arch/riscv/net/bpf_jit_comp32.c

// SPDX-License-Identifier: GPL-2.0
/*
 * BPF JIT compiler for RV32G
 *
 * Copyright (c) 2020 Luke Nelson <luke.r.nels@gmail.com>
 * Copyright (c) 2020 Xi Wang <xi.wang@gmail.com>
 *
 * The code is based on the BPF JIT compiler for RV64G by Björn Töpel and
 * the BPF JIT compiler for 32-bit ARM by Shubham Bansal and Mircea Gherzan.
 */

#include <linux/bpf.h>
#include <linux/filter.h>
#include "bpf_jit.h"

enum {
	/* Stack layout - these are offsets from (top of stack - 4). */
	BPF_R6_HI,
	BPF_R6_LO,
	BPF_R7_HI,
	BPF_R7_LO,
	BPF_R8_HI,
	BPF_R8_LO,
	BPF_R9_HI,
	BPF_R9_LO,
	BPF_AX_HI,
	BPF_AX_LO,
	/* Stack space for BPF_REG_6 through BPF_REG_9 and BPF_REG_AX. */
	BPF_JIT_SCRATCH_REGS,
};

#define STACK_OFFSET(k) (-4 - ((k) * 4))

#define TMP_REG_1	(MAX_BPF_JIT_REG + 0)
#define TMP_REG_2	(MAX_BPF_JIT_REG + 1)

#define RV_REG_TCC		RV_REG_T6
#define RV_REG_TCC_SAVED	RV_REG_S7

static const s8 bpf2rv32[][2] = {
	/* Return value from in-kernel function, and exit value from eBPF. */
	[BPF_REG_0] = {RV_REG_S2, RV_REG_S1},
	/* Arguments from eBPF program to in-kernel function. */
	[BPF_REG_1] = {RV_REG_A1, RV_REG_A0},
	[BPF_REG_2] = {RV_REG_A3, RV_REG_A2},
	[BPF_REG_3] = {RV_REG_A5, RV_REG_A4},
	[BPF_REG_4] = {RV_REG_A7, RV_REG_A6},
	[BPF_REG_5] = {RV_REG_S4, RV_REG_S3},
	/*
	 * Callee-saved registers that in-kernel function will preserve.
	 * Stored on the stack.
	 */
	[BPF_REG_6] = {STACK_OFFSET(BPF_R6_HI), STACK_OFFSET(BPF_R6_LO)},
	[BPF_REG_7] = {STACK_OFFSET(BPF_R7_HI), STACK_OFFSET(BPF_R7_LO)},
	[BPF_REG_8] = {STACK_OFFSET(BPF_R8_HI), STACK_OFFSET(BPF_R8_LO)},
	[BPF_REG_9] = {STACK_OFFSET(BPF_R9_HI), STACK_OFFSET(BPF_R9_LO)},
	/* Read-only frame pointer to access BPF stack. */
	[BPF_REG_FP] = {RV_REG_S6, RV_REG_S5},
	/* Temporary register for blinding constants. Stored on the stack. */
	[BPF_REG_AX] = {STACK_OFFSET(BPF_AX_HI), STACK_OFFSET(BPF_AX_LO)},
	/*
	 * Temporary registers used by the JIT to operate on registers stored
	 * on the stack. Save t0 and t1 to be used as temporaries in generated
	 * code.
	 */
	[TMP_REG_1] = {RV_REG_T3, RV_REG_T2},
	[TMP_REG_2] = {RV_REG_T5, RV_REG_T4},
};

static s8 hi(const s8 *r)
{
	return r[0];
}

static s8 lo(const s8 *r)
{
	return r[1];
}

static void emit_imm(const s8 rd, s32 imm, struct rv_jit_context *ctx)
{
	u32 upper = (imm + (1 << 11)) >> 12;
	u32 lower = imm & 0xfff;

	if (upper) {
		emit(rv_lui(rd, upper), ctx);
		emit(rv_addi(rd, rd, lower), ctx);
	} else {
		emit(rv_addi(rd, RV_REG_ZERO, lower), ctx);
	}
}

static void emit_imm32(const s8 *rd, s32 imm, struct rv_jit_context *ctx)
{
	/* Emit immediate into lower bits. */
	emit_imm(lo(rd), imm, ctx);

	/* Sign-extend into upper bits. */
	if (imm >= 0)
		emit(rv_addi(hi(rd), RV_REG_ZERO, 0), ctx);
	else
		emit(rv_addi(hi(rd), RV_REG_ZERO, -1), ctx);
}

static void emit_imm64(const s8 *rd, s32 imm_hi, s32 imm_lo,
		       struct rv_jit_context *ctx)
{
	emit_imm(lo(rd), imm_lo, ctx);
	emit_imm(hi(rd), imm_hi, ctx);
}

static void __build_epilogue(bool is_tail_call, struct rv_jit_context *ctx)
{
	int stack_adjust = ctx->stack_size, store_offset = stack_adjust - 4;
	const s8 *r0 = bpf2rv32[BPF_REG_0];

	store_offset -= 4 * BPF_JIT_SCRATCH_REGS;

	/* Set return value if not tail call. */
	if (!is_tail_call) {
		emit(rv_addi(RV_REG_A0, lo(r0), 0), ctx);
		emit(rv_addi(RV_REG_A1, hi(r0), 0), ctx);
	}

	/* Restore callee-saved registers. */
	emit(rv_lw(RV_REG_RA, store_offset - 0, RV_REG_SP), ctx);
	emit(rv_lw(RV_REG_FP, store_offset - 4, RV_REG_SP), ctx);
	emit(rv_lw(RV_REG_S1, store_offset - 8, RV_REG_SP), ctx);
	emit(rv_lw(RV_REG_S2, store_offset - 12, RV_REG_SP), ctx);
	emit(rv_lw(RV_REG_S3, store_offset - 16, RV_REG_SP), ctx);
	emit(rv_lw(RV_REG_S4, store_offset - 20, RV_REG_SP), ctx);
	emit(rv_lw(RV_REG_S5, store_offset - 24, RV_REG_SP), ctx);
	emit(rv_lw(RV_REG_S6, store_offset - 28, RV_REG_SP), ctx);
	emit(rv_lw(RV_REG_S7, store_offset - 32, RV_REG_SP), ctx);

	emit(rv_addi(RV_REG_SP, RV_REG_SP, stack_adjust), ctx);

	if (is_tail_call) {
		/*
		 * goto *(t0 + 4);
		 * Skips first instruction of prologue which initializes tail
		 * call counter. Assumes t0 contains address of target program,
		 * see emit_bpf_tail_call.
		 */
		emit(rv_jalr(RV_REG_ZERO, RV_REG_T0, 4), ctx);
	} else {
		emit(rv_jalr(RV_REG_ZERO, RV_REG_RA, 0), ctx);
	}
}

static bool is_stacked(s8 reg)
{
	return reg < 0;
}

static const s8 *bpf_get_reg64(const s8 *reg, const s8 *tmp,
			       struct rv_jit_context *ctx)
{
	if (is_stacked(hi(reg))) {
		emit(rv_lw(hi(tmp), hi(reg), RV_REG_FP), ctx);
		emit(rv_lw(lo(tmp), lo(reg), RV_REG_FP), ctx);
		reg = tmp;
	}
	return reg;
}

