From: Steven Rostedt (VMware) rostedt@goodmis.org
commit 20279420ae3a8ef4c5d9fedc360a2c37a1dbdf1b upstream.
Thomas Richter reported:
Test case 66 'Use vfs_getname probe to get syscall args filenames' is broken on s390, but works on x86. The test case fails with:
[root@m35lp76 perf]# perf test -F 66 66: Use vfs_getname probe to get syscall args filenames :Recording open file: [ perf record: Woken up 1 times to write data ] [ perf record: Captured and wrote 0.004 MB /tmp/__perf_test.perf.data.TCdYj\ (20 samples) ] Looking at perf.data file for vfs_getname records for the file we touched: FAILED! [root@m35lp76 perf]#
The root cause was the print_fmt of the kprobe event that referenced the "ustring"
Setting up the kprobe event using perf command:
# ./perf probe "vfs_getname=getname_flags:72 pathname=filename:ustring"
generates this format file: [root@m35lp76 perf]# cat /sys/kernel/debug/tracing/events/probe/\ vfs_getname/format name: vfs_getname ID: 1172 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:unsigned long __probe_ip; offset:8; size:8; signed:0; field:__data_loc char[] pathname; offset:16; size:4; signed:1; print fmt: "(%lx) pathname=\"%s\"", REC->__probe_ip, REC->pathname
Instead of using "__get_str(pathname)" it referenced it directly.
Link: http://lkml.kernel.org/r/20200124100742.4050c15e@gandalf.local.home
Cc: stable@vger.kernel.org Fixes: 88903c464321 ("tracing/probe: Add ustring type for user-space string") Acked-by: Masami Hiramatsu mhiramat@kernel.org Reported-by: Thomas Richter tmricht@linux.ibm.com Tested-by: Thomas Richter tmricht@linux.ibm.com Signed-off-by: Steven Rostedt (VMware) rostedt@goodmis.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- kernel/trace/trace_probe.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-)
--- a/kernel/trace/trace_probe.c +++ b/kernel/trace/trace_probe.c @@ -876,7 +876,8 @@ static int __set_print_fmt(struct trace_ for (i = 0; i < tp->nr_args; i++) { parg = tp->args + i; if (parg->count) { - if (strcmp(parg->type->name, "string") == 0) + if ((strcmp(parg->type->name, "string") == 0) || + (strcmp(parg->type->name, "ustring") == 0)) fmt = ", __get_str(%s[%d])"; else fmt = ", REC->%s[%d]"; @@ -884,7 +885,8 @@ static int __set_print_fmt(struct trace_ pos += snprintf(buf + pos, LEN_OR_ZERO, fmt, parg->name, j); } else { - if (strcmp(parg->type->name, "string") == 0) + if ((strcmp(parg->type->name, "string") == 0) || + (strcmp(parg->type->name, "ustring") == 0)) fmt = ", __get_str(%s)"; else fmt = ", REC->%s";