arch/riscv/net/bpf_jit.h

/* SPDX-License-Identifier: GPL-2.0 */
/*
 * Common functionality for RV32 and RV64 BPF JIT compilers
 *
 * Copyright (c) 2019 Björn Töpel <bjorn.topel@gmail.com>
 *
 */

#ifndef _BPF_JIT_H
#define _BPF_JIT_H

#include <linux/bpf.h>
#include <linux/filter.h>
#include <asm/cacheflush.h>

enum {
	RV_REG_ZERO =	0,	/* The constant value 0 */
	RV_REG_RA =	1,	/* Return address */
	RV_REG_SP =	2,	/* Stack pointer */
	RV_REG_GP =	3,	/* Global pointer */
	RV_REG_TP =	4,	/* Thread pointer */
	RV_REG_T0 =	5,	/* Temporaries */
	RV_REG_T1 =	6,
	RV_REG_T2 =	7,
	RV_REG_FP =	8,	/* Saved register/frame pointer */
	RV_REG_S1 =	9,	/* Saved register */
	RV_REG_A0 =	10,	/* Function argument/return values */
	RV_REG_A1 =	11,	/* Function arguments */
	RV_REG_A2 =	12,
	RV_REG_A3 =	13,
	RV_REG_A4 =	14,
	RV_REG_A5 =	15,
	RV_REG_A6 =	16,
	RV_REG_A7 =	17,
	RV_REG_S2 =	18,	/* Saved registers */
	RV_REG_S3 =	19,
	RV_REG_S4 =	20,
	RV_REG_S5 =	21,
	RV_REG_S6 =	22,
	RV_REG_S7 =	23,
	RV_REG_S8 =	24,
	RV_REG_S9 =	25,
	RV_REG_S10 =	26,
	RV_REG_S11 =	27,
	RV_REG_T3 =	28,	/* Temporaries */
	RV_REG_T4 =	29,
	RV_REG_T5 =	30,
	RV_REG_T6 =	31,
};

struct rv_jit_context {
	struct bpf_prog *prog;
	u32 *insns;		/* RV insns */
	int ninsns;
	int epilogue_offset;
	int *offset;		/* BPF to RV */
	unsigned long flags;
	int stack_size;
};

struct rv_jit_data {
	struct bpf_binary_header *header;
	u8 *image;
	struct rv_jit_context ctx;
};

static inline void bpf_fill_ill_insns(void *area, unsigned int size)
{
	memset(area, 0, size);
}

static inline void bpf_flush_icache(void *start, void *end)
{
	flush_icache_range((unsigned long)start, (unsigned long)end);
}

static inline void emit(const u32 insn, struct rv_jit_context *ctx)
{
	if (ctx->insns)
		ctx->insns[ctx->ninsns] = insn;

	ctx->ninsns++;
}

static inline int epilogue_offset(struct rv_jit_context *ctx)
{
	int to = ctx->epilogue_offset, from = ctx->ninsns;

	return (to - from) << 2;
}

/* Return -1 or inverted cond. */
static inline int invert_bpf_cond(u8 cond)
{
	switch (cond) {
	case BPF_JEQ:
		return BPF_JNE;
	case BPF_JGT:
		return BPF_JLE;
	case BPF_JLT:
		return BPF_JGE;
	case BPF_JGE:
		return BPF_JLT;
	case BPF_JLE:
		return BPF_JGT;
	case BPF_JNE:
		return BPF_JEQ;
	case BPF_JSGT:
		return BPF_JSLE;
	case BPF_JSLT:
		return BPF_JSGE;
	case BPF_JSGE:
		return BPF_JSLT;
	case BPF_JSLE:
		return BPF_JSGT;
	}
	return -1;
}

static inline bool is_12b_int(long val)
{
	return -(1L << 11) <= val && val < (1L << 11);
}

static inline int is_12b_check(int off, int insn)
{
	if (!is_12b_int(off)) {
		pr_err("bpf-jit: insn=%d 12b < offset=%d not supported yet!\n",
		       insn, (int)off);
		return -1;
	}
	return 0;
}

static inline bool is_13b_int(long val)
{
	return -(1L << 12) <= val && val < (1L << 12);
}

static inline bool is_21b_int(long val)
{
	return -(1L << 20) <= val && val < (1L << 20);
}

static inline int rv_offset(int insn, int off, struct rv_jit_context *ctx)
{
	int from, to;

	off++; /* BPF branch is from PC+1, RV is from PC */
	from = (insn > 0) ? ctx->offset[insn - 1] : 0;
	to = (insn + off > 0) ? ctx->offset[insn + off - 1] : 0;
	return (to - from) << 2;
}

