path: root/arch/parisc/net/bpf_jit_comp64.c

// SPDX-License-Identifier: GPL-2.0
/*
 * BPF JIT compiler for PA-RISC (64-bit)
 *
 * Copyright(c) 2023 Helge Deller <deller@gmx.de>
 *
 * The code is based on the BPF JIT compiler for RV64 by Björn Töpel.
 *
 * TODO:
 * - check if bpf_jit_needs_zext() is needed (currently enabled)
 * - implement arch_prepare_bpf_trampoline(), poke(), ...
 */

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

static const int regmap[] = {
	[BPF_REG_0] =	HPPA_REG_RET0,
	[BPF_REG_1] =	HPPA_R(5),
	[BPF_REG_2] =	HPPA_R(6),
	[BPF_REG_3] =	HPPA_R(7),
	[BPF_REG_4] =	HPPA_R(8),
	[BPF_REG_5] =	HPPA_R(9),
	[BPF_REG_6] =	HPPA_R(10),
	[BPF_REG_7] =	HPPA_R(11),
	[BPF_REG_8] =	HPPA_R(12),
	[BPF_REG_9] =	HPPA_R(13),
	[BPF_REG_FP] =	HPPA_R(14),
	[BPF_REG_AX] =	HPPA_R(15),
};

/*
 * Stack layout during BPF program execution (note: stack grows up):
 *
 *                     high
 *   HPPA64 sp =>  +----------+ <= HPPA64 fp
 *                 | saved sp |
 *                 | saved rp |
 *                 |   ...    | HPPA64 callee-saved registers
 *                 | curr args|
 *                 | local var|
 *                 +----------+ <= (BPF FP)
 *                 |          |
 *                 |   ...    | BPF program stack
 *                 |          |
 *                 |   ...    | Function call stack
 *                 |          |
 *                 +----------+
 *                     low
 */

/* Offset from fp for BPF registers stored on stack. */
#define STACK_ALIGN	FRAME_SIZE

#define EXIT_PTR_LOAD(reg)	hppa64_ldd_im16(-FRAME_SIZE, HPPA_REG_SP, reg)
#define EXIT_PTR_STORE(reg)	hppa64_std_im16(reg, -FRAME_SIZE, HPPA_REG_SP)
#define EXIT_PTR_JUMP(reg, nop)	hppa_bv(HPPA_REG_ZERO, reg, nop)

static u8 bpf_to_hppa_reg(int bpf_reg, struct hppa_jit_context *ctx)
{
	u8 reg = regmap[bpf_reg];

	REG_SET_SEEN(ctx, reg);
	return reg;
};

static void emit_hppa_copy(const s8 rs, const s8 rd, struct hppa_jit_context *ctx)
{
	REG_SET_SEEN(ctx, rd);
	if (OPTIMIZE_HPPA && (rs == rd))
		return;
	REG_SET_SEEN(ctx, rs);
	emit(hppa_copy(rs, rd), ctx);
}

static void emit_hppa64_depd(u8 src, u8 pos, u8 len, u8 target, bool no_zero, struct hppa_jit_context *ctx)
{
	int c;

	pos &= (BITS_PER_LONG - 1);
	pos = 63 - pos;
	len = 64 - len;
	c =  (len < 32)  ? 0x4 : 0;
	c |= (pos >= 32) ? 0x2 : 0;
	c |= (no_zero)   ? 0x1 : 0;
	emit(hppa_t10_insn(0x3c, target, src, 0, c, pos & 0x1f, len & 0x1f), ctx);
}

static void emit_hppa64_shld(u8 src, int num, u8 target, struct hppa_jit_context *ctx)
{
	emit_hppa64_depd(src, 63-num, 64-num, target, 0, ctx);
}

static void emit_hppa64_extrd(u8 src, u8 pos, u8 len, u8 target, bool signed_op, struct hppa_jit_context *ctx)
{
	int c;

	pos &= (BITS_PER_LONG - 1);
	len = 64 - len;
	c =  (len <  32) ? 0x4 : 0;
	c |= (pos >= 32) ? 0x2 : 0;
	c |= signed_op   ? 0x1 : 0;
	emit(hppa_t10_insn(0x36, src, target, 0, c, pos & 0x1f, len & 0x1f), ctx);
}

static void emit_hppa64_extrw(u8 src, u8 pos, u8 len, u8 target, bool signed_op, struct hppa_jit_context *ctx)
{
	int c;

	pos &= (32 - 1);
	len = 32 - len;
	c = 0x06