (diff)
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@linux.ibm.com> Cc: Heiko Carstens <heiko.carstens@de.ibm.com> Cc: Vasily Gorbik <gor@linux.ibm.com> Cc: sumanthk@linux.ibm.com Link: http://lore.kernel.org/lkml/20200120132011.64698-2-tmricht@linux.ibm.com Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Diffstat (limited to 'tools')
1 files changed, 2 insertions, 1 deletions
diff --git a/tools/perf/util/probe-finder.c b/tools/perf/util/probe-finder.c
index c470c49a804f..1c817add6ca4 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 */