/* Instruction formats. */

static inline u32 rv_r_insn(u8 funct7, u8 rs2, u8 rs1, u8 funct3, u8 rd,
			    u8 opcode)
{
	return (funct7 << 25) | (rs2 << 20) | (rs1 << 15) | (funct3 << 12) |
		(rd << 7) | opcode;
}

static inline u32 rv_i_insn(u16 imm11_0, u8 rs1, u8 funct3, u8 rd, u8 opcode)
{
	return (imm11_0 << 20) | (rs1 << 15) | (funct3 << 12) | (rd << 7) |
		opcode;
}

static inline u32 rv_s_insn(u16 imm11_0, u8 rs2, u8 rs1, u8 funct3, u8 opcode)
{
	u8 imm11_5 = imm11_0 >> 5, imm4_0 = imm11_0 & 0x1f;

	return (imm11_5 << 25) | (rs2 << 20) | (rs1 << 15) | (funct3 << 12) |
		(imm4_0 << 7) | opcode;
}

static inline u32 rv_b_insn(u16 imm12_1, u8 rs2, u8 rs1, u8 funct3, u8 opcode)
{
	u8 imm12 = ((imm12_1 & 0x800) >> 5) | ((imm12_1 & 0x3f0) >> 4);
	u8 imm4_1 = ((imm12_1 & 0xf) << 1) | ((imm12_1 & 0x400) >> 10);

	return (imm12 << 25) | (rs2 << 20) | (rs1 << 15) | (funct3 << 12) |
		(imm4_1 << 7) | opcode;
}

static inline u32 rv_u_insn(u32 imm31_12, u8 rd, u8 opcode)
{
	return (imm31_12 << 12) | (rd << 7) | opcode;
}

static inline u32 rv_j_insn(u32 imm20_1, u8 rd, u8 opcode)
{
	u32 imm;

	imm = (imm20_1 & 0x80000) | ((imm20_1 & 0x3ff) << 9) |
		((imm20_1 & 0x400) >> 2) | ((imm20_1 & 0x7f800) >> 11);

	return (imm << 12) | (rd << 7) | opcode;
}

static inline u32 rv_amo_insn(u8 funct5, u8 aq, u8 rl, u8 rs2, u8 rs1,
			      u8 funct3, u8 rd, u8 opcode)
{
	u8 funct7 = (funct5 << 2) | (aq << 1) | rl;

	return rv_r_insn(funct7, rs2, rs1, funct3, rd, opcode);
}

/* Instructions shared by both RV32 and RV64. */

static inline u32 rv_addi(u8 rd, u8 rs1, u16 imm11_0)
{
	return rv_i_insn(imm11_0, rs1, 0, rd, 0x13);
}

static inline u32 rv_andi(u8 rd, u8 rs1, u16 imm11_0)
{
	return rv_i_insn(imm11_0, rs1, 7, rd, 0x13);
}

static inline u32 rv_ori(u8 rd, u8 rs1, u16 imm11_0)
{
	return rv_i_insn(imm11_0, rs1, 6, rd, 0x13);
}

static inline u32 rv_xori(u8 rd, u8 rs1, u16 imm11_0)
{
	return rv_i_insn(imm11_0, rs1, 4, rd, 0x13);
}

static inline u32 rv_slli(u8 rd, u8 rs1, u16 imm11_0)
{
	return rv_i_insn(imm11_0, rs1, 1, rd, 0x13);
}

static inline u32 rv_srli(u8 rd, u8 rs1, u16 imm11_0)
{
	return rv_i_insn(imm11_0, rs1, 5, rd, 0x13);
}

static inline u32 rv_srai(u8 rd, u8 rs1, u16 imm11_0)
{
	return rv_i_insn(0x400 | imm11_0, rs1, 5, rd, 0x13);
}

static inline u32 rv_lui(u8 rd, u32 imm31_12)
{
	return rv_u_insn(imm31_12, rd, 0x37);
}

static inline u32 rv_auipc(u8 rd, u32 imm31_12)
{
	return rv_u_insn(imm31_12, rd, 0x17);
}

static inline u32 rv_add(u8 rd, u8 rs1, u8 rs2)
{
	return rv_r_insn(0, rs2, rs1, 0, rd, 0x33);
}

