With the latest linux-next i noticed that some tests in the
ftrace test suites are failing on s390, namely:
[FAIL] Kprobe event symbol argument
[FAIL] Kprobe event with comm arguments
The following doesn't work anymore:
cd /sys/kernel/tracing
echo 'p:testprobe _do_fork comm=$comm ' >kprobe_events
echo 1 >events/kprobes/testprobe/enable
cat trace
it will just show
test.sh-519 [012] .... 18.580625: testprobe: (_do_fork+0x0/0x3c8) comm=(fault)
Looking at the source i see that there are two helpers for reading strings:
fetch_store_string_user() -> read string from user space
fetch_store_string() -> read string from kernel space(?)
but in the end both are using strncpy_from_user_nofault(), but
fetch_store_string() should use strncpy_from_kernel_nofault().
Signed-off-by: Sven Schnelle <[email protected]>
Acked-by: Masami Hiramatsu <[email protected]>
Acked-by: Christoph Hellwig <[email protected]>
---
kernel/trace/trace_kprobe.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/kernel/trace/trace_kprobe.c b/kernel/trace/trace_kprobe.c
index b1f21d558e45..ea8d0b094f1b 100644
--- a/kernel/trace/trace_kprobe.c
+++ b/kernel/trace/trace_kprobe.c
@@ -1278,7 +1278,7 @@ fetch_store_string(unsigned long addr, void *dest, void *base)
* Try to get string again, since the string can be changed while
* probing.
*/
- ret = strncpy_from_user_nofault(__dest, (void *)addr, maxlen);
+ ret = strncpy_from_kernel_nofault(__dest, (void *)addr, maxlen);
if (ret >= 0)
*(u32 *)dest = make_data_loc(ret, __dest - base);
--
2.17.1