path: root/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>

static inline bool rvc_enabled(void)
{
	return IS_ENABLED(CONFIG_RISCV_ISA_C);
}

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,
};

static inline bool is_creg(u8 reg)
{
	return (1 << reg) & (BIT(RV_REG_FP) |
			     BIT(RV_REG_S1) |
			     BIT(RV_REG_A0) |
			     BIT(RV_REG_A1) |
			     BIT(RV_REG_A2) |
			     BIT(RV_REG_A3) |
			     BIT(RV_REG_A4) |
			     BIT(RV_REG_A5));
}

struct rv_jit_context {
	struct bpf_prog *prog;
	u16 *insns;		/* RV insns */
	int ninsns;
	int epilogue_offset;
	int *offset;		/* BPF to RV */
	unsigned long flags;
	int stack_size;
};

/* Convert from ninsns to bytes. */
static inline int ninsns_rvoff(int ninsns)
{
	return ninsns << 1;
}

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);
}

/* Emit a 4-byte riscv instruction. */
static inline void emit(const u32 insn, struct rv_jit_context *ctx)
{
	if (ctx->insns) {
		ctx->insns[ctx->ninsns] = insn;
		ctx->insns[ctx->ninsns + 1] = (insn >> 16);
	}

	ctx->ninsns += 2;
}

/* Emit a 2-byte riscv compressed instruction. */
static inline void emitc(const u16 insn, struct rv_jit_context *ctx)
{
	BUILD_BUG_ON(!rvc_enabled());

	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 ninsns_rvoff(to - from);
}

/* 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_6b_int(long val)
{
	return -(1L << 5) <= val && val < (1L << 5);
}

static inline bool is_7b_uint(unsigned long val)
{
	return val < (1UL << 7);
}

static inline bool is_8b_uint(unsigned long val)
{
	return val < (1UL << 8);
}

static inline bool is_9b_uint(unsigned long val)
{
	return val < (1UL << 9);
}

static inline bool is_10b_int(long val)
{
	return -(1L << 9) <= val && val < (1L << 9);
}

static inline bool is_10b_uint(unsigned long val)
{
	return val < (1UL << 10);
}

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 &l