netdev - [PATCH 1/5] bpf ppc64: add support for BPF

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Date:   Thu, 12 May 2022 13:15:42 +0530
From:   Hari Bathini <hbathini@...ux.ibm.com>
To:     bpf@...r.kernel.org, linuxppc-dev <linuxppc-dev@...ts.ozlabs.org>
Cc:     Michael Ellerman <mpe@...erman.id.au>,
        "Naveen N. Rao" <naveen.n.rao@...ux.ibm.com>,
        Christophe Leroy <christophe.leroy@...roup.eu>,
        netdev@...r.kernel.org,
        Benjamin Herrenschmidt <benh@...nel.crashing.org>,
        Paul Mackerras <paulus@...ba.org>,
        Alexei Starovoitov <ast@...nel.org>,
        Daniel Borkmann <daniel@...earbox.net>,
        Andrii Nakryiko <andrii@...nel.org>,
        Martin KaFai Lau <kafai@...com>,
        Song Liu <songliubraving@...com>, Yonghong Song <yhs@...com>,
        John Fastabend <john.fastabend@...il.com>,
        KP Singh <kpsingh@...nel.org>,
        Jordan Niethe <jniethe5@...il.com>
Subject: [PATCH 1/5] bpf ppc64: add support for BPF_ATOMIC bitwise operations

Adding instructions for ppc64 for

atomic[64]_and
atomic[64]_or
atomic[64]_xor

Signed-off-by: Hari Bathini <hbathini@...ux.ibm.com>
---
 arch/powerpc/net/bpf_jit_comp64.c | 57 ++++++++++++++++---------------
 1 file changed, 29 insertions(+), 28 deletions(-)

diff --git a/arch/powerpc/net/bpf_jit_comp64.c b/arch/powerpc/net/bpf_jit_comp64.c
index 183a73f8fcc4..b34ed88167f0 100644
--- a/arch/powerpc/net/bpf_jit_comp64.c
+++ b/arch/powerpc/net/bpf_jit_comp64.c
@@ -782,41 +782,42 @@ 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 */
-
-			/* Get EA into TMP_REG_1 */
-			EMIT(PPC_RAW_ADDI(tmp1_reg, dst_reg, off));
+		case BPF_STX | BPF_ATOMIC | BPF_DW:
+			/* Get offset into TMP_REG_1 */
+			EMIT(PPC_RAW_LI(tmp1_reg, off));
 			tmp_idx = ctx->idx * 4;
 			/* load value from memory into TMP_REG_2 */
-			EMIT(PPC_RAW_LWARX(tmp2_reg, 0, tmp1_reg, 0));
-			/* add value from src_reg into this */
-			EMIT(PPC_RAW_ADD(tmp2_reg, tmp2_reg, src_reg));
-			/* store result back */
-			EMIT(PPC_RAW_STWCX(tmp2_reg, 0, tmp1_reg));
-			/* we're done if this succeeded */
-			PPC_BCC_SHORT(COND_NE, tmp_idx);
-			break;
-		case BPF_STX | BPF_ATOMIC | BPF_DW:
-			if (imm != BPF_ADD) {
+			if (size == BPF_DW)
+				EMIT(PPC_RAW_LDARX(tmp2_reg, tmp1_reg, dst_reg, 0));
+			else
+				EMIT(PPC_RAW_LWARX(tmp2_reg, tmp1_reg, dst_reg, 0));
+
+			switch (imm) {
+			case BPF_ADD:
+				EMIT(PPC_RAW_ADD(tmp2_reg, tmp2_reg, src_reg));
+				break;
+			case BPF_AND:
+				EMIT(PPC_RAW_AND(tmp2_reg, tmp2_reg, src_reg));
+				break;
+			case BPF_OR:
+				EMIT(PPC_RAW_OR(tmp2_reg, tmp2_reg, src_reg));
+				break;
+			case BPF_XOR:
+				EMIT(PPC_RAW_XOR(tmp2_reg, tmp2_reg, src_reg));
+				break;
+			default:
 				pr_err_ratelimited(
 					"eBPF filter atomic op code %02x (@%d) unsupported\n",
 					code, i);
-				return -ENOTSUPP;
+				return -EOPNOTSUPP;
 			}
-			/* *(u64 *)(dst + off) += src */
 
-			EMIT(PPC_RAW_ADDI(tmp1_reg, dst_reg, off));
-			tmp_idx = ctx->idx * 4;
-			EMIT(PPC_RAW_LDARX(tmp2_reg, 0, tmp1_reg, 0));
-			EMIT(PPC_RAW_ADD(tmp2_reg, tmp2_reg, src_reg));
-			EMIT(PPC_RAW_STDCX(tmp2_reg, 0, tmp1_reg));
+			/* store result back */
+			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);
 			break;
 
-- 
2.35.1