static void bpf_put_reg64(const s8 *reg, const s8 *src,
			  struct rv_jit_context *ctx)
{
	if (is_stacked(hi(reg))) {
		emit(rv_sw(RV_REG_FP, hi(reg), hi(src)), ctx);
		emit(rv_sw(RV_REG_FP, lo(reg), lo(src)), ctx);
	}
}

static const s8 *bpf_get_reg32(const s8 *reg, const s8 *tmp,
			       struct rv_jit_context *ctx)
{
	if (is_stacked(lo(reg))) {
		emit(rv_lw(lo(tmp), lo(reg), RV_REG_FP), ctx);
		reg = tmp;
	}
	return reg;
}

static void bpf_put_reg32(const s8 *reg, const s8 *src,
			  struct rv_jit_context *ctx)
{
	if (is_stacked(lo(reg))) {
		emit(rv_sw(RV_REG_FP, lo(reg), lo(src)), ctx);
		if (!ctx->prog->aux->verifier_zext)
			emit(rv_sw(RV_REG_FP, hi(reg), RV_REG_ZERO), ctx);
	} else if (!ctx->prog->aux->verifier_zext) {
		emit(rv_addi(hi(reg), RV_REG_ZERO, 0), ctx);
	}
}

static void emit_jump_and_link(u8 rd, s32 rvoff, bool force_jalr,
			       struct rv_jit_context *ctx)
{
	s32 upper, lower;

	if (rvoff && is_21b_int(rvoff) && !force_jalr) {
		emit(rv_jal(rd, rvoff >> 1), ctx);
		return;
	}

	upper = (rvoff + (1 << 11)) >> 12;
	lower = rvoff & 0xfff;
	emit(rv_auipc(RV_REG_T1, upper), ctx);
	emit(rv_jalr(rd, RV_REG_T1, lower), ctx);
}

static void emit_alu_i64(const s8 *dst, s32 imm,
			 struct rv_jit_context *ctx, const u8 op)
{
	const s8 *tmp1 = bpf2rv32[TMP_REG_1];
	const s8 *rd = bpf_get_reg64(dst, tmp1, ctx);

	switch (op) {
	case BPF_MOV:
		emit_imm32(rd, imm, ctx);
		break;
	case BPF_AND:
		if (is_12b_int(imm)) {
			emit(rv_andi(lo(rd), lo(rd), imm), ctx);
		} else {
			emit_imm(RV_REG_T0, imm, ctx);
			emit(rv_and(lo(rd), lo(rd), RV_REG_T0), ctx);
		}
		if (imm >= 0)
			emit(rv_addi(hi(rd), RV_REG_ZERO, 0), ctx);
		break;
	case BPF_OR:
		if (is_12b_int(imm)) {
			emit(rv_ori(lo(rd), lo(rd), imm), ctx);
		} else {
			emit_imm(RV_REG_T0, imm, ctx);
			emit(rv_or(lo(rd), lo(rd), RV_REG_T0), ctx);
		}
		if (imm < 0)
			emit(rv_ori(hi(rd), RV_REG_ZERO, -1), ctx);
		break;
	case BPF_XOR:
		if (is_12b_int(imm)) {
			emit(rv_xori(lo(rd), lo(rd), imm), ctx);
		} else {
			emit_imm(RV_REG_T0, imm, ctx);
			emit(rv_xor(lo(rd), lo(rd), RV_REG_T0), ctx);
		}
		if (imm < 0)
			emit(rv_xori(hi(rd), hi(rd), -1), ctx);
		break;
	case BPF_LSH:
		if (imm >= 32) {
			emit(rv_slli(hi(rd), lo(rd), imm - 32), ctx);
			emit(rv_addi(lo(rd), RV_REG_ZERO, 0), ctx);
		} else if (imm == 0) {
			/* Do nothing. */
		} else {
			emit(rv_srli(RV_REG_T0, lo(rd), 32 - imm), ctx);
			emit(rv_slli(hi(rd), hi(rd), imm), ctx);
			emit(rv_or(hi(rd), RV_REG_T0, hi(rd)), ctx);
			emit(rv_slli(lo(rd), lo(rd), imm), ctx);
		}
		break;
	case BPF_RSH:
		if (imm >= 32) {
			emit(rv_srli(lo(rd), hi(rd), imm - 32), ctx);
			emit(rv_addi(hi(rd), RV_REG_ZERO, 0), ctx);
		} else if (imm == 0) {
			/* Do nothing. */
		} else {
			emit(rv_slli(RV_REG_T0, hi(rd), 32 - imm), ctx);
			emit(rv_srli(lo(rd), lo(rd), imm), ctx);
			emit(rv_or(lo(rd), RV_REG_T0, lo(rd)), ctx);
			emit(rv_srli(hi(rd), hi(rd), imm), ctx);
		}
		break;
	case BPF_ARSH:
		if (imm >= 32) {
			emit(rv_srai(lo(rd), hi(rd), imm - 32), ctx);
			emit(rv_srai(hi(rd), hi(rd), 31), ctx);
		} else if (imm == 0) {
			/* Do nothing. */
		} else {
			emit(rv_slli(RV_REG_T0, hi(rd), 32 - imm), ctx);
			emit(rv_srli(lo(rd), lo(rd), imm), ctx);
			emit(rv_or(lo(rd), RV_REG_T0, lo(rd)), ctx);
			emit(rv_srai(hi(rd), hi(rd), imm), ctx);
		}
		break;
	}

	bpf_put_reg64(dst, rd, ctx);
}

static void emit_alu_i32(const s8 *dst, s32 imm,
			 struct rv_jit_context *ctx, const u8 op)
{
	const s8 *tmp1 = bpf2rv32[TMP_REG_1];
	const s8 *rd = bpf_get_reg32(dst, tmp1, ctx);

	switch (op) {
	case BPF_MOV:
		emit_imm(lo(rd), imm, ctx);
		break;
	case BPF_ADD:
		if (is_12b_int(imm)) {
			emit(rv_addi(lo(rd), lo(rd), imm), ctx);
		} else {
			emit_imm(RV_REG_T0, imm, ctx);
			emit(rv_add(lo(rd), lo(rd), RV_REG_T0), ctx);
		}
		break;
	case BPF_SUB:
		if (is_12b_int(-imm)) {
			emit(rv_addi(lo(rd), lo(rd), -imm), ctx);
		} else {
			emit_imm(RV_REG_T0, imm, ctx);
			emit(rv_sub(lo(rd), lo(rd), RV_REG_T0), ctx);
		}
		break;
	case BPF_AND:
		if (is_12b_int(imm)) {
			emit(rv_andi(lo(rd), lo(rd), imm), ctx);
		} else {
			emit_imm(RV_REG_T0, imm, ctx);
			emit(rv_and(lo(rd), lo(rd), RV_REG_T0), ctx);
		}
		break;
	case BPF_OR:
		if (is_12b_int(imm)) {
			emit(rv_ori(lo(rd), lo(rd), imm), ctx);
		} else {
			emit_imm(RV_REG_T0, imm, ctx);
			emit(rv_or(lo(rd), lo(rd), RV_REG_T0), ctx);
		}
		break;
	case BPF_XOR:
		if (is_12b_int(imm)) {
			emit(rv_xori(lo(rd), lo(rd), imm), ctx);
		} else {
			emit_imm(RV_REG_T0, imm, ctx);
			emit(rv_xor(lo(rd), lo(rd), RV_REG_T0), ctx);
		}
		break;
	case BPF_LSH:
		if (is_12b_int(imm)) {
			emit(rv_slli(lo(rd), lo(rd), imm), ctx);
		} else {
			emit_imm(RV_REG_T0, imm, ctx);
			emit(rv_sll(lo(rd), lo(rd), RV_REG_T0), ctx);
		}
		break;
	case BPF_RSH:
		if (is_12b_int(imm)) {
			emit(rv_srli(lo(rd), lo(rd), imm), ctx);
		} else {
			emit_imm(RV_REG_T0, imm, ctx);
			emit(rv_srl(lo(rd), lo(rd), RV_REG_T0), ctx);
		}
		break;
	case BPF_ARSH:
		if (is_12b_int(imm)) {
			emit(rv_srai(lo(rd), lo(rd), imm), ctx);
		} else {
			emit_imm(RV_REG_T0, imm, ctx);
			emit(rv_sra(lo(rd), lo(rd), RV_REG_T0), ctx);
		}
		break;
	}

