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 f06c62089b14578c8d9c7595366554462d3e3719..d67f6d62e2e1ffd76cb08bcf72611d2f3c566f9a 100644 (file)
--- 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)) {