powerpc/bpf: Reject atomic ops in ppc32 JIT

Commit 91c960b0056672 ("bpf: Rename BPF_XADD and prepare to encode other
atomics in .imm") converted BPF_XADD to BPF_ATOMIC and updated all JIT
implementations to reject JIT'ing instructions with an immediate value
different from BPF_ADD. However, ppc32 BPF JIT was implemented around
the same time and didn't include the same change. Update the ppc32 JIT
accordingly.

Fixes: 51c66ad849a7 ("powerpc/bpf: Implement extended BPF on PPC32")
Cc: stable@vger.kernel.org # v5.13+
Signed-off-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/426699046d89fe50f66ecf74bd31c01eda976ba5.1625145429.git.naveen.n.rao@linux.vnet.ibm.com

diff --git a/arch/powerpc/net/bpf_jit_comp32.c b/arch/powerpc/net/bpf_jit_comp32.c
index cbe5b399ed869dc9e547bbf406168f9c6c37b6ad..34bb1583fc0cb0286a48252d8fae48afc56d65dc 100644 (file)
--- a/arch/powerpc/net/bpf_jit_comp32.c
+++ b/arch/powerpc/net/bpf_jit_comp32.c
@@ -773,9 +773,17 @@ int bpf_jit_build_body(struct bpf_prog *fp, u32 *image, struct codegen_context *
                        break;
 
                /*
-                * BPF_STX XADD (atomic_add)
+                * BPF_STX ATOMIC (atomic ops)
                 */
-               case BPF_STX | BPF_XADD | BPF_W: /* *(u32 *)(dst + off) += src */
+               case BPF_STX | BPF_ATOMIC | BPF_W:
+                       if (imm != BPF_ADD) {
+                               pr_err_ratelimited("eBPF filter atomic op code %02x (@%d) unsupported\n",
+                                                  code, i);
+                               return -ENOTSUPP;
+                       }
+
+                       /* *(u32 *)(dst + off) += src */
+
                        bpf_set_seen_register(ctx, tmp_reg);
                        /* Get offset into TMP_REG */
                        EMIT(PPC_RAW_LI(tmp_reg, off));
@@ -789,7 +797,7 @@ int bpf_jit_build_body(struct bpf_prog *fp, u32 *image, struct codegen_context *
                        PPC_BCC_SHORT(COND_NE, (ctx->idx - 3) * 4);
                        break;
 
-               case BPF_STX | BPF_XADD | BPF_DW: /* *(u64 *)(dst + off) += src */
+               case BPF_STX | BPF_ATOMIC | BPF_DW: /* *(u64 *)(dst + off) += src */
                        return -EOPNOTSUPP;
 
                /*