	bpf_put_reg32(dst, rd, ctx);
}

static void emit_alu_r64(const s8 *dst, const s8 *src,
			 struct rv_jit_context *ctx, const u8 op)
{
	const s8 *tmp1 = bpf2rv32[TMP_REG_1];
	const s8 *tmp2 = bpf2rv32[TMP_REG_2];
	const s8 *rd = bpf_get_reg64(dst, tmp1, ctx);
	const s8 *rs = bpf_get_reg64(src, tmp2, ctx);

	switch (op) {
	case BPF_MOV:
		emit(rv_addi(lo(rd), lo(rs), 0), ctx);
		emit(rv_addi(hi(rd), hi(rs), 0), ctx);
		break;
	case BPF_ADD:
		if (rd == rs) {
			emit(rv_srli(RV_REG_T0, lo(rd), 31), ctx);
			emit(rv_slli(hi(rd), hi(rd), 1), ctx);
			emit(rv_or(hi(rd), RV_REG_T0, hi(rd)), ctx);
			emit(rv_slli(lo(rd), lo(rd), 1), ctx);
		} else {
			emit(rv_add(lo(rd), lo(rd), lo(rs)), ctx);
			emit(rv_sltu(RV_REG_T0, lo(rd), lo(rs)), ctx);
			emit(rv_add(hi(rd), hi(rd), hi(rs)), ctx);
			emit(rv_add(hi(rd), hi(rd), RV_REG_T0), ctx);
		}
		break;
	case BPF_SUB:
		emit(rv_sub(RV_REG_T1, hi(rd), hi(rs)), ctx);
		emit(rv_sltu(RV_REG_T0, lo(rd), lo(rs)), ctx);
		emit(rv_sub(hi(rd), RV_REG_T1, RV_REG_T0), ctx);
		emit(rv_sub(lo(rd), lo(rd), lo(rs)), ctx);
		break;
	case BPF_AND:
		emit(rv_and(lo(rd), lo(rd), lo(rs)), ctx);
		emit(rv_and(hi(rd), hi(rd), hi(rs)), ctx);
		break;
	case BPF_OR:
		emit(rv_or(lo(rd), lo(rd), lo(rs)), ctx);
		emit(rv_or(hi(rd), hi(rd), hi(rs)), ctx);
		break;
	case BPF_XOR:
		emit(rv_xor(lo(rd), lo(rd), lo(rs)), ctx);
		emit(rv_xor(hi(rd), hi(rd), hi(rs)), ctx);
		break;
	case BPF_MUL:
		emit(rv_mul(RV_REG_T0, hi(rs), lo(rd)), ctx);
		emit(rv_mul(hi(rd), hi(rd), lo(rs)), ctx);
		emit(rv_mulhu(RV_REG_T1, lo(rd), lo(rs)), ctx);
		emit(rv_add(hi(rd), hi(rd), RV_REG_T0), ctx);
		emit(rv_mul(lo(rd), lo(rd), lo(rs)), ctx);
		emit(rv_add(hi(rd), hi(rd), RV_REG_T1), ctx);
		break;
	case BPF_LSH:
		emit(rv_addi(RV_REG_T0, lo(rs), -32), ctx);
		emit(rv_blt(RV_REG_T0, RV_REG_ZERO, 8), ctx);
		emit(rv_sll(hi(rd), lo(rd), RV_REG_T0), ctx);
		emit(rv_addi(lo(rd), RV_REG_ZERO, 0), ctx);
		emit(rv_jal(RV_REG_ZERO, 16), ctx);
		emit(rv_addi(RV_REG_T1, RV_REG_ZERO, 31), ctx);
		emit(rv_srli(RV_REG_T0, lo(rd), 1), ctx);
		emit(rv_sub(RV_REG_T1, RV_REG_T1, lo(rs)), ctx);
		emit(rv_srl(RV_REG_T0, RV_REG_T0, RV_REG_T1), ctx);
		emit(rv_sll(hi(rd), hi(rd), lo(rs)), ctx);
		emit(rv_or(hi(rd), RV_REG_T0, hi(rd)), ctx);
		emit(rv_sll(lo(rd), lo(rd), lo(rs)), ctx);
		break;
	case BPF_RSH:
		emit(rv_addi(RV_REG_T0, lo(rs), -32), ctx);
		emit(rv_blt(RV_REG_T0, RV_REG_ZERO, 8), ctx);
		emit(rv_srl(lo(rd), hi(rd), RV_REG_T0), ctx);
		emit(rv_addi(hi(rd), RV_REG_ZERO, 0), ctx);
		emit(rv_jal(RV_REG_ZERO, 16), ctx);
		emit(rv_addi(RV_REG_T1, RV_REG_ZERO, 31), ctx);
		emit(rv_slli(RV_REG_T0, hi(rd), 1), ctx);
		emit(rv_sub(RV_REG_T1, RV_REG_T1, lo(rs)), ctx);
		emit(rv_sll(RV_REG_T0, RV_REG_T0, RV_REG_T1), ctx);
		emit(rv_srl(lo(rd), lo(rd), lo(rs)), ctx);
		emit(rv_or(lo(rd), RV_REG_T0, lo(rd)), ctx);
		emit(rv_srl(hi(rd), hi(rd), lo(rs)), ctx);
		break;
	case BPF_ARSH:
		emit(rv_addi(RV_REG_T0, lo(rs), -32), ctx);
		emit(rv_blt(RV_REG_T0, RV_REG_ZERO, 8), ctx);
		emit(rv_sra(lo(rd), hi(rd), RV_REG_T0), ctx);
		emit(rv_srai(hi(rd), hi(rd), 31), ctx);
		emit(rv_jal(RV_REG_ZERO, 16), ctx);
		emit(rv_addi(RV_REG_T1, RV_REG_ZERO, 31), ctx);
		emit(rv_slli(RV_REG_T0, hi(rd), 1), ctx);
		emit(rv_sub(RV_REG_T1, RV_REG_T1, lo(rs)), ctx);
		emit(rv_sll(RV_REG_T0, RV_REG_T0, RV_REG_T1), ctx);
		emit(rv_srl(lo(rd), lo(rd), lo(rs)), ctx);
		emit(rv_or(lo(rd), RV_REG_T0, lo(rd)), ctx);
		emit(rv_sra(hi(rd), hi(rd), lo(rs)), ctx);
		break;
	case BPF_NEG:
		emit(rv_sub(lo(rd), RV_REG_ZERO, lo(rd)), ctx);
		emit(rv_sltu(RV_REG_T0, RV_REG_ZERO, lo(rd)), ctx);
		emit(rv_sub(hi(rd), RV_REG_ZERO, hi(rd)), ctx);
		emit(rv_sub(hi(rd), hi(rd), RV_REG_T0), ctx);
		break;
	}

