From 096d4c941f0e236ae35ecae9ca75cb3248cb4df8 Mon Sep 17 00:00:00 2001
From: "Naveen N. Rao" <naveen.n.rao@linux.vnet.ibm.com>
Date: Wed, 6 Oct 2021 01:55:23 +0530
Subject: [PATCH] powerpc/bpf: Fix BPF_SUB when imm == 0x80000000
Git-commit: 5855c4c1f415ca3ba1046e77c0b3d3dfc96c9025
Patch-mainline: v5.15-rc5
References: stable-5.14.12
[ Upstream commit 5855c4c1f415ca3ba1046e77c0b3d3dfc96c9025 ]
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>
Reviewed-by: Christophe Leroy <christophe.leroy@csgroup.eu>
[mpe: Fold in fix from Naveen to use imm <= 32768]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/fc4b1276eb10761fd7ce0814c8dd089da2815251.1633464148.git.naveen.n.rao@linux.vnet.ibm.com
Signed-off-by: Sasha Levin <sashal@kernel.org>
Acked-by: Takashi Iwai <tiwai@suse.de>
---
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 d16b97179646..dff4a2930970 100644
--- a/arch/powerpc/net/bpf_jit_comp64.c
+++ b/arch/powerpc/net/bpf_jit_comp64.c
@@ -328,18 +328,25 @@ 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) {
+ 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 */
--
2.26.2