linux-kernel - [PATCH v3] perf test: Fix test trace+probe_vfs

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Date:   Thu, 13 Feb 2020 13:20:09 +0100
From:   Thomas Richter <tmricht@...ux.ibm.com>
To:     linux-kernel@...r.kernel.org, linux-perf-users@...r.kernel.org,
        acme@...nel.org
Cc:     gor@...ux.ibm.com, sumanthk@...ux.ibm.com,
        heiko.carstens@...ibm.com, Thomas Richter <tmricht@...ux.ibm.com>
Subject: [PATCH v3] perf test: Fix test trace+probe_vfs_getname.sh

This test places a kprobe to function getname_flags() in the kernel
which has the following prototype:

  struct filename *
  getname_flags(const char __user *filename, int flags, int *empty)

Variable filename points to a filename located in user space memory.
Looking at
commit 88903c464321c ("tracing/probe: Add ustring type for user-space string")
the kprobe should indicate that user space memory is accessed.

The following patch specifies user space memory access first and if this
fails use type 'string' in case 'ustring' is not supported.

Signed-off-by: Thomas Richter <tmricht@...ux.ibm.com>
---
 tools/perf/tests/shell/lib/probe_vfs_getname.sh | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/tools/perf/tests/shell/lib/probe_vfs_getname.sh b/tools/perf/tests/shell/lib/probe_vfs_getname.sh
index 7cb99b433888..30c1eadbc5be 100644
--- a/tools/perf/tests/shell/lib/probe_vfs_getname.sh
+++ b/tools/perf/tests/shell/lib/probe_vfs_getname.sh
@@ -13,7 +13,9 @@ add_probe_vfs_getname() {
 	local verbose=$1
 	if [ $had_vfs_getname -eq 1 ] ; then
 		line=$(perf probe -L getname_flags 2>&1 | egrep 'result.*=.*filename;' | sed -r 's/[[:space:]]+([[:digit:]]+)[[:space:]]+result->uptr.*/\1/')
-		perf probe -q       "vfs_getname=getname_flags:${line} pathname=result->name:string" || \
+		perf probe -q       "vfs_getname=getname_flags:${line} pathname=result->uptr:ustring" || \
+		perf probe $verbose "vfs_getname=getname_flags:${line} pathname=filename:ustring" || \
+		perf probe -q       "vfs_getname=getname_flags:${line} pathname=result->uptr:string" || \
 		perf probe $verbose "vfs_getname=getname_flags:${line} pathname=filename:string"
 	fi
 }
-- 
2.21.0