powerpc/bpf/32: add support for BPF_ATOMIC bitwise operations

Adding instructions for ppc32 for

atomic_and
atomic_or
atomic_xor
atomic_fetch_add
atomic_fetch_and
atomic_fetch_or
atomic_fetch_xor

Signed-off-by: Hari Bathini <hbathini@linux.ibm.com>
Tested-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com> (ppc64le)
Reviewed-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/20220610155552.25892-5-hbathini@linux.ibm.com

diff --git a/arch/powerpc/net/bpf_jit_comp32.c b/arch/powerpc/net/bpf_jit_comp32.c
index e46ed1e8c6ca65abf8ae3505f8999b185932fe4b..28dc6a1a8f2fef6a9ea7133bf64598ba5dee7c92 100644 (file)
--- a/arch/powerpc/net/bpf_jit_comp32.c
+++ b/arch/powerpc/net/bpf_jit_comp32.c
@@ -294,6 +294,7 @@ int bpf_jit_build_body(struct bpf_prog *fp, u32 *image, struct codegen_context *
                u32 dst_reg_h = dst_reg - 1;
                u32 src_reg = bpf_to_ppc(insn[i].src_reg);
                u32 src_reg_h = src_reg - 1;
+               u32 ax_reg = bpf_to_ppc(BPF_REG_AX);
                u32 tmp_reg = bpf_to_ppc(TMP_REG);
                u32 size = BPF_SIZE(code);
                s16 off = insn[i].off;
@@ -798,25 +799,53 @@ int bpf_jit_build_body(struct bpf_prog *fp, u32 *image, struct codegen_context *
                 * BPF_STX ATOMIC (atomic ops)
                 */
                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);
+                       bpf_set_seen_register(ctx, ax_reg);
+
                        /* Get offset into TMP_REG */
                        EMIT(PPC_RAW_LI(tmp_reg, off));
+                       tmp_idx = ctx->idx * 4;
                        /* load value from memory into r0 */
                        EMIT(PPC_RAW_LWARX(_R0, tmp_reg, dst_reg, 0));
-                       /* add value from src_reg into this */
-                       EMIT(PPC_RAW_ADD(_R0, _R0, src_reg));
-                       /* store result back */
+
+                       /* Save old value in BPF_REG_AX */
+                       if (imm & BPF_FETCH)
+                               EMIT(PPC_RAW_MR(ax_reg, _R0));
+
+                       switch (imm) {
+                       case BPF_ADD:
+                       case BPF_ADD | BPF_FETCH:
+                               EMIT(PPC_RAW_ADD(_R0, _R0, src_reg));
+                               break;
+                       case BPF_AND:
+                       case BPF_AND | BPF_FETCH:
+                               EMIT(PPC_RAW_AND(_R0, _R0, src_reg));
+                               break;
+                       case BPF_OR:
+                       case BPF_OR | BPF_FETCH:
+                               EMIT(PPC_RAW_OR(_R0, _R0, src_reg));
+                               break;
+                       case BPF_XOR:
+                       case BPF_XOR | BPF_FETCH:
+                               EMIT(PPC_RAW_XOR(_R0, _R0, src_reg));
+                               break;
+                       default:
+                               pr_err_ratelimited("eBPF filter atomic op code %02x (@%d) unsupported\n",
+                                                  code, i);
+                               return -EOPNOTSUPP;
+                       }
+
+                       /* store new value */
                        EMIT(PPC_RAW_STWCX(_R0, tmp_reg, dst_reg));
                        /* we're done if this succeeded */
-                       PPC_BCC_SHORT(COND_NE, (ctx->idx - 3) * 4);
+                       PPC_BCC_SHORT(COND_NE, tmp_idx);
+
+                       /* For the BPF_FETCH variant, get old data into src_reg */
+                       if (imm & BPF_FETCH) {
+                               EMIT(PPC_RAW_MR(src_reg, ax_reg));
+                               if (!fp->aux->verifier_zext)
+                                       EMIT(PPC_RAW_LI(src_reg_h, 0));
+                       }
                        break;
 
                case BPF_STX | BPF_ATOMIC | BPF_DW: /* *(u64 *)(dst + off) += src */