linux-kernel - [bpf-next 1/6] bpf,powerpc: Introduce bpf_jit_emit_probe_mem

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Message-ID: <20250805062747.3479221-2-skb99@linux.ibm.com>
Date: Tue,  5 Aug 2025 11:57:42 +0530
From: Saket Kumar Bhaskar <skb99@...ux.ibm.com>
To: bpf@...r.kernel.org, linuxppc-dev@...ts.ozlabs.org,
        linux-kselftest@...r.kernel.org, linux-kernel@...r.kernel.org
Cc: hbathini@...ux.ibm.com, sachinpb@...ux.ibm.com, venkat88@...ux.ibm.com,
        andrii@...nel.org, eddyz87@...il.com, mykolal@...com, ast@...nel.org,
        daniel@...earbox.net, martin.lau@...ux.dev, song@...nel.org,
        yonghong.song@...ux.dev, john.fastabend@...il.com, kpsingh@...nel.org,
        sdf@...ichev.me, haoluo@...gle.com, jolsa@...nel.org,
        christophe.leroy@...roup.eu, naveen@...nel.org, maddy@...ux.ibm.com,
        mpe@...erman.id.au, npiggin@...il.com, memxor@...il.com,
        iii@...ux.ibm.com, shuah@...nel.org
Subject: [bpf-next 1/6] bpf,powerpc: Introduce bpf_jit_emit_probe_mem_store() to emit store instructions

bpf_jit_emit_probe_mem_store() is introduced to emit instructions for
storing memory values depending on the size (byte, halfword,
word, doubleword).

Signed-off-by: Saket Kumar Bhaskar <skb99@...ux.ibm.com>
---
 arch/powerpc/net/bpf_jit_comp64.c | 30 ++++++++++++++++++++++++++++++
 1 file changed, 30 insertions(+)

diff --git a/arch/powerpc/net/bpf_jit_comp64.c b/arch/powerpc/net/bpf_jit_comp64.c
index 025524378443..489de21fe3d6 100644
--- a/arch/powerpc/net/bpf_jit_comp64.c
+++ b/arch/powerpc/net/bpf_jit_comp64.c
@@ -409,6 +409,36 @@ asm (
 "		blr				;"
 );
 
+static int bpf_jit_emit_probe_mem_store(struct codegen_context *ctx, u32 src_reg, s16 off,
+					u32 code, u32 *image)
+{
+	u32 tmp1_reg = bpf_to_ppc(TMP_REG_1);
+	u32 tmp2_reg = bpf_to_ppc(TMP_REG_2);
+
+	switch (BPF_SIZE(code)) {
+	case BPF_B:
+		EMIT(PPC_RAW_STB(src_reg, tmp1_reg, off));
+		break;
+	case BPF_H:
+		EMIT(PPC_RAW_STH(src_reg, tmp1_reg, off));
+		break;
+	case BPF_W:
+		EMIT(PPC_RAW_STW(src_reg, tmp1_reg, off));
+		break;
+	case BPF_DW:
+		if (off % 4) {
+			EMIT(PPC_RAW_LI(tmp2_reg, off));
+			EMIT(PPC_RAW_STDX(src_reg, tmp1_reg, tmp2_reg));
+		} else {
+			EMIT(PPC_RAW_STD(src_reg, tmp1_reg, off));
+		}
+		break;
+	default:
+		return -EINVAL;
+	}
+	return 0;
+}
+
 static int emit_atomic_ld_st(const struct bpf_insn insn, struct codegen_context *ctx, u32 *image)
 {
 	u32 code = insn.code;
-- 
2.43.5