From: Christophe Leroy <christophe.leroy@csgroup.eu>
To: "Naveen N. Rao" <naveen.n.rao@linux.vnet.ibm.com>,
Michael Ellerman <mpe@ellerman.id.au>,
Nicholas Piggin <npiggin@gmail.com>,
Jordan Niethe <jniethe5@gmail.com>,
Daniel Borkmann <daniel@iogearbox.net>,
Alexei Starovoitov <alexei.starovoitov@gmail.com>,
Johan Almbladh <johan.almbladh@anyfinetworks.com>,
Song Liu <songliubraving@fb.com>
Cc: bpf@vger.kernel.org, linuxppc-dev@lists.ozlabs.org
Subject: Re: [PATCH v2 04/10] powerpc/bpf: Fix BPF_SUB when imm == 0x80000000
Date: Wed, 6 Oct 2021 06:55:35 +0200 [thread overview]
Message-ID: <90494652-7551-7ecb-e44d-a2adbb6a1afe@csgroup.eu> (raw)
In-Reply-To: <fc4b1276eb10761fd7ce0814c8dd089da2815251.1633464148.git.naveen.n.rao@linux.vnet.ibm.com>
Le 05/10/2021 à 22:25, Naveen N. Rao a écrit :
> We aren't handling subtraction involving an immediate value of
> 0x80000000 properly. Fix the same.
>
> Fixes: 156d0e290e969c ("powerpc/ebpf/jit: Implement JIT compiler for extended BPF")
> Signed-off-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
> ---
> Changelog:
> - Split up BPF_ADD and BPF_SUB cases per Christophe's comments
>
> arch/powerpc/net/bpf_jit_comp64.c | 27 +++++++++++++++++----------
> 1 file changed, 17 insertions(+), 10 deletions(-)
>
> diff --git a/arch/powerpc/net/bpf_jit_comp64.c b/arch/powerpc/net/bpf_jit_comp64.c
> index d67f6d62e2e1ff..6626e6c17d4ed2 100644
> --- a/arch/powerpc/net/bpf_jit_comp64.c
> +++ b/arch/powerpc/net/bpf_jit_comp64.c
> @@ -330,18 +330,25 @@ int bpf_jit_build_body(struct bpf_prog *fp, u32 *image, struct codegen_context *
> EMIT(PPC_RAW_SUB(dst_reg, dst_reg, src_reg));
> goto bpf_alu32_trunc;
> case BPF_ALU | BPF_ADD | BPF_K: /* (u32) dst += (u32) imm */
> - case BPF_ALU | BPF_SUB | BPF_K: /* (u32) dst -= (u32) imm */
> case BPF_ALU64 | BPF_ADD | BPF_K: /* dst += imm */
> + if (!imm) {
> + goto bpf_alu32_trunc;
> + } else if (imm >= -32768 && imm < 32768) {
> + EMIT(PPC_RAW_ADDI(dst_reg, dst_reg, IMM_L(imm)));
> + } else {
> + PPC_LI32(b2p[TMP_REG_1], imm);
> + EMIT(PPC_RAW_ADD(dst_reg, dst_reg, b2p[TMP_REG_1]));
> + }
> + goto bpf_alu32_trunc;
> + case BPF_ALU | BPF_SUB | BPF_K: /* (u32) dst -= (u32) imm */
> case BPF_ALU64 | BPF_SUB | BPF_K: /* dst -= imm */
> - if (BPF_OP(code) == BPF_SUB)
> - imm = -imm;
> - if (imm) {
> - if (imm >= -32768 && imm < 32768)
> - EMIT(PPC_RAW_ADDI(dst_reg, dst_reg, IMM_L(imm)));
> - else {
> - PPC_LI32(b2p[TMP_REG_1], imm);
> - EMIT(PPC_RAW_ADD(dst_reg, dst_reg, b2p[TMP_REG_1]));
> - }
> + if (!imm) {
> + goto bpf_alu32_trunc;
> + } else if (imm > -32768 && imm < 32768) {
Why do you exclude imm == 32768 ?
Reviewed-by: Christophe Leroy <christophe.leroy@csgroup.eu>
> + EMIT(PPC_RAW_ADDI(dst_reg, dst_reg, IMM_L(-imm)));
> + } else {
> + PPC_LI32(b2p[TMP_REG_1], imm);
> + EMIT(PPC_RAW_SUB(dst_reg, dst_reg, b2p[TMP_REG_1]));
> }
> goto bpf_alu32_trunc;
> case BPF_ALU | BPF_MUL | BPF_X: /* (u32) dst *= (u32) src */
>
next prev parent reply other threads:[~2021-10-06 4:55 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-10-05 20:25 [PATCH v2 00/10] powerpc/bpf: Various fixes Naveen N. Rao
2021-10-05 20:25 ` [PATCH v2 01/10] powerpc/lib: Add helper to check if offset is within conditional branch range Naveen N. Rao
2021-10-06 4:50 ` Christophe Leroy
2021-10-05 20:25 ` [PATCH v2 02/10] powerpc/bpf: Validate branch ranges Naveen N. Rao
2021-10-06 4:51 ` LEROY Christophe
2021-10-06 4:51 ` Christophe Leroy
2021-10-05 20:25 ` [PATCH v2 03/10] powerpc/bpf: Fix BPF_MOD when imm == 1 Naveen N. Rao
2021-10-06 4:52 ` Christophe Leroy
2021-10-05 20:25 ` [PATCH v2 04/10] powerpc/bpf: Fix BPF_SUB when imm == 0x80000000 Naveen N. Rao
2021-10-06 4:55 ` Christophe Leroy [this message]
2021-10-07 8:47 ` Naveen N. Rao
2021-10-05 20:25 ` [PATCH v2 05/10] powerpc/security: Add a helper to query stf_barrier type Naveen N. Rao
2021-10-05 20:25 ` [PATCH v2 06/10] powerpc/bpf: Emit stf barrier instruction sequences for BPF_NOSPEC Naveen N. Rao
2021-10-05 20:25 ` [PATCH v2 07/10] powerpc/bpf ppc32: Fix ALU32 BPF_ARSH operation Naveen N. Rao
2021-10-06 4:56 ` Christophe Leroy
2021-10-05 20:25 ` [PATCH v2 08/10] powerpc/bpf ppc32: Fix JMP32_JSET_K Naveen N. Rao
2021-10-06 5:00 ` Christophe Leroy
2021-10-05 20:25 ` [PATCH v2 09/10] powerpc/bpf ppc32: Do not emit zero extend instruction for 64-bit BPF_END Naveen N. Rao
2021-10-06 5:03 ` Christophe Leroy
2021-10-05 20:25 ` [PATCH v2 10/10] powerpc/bpf ppc32: Fix BPF_SUB when imm == 0x80000000 Naveen N. Rao
2021-10-06 5:02 ` Christophe Leroy
2021-10-08 13:22 ` [PATCH v2 00/10] powerpc/bpf: Various fixes Michael Ellerman
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