	bpf_put_reg64(dst, rd, ctx);
}

static void emit_alu_r32(const s8 *dst, const s8 *src,
			 struct rv_jit_context *ctx, const u8 op)
{
	const s8 *tmp1 = bpf2rv32[TMP_REG_1];
	const s8 *tmp2 = bpf2rv32[TMP_REG_2];
	const s8 *rd = bpf_get_reg32(dst, tmp1, ctx);
	const s8 *rs = bpf_get_reg32(src, tmp2, ctx);

	switch (op) {
	case BPF_MOV:
		emit(rv_addi(lo(rd), lo(rs), 0), ctx);
		break;
	case BPF_ADD:
		emit(rv_add(lo(rd), lo(rd), lo(rs)), ctx);
		break;
	case BPF_SUB:
		emit(rv_sub(lo(rd), lo(rd), lo(rs)), ctx);
		break;
	case BPF_AND:
		emit(rv_and(lo(rd), lo(rd), lo(rs)), ctx);
		break;
	case BPF_OR:
		emit(rv_or(lo(rd), lo(rd), lo(rs)), ctx);
		break;
	case BPF_XOR:
		emit(rv_xor(lo(rd), lo(rd), lo(rs)), ctx);
		break;
	case BPF_MUL:
		emit(rv_mul(lo(rd), lo(rd), lo(rs)), ctx);
		break;
	case BPF_DIV:
		emit(rv_divu(lo(rd), lo(rd), lo(rs)), ctx);
		break;
	case BPF_MOD:
		emit(rv_remu(lo(rd), lo(rd), lo(rs)), ctx);
		break;
	case BPF_LSH:
		emit(rv_sll(lo(rd), lo(rd), lo(rs)), ctx);
		break;
	case BPF_RSH:
		emit(rv_srl(lo(rd), lo(rd), lo(rs)), ctx);
		break;
	case BPF_ARSH:
		emit(rv_sra(lo(rd), lo(rd), lo(rs)), ctx);
		break;
	case BPF_NEG:
		emit(rv_sub(lo(rd), RV_REG_ZERO, lo(rd)), ctx);
		break;
	}

	bpf_put_reg32(dst, rd, ctx);
}

static int emit_branch_r64(const s8 *src1, const s8 *src2, s32 rvoff,
			   struct rv_jit_context *ctx, const u8 op)
{
	int e, s = ctx->ninsns;
	const s8 *tmp1 = bpf2rv32[TMP_REG_1];
	const s8 *tmp2 = bpf2rv32[TMP_REG_2];

	const s8 *rs1 = bpf_get_reg64(src1, tmp1, ctx);
	const s8 *rs2 = bpf_get_reg64(src2, tmp2, ctx);

	/*
	 * NO_JUMP skips over the rest of the instructions and the
	 * emit_jump_and_link, meaning the BPF branch is not taken.
	 * JUMP skips directly to the emit_jump_and_link, meaning
	 * the BPF branch is taken.
	 *
	 * The fallthrough case results in the BPF branch being taken.
	 */
#define NO_JUMP(idx) (6 + (2 * (idx)))
#define JUMP(idx) (2 + (2 * (idx)))

	switch (op) {
	case BPF_JEQ:
		emit(rv_bne(hi(rs1), hi(rs2), NO_JUMP(1)), ctx);
		emit(rv_bne(lo(rs1), lo(rs2), NO_JUMP(0)), ctx);
		break;
	case BPF_JGT:
		emit(rv_bgtu(hi(rs1), hi(rs2), JUMP(2)), ctx);
		emit(rv_bltu(hi(rs1), hi(rs2), NO_JUMP(1)), ctx);
		emit(rv_bleu(lo(rs1), lo(rs2), NO_JUMP(0)), ctx);
		break;
	case BPF_JLT:
		emit(rv_bltu(hi(rs1), hi(rs2), JUMP(2)), ctx);
		emit(rv_bgtu(hi(rs1), hi(rs2), NO_JUMP(1)), ctx);
		emit(rv_bgeu(lo(rs1), lo(rs2), NO_JUMP(0)), ctx);
		break;
	case BPF_JGE:
		emit(rv_bgtu(hi(rs1), hi(rs2), JUMP(2)), ctx);
		emit(rv_bltu(hi(rs1), hi(rs2), NO_JUMP(1)), ctx);
		emit(rv_bltu(lo(rs1), lo(rs2), NO_JUMP(0)), ctx);
		break;
	case BPF_JLE:
		emit(rv_bltu(hi(rs1), hi(rs2), JUMP(2)), ctx);
		emit(rv_bgtu(hi(rs1), hi(rs2), NO_JUMP(1)), ctx);
		emit(rv_bgtu(lo(rs1), lo(rs2), NO_JUMP(0)), ctx);
		break;
	case BPF_JNE:
		emit(rv_bne(hi(rs1), hi(rs2), JUMP(1)), ctx);
		emit(rv_beq(lo(rs1), lo(rs2), NO_JUMP(0)), ctx);
		break;
	case BPF_JSGT:
		emit(rv_bgt(hi(rs1), hi(rs2), JUMP(2)), ctx);
		emit(rv_blt(hi(rs1), hi(rs2), NO_JUMP(1)), ctx);
		emit(rv_bleu(lo(rs1), lo(rs2), NO_JUMP(0)), ctx);
		break;
	case BPF_JSLT:
		emit(rv_blt(hi(rs1), hi(rs2), JUMP(2)), ctx);
		emit(rv_bgt(hi(rs1), hi(rs2), NO_JUMP(1)), ctx);
		emit(rv_bgeu(lo(rs1), lo(rs2), NO_JUMP(0)), ctx);
		break;
	case BPF_JSGE:
		emit(rv_bgt(hi(rs1), hi(rs2), JUMP(2)), ctx);
		emit(rv_blt(hi(rs1), hi(rs2), NO_JUMP(1)), ctx);
		emit(rv_bltu(lo(rs1), lo(rs2), NO_JUMP(0)), ctx);
		break;
	case BPF_JSLE:
		emit(rv_blt(hi(rs1), hi(rs2), JUMP(2)), ctx);
		emit(rv_bgt(hi(rs1), hi(rs2), NO_JUMP(1)), ctx);
		emit(rv_bgtu(lo(rs1), lo(rs2), NO_JUMP(0)), ctx);
		break;
	case BPF_JSET:
		emit(rv_and(RV_REG_T0, hi(rs1), hi(rs2)), ctx);
		emit(rv_bne(RV_REG_T0, RV_REG_ZERO, JUMP(2)), ctx);
		emit(rv_and(RV_REG_T0, lo(rs1), lo(rs2)), ctx);
		emit(rv_beq(RV_REG_T0, RV_REG_ZERO, NO_JUMP(0)), ctx);
		break;
	}