static inline u32 rv_sub(u8 rd, u8 rs1, u8 rs2)
{
	return rv_r_insn(0x20, rs2, rs1, 0, rd, 0x33);
}

static inline u32 rv_sltu(u8 rd, u8 rs1, u8 rs2)
{
	return rv_r_insn(0, rs2, rs1, 3, rd, 0x33);
}

static inline u32 rv_and(u8 rd, u8 rs1, u8 rs2)
{
	return rv_r_insn(0, rs2, rs1, 7, rd, 0x33);
}

static inline u32 rv_or(u8 rd, u8 rs1, u8 rs2)
{
	return rv_r_insn(0, rs2, rs1, 6, rd, 0x33);
}

static inline u32 rv_xor(u8 rd, u8 rs1, u8 rs2)
{
	return rv_r_insn(0, rs2, rs1, 4, rd, 0x33);
}

static inline u32 rv_sll(u8 rd, u8 rs1, u8 rs2)
{
	return rv_r_insn(0, rs2, rs1, 1, rd, 0x33);
}

static inline u32 rv_srl(u8 rd, u8 rs1, u8 rs2)
{
	return rv_r_insn(0, rs2, rs1, 5, rd, 0x33);
}

static inline u32 rv_sra(u8 rd, u8 rs1, u8 rs2)
{
	return rv_r_insn(0x20, rs2, rs1, 5, rd, 0x33);
}

static inline u32 rv_mul(u8 rd, u8 rs1, u8 rs2)
{
	return rv_r_insn(1, rs2, rs1, 0, rd, 0x33);
}

static inline u32 rv_mulhu(u8 rd, u8 rs1, u8 rs2)
{
	return rv_r_insn(1, rs2, rs1, 3, rd, 0x33);
}

static inline u32 rv_divu(u8 rd, u8 rs1, u8 rs2)
{
	return rv_r_insn(1, rs2, rs1, 5, rd, 0x33);
}

static inline u32 rv_remu(u8 rd, u8 rs1, u8 rs2)
{
	return rv_r_insn(1, rs2, rs1, 7, rd, 0x33);
}

static inline u32 rv_jal(u8 rd, u32 imm20_1)
{
	return rv_j_insn(imm20_1, rd, 0x6f);
}

static inline u32 rv_jalr(u8 rd, u8 rs1, u16 imm11_0)
{
	return rv_i_insn(imm11_0, rs1, 0, rd, 0x67);
}

static inline u32 rv_beq(u8 rs1, u8 rs2, u16 imm12_1)
{
	return rv_b_insn(imm12_1, rs2, rs1, 0, 0x63);
}

static inline u32 rv_bne(u8 rs1, u8 rs2, u16 imm12_1)
{
	return rv_b_insn(imm12_1, rs2, rs1, 1, 0x63);
}

static inline u32 rv_bltu(u8 rs1, u8 rs2, u16 imm12_1)
{
	return rv_b_insn(imm12_1, rs2, rs1, 6, 0x63);
}

static inline u32 rv_bgtu(u8 rs1, u8 rs2, u16 imm12_1)
{
	return rv_bltu(rs2, rs1, imm12_1);
}

static inline u32 rv_bgeu(u8 rs1, u8 rs2, u16 imm12_1)
{
	return rv_b_insn(imm12_1, rs2, rs1, 7, 0x63);
}

static inline u32 rv_bleu(u8 rs1, u8 rs2, u16 imm12_1)
{
	return rv_bgeu(rs2, rs1, imm12_1);
}

static inline u32 rv_blt(u8 rs1, u8 rs2, u16 imm12_1)
{
	return rv_b_insn(imm12_1, rs2, rs1, 4, 0x63);
}

static inline u32 rv_bgt(u8 rs1, u8 rs2, u16 imm12_1)
{
	return rv_blt(rs2, rs1, imm12_1);
}

static inline u32 rv_bge(u8 rs1, u8 rs2, u16 imm12_1)
{
	return rv_b_insn(imm12_1, rs2, rs1, 5, 0x63);
}

static inline u32 rv_ble(u8 rs1, u8 rs2, u16 imm12_1)
{
	return rv_bge(rs2, rs1, imm12_1);
}

static inline u32 rv_lw(u8 rd, u16 imm11_0, u8 rs1)
{
	return rv_i_insn(imm11_0, rs1, 2, rd, 0x03);
}

static inline u32 rv_lbu(u8 rd, u16 imm11_0, u8 rs1)
{
	return rv_i_insn(imm11_0, rs1, 4, rd, 0x03);
}

