/*
* BPF JIT compiler for ARM64
*
* Copyright (C) 2014-2016 Zi Shen Lim <zlim.lnx@gmail.com>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
#define pr_fmt(fmt) "bpf_jit: " fmt
#include <linux/bpf.h>
#include <linux/filter.h>
#include <linux/printk.h>
#include <linux/slab.h>
#include <asm/byteorder.h>
#include <asm/cacheflush.h>
#include <asm/debug-monitors.h>
#include <asm/set_memory.h>
#include "bpf_jit.h"
#define TMP_REG_1 (MAX_BPF_JIT_REG + 0)
#define TMP_REG_2 (MAX_BPF_JIT_REG + 1)
#define TCALL_CNT (MAX_BPF_JIT_REG + 2)
#define TMP_REG_3 (MAX_BPF_JIT_REG + 3)
/* Map BPF registers to A64 registers */
static const int bpf2a64[] = {
/* return value from in-kernel function, and exit value from eBPF */
[BPF_REG_0] = A64_R(7),
/* arguments from eBPF program to in-kernel function */
[BPF_REG_1] = A64_R(0),
[BPF_REG_2] = A64_R(1),
[BPF_REG_3] = A64_R(2),
[BPF_REG_4] = A64_R(3),
[BPF_REG_5] = A64_R(4),
/* callee saved registers that in-kernel function will preserve */
[BPF_REG_6] = A64_R(19),
[BPF_REG_7] = A64_R(20),
[BPF_REG_8] = A64_R(21),
[BPF_REG_9] = A64_R(22),
/* read-only frame pointer to access stack */
[BPF_REG_FP] = A64_R(25),
/* temporary registers for internal BPF JIT */
[TMP_REG_1] = A64_R(10),
[TMP_REG_2] = A64_R(11),
[TMP_REG_3] = A64_R(12),
/* tail_call_cnt */
[TCALL_CNT] = A64_R(26),
/* temporary register for blinding constants */
[BPF_REG_AX] = A64_R(9),
};
struct jit_ctx {
const struct bpf_prog *prog;
int idx;
int epilogue_offset;
int *offset;
__le32 *image;
u32 stack_size;
};
static inline void emit(const u32 insn, struct jit_ctx *ctx)
{
if (ctx->image != NULL)
ctx->image[ctx->idx] = cpu_to_le32(insn);
ctx->idx++;
}
static inline void emit_a64_mov_i(const int is64, const int reg,
const s32 val, struct jit_ctx *ctx)
{
u16 hi = val >> 16;
u16 lo = val & 0xffff;
if (hi & 0x8000) {
if (hi == 0xffff) {
emit(A64_MOVN(is64, reg, (u16)~lo, 0), ctx);
} else {
emit(A64_MOVN(is64, reg, (u16)~hi, 16), ctx);
if (lo != 0xffff)
emit(A64_MOVK(is64, reg, lo, 0), ctx);
}
} else {
emit(A64_MOVZ(is64, reg, lo, 0), ctx);
if (hi)
emit(A64_MOVK(is64, reg, hi, 16), ctx);
}
}
static int i64_i16_blocks(const u64 val, bool inverse)
{
return (((val >> 0) & 0xffff) != (inverse ? 0xffff : 0x0000)) +
(((val >> 16) & 0xffff) != (inverse ? 0xffff : 0x0000)) +
(((val >> 32) & 0xffff) != (inverse ? 0xffff : 0x0000)) +
(((val >> 48) & 0xffff) != (inverse ? 0xffff : 0x0000));
}
static inline void emit_a64_mov_i64(const int reg, const u64 val,
struct jit_ctx *ctx)
{
u64 nrm_tmp = val, rev_tmp = ~val;
bool inverse;
int shift;
if (!(nrm_tmp >> 32))
return emit_a64_mov_i(0, reg, (u32)val, ctx);
inverse = i64_i16_blocks(nrm_tmp, true) < i64_i16_blocks(nrm_tmp, false);
shift = max(round_down((inverse ? (fls64(rev_tmp) - 1) :