cregit-Linux how code gets into the kernel

Release 4.7 tools/include/linux/filter.h

/*
 * Linux Socket Filter Data Structures
 */
#ifndef __TOOLS_LINUX_FILTER_H

#define __TOOLS_LINUX_FILTER_H

#include <linux/bpf.h>

/* ArgX, context and stack frame pointer register positions. Note,
 * Arg1, Arg2, Arg3, etc are used as argument mappings of function
 * calls in BPF_CALL instruction.
 */

#define BPF_REG_ARG1	BPF_REG_1

#define BPF_REG_ARG2	BPF_REG_2

#define BPF_REG_ARG3	BPF_REG_3

#define BPF_REG_ARG4	BPF_REG_4

#define BPF_REG_ARG5	BPF_REG_5

#define BPF_REG_CTX	BPF_REG_6

#define BPF_REG_FP	BPF_REG_10

/* Additional register mappings for converted user programs. */

#define BPF_REG_A	BPF_REG_0

#define BPF_REG_X	BPF_REG_7

#define BPF_REG_TMP	BPF_REG_8

/* BPF program can access up to 512 bytes of stack space. */

#define MAX_BPF_STACK	512

/* Helper macros for filter block array initializers. */

/* ALU ops on registers, bpf_add|sub|...: dst_reg += src_reg */


#define BPF_ALU64_REG(OP, DST, SRC)				\
	((struct bpf_insn) {                                    \
                .code  = BPF_ALU64 | BPF_OP(OP) | BPF_X,        \
                .dst_reg = DST,                                 \
                .src_reg = SRC,                                 \
                .off   = 0,                                     \
                .imm   = 0 })


#define BPF_ALU32_REG(OP, DST, SRC)				\
	((struct bpf_insn) {                                    \
                .code  = BPF_ALU | BPF_OP(OP) | BPF_X,          \
                .dst_reg = DST,                                 \
                .src_reg = SRC,                                 \
                .off   = 0,                                     \
                .imm   = 0 })

/* ALU ops on immediates, bpf_add|sub|...: dst_reg += imm32 */


#define BPF_ALU64_IMM(OP, DST, IMM)				\
	((struct bpf_insn) {                                    \
                .code  = BPF_ALU64 | BPF_OP(OP) | BPF_K,        \
                .dst_reg = DST,                                 \
                .src_reg = 0,                                   \
                .off   = 0,                                     \
                .imm   = IMM })


#define BPF_ALU32_IMM(OP, DST, IMM)				\
	((struct bpf_insn) {                                    \
                .code  = BPF_ALU | BPF_OP(OP) | BPF_K,          \
                .dst_reg = DST,                                 \
                .src_reg = 0,                                   \
                .off   = 0,                                     \
                .imm   = IMM })

/* Endianess conversion, cpu_to_{l,b}e(), {l,b}e_to_cpu() */


#define BPF_ENDIAN(TYPE, DST, LEN)				\
	((struct bpf_insn) {                                    \
                .code  = BPF_ALU | BPF_END | BPF_SRC(TYPE),     \
                .dst_reg = DST,                                 \
                .src_reg = 0,                                   \
                .off   = 0,                                     \
                .imm   = LEN })

/* Short form of mov, dst_reg = src_reg */


#define BPF_MOV64_REG(DST, SRC)					\
	((struct bpf_insn) {                                    \
                .code  = BPF_ALU64 | BPF_MOV | BPF_X,           \
                .dst_reg = DST,                                 \
                .src_reg = SRC,                                 \
                .off   = 0,                                     \
                .imm   = 0 })


#define BPF_MOV32_REG(DST, SRC)					\
	((struct bpf_insn) {                                    \
                .code  = BPF_ALU | BPF_MOV | BPF_X,             \
                .dst_reg = DST,                                 \
                .src_reg = SRC,                                 \
                .off   = 0,                                     \
                .imm   = 0 })

/* Short form of mov, dst_reg = imm32 */


#define BPF_MOV64_IMM(DST, IMM)					\
	((struct bpf_insn) {                                    \
                .code  = BPF_ALU64 | BPF_MOV | BPF_K,           \
                .dst_reg = DST,                                 \
                .src_reg = 0,                                   \
                .off   = 0,                                     \
                .imm   = IMM })


#define BPF_MOV32_IMM(DST, IMM)					\
	((struct bpf_insn) {                                    \
                .code  = BPF_ALU | BPF_MOV | BPF_K,             \
                .dst_reg = DST,                                 \
                .src_reg = 0,                                   \
                .off   = 0,                                     \
                .imm   = IMM })

/* Short form of mov based on type,  BPF_X: dst_reg = src_reg, BPF_K: dst_reg = imm32 */


