Re: [dpdk-dev] [PATCH v8 05/12] bpf: add function to dump eBPF instructions

["Ananyev, Konstantin" <konstantin.ananyev@intel.com>]

> When debugging converted (and other) programs it is useful
> to see disassembled eBPF output.
> 
> Signed-off-by: Stephen Hemminger <stephen@networkplumber.org>
> ---
>  lib/bpf/bpf_convert.c |   7 ++-
>  lib/bpf/bpf_dump.c    | 118 ++++++++++++++++++++++++++++++++++++++++++
>  lib/bpf/meson.build   |   1 +
>  lib/bpf/rte_bpf.h     |  14 +++++
>  lib/bpf/version.map   |   1 +
>  5 files changed, 140 insertions(+), 1 deletion(-)
>  create mode 100644 lib/bpf/bpf_dump.c
> 
> diff --git a/lib/bpf/bpf_convert.c b/lib/bpf/bpf_convert.c
> index a46ffeb067dd..db84add7dcce 100644
> --- a/lib/bpf/bpf_convert.c
> +++ b/lib/bpf/bpf_convert.c
> @@ -331,7 +331,12 @@ static int bpf_convert_filter(const struct bpf_insn *prog, size_t len,
>  		case BPF_LD | BPF_IND | BPF_H:
>  		case BPF_LD | BPF_IND | BPF_B:
>  			/* All arithmetic insns map as-is. */
> -			*insn = BPF_RAW_INSN(fp->code, BPF_REG_A, BPF_REG_X, 0, fp->k);
> +			insn->code = fp->code;
> +			insn->dst_reg = BPF_REG_A;
> +			bpf_src = BPF_SRC(fp->code);
> +			insn->src_reg = bpf_src == BPF_X ? BPF_REG_X : 0;
> +			insn->off = 0;
> +			insn->imm = fp->k;
>  			break;

Should it be part of that patch?
Looks like belongs to previous one, no?

