| From 20279420ae3a8ef4c5d9fedc360a2c37a1dbdf1b Mon Sep 17 00:00:00 2001 |
| From: "Steven Rostedt (VMware)" <rostedt@goodmis.org> |
| Date: Fri, 24 Jan 2020 10:07:42 -0500 |
| Subject: tracing/kprobes: Have uname use __get_str() in print_fmt |
| |
| 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"; |