#define BPF_MOV64_RAW(TYPE, DST, SRC, IMM)			\
	((struct bpf_insn) {                                    \
                .code  = BPF_ALU64 | BPF_MOV | BPF_SRC(TYPE),   \
                .dst_reg = DST,                                 \
                .src_reg = SRC,                                 \
                .off   = 0,                                     \
                .imm   = IMM })


#define BPF_MOV32_RAW(TYPE, DST, SRC, IMM)			\
	((struct bpf_insn) {                                    \
                .code  = BPF_ALU | BPF_MOV | BPF_SRC(TYPE),     \
                .dst_reg = DST,                                 \
                .src_reg = SRC,                                 \
                .off   = 0,                                     \
                .imm   = IMM })

/* Direct packet access, R0 = *(uint *) (skb->data + imm32) */


#define BPF_LD_ABS(SIZE, IMM)					\
	((struct bpf_insn) {                                    \
                .code  = BPF_LD | BPF_SIZE(SIZE) | BPF_ABS,     \
                .dst_reg = 0,                                   \
                .src_reg = 0,                                   \
                .off   = 0,                                     \
                .imm   = IMM })

/* Indirect packet access, R0 = *(uint *) (skb->data + src_reg + imm32) */


#define BPF_LD_IND(SIZE, SRC, IMM)				\
	((struct bpf_insn) {                                    \
                .code  = BPF_LD | BPF_SIZE(SIZE) | BPF_IND,     \
                .dst_reg = 0,                                   \
                .src_reg = SRC,                                 \
                .off   = 0,                                     \
                .imm   = IMM })

/* Memory load, dst_reg = *(uint *) (src_reg + off16) */


#define BPF_LDX_MEM(SIZE, DST, SRC, OFF)			\
	((struct bpf_insn) {                                    \
                .code  = BPF_LDX | BPF_SIZE(SIZE) | BPF_MEM,    \
                .dst_reg = DST,                                 \
                .src_reg = SRC,                                 \
                .off   = OFF,                                   \
                .imm   = 0 })

/* Memory store, *(uint *) (dst_reg + off16) = src_reg */


#define BPF_STX_MEM(SIZE, DST, SRC, OFF)			\
	((struct bpf_insn) {                                    \
                .code  = BPF_STX | BPF_SIZE(SIZE) | BPF_MEM,    \
                .dst_reg = DST,                                 \
                .src_reg = SRC,                                 \
                .off   = OFF,                                   \
                .imm   = 0 })

/* Memory store, *(uint *) (dst_reg + off16) = imm32 */


#define BPF_ST_MEM(SIZE, DST, OFF, IMM)				\
	((struct bpf_insn) {                                    \
                .code  = BPF_ST | BPF_SIZE(SIZE) | BPF_MEM,     \
                .dst_reg = DST,                                 \
                .src_reg = 0,                                   \
                .off   = OFF,                                   \
                .imm   = IMM })

/* Conditional jumps against registers, if (dst_reg 'op' src_reg) goto pc + off16 */


#define BPF_JMP_REG(OP, DST, SRC, OFF)				\
	((struct bpf_insn) {                                    \
                .code  = BPF_JMP | BPF_OP(OP) | BPF_X,          \
                .dst_reg = DST,                                 \
                .src_reg = SRC,                                 \
                .off   = OFF,                                   \
                .imm   = 0 })

/* Conditional jumps against immediates, if (dst_reg 'op' imm32) goto pc + off16 */


#define BPF_JMP_IMM(OP, DST, IMM, OFF)				\
	((struct bpf_insn) {                                    \
                .code  = BPF_JMP | BPF_OP(OP) | BPF_K,          \
                .dst_reg = DST,                                 \
                .src_reg = 0,                                   \
                .off   = OFF,                                   \
                .imm   = IMM })

/* Function call */


#define BPF_EMIT_CALL(FUNC)					\
	((struct bpf_insn) {                                    \
                .code  = BPF_JMP | BPF_CALL,                    \
                .dst_reg = 0,                                   \
                .src_reg = 0,                                   \
                .off   = 0,                                     \
                .imm   = ((FUNC) - BPF_FUNC_unspec) })

/* Raw code statement block */


#define BPF_RAW_INSN(CODE, DST, SRC, OFF, IMM)			\
	((struct bpf_insn) {                                    \
                .code  = CODE,                                  \
                .dst_reg = DST,                                 \
                .src_reg = SRC,                                 \
                .off   = OFF,                                   \
                .imm   = IMM })

/* Program exit */


#define BPF_EXIT_INSN()						\
	((struct bpf_insn) {                                    \
                .code  = BPF_JMP | BPF_EXIT,                    \
                .dst_reg = 0,                                   \
                .src_reg = 0,                                   \
                .off   = 0,                                     \
                .imm   = 0 })

#endif /* __TOOLS_LINUX_FILTER_H */

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