powerpc/bpf/64: add support for atomic fetch operations

Adding instructions for ppc64 for

atomic[64]_fetch_add
atomic[64]_fetch_and
atomic[64]_fetch_or
atomic[64]_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/20220610155552.25892-3-hbathini@linux.ibm.com

diff --git a/arch/powerpc/net/bpf_jit_comp64.c b/arch/powerpc/net/bpf_jit_comp64.c
index c421bedd0e9805577115eb78093aff3363c353c2..c53236b3a8b1f590d0c448de57d00fd255f9d124 100644 (file)
--- a/arch/powerpc/net/bpf_jit_comp64.c
+++ b/arch/powerpc/net/bpf_jit_comp64.c
@@ -787,17 +787,25 @@ emit_clear:
                        else
                                EMIT(PPC_RAW_LWARX(tmp2_reg, tmp1_reg, dst_reg, 0));
 
+                       /* Save old value in _R0 */
+                       if (imm & BPF_FETCH)
+                               EMIT(PPC_RAW_MR(_R0, tmp2_reg));
+
                        switch (imm) {
                        case BPF_ADD:
+                       case BPF_ADD | BPF_FETCH:
                                EMIT(PPC_RAW_ADD(tmp2_reg, tmp2_reg, src_reg));
                                break;
                        case BPF_AND:
+                       case BPF_AND | BPF_FETCH:
                                EMIT(PPC_RAW_AND(tmp2_reg, tmp2_reg, src_reg));
                                break;
                        case BPF_OR:
+                       case BPF_OR | BPF_FETCH:
                                EMIT(PPC_RAW_OR(tmp2_reg, tmp2_reg, src_reg));
                                break;
                        case BPF_XOR:
+                       case BPF_XOR | BPF_FETCH:
                                EMIT(PPC_RAW_XOR(tmp2_reg, tmp2_reg, src_reg));
                                break;
                        default:
@@ -807,13 +815,17 @@ emit_clear:
                                return -EOPNOTSUPP;
                        }
 
-                       /* store result back */
+                       /* store new value */
                        if (size == BPF_DW)
                                EMIT(PPC_RAW_STDCX(tmp2_reg, tmp1_reg, dst_reg));
                        else
                                EMIT(PPC_RAW_STWCX(tmp2_reg, tmp1_reg, dst_reg));
                        /* we're done if this succeeded */
                        PPC_BCC_SHORT(COND_NE, tmp_idx);
+
+                       /* For the BPF_FETCH variant, get old value into src_reg */
+                       if (imm & BPF_FETCH)
+                               EMIT(PPC_RAW_MR(src_reg, _R0));
                        break;
 
                /*