Subject: [PATCH] mips: bpf: Remove old BPF JIT implementations
From: Johan Almbladh <[email-masked]>
Date: Tue, 5 Oct 2021 18:54:08 +0200

This patch removes the old 32-bit cBPF and 64-bit eBPF JIT implementations.
They are replaced by a new eBPF implementation that supports both 32-bit
and 64-bit MIPS CPUs.

Signed-off-by: Johan Almbladh <[email-masked]>
---
 delete mode 100644 arch/mips/net/bpf_jit.c
 delete mode 100644 arch/mips/net/bpf_jit.h
 delete mode 100644 arch/mips/net/bpf_jit_asm.S
 delete mode 100644 arch/mips/net/ebpf_jit.c

--- a/arch/mips/net/bpf_jit.h
+++ /dev/null
@@ -1,81 +0,0 @@
-/* SPDX-License-Identifier: GPL-2.0-only */
-/*
- * Just-In-Time compiler for BPF filters on MIPS
- *
- * Copyright (c) 2014 Imagination Technologies Ltd.
- * Author: Markos Chandras <[email-masked]>
- */
-
-#ifndef BPF_JIT_MIPS_OP_H
-#define BPF_JIT_MIPS_OP_H
-
-/* Registers used by JIT */
-#define MIPS_R_ZERO	0
-#define MIPS_R_V0	2
-#define MIPS_R_A0	4
-#define MIPS_R_A1	5
-#define MIPS_R_T4	12
-#define MIPS_R_T5	13
-#define MIPS_R_T6	14
-#define MIPS_R_T7	15
-#define MIPS_R_S0	16
-#define MIPS_R_S1	17
-#define MIPS_R_S2	18
-#define MIPS_R_S3	19
-#define MIPS_R_S4	20
-#define MIPS_R_S5	21
-#define MIPS_R_S6	22
-#define MIPS_R_S7	23
-#define MIPS_R_SP	29
-#define MIPS_R_RA	31
-
-/* Conditional codes */
-#define MIPS_COND_EQ	0x1
-#define MIPS_COND_GE	(0x1 << 1)
-#define MIPS_COND_GT	(0x1 << 2)
-#define MIPS_COND_NE	(0x1 << 3)
-#define MIPS_COND_ALL	(0x1 << 4)
-/* Conditionals on X register or K immediate */
-#define MIPS_COND_X	(0x1 << 5)
-#define MIPS_COND_K	(0x1 << 6)
-
-#define r_ret	MIPS_R_V0
-
-/*
- * Use 2 scratch registers to avoid pipeline interlocks.
- * There is no overhead during epilogue and prologue since
- * any of the $s0-$s6 registers will only be preserved if
- * they are going to actually be used.
- */
-#define r_skb_hl	MIPS_R_S0 /* skb header length */
-#define r_skb_data	MIPS_R_S1 /* skb actual data */
-#define r_off		MIPS_R_S2
-#define r_A		MIPS_R_S3
-#define r_X		MIPS_R_S4
-#define r_skb		MIPS_R_S5
-#define r_M		MIPS_R_S6
-#define r_skb_len	MIPS_R_S7
-#define r_s0		MIPS_R_T4 /* scratch reg 1 */
-#define r_s1		MIPS_R_T5 /* scratch reg 2 */
-#define r_tmp_imm	MIPS_R_T6 /* No need to preserve this */
-#define r_tmp		MIPS_R_T7 /* No need to preserve this */
-#define r_zero		MIPS_R_ZERO
-#define r_sp		MIPS_R_SP
-#define r_ra		MIPS_R_RA
-
-#ifndef __ASSEMBLY__
-
-/* Declare ASM helpers */
-
-#define DECLARE_LOAD_FUNC(func) \
-	extern u8 func(unsigned long *skb, int offset); \
-	extern u8 func##_negative(unsigned long *skb, int offset); \
-	extern u8 func##_positive(unsigned long *skb, int offset)
-
-DECLARE_LOAD_FUNC(sk_load_word);
-DECLARE_LOAD_FUNC(sk_load_half);
-DECLARE_LOAD_FUNC(sk_load_byte);
-
-#endif
-
-#endif /* BPF_JIT_MIPS_OP_H */
--- a/arch/mips/net/bpf_jit_asm.S
+++ /dev/null
@@ -1,285 +0,0 @@
-/*
- * bpf_jib_asm.S: Packet/header access helper functions for MIPS/MIPS64 BPF
- * compiler.
- *
- * Copyright (C) 2015 Imagination Technologies Ltd.
- * Author: Markos Chandras <[email-masked]>
- *
- * This program is free software; you can redistribute it and/or modify it
- * under the terms of the GNU General Public License as published by the
- * Free Software Foundation; version 2 of the License.
