Re: [PATCH v4 3/8] bpf powerpc: refactor JIT compiler code

Christophe Leroy <christophe.leroy@xxxxxxxxxx> · Wed, 29 Sep 2021 13:42:59 +0200

Le 29/09/2021 à 13:18, Hari Bathini a écrit :
Refactor powerpc LDX JITing code to simplify adding BPF_PROBE_MEM
support.

Signed-off-by: Hari Bathini <hbathini@xxxxxxxxxxxxx>

Reviewed-by: Christophe Leroy <christophe.leroy@xxxxxxxxxx>

---

Changes in v4:
* Dropped the default case in the switch statement for bpf size.
* Dropped explicit fallthrough statement for empty switch cases.


  arch/powerpc/net/bpf_jit_comp32.c | 33 ++++++++++++++++++-------------
  arch/powerpc/net/bpf_jit_comp64.c | 31 +++++++++++++++++------------
  2 files changed, 37 insertions(+), 27 deletions(-)

diff --git a/arch/powerpc/net/bpf_jit_comp32.c b/arch/powerpc/net/bpf_jit_comp32.c
index b60b59426a24..65a4d1ed97bf 100644
--- a/arch/powerpc/net/bpf_jit_comp32.c
+++ b/arch/powerpc/net/bpf_jit_comp32.c
@@ -282,6 +282,7 @@ int bpf_jit_build_body(struct bpf_prog *fp, u32 *image, struct codegen_context *
  		u32 src_reg = bpf_to_ppc(ctx, insn[i].src_reg);
  		u32 src_reg_h = src_reg - 1;
  		u32 tmp_reg = bpf_to_ppc(ctx, TMP_REG);
+		u32 size = BPF_SIZE(code);
  		s16 off = insn[i].off;
  		s32 imm = insn[i].imm;
  		bool func_addr_fixed;
@@ -810,23 +811,27 @@ int bpf_jit_build_body(struct bpf_prog *fp, u32 *image, struct codegen_context *
  		 * BPF_LDX
  		 */
  		case BPF_LDX | BPF_MEM | BPF_B: /* dst = *(u8 *)(ul) (src + off) */
-			EMIT(PPC_RAW_LBZ(dst_reg, src_reg, off));
-			if (!fp->aux->verifier_zext)
-				EMIT(PPC_RAW_LI(dst_reg_h, 0));
-			break;
  		case BPF_LDX | BPF_MEM | BPF_H: /* dst = *(u16 *)(ul) (src + off) */
-			EMIT(PPC_RAW_LHZ(dst_reg, src_reg, off));
-			if (!fp->aux->verifier_zext)
-				EMIT(PPC_RAW_LI(dst_reg_h, 0));
-			break;
  		case BPF_LDX | BPF_MEM | BPF_W: /* dst = *(u32 *)(ul) (src + off) */
-			EMIT(PPC_RAW_LWZ(dst_reg, src_reg, off));
-			if (!fp->aux->verifier_zext)
-				EMIT(PPC_RAW_LI(dst_reg_h, 0));
-			break;
  		case BPF_LDX | BPF_MEM | BPF_DW: /* dst = *(u64 *)(ul) (src + off) */
-			EMIT(PPC_RAW_LWZ(dst_reg_h, src_reg, off));
-			EMIT(PPC_RAW_LWZ(dst_reg, src_reg, off + 4));
+			switch (size) {
+			case BPF_B:
+				EMIT(PPC_RAW_LBZ(dst_reg, src_reg, off));
+				break;
+			case BPF_H:
+				EMIT(PPC_RAW_LHZ(dst_reg, src_reg, off));
+				break;
+			case BPF_W:
+				EMIT(PPC_RAW_LWZ(dst_reg, src_reg, off));
+				break;
+			case BPF_DW:
+				EMIT(PPC_RAW_LWZ(dst_reg_h, src_reg, off));
+				EMIT(PPC_RAW_LWZ(dst_reg, src_reg, off + 4));
+				break;
+			}
+
+			if (size != BPF_DW && !fp->aux->verifier_zext)
+				EMIT(PPC_RAW_LI(dst_reg_h, 0));
  			break;
  
  		/*
diff --git a/arch/powerpc/net/bpf_jit_comp64.c b/arch/powerpc/net/bpf_jit_comp64.c
index 2a87da50d9a4..49e6e0b6e4d2 100644
--- a/arch/powerpc/net/bpf_jit_comp64.c
+++ b/arch/powerpc/net/bpf_jit_comp64.c
@@ -285,6 +285,7 @@ int bpf_jit_build_body(struct bpf_prog *fp, u32 *image, struct codegen_context *
  		u32 code = insn[i].code;
  		u32 dst_reg = b2p[insn[i].dst_reg];
  		u32 src_reg = b2p[insn[i].src_reg];
+		u32 size = BPF_SIZE(code);
  		s16 off = insn[i].off;
  		s32 imm = insn[i].imm;
  		bool func_addr_fixed;
@@ -716,25 +717,29 @@ int bpf_jit_build_body(struct bpf_prog *fp, u32 *image, struct codegen_context *
  		 */
  		/* dst = *(u8 *)(ul) (src + off) */
  		case BPF_LDX | BPF_MEM | BPF_B:
-			EMIT(PPC_RAW_LBZ(dst_reg, src_reg, off));
-			if (insn_is_zext(&insn[i + 1]))
-				addrs[++i] = ctx->idx * 4;
-			break;
  		/* dst = *(u16 *)(ul) (src + off) */
  		case BPF_LDX | BPF_MEM | BPF_H:
-			EMIT(PPC_RAW_LHZ(dst_reg, src_reg, off));
-			if (insn_is_zext(&insn[i + 1]))
-				addrs[++i] = ctx->idx * 4;
-			break;
  		/* dst = *(u32 *)(ul) (src + off) */
  		case BPF_LDX | BPF_MEM | BPF_W:
-			EMIT(PPC_RAW_LWZ(dst_reg, src_reg, off));
-			if (insn_is_zext(&insn[i + 1]))
-				addrs[++i] = ctx->idx * 4;
-			break;
  		/* dst = *(u64 *)(ul) (src + off) */
  		case BPF_LDX | BPF_MEM | BPF_DW:
-			PPC_BPF_LL(dst_reg, src_reg, off);
+			switch (size) {
+			case BPF_B:
+				EMIT(PPC_RAW_LBZ(dst_reg, src_reg, off));
+				break;
+			case BPF_H:
+				EMIT(PPC_RAW_LHZ(dst_reg, src_reg, off));
+				break;
+			case BPF_W:
+				EMIT(PPC_RAW_LWZ(dst_reg, src_reg, off));
+				break;
+			case BPF_DW:
+				PPC_BPF_LL(dst_reg, src_reg, off);
+				break;
+			}
+
+			if (size != BPF_DW && insn_is_zext(&insn[i + 1]))
+				addrs[++i] = ctx->idx * 4;
  			break;
  
  		/*