static inline u32 rv_lhu(u8 rd, u16 imm11_0, u8 rs1)
{
	return rv_i_insn(imm11_0, rs1, 5, rd, 0x03);
}

static inline u32 rv_sb(u8 rs1, u16 imm11_0, u8 rs2)
{
	return rv_s_insn(imm11_0, rs2, rs1, 0, 0x23);
}

static inline u32 rv_sh(u8 rs1, u16 imm11_0, u8 rs2)
{
	return rv_s_insn(imm11_0, rs2, rs1, 1, 0x23);
}

static inline u32 rv_sw(u8 rs1, u16 imm11_0, u8 rs2)
{
	return rv_s_insn(imm11_0, rs2, rs1, 2, 0x23);
}

static inline u32 rv_amoadd_w(u8 rd, u8 rs2, u8 rs1, u8 aq, u8 rl)
{
	return rv_amo_insn(0, aq, rl, rs2, rs1, 2, rd, 0x2f);
}

/*
 * RV64-only instructions.
 *
 * These instructions are not available on RV32.  Wrap them below a #if to
 * ensure that the RV32 JIT doesn't emit any of these instructions.
 */

#if __riscv_xlen == 64

static inline u32 rv_addiw(u8 rd, u8 rs1, u16 imm11_0)
{
	return rv_i_insn(imm11_0, rs1, 0, rd, 0x1b);
}

static inline u32 rv_slliw(u8 rd, u8 rs1, u16 imm11_0)
{
	return rv_i_insn(imm11_0, rs1, 1, rd, 0x1b);
}

static inline u32 rv_srliw(u8 rd, u8 rs1, u16 imm11_0)
{
	return rv_i_insn(imm11_0, rs1, 5, rd, 0x1b);
}

static inline u32 rv_sraiw(u8 rd, u8 rs1, u16 imm11_0)
{
	return rv_i_insn(0x400 | imm11_0, rs1, 5, rd, 0x1b);
}

static inline u32 rv_addw(u8 rd, u8 rs1, u8 rs2)
{
	return rv_r_insn(0, rs2, rs1, 0, rd, 0x3b);
}

static inline u32 rv_subw(u8 rd, u8 rs1, u8 rs2)
{
	return rv_r_insn(0x20, rs2, rs1, 0, rd, 0x3b);
}

static inline u32 rv_sllw(u8 rd, u8 rs1, u8 rs2)
{
	return rv_r_insn(0, rs2, rs1, 1, rd, 0x3b);
}

static inline u32 rv_srlw(u8 rd, u8 rs1, u8 rs2)
{
	return rv_r_insn(0, rs2, rs1, 5, rd, 0x3b);
}

static inline u32 rv_sraw(u8 rd, u8 rs1, u8 rs2)
{
	return rv_r_insn(0x20, rs2, rs1, 5, rd, 0x3b);
}

static inline u32 rv_mulw(u8 rd, u8 rs1, u8 rs2)
{
	return rv_r_insn(1, rs2, rs1, 0, rd, 0x3b);
}

static inline u32 rv_divuw(u8 rd, u8 rs1, u8 rs2)
{
	return rv_r_insn(1, rs2, rs1, 5, rd, 0x3b);
}

static inline u32 rv_remuw(u8 rd, u8 rs1, u8 rs2)
{
	return rv_r_insn(1, rs2, rs1, 7, rd, 0x3b);
}

static inline u32 rv_ld(u8 rd, u16 imm11_0, u8 rs1)
{
	return rv_i_insn(imm11_0, rs1, 3, rd, 0x03);
}

static inline u32 rv_lwu(u8 rd, u16 imm11_0, u8 rs1)
{
	return rv_i_insn(imm11_0, rs1, 6, rd, 0x03);
}

static inline u32 rv_sd(u8 rs1, u16 imm11_0, u8 rs2)
{
	return rv_s_insn(imm11_0, rs2, rs1, 3, 0x23);
}

static inline u32 rv_amoadd_d(u8 rd, u8 rs2, u8 rs1, u8 aq, u8 rl)
{
	return rv_amo_insn(0, aq, rl, rs2, rs1, 3, rd, 0x2f);
}

#endif /* __riscv_xlen == 64 */

void bpf_jit_build_prologue(struct rv_jit_context *ctx);
void bpf_jit_build_epilogue(struct rv_jit_context *ctx);

int bpf_jit_emit_insn(const struct bpf_insn *insn, struct rv_jit_context *ctx,
		      bool extra_pass);

#endif /* _BPF_JIT_H */