From: "Naveen N. Rao" <naveen.n.rao@linux.vnet.ibm.com>
To: Alexei Starovoitov <alexei.starovoitov@gmail.com>,
Christophe Leroy <christophe.leroy@csgroup.eu>,
Daniel Borkmann <daniel@iogearbox.net>,
Jordan Niethe <jniethe5@gmail.com>,
Johan Almbladh <johan.almbladh@anyfinetworks.com>,
Michael Ellerman <mpe@ellerman.id.au>,
Nicholas Piggin <npiggin@gmail.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: Thu, 07 Oct 2021 14:17:28 +0530 [thread overview]
Message-ID: <1633596209.h2aj4uqpon.naveen@linux.ibm.com> (raw)
In-Reply-To: <90494652-7551-7ecb-e44d-a2adbb6a1afe@csgroup.eu>
Christophe Leroy wrote:
>
>
> 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>
Good catch -- that was from an earlier version where this was shared
across BPF_ADD and BPF_SUB. I missed updating this section before
posting.
Michael, please consider squashing in the below diff into this patch.
Thanks!
- Naveen
---
diff --git a/arch/powerpc/net/bpf_jit_comp64.c b/arch/powerpc/net/bpf_jit_comp64.c
index f5a804d8c95bc1..0fdc1ff86e4f1c 100644
--- a/arch/powerpc/net/bpf_jit_comp64.c
+++ b/arch/powerpc/net/bpf_jit_comp64.c
@@ -368,7 +368,7 @@ int bpf_jit_build_body(struct bpf_prog *fp, u32 *image, struct codegen_context *
case BPF_ALU64 | BPF_SUB | BPF_K: /* dst -= imm */
if (!imm) {
goto bpf_alu32_trunc;
- } else if (imm > -32768 && imm < 32768) {
+ } 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);
next prev parent reply other threads:[~2021-10-07 8:48 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
2021-10-07 8:47 ` Naveen N. Rao [this message]
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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