> 
>  			/* Jump transformation cannot use BPF block macros
> diff --git a/lib/bpf/bpf_dump.c b/lib/bpf/bpf_dump.c
> new file mode 100644
> index 000000000000..a6a431e64903
> --- /dev/null
> +++ b/lib/bpf/bpf_dump.c
> @@ -0,0 +1,118 @@
> +/* SPDX-License-Identifier: BSD-3-Clause
> + * Copyright (c) 2021 Stephen Hemminger
> + * Based on filter2xdp
> + * Copyright (C) 2017 Tobias Klauser
> + */
> +
> +#include <stdio.h>
> +#include <stdint.h>
> +
> +#include "rte_bpf.h"
> +
> +#define BPF_OP_INDEX(x) (BPF_OP(x) >> 4)
> +#define BPF_SIZE_INDEX(x) (BPF_SIZE(x) >> 3)
> +
> +static const char *const class_tbl[] = {
> +	[BPF_LD] = "ld",   [BPF_LDX] = "ldx",	 [BPF_ST] = "st",
> +	[BPF_STX] = "stx", [BPF_ALU] = "alu",	 [BPF_JMP] = "jmp",
> +	[BPF_RET] = "ret", [BPF_MISC] = "alu64",
> +};
> +
> +static const char *const alu_op_tbl[16] = {
> +	[BPF_ADD >> 4] = "add",	   [BPF_SUB >> 4] = "sub",
> +	[BPF_MUL >> 4] = "mul",	   [BPF_DIV >> 4] = "div",
> +	[BPF_OR >> 4] = "or",	   [BPF_AND >> 4] = "and",
> +	[BPF_LSH >> 4] = "lsh",	   [BPF_RSH >> 4] = "rsh",
> +	[BPF_NEG >> 4] = "neg",	   [BPF_MOD >> 4] = "mod",
> +	[BPF_XOR >> 4] = "xor",	   [EBPF_MOV >> 4] = "mov",
> +	[EBPF_ARSH >> 4] = "arsh", [EBPF_END >> 4] = "endian",
> +};
> +
> +static const char *const size_tbl[] = {
> +	[BPF_W >> 3] = "w",
> +	[BPF_H >> 3] = "h",
> +	[BPF_B >> 3] = "b",
> +	[EBPF_DW >> 3] = "dw",
> +};
> +
> +static const char *const jump_tbl[16] = {
> +	[BPF_JA >> 4] = "ja",	   [BPF_JEQ >> 4] = "jeq",
> +	[BPF_JGT >> 4] = "jgt",	   [BPF_JGE >> 4] = "jge",
> +	[BPF_JSET >> 4] = "jset",  [EBPF_JNE >> 4] = "jne",
> +	[EBPF_JSGT >> 4] = "jsgt", [EBPF_JSGE >> 4] = "jsge",
> +	[EBPF_CALL >> 4] = "call", [EBPF_EXIT >> 4] = "exit",
> +};
> +
> +static void ebpf_dump(FILE *f, const struct ebpf_insn insn, size_t n)
> +{
> +	const char *op, *postfix = "";
> +	uint8_t cls = BPF_CLASS(insn.code);
> +
> +	fprintf(f, " L%zu:\t", n);
> +
> +	switch (cls) {
> +	default:
> +		fprintf(f, "unimp 0x%x // class: %s\n", insn.code,
> +			class_tbl[cls]);
> +		break;
> +	case BPF_ALU:
> +		postfix = "32";
> +		/* fall through */
> +	case EBPF_ALU64:
> +		op = alu_op_tbl[BPF_OP_INDEX(insn.code)];
> +		if (BPF_SRC(insn.code) == BPF_X)
> +			fprintf(f, "%s%s r%u, r%u\n", op, postfix, insn.dst_reg,
> +				insn.src_reg);
> +		else
> +			fprintf(f, "%s%s r%u, #0x%x\n", op, postfix,
> +				insn.dst_reg, insn.imm);
> +		break;
> +	case BPF_LD:
> +		op = "ld";
> +		postfix = size_tbl[BPF_SIZE_INDEX(insn.code)];
> +		if (BPF_MODE(insn.code) == BPF_IMM)
> +			fprintf(f, "%s%s r%d, #0x%x\n", op, postfix,
> +				insn.dst_reg, insn.imm);
> +		else if (BPF_MODE(insn.code) == BPF_ABS)
> +			fprintf(f, "%s%s r%d, [%d]\n", op, postfix,
> +				insn.dst_reg, insn.imm);
> +		else if (BPF_MODE(insn.code) == BPF_IND)
> +			fprintf(f, "%s%s r%d, [r%u + %d]\n", op, postfix,
> +				insn.dst_reg, insn.src_reg, insn.imm);
> +		else
> +			fprintf(f, "// BUG: LD opcode 0x%02x in eBPF insns\n",
> +				insn.code);
> +		break;
> +	case BPF_LDX:
> +		op = "ldx";
> +		postfix = size_tbl[BPF_SIZE_INDEX(insn.code)];
> +		fprintf(f, "%s%s r%d, [r%u + %d]\n", op, postfix, insn.dst_reg,
> +			insn.src_reg, insn.off);
> +		break;
> +#define L(pc, off) ((int)(pc) + 1 + (off))
> +	case BPF_JMP:
> +		op = jump_tbl[BPF_OP_INDEX(insn.code)];
> +		if (op == NULL)
> +			fprintf(f, "invalid jump opcode: %#x\n", insn.code);
> +		else if (BPF_OP(insn.code) == BPF_JA)
> +			fprintf(f, "%s L%d\n", op, L(n, insn.off));
> +		else if (BPF_OP(insn.code) == EBPF_EXIT)
> +			fprintf(f, "%s\n", op);
> +		else
> +			fprintf(f, "%s r%u, #0x%x, L%d\n", op, insn.dst_reg,
> +				insn.imm, L(n, insn.off));
> +		break;
> +	case BPF_RET:
> +		fprintf(f, "// BUG: RET opcode 0x%02x in eBPF insns\n",
> +			insn.code);
> +		break;
> +	}
> +}
> +
> +void rte_bpf_dump(FILE *f, const struct ebpf_insn *buf, uint32_t len)
> +{
> +	uint32_t i;
> +
> +	for (i = 0; i < len; ++i)
> +		ebpf_dump(f, buf[i], i);
> +}
> diff --git a/lib/bpf/meson.build b/lib/bpf/meson.build
> index 54f7610ae990..5b5585173aeb 100644
> --- a/lib/bpf/meson.build
> +++ b/lib/bpf/meson.build
> @@ -2,6 +2,7 @@
>  # Copyright(c) 2018 Intel Corporation
> 
>  sources = files('bpf.c',
> +	'bpf_dump.c',
>          'bpf_exec.c',
>          'bpf_load.c',
>          'bpf_pkt.c',
> diff --git a/lib/bpf/rte_bpf.h b/lib/bpf/rte_bpf.h
> index 2f23e272a376..0d0a84b130a0 100644
> --- a/lib/bpf/rte_bpf.h
> +++ b/lib/bpf/rte_bpf.h
> @@ -198,6 +198,20 @@ rte_bpf_exec_burst(const struct rte_bpf *bpf, void *ctx[], uint64_t rc[],
>  int
>  rte_bpf_get_jit(const struct rte_bpf *bpf, struct rte_bpf_jit *jit);
> 
> +/**
> + * Dump epf instructions to a file.
> + *
> + * @param f
> + *   A pointer to a file for output
> + * @param buf
> + *   A pointer to BPF instructions
> + * @param len
> + *   Number of BPF instructions to dump.
> + */
> +__rte_experimental
> +void
> +rte_bpf_dump(FILE *f, const struct ebpf_insn *buf, uint32_t len);
> +
>  #ifdef RTE_PORT_PCAP
> 
>  struct bpf_program;
> diff --git a/lib/bpf/version.map b/lib/bpf/version.map
> index 47082d5003ef..3b953f2f4592 100644
> --- a/lib/bpf/version.map
> +++ b/lib/bpf/version.map
> @@ -19,4 +19,5 @@ EXPERIMENTAL {
>  	global:
> 
>  	rte_bpf_convert;
> +	rte_bpf_dump;
>  };
> --

Acked-by: Konstantin Ananyev <konstantin.ananyev@intel.com>

> 2.30.2