[PATCH 4.9 185/240] samples/bpf: Fix broken tracex1 due to kprobe argument change

Greg Kroah-Hartman
2021-05-20T11:24:24Z

From: Yaqi Chen <chendotjs@gmail.com>

[ Upstream commit 137733d08f4ab14a354dacaa9a8fc35217747605 ]

>From commit c0bbbdc32feb ("__netif_receive_skb_core: pass skb by
reference"), the first argument passed into __netif_receive_skb_core
has changed to reference of a skb pointer.

This commit fixes by using bpf_probe_read_kernel.

Signed-off-by: Yaqi Chen <chendotjs@gmail.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Yonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/bpf/20210416154803.37157-1-chendotjs@gmail.com
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
samples/bpf/tracex1_kern.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/samples/bpf/tracex1_kern.c b/samples/bpf/tracex1_kern.c
index 107da148820f..9c74b45c5720 100644
--- a/samples/bpf/tracex1_kern.c
+++ b/samples/bpf/tracex1_kern.c
@@ -20,7 +20,7 @@
SEC("kprobe/__netif_receive_skb_core")
int bpf_prog1(struct pt_regs *ctx)
{
- /* attaches to kprobe netif_receive_skb,
+ /* attaches to kprobe __netif_receive_skb_core,
* looks for packets on loobpack device and prints them
*/
char devname[IFNAMSIZ];
@@ -29,7 +29,7 @@ int bpf_prog1(struct pt_regs *ctx)
int len;

/* non-portable! works for the given kernel only */
- skb = (struct sk_buff *) PT_REGS_PARM1(ctx);
+ bpf_probe_read_kernel(&skb, sizeof(skb), (void *)PT_REGS_PARM1(ctx));
dev = _(skb->dev);
len = _(skb->len);

--
2.30.2