On Mon, Mar 22, 2021 at 10:02 AM Borislav Petkov [off-list ref] wrote:

On Mon, Mar 22, 2021 at 02:37:14PM +1100, Stephen Rothwell wrote:

quoted

Hi all,

After merging the tip tree, today's linux-next build (x86_64 allmodconfig)
failed like this:

arch/x86/net/bpf_jit_comp.c: In function 'arch_prepare_bpf_trampoline':
arch/x86/net/bpf_jit_comp.c:2015:16: error: 'ideal_nops' undeclared (first use in this function)
 2015 |   memcpy(prog, ideal_nops[NOP_ATOMIC5], X86_PATCH_SIZE);
      |                ^~~~~~~~~~
arch/x86/net/bpf_jit_comp.c:2015:16: note: each undeclared identifier is reported only once for each function it appears in
arch/x86/net/bpf_jit_comp.c:2015:27: error: 'NOP_ATOMIC5' undeclared (first use in this function); did you mean 'GFP_ATOMIC'?
 2015 |   memcpy(prog, ideal_nops[NOP_ATOMIC5], X86_PATCH_SIZE);
      |                           ^~~~~~~~~~~
      |                           GFP_ATOMIC

Caused by commit

  a89dfde3dc3c ("x86: Remove dynamic NOP selection")

interacting with commit

  b90829704780 ("bpf: Use NOP_ATOMIC5 instead of emit_nops(&prog, 5) for BPF_TRAMP_F_CALL_ORIG")

from the net tree.

I have applied the following merge fix patch.

From: Stephen Rothwell <redacted>
Date: Mon, 22 Mar 2021 14:30:37 +1100
Subject: [PATCH] x86: fix up for "bpf: Use NOP_ATOMIC5 instead of
 emit_nops(&prog, 5) for BPF_TRAMP_F_CALL_ORIG"

Signed-off-by: Stephen Rothwell <redacted>
---
 arch/x86/net/bpf_jit_comp.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/x86/net/bpf_jit_comp.c b/arch/x86/net/bpf_jit_comp.c
index db50ab14df67..e2b5da5d441d 100644
--- a/arch/x86/net/bpf_jit_comp.c
+++ b/arch/x86/net/bpf_jit_comp.c

@@ -2012,7 +2012,7 @@ int arch_prepare_bpf_trampoline(struct bpf_tramp_image *im, void *image, void *i
              /* remember return value in a stack for bpf prog to access */
              emit_stx(&prog, BPF_DW, BPF_REG_FP, BPF_REG_0, -8);
              im->ip_after_call = prog;
-             memcpy(prog, ideal_nops[NOP_ATOMIC5], X86_PATCH_SIZE);
+             memcpy(prog, x86_nops[5], X86_PATCH_SIZE);
              prog += X86_PATCH_SIZE;
      }

--

I guess we can do the same as with the hyperv tree - the folks who send the
respective branches to Linus in the next merge window should point to this patch
of yours which Linus can apply after merging the second branch in order.

Thx.

The commit b90829704780 "bpf: Use NOP_ATOMIC5 instead of
emit_nops(&prog, 5) for BPF_TRAMP_F_CALL_ORIG" is now in Linus Git
(see [1]).

Where will Stephen's fixup-patch be carried?
Linux-next?
net-next?
<tip.git#x86/cpu>?

Thanks.

- Sedat -

[1] https://git.kernel.org/linus/b9082970478009b778aa9b22d5561eef35b53b63