- */
-
-#include <asm/asm.h>
-#include <asm/isa-rev.h>
-#include <asm/regdef.h>
-#include "bpf_jit.h"
-
-/* ABI
- *
- * r_skb_hl	skb header length
- * r_skb_data	skb data
- * r_off(a1)	offset register
- * r_A		BPF register A
- * r_X		PF register X
- * r_skb(a0)	*skb
- * r_M		*scratch memory
- * r_skb_le	skb length
- * r_s0		Scratch register 0
- * r_s1		Scratch register 1
- *
- * On entry:
- * a0: *skb
- * a1: offset (imm or imm + X)
- *
- * All non-BPF-ABI registers are free for use. On return, we only
- * care about r_ret. The BPF-ABI registers are assumed to remain
- * unmodified during the entire filter operation.
- */
-
-#define skb	a0
-#define offset	a1
-#define SKF_LL_OFF  (-0x200000) /* Can't include linux/filter.h in assembly */
-
-	/* We know better :) so prevent assembler reordering etc */
-	.set 	noreorder
-
-#define is_offset_negative(TYPE)				\
-	/* If offset is negative we have more work to do */	\
-	slti	t0, offset, 0;					\
-	bgtz	t0, bpf_slow_path_##TYPE##_neg;			\
-	/* Be careful what follows in DS. */
-
-#define is_offset_in_header(SIZE, TYPE)				\
-	/* Reading from header? */				\
-	addiu	$r_s0, $r_skb_hl, -SIZE;			\
-	slt	t0, $r_s0, offset;				\
-	bgtz	t0, bpf_slow_path_##TYPE;			\
-
-LEAF(sk_load_word)
-	is_offset_negative(word)
-FEXPORT(sk_load_word_positive)
-	is_offset_in_header(4, word)
-	/* Offset within header boundaries */
-	PTR_ADDU t1, $r_skb_data, offset
-	.set	reorder
-	lw	$r_A, 0(t1)
-	.set	noreorder
-#ifdef CONFIG_CPU_LITTLE_ENDIAN
-# if MIPS_ISA_REV >= 2
-	wsbh	t0, $r_A
-	rotr	$r_A, t0, 16
-# else
-	sll	t0, $r_A, 24
-	srl	t1, $r_A, 24
-	srl	t2, $r_A, 8
-	or	t0, t0, t1
-	andi	t2, t2, 0xff00
-	andi	t1, $r_A, 0xff00
-	or	t0, t0, t2
-	sll	t1, t1, 8
-	or	$r_A, t0, t1
-# endif
-#endif
-	jr	$r_ra
-	 move	$r_ret, zero
-	END(sk_load_word)
-
-LEAF(sk_load_half)
-	is_offset_negative(half)
-FEXPORT(sk_load_half_positive)
-	is_offset_in_header(2, half)
-	/* Offset within header boundaries */
-	PTR_ADDU t1, $r_skb_data, offset
-	lhu	$r_A, 0(t1)
-#ifdef CONFIG_CPU_LITTLE_ENDIAN
-# if MIPS_ISA_REV >= 2
-	wsbh	$r_A, $r_A
-# else
-	sll	t0, $r_A, 8
-	srl	t1, $r_A, 8
-	andi	t0, t0, 0xff00
-	or	$r_A, t0, t1
-# endif
-#endif
-	jr	$r_ra
-	 move	$r_ret, zero
-	END(sk_load_half)
-
-LEAF(sk_load_byte)
-	is_offset_negative(byte)
-FEXPORT(sk_load_byte_positive)
-	is_offset_in_header(1, byte)
-	/* Offset within header boundaries */
-	PTR_ADDU t1, $r_skb_data, offset
-	lbu	$r_A, 0(t1)
-	jr	$r_ra
-	 move	$r_ret, zero
-	END(sk_load_byte)
-
-/*
- * call skb_copy_bits:
- * (prototype in linux/skbuff.h)
- *
- * int skb_copy_bits(sk_buff *skb, int offset, void *to, int len)
- *
- * o32 mandates we leave 4 spaces for argument registers in case
- * the callee needs to use them. Even though we don't care about
- * the argument registers ourselves, we need to allocate that space
- * to remain ABI compliant since the callee may want to use that space.
- * We also allocate 2 more spaces for $r_ra and our return register (*to).
- *
- * n64 is a bit different. The *caller* will allocate the space to preserve
- * the arguments. So in 64-bit kernels, we allocate the 4-arg space for no
- * good reason but it does not matter that much really.