#undef NO_JUMP
#undef JUMP

	e = ctx->ninsns;
	/* Adjust for extra insns. */
	rvoff -= (e - s) << 2;
	emit_jump_and_link(RV_REG_ZERO, rvoff, true, ctx);
	return 0;
}

static int emit_bcc(u8 op, u8 rd, u8 rs, int rvoff, struct rv_jit_context *ctx)
{
	int e, s = ctx->ninsns;
	bool far = false;
	int off;

	if (op == BPF_JSET) {
		/*
		 * BPF_JSET is a special case: it has no inverse so we always
		 * treat it as a far branch.
		 */
		far = true;
	} else if (!is_13b_int(rvoff)) {
		op = invert_bpf_cond(op);
		far = true;
	}

	/*
	 * For a far branch, the condition is negated and we jump over the
	 * branch itself, and the two instructions from emit_jump_and_link.
	 * For a near branch, just use rvoff.
	 */
	off = far ? 6 : (rvoff >> 1);

	switch (op) {
	case BPF_JEQ:
		emit(rv_beq(rd, rs, off), ctx);
		break;
	case BPF_JGT:
		emit(rv_bgtu(rd, rs, off), ctx);
		break;
	case BPF_JLT:
		emit(rv_bltu(rd, rs, off), ctx);
		break;
	case BPF_JGE:
		emit(rv_bgeu(rd, rs, off), ctx);
		break;
	case BPF_JLE:
		emit(rv_bleu(rd, rs, off), ctx);
		break;
	case BPF_JNE:
		emit(rv_bne(rd, rs, off), ctx);
		break;
	case BPF_JSGT:
		emit(rv_bgt(rd, rs, off), ctx);
		break;
	case BPF_JSLT:
		emit(rv_blt(rd, rs, off), ctx);
		break;
	case BPF_JSGE:
		emit(rv_bge(rd, rs, off), ctx);
		break;
	case BPF_JSLE:
		emit(rv_ble(rd, rs, off), ctx);
		break;
	case BPF_JSET:
		emit(rv_and(RV_REG_T0, rd, rs), ctx);
		emit(rv_beq(RV_REG_T0, RV_REG_ZERO, off), ctx);
		break;
	}

	if (far) {
		e = ctx->ninsns;
		/* Adjust for extra insns. */
		rvoff -= (e - s) << 2;
		emit_jump_and_link(RV_REG_ZERO, rvoff, true, ctx);
	}
	return 0;
}

static int emit_branch_r32(const s8 *src1, const s8 *src2, s32 rvoff,
			   struct rv_jit_context *ctx, const u8 op)
{
	int e, s = ctx->ninsns;
	const s8 *tmp1 = bpf2rv32[TMP_REG_1];
	const s8 *tmp2 = bpf2rv32[TMP_REG_2];

	const s8 *rs1 = bpf_get_reg32(src1, tmp1, ctx);
	const s8 *rs2 = bpf_get_reg32(src2, tmp2, ctx);

	e = ctx->ninsns;
	/* Adjust for extra insns. */
	rvoff -= (e - s) << 2;

	if (emit_bcc(op, lo(rs1), lo(rs2), rvoff, ctx))
		return -1;

	return 0;
}

static void emit_call(bool fixed, u64 addr, struct rv_jit_context *ctx)
{
	const s8 *r0 = bpf2rv32[BPF_REG_0];
	const s8 *r5 = bpf2rv32[BPF_REG_5];
	u32 upper = ((u32)addr + (1 << 11)) >> 12;
	u32 lower = addr & 0xfff;

	/* R1-R4 already in correct registers---need to push R5 to stack. */
	emit(rv_addi(RV_REG_SP, RV_REG_SP, -16), ctx);
	emit(rv_sw(RV_REG_SP, 0, lo(r5)), ctx);
	emit(rv_sw(RV_REG_SP, 4, hi(r5)), ctx);

	/* Backup TCC. */
	emit(rv_addi(RV_REG_TCC_SAVED, RV_REG_TCC, 0), ctx);

	/*
	 * Use lui/jalr pair to jump to absolute address. Don't use emit_imm as
	 * the number of emitted instructions should not depend on the value of
	 * addr.
	 */
	emit(rv_lui(RV_REG_T1, upper), ctx);
	emit(rv_jalr(RV_REG_RA, RV_REG_T1, lower), ctx);

	/* Restore TCC. */
	emit(rv_addi(RV_REG_TCC, RV_REG_TCC_SAVED, 0), ctx);

	/* Set return value and restore stack. */
	emit(rv_addi(lo(r0), RV_REG_A0, 0), ctx);
	emit(rv_addi(hi(r0), RV_REG_A1, 0), ctx);
	emit(rv_addi(RV_REG_SP, RV_REG_SP, 16), ctx);
}

static int emit_bpf_tail_call(int insn, struct rv_jit_context *ctx)
{
	/*
	 * R1 -> &ctx
	 * R2 -> &array
	 * R3 -> index
	 */
	int tc_ninsn, off, start_insn = ctx->ninsns;
	const s8 *arr_reg = bpf2rv32[BPF_REG_2];
	const s8 *idx_reg = bpf2rv32[BPF_REG_3];

	tc_ninsn = insn ? ctx->offset[insn] - ctx->offset[insn - 1] :
		ctx->offset[0];

	/* max_entries = array->map.max_entries; */
	off = offsetof(struct bpf_array, map.max_entries);
	if (is_12b_check(off, insn))
		return -1;
	emit(rv_lw(RV_REG_T1, off, lo(arr_reg)), ctx);

	/*
	 * if (index >= max_entries)
	 *   goto out;
	 */
	off = (tc_ninsn - (ctx->ninsns - start_insn)) << 2;
	emit_bcc(BPF_JGE, lo(idx_reg), RV_REG_T1, off, ctx);

	/*
	 * if ((temp_tcc = tcc - 1) < 0)
	 *   goto out;
	 */
	emit(rv_addi(RV_REG_T1, RV_REG_TCC, -1), ctx);
	off = (tc_ninsn - (ctx->ninsns - start_insn)) << 2;
	emit_bcc(BPF_JSLT, RV_REG_T1, RV_REG_ZERO, off, ctx);

	/*
	 * prog = array->ptrs[index];
	 * if (!prog)
	 *   goto out;
	 */
	emit(rv_slli(RV_REG_T0, lo(idx_reg), 2), ctx);
	emit(rv_add(RV_REG_T0, RV_REG_T0, lo(arr_reg)), ctx);
	off = offsetof(struct bpf_array, ptrs);
	if (is_12b_check(off, insn))
		return -1;
	emit(rv_lw(RV_REG_T0, off, RV_REG_T0), ctx);
	off = (tc_ninsn - (ctx->ninsns - start_insn)) << 2;
	emit_bcc(BPF_JEQ, RV_REG_T0, RV_REG_ZERO, off, ctx);

