From: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
Date: Tue, 5 Oct 2021 20:25:22 +0000 (+0530)
Subject: powerpc/bpf: Fix BPF_MOD when imm == 1
X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=8bbc9d822421d9ac8ff9ed26a3713c9afc69d6c8;p=linux.git

powerpc/bpf: Fix BPF_MOD when imm == 1

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
---

diff --git a/arch/powerpc/net/bpf_jit_comp64.c b/arch/powerpc/net/bpf_jit_comp64.c
index f06c62089b145..d67f6d62e2e1f 100644
--- a/arch/powerpc/net/bpf_jit_comp64.c
+++ b/arch/powerpc/net/bpf_jit_comp64.c
@@ -391,8 +391,14 @@ int bpf_jit_build_body(struct bpf_prog *fp, u32 *image, struct codegen_context *
 		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));
+					break;
+				}
+			}
 
 			PPC_LI32(b2p[TMP_REG_1], imm);
 			switch (BPF_CLASS(code)) {