- *
- * (void *to) is returned in r_s0
- *
- */
-#ifdef CONFIG_CPU_LITTLE_ENDIAN
-#define DS_OFFSET(SIZE) (4 * SZREG)
-#else
-#define DS_OFFSET(SIZE) ((4 * SZREG) + (4 - SIZE))
-#endif
-#define bpf_slow_path_common(SIZE)				\
-	/* Quick check. Are we within reasonable boundaries? */ \
-	LONG_ADDIU	$r_s1, $r_skb_len, -SIZE;		\
-	sltu		$r_s0, offset, $r_s1;			\
-	beqz		$r_s0, fault;				\
-	/* Load 4th argument in DS */				\
-	 LONG_ADDIU	a3, zero, SIZE;				\
-	PTR_ADDIU	$r_sp, $r_sp, -(6 * SZREG);		\
-	PTR_LA		t0, skb_copy_bits;			\
-	PTR_S		$r_ra, (5 * SZREG)($r_sp);		\
-	/* Assign low slot to a2 */				\
-	PTR_ADDIU	a2, $r_sp, DS_OFFSET(SIZE);		\
-	jalr		t0;					\
-	/* Reset our destination slot (DS but it's ok) */	\
-	 INT_S		zero, (4 * SZREG)($r_sp);		\
-	/*							\
-	 * skb_copy_bits returns 0 on success and -EFAULT	\
-	 * on error. Our data live in a2. Do not bother with	\
-	 * our data if an error has been returned.		\
-	 */							\
-	/* Restore our frame */					\
-	PTR_L		$r_ra, (5 * SZREG)($r_sp);		\
-	INT_L		$r_s0, (4 * SZREG)($r_sp);		\
-	bltz		v0, fault;				\
-	 PTR_ADDIU	$r_sp, $r_sp, 6 * SZREG;		\
-	move		$r_ret, zero;				\
-
-NESTED(bpf_slow_path_word, (6 * SZREG), $r_sp)
-	bpf_slow_path_common(4)
-#ifdef CONFIG_CPU_LITTLE_ENDIAN
-# if MIPS_ISA_REV >= 2
-	wsbh	t0, $r_s0
-	jr	$r_ra
-	 rotr	$r_A, t0, 16
-# else
-	sll	t0, $r_s0, 24
-	srl	t1, $r_s0, 24
-	srl	t2, $r_s0, 8
-	or	t0, t0, t1
-	andi	t2, t2, 0xff00
-	andi	t1, $r_s0, 0xff00
-	or	t0, t0, t2
-	sll	t1, t1, 8
-	jr	$r_ra
-	 or	$r_A, t0, t1
-# endif
-#else
-	jr	$r_ra
-	 move	$r_A, $r_s0
-#endif
-
-	END(bpf_slow_path_word)
-
-NESTED(bpf_slow_path_half, (6 * SZREG), $r_sp)
-	bpf_slow_path_common(2)
-#ifdef CONFIG_CPU_LITTLE_ENDIAN
-# if MIPS_ISA_REV >= 2
-	jr	$r_ra
-	 wsbh	$r_A, $r_s0
-# else
-	sll	t0, $r_s0, 8
-	andi	t1, $r_s0, 0xff00
-	andi	t0, t0, 0xff00
-	srl	t1, t1, 8
-	jr	$r_ra
-	 or	$r_A, t0, t1
-# endif
-#else
-	jr	$r_ra
-	 move	$r_A, $r_s0
-#endif
-
-	END(bpf_slow_path_half)
-
-NESTED(bpf_slow_path_byte, (6 * SZREG), $r_sp)
-	bpf_slow_path_common(1)
-	jr	$r_ra
-	 move	$r_A, $r_s0
-
-	END(bpf_slow_path_byte)
-
-/*
- * Negative entry points
- */
-	.macro bpf_is_end_of_data
-	li	t0, SKF_LL_OFF
-	/* Reading link layer data? */
-	slt	t1, offset, t0
-	bgtz	t1, fault
-	/* Be careful what follows in DS. */
-	.endm
-/*
- * call skb_copy_bits:
- * (prototype in linux/filter.h)
- *
- * void *bpf_internal_load_pointer_neg_helper(const struct sk_buff *skb,
- *                                            int k, unsigned int size)
- *
- * see above (bpf_slow_path_common) for ABI restrictions
- */
-#define bpf_negative_common(SIZE)					\
-	PTR_ADDIU	$r_sp, $r_sp, -(6 * SZREG);			\
-	PTR_LA		t0, bpf_internal_load_pointer_neg_helper;	\
-	PTR_S		$r_ra, (5 * SZREG)($r_sp);			\
-	jalr		t0;						\
-	 li		a2, SIZE;					\
-	PTR_L		$r_ra, (5 * SZREG)($r_sp);			\
-	/* Check return pointer */					\
-	beqz		v0, fault;					\
-	 PTR_ADDIU	$r_sp, $r_sp, 6 * SZREG;			\
-	/* Preserve our pointer */					\
-	move		$r_s0, v0;					\
-	/* Set return value */						\
-	move		$r_ret, zero;					\
-
-bpf_slow_path_word_neg:
-	bpf_is_end_of_data
-NESTED(sk_load_word_negative, (6 * SZREG), $r_sp)
-	bpf_negative_common(4)
-	jr	$r_ra
-	 lw	$r_A, 0($r_s0)
-	END(sk_load_word_negative)
-
-bpf_slow_path_half_neg:
-	bpf_is_end_of_data
-NESTED(sk_load_half_negative, (6 * SZREG), $r_sp)
-	bpf_negative_common(2)
-	jr	$r_ra
-	 lhu	$r_A, 0($r_s0)
-	END(sk_load_half_negative)
-
-bpf_slow_path_byte_neg:
-	bpf_is_end_of_data
-NESTED(sk_load_byte_negative, (6 * SZREG), $r_sp)
-	bpf_negative_common(1)
-	jr	$r_ra
-	 lbu	$r_A, 0($r_s0)
-	END(sk_load_byte_negative)
-
-fault:
-	jr	$r_ra
-	 addiu $r_ret, zero, 1