	/*
	 * tcc = temp_tcc;
	 * goto *(prog->bpf_func + 4);
	 */
	off = offsetof(struct bpf_prog, bpf_func);
	if (is_12b_check(off, insn))
		return -1;
	emit(rv_lw(RV_REG_T0, off, RV_REG_T0), ctx);
	emit(rv_addi(RV_REG_TCC, RV_REG_T1, 0), ctx);
	/* Epilogue jumps to *(t0 + 4). */
	__build_epilogue(true, ctx);
	return 0;
}

static int emit_load_r64(const s8 *dst, const s8 *src, s16 off,
			 struct rv_jit_context *ctx, const u8 size)
{
	const s8 *tmp1 = bpf2rv32[TMP_REG_1];
	const s8 *tmp2 = bpf2rv32[TMP_REG_2];
	const s8 *rd = bpf_get_reg64(dst, tmp1, ctx);
	const s8 *rs = bpf_get_reg64(src, tmp2, ctx);

	emit_imm(RV_REG_T0, off, ctx);
	emit(rv_add(RV_REG_T0, RV_REG_T0, lo(rs)), ctx);

	switch (size) {
	case BPF_B:
		emit(rv_lbu(lo(rd), 0, RV_REG_T0), ctx);
		if (!ctx->prog->aux->verifier_zext)
			emit(rv_addi(hi(rd), RV_REG_ZERO, 0), ctx);
		break;
	case BPF_H:
		emit(rv_lhu(lo(rd), 0, RV_REG_T0), ctx);
		if (!ctx->prog->aux->verifier_zext)
			emit(rv_addi(hi(rd), RV_REG_ZERO, 0), ctx);
		break;
	case BPF_W:
		emit(rv_lw(lo(rd), 0, RV_REG_T0), ctx);
		if (!ctx->prog->aux->verifier_zext)
			emit(rv_addi(hi(rd), RV_REG_ZERO, 0), ctx);
		break;
	case BPF_DW:
		emit(rv_lw(lo(rd), 0, RV_REG_T0), ctx);
		emit(rv_lw(hi(rd), 4, RV_REG_T0), ctx);
		break;
	}

	bpf_put_reg64(dst, rd, ctx);
	return 0;
}

static int emit_store_r64(const s8 *dst, const s8 *src, s16 off,
			  struct rv_jit_context *ctx, const u8 size,
			  const u8 mode)
{
	const s8 *tmp1 = bpf2rv32[TMP_REG_1];
	const s8 *tmp2 = bpf2rv32[TMP_REG_2];
	const s8 *rd = bpf_get_reg64(dst, tmp1, ctx);
	const s8 *rs = bpf_get_reg64(src, tmp2, ctx);

	if (mode == BPF_XADD && size != BPF_W)
		return -1;

	emit_imm(RV_REG_T0, off, ctx);
	emit(rv_add(RV_REG_T0, RV_REG_T0, lo(rd)), ctx);

	switch (size) {
	case BPF_B:
		emit(rv_sb(RV_REG_T0, 0, lo(rs)), ctx);
		break;
	case BPF_H:
		emit(rv_sh(RV_REG_T0, 0, lo(rs)), ctx);
		break;
	case BPF_W:
		switch (mode) {
		case BPF_MEM:
			emit(rv_sw(RV_REG_T0, 0, lo(rs)), ctx);
			break;
		case BPF_XADD:
			emit(rv_amoadd_w(RV_REG_ZERO, lo(rs), RV_REG_T0, 0, 0),
			     ctx);
			break;
		}
		break;
	case BPF_DW:
		emit(rv_sw(RV_REG_T0, 0, lo(rs)), ctx);
		emit(rv_sw(RV_REG_T0, 4, hi(rs)), ctx);
		break;
	}

	return 0;
}

static void emit_rev16(const s8 rd, struct rv_jit_context *ctx)
{
	emit(rv_slli(rd, rd, 16), ctx);
	emit(rv_slli(RV_REG_T1, rd, 8), ctx);
	emit(rv_srli(rd, rd, 8), ctx);
	emit(rv_add(RV_REG_T1, rd, RV_REG_T1), ctx);
	emit(rv_srli(rd, RV_REG_T1, 16), ctx);
}

static void emit_rev32(const s8 rd, struct rv_jit_context *ctx)
{
	emit(rv_addi(RV_REG_T1, RV_REG_ZERO, 0), ctx);
	emit(rv_andi(RV_REG_T0, rd, 255), ctx);
	emit(rv_add(RV_REG_T1, RV_REG_T1, RV_REG_T0), ctx);
	emit(rv_slli(RV_REG_T1, RV_REG_T1, 8), ctx);
	emit(rv_srli(rd, rd, 8), ctx);
	emit(rv_andi(RV_REG_T0, rd, 255), ctx);
	emit(rv_add(RV_REG_T1, RV_REG_T1, RV_REG_T0), ctx);
	emit(rv_slli(RV_REG_T1, RV_REG_T1, 8), ctx);
	emit(rv_srli(rd, rd, 8), ctx);
	emit(rv_andi(RV_REG_T0, rd, 255), ctx);
	emit(rv_add(RV_REG_T1, RV_REG_T1, RV_REG_T0), ctx);
	emit(rv_slli(RV_REG_T1, RV_REG_T1, 8), ctx);
	emit(rv_srli(rd, rd, 8), ctx);
	emit(rv_andi(RV_REG_T0, rd, 255), ctx);
	emit(rv_add(RV_REG_T1, RV_REG_T1, RV_REG_T0), ctx);
	emit(rv_addi(rd, RV_REG_T1, 0), ctx);
}

static void emit_zext64(const s8 *dst, struct rv_jit_context *ctx)
{
	const s8 *rd;
	const s8 *tmp1 = bpf2rv32[TMP_REG_1];

	rd = bpf_get_reg64(dst, tmp1, ctx);
	emit(rv_addi(hi(rd), RV_REG_ZERO, 0), ctx);
	bpf_put_reg64(dst, rd, ctx);
}

int bpf_jit_emit_insn(const struct bpf_insn *insn, struct rv_jit_context *ctx,
		      bool extra_pass)
{
	bool is64 = BPF_CLASS(insn->code) == BPF_ALU64 ||
		BPF_CLASS(insn->code) == BPF_JMP;
	int s, e, rvoff, i = insn - ctx->prog->insnsi;
	u8 code = insn->code;
	s16 off = insn->off;
	s32 imm = insn->imm;

	const s8 *dst = bpf2rv32[insn->dst_reg];
	const s8 *src = bpf2rv32[insn->src_reg];
	const s8 *tmp1 = bpf2rv32[TMP_REG_1];
	const s8 *tmp2 = bpf2rv32[TMP_REG_2];

	switch (code) {
	case BPF_ALU64 | BPF_MOV | BPF_X:

	case BPF_ALU64 | BPF_ADD | BPF_X:
	case BPF_ALU64 | BPF_ADD | BPF_K:

	case BPF_ALU64 | BPF_SUB | BPF_X:
	case BPF_ALU64 | BPF_SUB | BPF_K:

	case BPF_ALU64 | BPF_AND | BPF_X:
	case BPF_ALU64 | BPF_OR | BPF_X:
	case BPF_ALU64 | BPF_XOR | BPF_X:

	case BPF_ALU64 | BPF_MUL | BPF_X:
	case BPF_ALU64 | BPF_MUL | BPF_K:

