Re: [PATCH 5.10 73/83] powerpc/bpf: Fix BPF_MOD when imm == 1

[Naresh Kamboju]

stable-rc 5.4 build failed due this patch.
 - powerpc gcc-10-defconfig - FAILED
 - powerpc gcc-11-defconfig - FAILED
 - powerpc gcc-8-defconfig - FAILED
 - powerpc gcc-9-defconfig - FAILED

On Mon, 11 Oct 2021 at 19:28, Greg Kroah-Hartman
<gregkh@xxxxxxxxxxxxxxxxxxx> wrote:
>
> From: Naveen N. Rao <naveen.n.rao@xxxxxxxxxxxxxxxxxx>
>
> [ Upstream commit 8bbc9d822421d9ac8ff9ed26a3713c9afc69d6c8 ]
>
> Only ignore the operation if dividing by 1.
>
> Fixes: 156d0e290e969c ("powerpc/ebpf/jit: Implement JIT compiler for extended BPF")
> Signed-off-by: Naveen N. Rao <naveen.n.rao@xxxxxxxxxxxxxxxxxx>
> Tested-by: Johan Almbladh <johan.almbladh@xxxxxxxxxxxxxxxxx>
> Reviewed-by: Christophe Leroy <christophe.leroy@xxxxxxxxxx>
> Acked-by: Song Liu <songliubraving@xxxxxx>
> Acked-by: Johan Almbladh <johan.almbladh@xxxxxxxxxxxxxxxxx>
> Signed-off-by: Michael Ellerman <mpe@xxxxxxxxxxxxxx>
> Link: https://lore.kernel.org/r/c674ca18c3046885602caebb326213731c675d06.1633464148.git.naveen.n.rao@xxxxxxxxxxxxxxxxxx
> Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
> ---
>  arch/powerpc/net/bpf_jit_comp64.c | 10 ++++++++--
>  1 file changed, 8 insertions(+), 2 deletions(-)
>
> diff --git a/arch/powerpc/net/bpf_jit_comp64.c b/arch/powerpc/net/bpf_jit_comp64.c
> index 658ca2bab13c..e79f9eae2bc0 100644
> --- a/arch/powerpc/net/bpf_jit_comp64.c
> +++ b/arch/powerpc/net/bpf_jit_comp64.c
> @@ -408,8 +408,14 @@ static int bpf_jit_build_body(struct bpf_prog *fp, u32 *image,
>                 case BPF_ALU64 | BPF_DIV | BPF_K: /* dst /= imm */
>                         if (imm == 0)
>                                 return -EINVAL;
> -                       else if (imm == 1)
> -                               goto bpf_alu32_trunc;
> +                       if (imm == 1) {
> +                               if (BPF_OP(code) == BPF_DIV) {
> +                                       goto bpf_alu32_trunc;
> +                               } else {
> +                                       EMIT(PPC_RAW_LI(dst_reg, 0));

In file included from arch/powerpc/net/bpf_jit64.h:11,
                 from arch/powerpc/net/bpf_jit_comp64.c:19:
arch/powerpc/net/bpf_jit_comp64.c: In function 'bpf_jit_build_body':
arch/powerpc/net/bpf_jit_comp64.c:415:46: error: implicit declaration
of function 'PPC_RAW_LI'; did you mean 'PPC_RLWIMI'?
[-Werror=implicit-function-declaration]
  415 |                                         EMIT(PPC_RAW_LI(dst_reg, 0));
      |                                              ^~~~~~~~~~
arch/powerpc/net/bpf_jit.h:32:34: note: in definition of macro 'PLANT_INSTR'
   32 |         do { if (d) { (d)[idx] = instr; } idx++; } while (0)
      |                                  ^~~~~
arch/powerpc/net/bpf_jit_comp64.c:415:41: note: in expansion of macro 'EMIT'
  415 |                                         EMIT(PPC_RAW_LI(dst_reg, 0));
      |                                         ^~~~
cc1: all warnings being treated as errors

Reported-by: Linux Kernel Functional Testing <lkft@xxxxxxxxxx>

-- 
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