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

Naresh Kamboju
2021-10-11T17:29:38Z

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@linuxfoundation.org> wrote:
>
> From: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
>
> [ 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@linux.vnet.ibm.com>
> Tested-by: Johan Almbladh <johan.almbladh@anyfinetworks.com>
> Reviewed-by: Christophe Leroy <christophe.leroy@csgroup.eu>
> Acked-by: Song Liu <songliubraving@fb.com>
> Acked-by: Johan Almbladh <johan.almbladh@anyfinetworks.com>
> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
> Link: https://lore.kernel.org/r/c674ca18c3046885602caebb326213731c675d06.1633464148.git.naveen.n.rao@linux.vnet.ibm.com
> Signed-off-by: Sasha Levin <sashal@kernel.org>
> ---
> 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@linaro.org>

--
Linaro LKFT