[PATCH v2 3/8] bpf powerpc: refactor JIT compiler code

Christophe Leroy christophe.leroy at csgroup.eu
Sat Sep 18 02:22:45 AEST 2021



Le 17/09/2021 à 17:30, Hari Bathini a écrit :
> Refactor powerpc JITing. This simplifies adding BPF_PROBE_MEM support.
> 
> Signed-off-by: Hari Bathini <hbathini at linux.ibm.com>
> ---
> 
> Changes in v2:
> * New patch to refactor a bit of JITing code.
> 
> 
>   arch/powerpc/net/bpf_jit_comp32.c | 50 +++++++++++---------
>   arch/powerpc/net/bpf_jit_comp64.c | 76 ++++++++++++++++---------------
>   2 files changed, 68 insertions(+), 58 deletions(-)
> 
> diff --git a/arch/powerpc/net/bpf_jit_comp32.c b/arch/powerpc/net/bpf_jit_comp32.c
> index b60b59426a24..c8ae14c316e3 100644
> --- a/arch/powerpc/net/bpf_jit_comp32.c
> +++ b/arch/powerpc/net/bpf_jit_comp32.c
> @@ -276,17 +276,17 @@ int bpf_jit_build_body(struct bpf_prog *fp, u32 *image, struct codegen_context *
>   	u32 exit_addr = addrs[flen];
>   
>   	for (i = 0; i < flen; i++) {
> -		u32 code = insn[i].code;
>   		u32 dst_reg = bpf_to_ppc(ctx, insn[i].dst_reg);
> -		u32 dst_reg_h = dst_reg - 1;
>   		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 true_cond, code = insn[i].code;
> +		u32 dst_reg_h = dst_reg - 1;
> +		u32 src_reg_h = src_reg - 1;
> +		u32 size = BPF_SIZE(code);
>   		s16 off = insn[i].off;
>   		s32 imm = insn[i].imm;
>   		bool func_addr_fixed;
>   		u64 func_addr;
> -		u32 true_cond;
>   
>   		/*
>   		 * addrs[] maps a BPF bytecode address into a real offset from
> @@ -809,25 +809,33 @@ 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)
> +		/* dst = *(u8 *)(ul) (src + off) */
> +		case BPF_LDX | BPF_MEM | BPF_B:
> +		/* dst = *(u16 *)(ul) (src + off) */
> +		case BPF_LDX | BPF_MEM | BPF_H:
> +		/* dst = *(u32 *)(ul) (src + off) */
> +		case BPF_LDX | BPF_MEM | BPF_W:
> +		/* dst = *(u64 *)(ul) (src + off) */
> +		case BPF_LDX | BPF_MEM | BPF_DW:

You have to add the 'fallthrough;' keyword to avoid build failure with 
later versions of GCC.


> +			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;
> -		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));
> -			break;
>   
>   		/*
>   		 * Doubleword load
> diff --git a/arch/powerpc/net/bpf_jit_comp64.c b/arch/powerpc/net/bpf_jit_comp64.c
> index 2a87da50d9a4..78b28f25555c 100644
> --- a/arch/powerpc/net/bpf_jit_comp64.c
> +++ b/arch/powerpc/net/bpf_jit_comp64.c
> @@ -282,16 +282,15 @@ int bpf_jit_build_body(struct bpf_prog *fp, u32 *image, struct codegen_context *
>   	u32 exit_addr = addrs[flen];
>   
>   	for (i = 0; i < flen; i++) {
> -		u32 code = insn[i].code;
>   		u32 dst_reg = b2p[insn[i].dst_reg];
>   		u32 src_reg = b2p[insn[i].src_reg];
> +		u32 tmp_idx, code = insn[i].code;
> +		u32 size = BPF_SIZE(code);
>   		s16 off = insn[i].off;
>   		s32 imm = insn[i].imm;
>   		bool func_addr_fixed;
> -		u64 func_addr;
> -		u64 imm64;
> +		u64 func_addr, imm64;
>   		u32 true_cond;
> -		u32 tmp_idx;
>   
>   		/*
>   		 * addrs[] maps a BPF bytecode address into a real offset from
> @@ -638,35 +637,34 @@ int bpf_jit_build_body(struct bpf_prog *fp, u32 *image, struct codegen_context *
>   		 */
>   		case BPF_STX | BPF_MEM | BPF_B: /* *(u8 *)(dst + off) = src */
>   		case BPF_ST | BPF_MEM | BPF_B: /* *(u8 *)(dst + off) = imm */
> -			if (BPF_CLASS(code) == BPF_ST) {
> -				EMIT(PPC_RAW_LI(b2p[TMP_REG_1], imm));
> -				src_reg = b2p[TMP_REG_1];
> -			}
> -			EMIT(PPC_RAW_STB(src_reg, dst_reg, off));
> -			break;
>   		case BPF_STX | BPF_MEM | BPF_H: /* (u16 *)(dst + off) = src */
>   		case BPF_ST | BPF_MEM | BPF_H: /* (u16 *)(dst + off) = imm */
> -			if (BPF_CLASS(code) == BPF_ST) {
> -				EMIT(PPC_RAW_LI(b2p[TMP_REG_1], imm));
> -				src_reg = b2p[TMP_REG_1];
> -			}
> -			EMIT(PPC_RAW_STH(src_reg, dst_reg, off));
> -			break;
>   		case BPF_STX | BPF_MEM | BPF_W: /* *(u32 *)(dst + off) = src */
>   		case BPF_ST | BPF_MEM | BPF_W: /* *(u32 *)(dst + off) = imm */
> -			if (BPF_CLASS(code) == BPF_ST) {
> -				PPC_LI32(b2p[TMP_REG_1], imm);
> -				src_reg = b2p[TMP_REG_1];
> -			}
> -			EMIT(PPC_RAW_STW(src_reg, dst_reg, off));
> -			break;


You have to add the 'fallthrough;' keyword to avoid build failure with 
later versions of GCC.


>   		case BPF_STX | BPF_MEM | BPF_DW: /* (u64 *)(dst + off) = src */
>   		case BPF_ST | BPF_MEM | BPF_DW: /* *(u64 *)(dst + off) = imm */
>   			if (BPF_CLASS(code) == BPF_ST) {
> -				PPC_LI32(b2p[TMP_REG_1], imm);
> +				if ((size == BPF_B) || (size == BPF_H))
> +					EMIT(PPC_RAW_LI(b2p[TMP_REG_1], imm));
> +				else /* size == BPF_W || size == BPF_DW */
> +					PPC_LI32(b2p[TMP_REG_1], imm);
>   				src_reg = b2p[TMP_REG_1];
>   			}
> -			PPC_BPF_STL(src_reg, dst_reg, off);
> +
> +			switch (size) {
> +			case BPF_B:
> +				EMIT(PPC_RAW_STB(src_reg, dst_reg, off));
> +				break;
> +			case BPF_H:
> +				EMIT(PPC_RAW_STH(src_reg, dst_reg, off));
> +				break;
> +			case BPF_W:
> +				EMIT(PPC_RAW_STW(src_reg, dst_reg, off));
> +				break;
> +			case BPF_DW:
> +				PPC_BPF_STL(src_reg, dst_reg, off);
> +				break;
> +			}
>   			break;
>   
>   		/*
> @@ -716,25 +714,29 @@ 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;
>   
>   		/*
> 


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