	case BPF_ALU64 | BPF_LSH | BPF_X:
	case BPF_ALU64 | BPF_RSH | BPF_X:
	case BPF_ALU64 | BPF_ARSH | BPF_X:
		if (BPF_SRC(code) == BPF_K) {
			emit_imm32(tmp2, imm, ctx);
			src = tmp2;
		}
		emit_alu_r64(dst, src, ctx, BPF_OP(code));
		break;

	case BPF_ALU64 | BPF_NEG:
		emit_alu_r64(dst, tmp2, ctx, BPF_OP(code));
		break;

	case BPF_ALU64 | BPF_DIV | BPF_X:
	case BPF_ALU64 | BPF_DIV | BPF_K:
	case BPF_ALU64 | BPF_MOD | BPF_X:
	case BPF_ALU64 | BPF_MOD | BPF_K:
		goto notsupported;

	case BPF_ALU64 | BPF_MOV | BPF_K:
	case BPF_ALU64 | BPF_AND | BPF_K:
	case BPF_ALU64 | BPF_OR | BPF_K:
	case BPF_ALU64 | BPF_XOR | BPF_K:
	case BPF_ALU64 | BPF_LSH | BPF_K:
	case BPF_ALU64 | BPF_RSH | BPF_K:
	case BPF_ALU64 | BPF_ARSH | BPF_K:
		emit_alu_i64(dst, imm, ctx, BPF_OP(code));
		break;

	case BPF_ALU | BPF_MOV | BPF_X:
		if (imm == 1) {
			/* Special mov32 for zext. */
			emit_zext64(dst, ctx);
			break;
		}
		/* Fallthrough. */

	case BPF_ALU | BPF_ADD | BPF_X:
	case BPF_ALU | BPF_SUB | BPF_X:
	case BPF_ALU | BPF_AND | BPF_X:
	case BPF_ALU | BPF_OR | BPF_X:
	case BPF_ALU | BPF_XOR | BPF_X:

	case BPF_ALU | BPF_MUL | BPF_X:
	case BPF_ALU | BPF_MUL | BPF_K:

	case BPF_ALU | BPF_DIV | BPF_X:
	case BPF_ALU | BPF_DIV | BPF_K:

	case BPF_ALU | BPF_MOD | BPF_X:
	case BPF_ALU | BPF_MOD | BPF_K:

	case BPF_ALU | BPF_LSH | BPF_X:
	case BPF_ALU | BPF_RSH | BPF_X:
	case BPF_ALU | BPF_ARSH | BPF_X:
		if (BPF_SRC(code) == BPF_K) {
			emit_imm32(tmp2, imm, ctx);
			src = tmp2;
		}
		emit_alu_r32(dst, src, ctx, BPF_OP(code));
		break;

	case BPF_ALU | BPF_MOV | BPF_K:
	case BPF_ALU | BPF_ADD | BPF_K:
	case BPF_ALU | BPF_SUB | BPF_K:
	case BPF_ALU | BPF_AND | BPF_K:
	case BPF_ALU | BPF_OR | BPF_K:
	case BPF_ALU | BPF_XOR | BPF_K:
	case BPF_ALU | BPF_LSH | BPF_K:
	case BPF_ALU | BPF_RSH | BPF_K:
	case BPF_ALU | BPF_ARSH | BPF_K:
		/*
		 * mul,div,mod are handled in the BPF_X case since there are
		 * no RISC-V I-type equivalents.
		 */
		emit_alu_i32(dst, imm, ctx, BPF_OP(code));
		break;

	case BPF_ALU | BPF_NEG:
		/*
		 * src is ignored---choose tmp2 as a dummy register since it
		 * is not on the stack.
		 */
		emit_alu_r32(dst, tmp2, ctx, BPF_OP(code));
		break;

	case BPF_ALU | BPF_END | BPF_FROM_LE:
	{
		const s8 *rd = bpf_get_reg64(dst, tmp1, ctx);

		switch (imm) {
		case 16:
			emit(rv_slli(lo(rd), lo(rd), 16), ctx);
			emit(rv_srli(lo(rd), lo(rd), 16), ctx);
			/* Fallthrough. */
		case 32:
			if (!ctx->prog->aux->verifier_zext)
				emit(rv_addi(hi(rd), RV_REG_ZERO, 0), ctx);
			break;
		case 64:
			/* Do nothing. */
			break;
		default:
			pr_err("bpf-jit: BPF_END imm %d invalid\n", imm);
			return -1;
		}

		bpf_put_reg64(dst, rd, ctx);
		break;
	}

	case BPF_ALU | BPF_END | BPF_FROM_BE:
	{
		const s8 *rd = bpf_get_reg64(dst, tmp1, ctx);

		switch (imm) {
		case 16:
			emit_rev16(lo(rd), ctx);
			if (!ctx->prog->aux->verifier_zext)
				emit(rv_addi(hi(rd), RV_REG_ZERO, 0), ctx);
			break;
		case 32:
			emit_rev32(lo(rd), ctx);
			if (!ctx->prog->aux->verifier_zext)
				emit(rv_addi(hi(rd), RV_REG_ZERO, 0), ctx);
			break;
		case 64:
			/* Swap upper and lower halves. */
			emit(rv_addi(RV_REG_T0, lo(rd), 0), ctx);
			emit(rv_addi(lo(rd), hi(rd), 0), ctx);
			emit(rv_addi(hi(rd), RV_REG_T0, 0), ctx);

			/* Swap each half. */
			emit_rev32(lo(rd), ctx);
			emit_rev32(hi(rd), ctx);
			break;
		default:
			pr_err("bpf-jit: BPF_END imm %d invalid\n", imm);
			return -1;
		}

		bpf_put_reg64(dst, rd, ctx);
		break;
	}

	case BPF_JMP | BPF_JA:
		rvoff = rv_offset(i, off, ctx);
		emit_jump_and_link(RV_REG_ZERO, rvoff, false, ctx);
		break;

	case BPF_JMP | BPF_CALL:
	{
		bool fixed;
		int ret;
		u64 addr;

		ret = bpf_jit_get_func_addr(ctx->prog, insn, extra_pass, &addr,
					    &fixed);
		if (ret < 0)
			return ret;
		emit_call(fixed, addr, ctx);
		break;
	}

	case BPF_JMP | BPF_TAIL_CALL:
		if (emit_bpf_tail_call(i, ctx))
			return -1;
		break;

	case BPF_JMP | BPF_JEQ | BPF_X:
	case BPF_JMP | BPF_JEQ | BPF_K:
	case BPF_JMP32 | BPF_JEQ | BPF_X:
	case BPF_JMP32 | BPF_JEQ | BPF_K:

	case BPF_JMP | BPF_JNE | BPF_X:
	case BPF_JMP | BPF_JNE | BPF_K:
	case BPF_JMP32 | BPF_JNE | BPF_X:
	case BPF_JMP32 | BPF_JNE | BPF_K:

	case BPF_JMP | BPF_JLE | BPF_X:
	case BPF_JMP | BPF_JLE | BPF_K:
	case BPF_JMP32 | BPF_JLE | BPF_X:
	case BPF_JMP32 | BPF_JLE | BPF_K:

	case BPF_JMP | BPF_JLT | BPF_X:
	case BPF_JMP | BPF_JLT | BPF_K:
	case BPF_JMP32 | BPF_JLT | BPF_X:
	case BPF_JMP32 | BPF_JLT | BPF_K:

	case BPF_JMP | BPF_JGE | BPF_X:
	case BPF_JMP | BPF_JGE | BPF_K:
	case BPF_JMP32 | BPF_JGE | BPF_X:
	case BPF_JMP32 | BPF_JGE | BPF_K:

	case BPF_JMP | BPF_JGT | BPF_X:
	case BPF_JMP | BPF_JGT | BPF_K:
	case BPF_JMP32 | BPF_JGT | BPF_X:
	case BPF_JMP32 | BPF_JGT | BPF_K:

	case BPF_JMP | BPF_JSLE | BPF_X:
	case BPF_JMP | BPF_JSLE | BPF_K:
	case BPF_JMP32 | BPF_JSLE | BPF_X:
	case BPF_JMP32 | BPF_JSLE | BPF_K:

	case BPF_JMP | BPF_JSLT | BPF_X:
	case BPF_JMP | BPF_JSLT | BPF_K:
	case BPF_JMP32 | BPF_JSLT | BPF_X:
	case BPF_JMP32 | BPF_JSLT | BPF_K:

	case BPF_JMP | BPF_JSGE | BPF_X:
	case BPF_JMP | BPF_JSGE | BPF_K:
	case BPF_JMP32 | BPF_JSGE | BPF_X:
	case BPF_JMP32 | BPF_JSGE | BPF_K:

	case BPF_JMP | BPF_JSGT | BPF_X:
	case BPF_JMP | BPF_JSGT | BPF_K:
	case BPF_JMP32 | BPF_JSGT | BPF_X:
	case BPF_JMP32 | BPF_JSGT | BPF_K:

	case BPF_JMP | BPF_JSET | BPF_X:
	case BPF_JMP | BPF_JSET | BPF_K:
	case BPF_JMP32 | BPF_JSET | BPF_X:
	case BPF_JMP32 | BPF_JSET | BPF_K:
		rvoff = rv_offset(i, off, ctx);
		if (BPF_SRC(code) == BPF_K) {
			s = ctx->ninsns;
			emit_imm32(tmp2, imm, ctx);
			src = tmp2;
			e = ctx->ninsns;
			rvoff -= (e - s) << 2;
		}

		if (is64)
			emit_branch_r64(dst, src, rvoff, ctx, BPF_OP(code));
		else
			emit_branch_r32(dst, src, rvoff, ctx, BPF_OP(code));
		break;

	case BPF_JMP | BPF_EXIT:
		if (i == ctx->prog->len - 1)
			break;

		rvoff = epilogue_offset(ctx);
		emit_jump_and_link(RV_REG_ZERO, rvoff, false, ctx);
		break;

	case BPF_LD | BPF_IMM | BPF_DW:
	{
		struct bpf_insn insn1 = insn[1];
		s32 imm_lo = imm;
		s32 imm_hi = insn1.imm;
		const s8 *rd = bpf_get_reg64(dst, tmp1, ctx);

		emit_imm64(rd, imm_hi, imm_lo, ctx);
		bpf_put_reg64(dst, rd, ctx);
		return 1;
	}

	case BPF_LDX | BPF_MEM | BPF_B:
	case BPF_LDX | BPF_MEM | BPF_H:
	case BPF_LDX | BPF_MEM | BPF_W:
	case BPF_LDX | BPF_MEM | BPF_DW:
		if (emit_load_r64(dst, src, off, ctx, BPF_SIZE(code)))
			return -1;
		break;

	case BPF_ST | BPF_MEM | BPF_B:
	case BPF_ST | BPF_MEM | BPF_H:
	case BPF_ST | BPF_MEM | BPF_W:
	case BPF_ST | BPF_MEM | BPF_DW:

	case BPF_STX | BPF_MEM | BPF_B:
	case BPF_STX | BPF_MEM | BPF_H:
	case BPF_STX | BPF_MEM | BPF_W:
	case BPF_STX | BPF_MEM | BPF_DW:
	case BPF_STX | BPF_XADD | BPF_W:
		if (BPF_CLASS(code) == BPF_ST) {
			emit_imm32(tmp2, imm, ctx);
			src = tmp2;
		}

		if (emit_store_r64(dst, src, off, ctx, BPF_SIZE(code),
				   BPF_MODE(code)))
			return -1;
		break;

	/* No hardware support for 8-byte atomics in RV32. */
	case BPF_STX | BPF_XADD | BPF_DW:
		/* Fallthrough. */

notsupported:
		pr_info_once("bpf-jit: not supported: opcode %02x ***\n", code);
		return -EFAULT;

	default:
		pr_err("bpf-jit: unknown opcode %02x\n", code);
		return -EINVAL;
	}

	return 0;
}

void bpf_jit_build_prologue(struct rv_jit_context *ctx)
{
	/* Make space to save 9 registers: ra, fp, s1--s7. */
	int stack_adjust = 9 * sizeof(u32), store_offset, bpf_stack_adjust;
	const s8 *fp = bpf2rv32[BPF_REG_FP];
	const s8 *r1 = bpf2rv32[BPF_REG_1];

	bpf_stack_adjust = round_up(ctx->prog->aux->stack_depth, 16);
	stack_adjust += bpf_stack_adjust;

	store_offset = stack_adjust - 4;

	stack_adjust += 4 * BPF_JIT_SCRATCH_REGS;

	/*
	 * The first instruction sets the tail-call-counter (TCC) register.
	 * This instruction is skipped by tail calls.
	 */
	emit(rv_addi(RV_REG_TCC, RV_REG_ZERO, MAX_TAIL_CALL_CNT), ctx);

	emit(rv_addi(RV_REG_SP, RV_REG_SP, -stack_adjust), ctx);

	/* Save callee-save registers. */
	emit(rv_sw(RV_REG_SP, store_offset - 0, RV_REG_RA), ctx);
	emit(rv_sw(RV_REG_SP, store_offset - 4, RV_REG_FP), ctx);
	emit(rv_sw(RV_REG_SP, store_offset - 8, RV_REG_S1), ctx);
	emit(rv_sw(RV_REG_SP, store_offset - 12, RV_REG_S2), ctx);
	emit(rv_sw(RV_REG_SP, store_offset - 16, RV_REG_S3), ctx);
	emit(rv_sw(RV_REG_SP, store_offset - 20, RV_REG_S4), ctx);
	emit(rv_sw(RV_REG_SP, store_offset - 24, RV_REG_S5), ctx);
	emit(rv_sw(RV_REG_SP, store_offset - 28, RV_REG_S6), ctx);
	emit(rv_sw(RV_REG_SP, store_offset - 32, RV_REG_S7), ctx);

	/* Set fp: used as the base address for stacked BPF registers. */
	emit(rv_addi(RV_REG_FP, RV_REG_SP, stack_adjust), ctx);

	/* Set up BPF stack pointer. */
	emit(rv_addi(lo(fp), RV_REG_SP, bpf_stack_adjust), ctx);
	emit(rv_addi(hi(fp), RV_REG_ZERO, 0), ctx);

	/* Set up context pointer. */
	emit(rv_addi(lo(r1), RV_REG_A0, 0), ctx);
	emit(rv_addi(hi(r1), RV_REG_ZERO, 0), ctx);

	ctx->stack_size = stack_adjust;
}

void bpf_jit_build_epilogue(struct rv_jit_context *ctx)
{
	__build_epilogue(false, ctx);
}