korg/linux
0
0
Fork 0
mirror of https://mirrors.bfsu.edu.cn/git/linux.git synced 2024-12-04 01:24:12 +08:00
Code Issues Packages Projects Releases Wiki Activity
60b58afc96
linux/arch/arm64/net/bpf_jit_comp.c
Alexei Starovoitov 60b58afc96 bpf: fix net.core.bpf_jit_enable race 
global bpf_jit_enable variable is tested multiple times in JITs,
blinding and verifier core. The malicious root can try to toggle
it while loading the programs. This race condition was accounted
for and there should be no issues, but it's safer to avoid
this race condition.

Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
2017-12-17 20:34:36 +01:00

936 lines
23 KiB
C
Raw Blame History

/*
* 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/skbuff.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"
int bpf_jit_enable __read_mostly;
#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_i64(const int reg, const u64 val,
struct jit_ctx *ctx)
{
u64 tmp = val;
int shift = 0;
emit(A64_MOVZ(1, reg, tmp & 0xffff, shift), ctx);
tmp >>= 16;
shift += 16;
while (tmp) {
if (tmp & 0xffff)
emit(A64_MOVK(1, reg, tmp & 0xffff, shift), ctx);
tmp >>= 16;
shift += 16;
}
}
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);
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 inline int bpf2a64_offset(int bpf_to, int bpf_from,
const struct jit_ctx *ctx)
{
int to = ctx->offset[bpf_to];
/* -1 to account for the Branch instruction */
int from = ctx->offset[bpf_from] - 1;
return to - from;
}
static void jit_fill_hole(void *area, unsigned int size)
{
__le32 *ptr;
/* We are guaranteed to have aligned memory. */
for (ptr = area; size >= sizeof(u32); size -= sizeof(u32))
*ptr++ = cpu_to_le32(AARCH64_BREAK_FAULT);
}
static inline int epilogue_offset(const struct jit_ctx *ctx)
{
int to = ctx->epilogue_offset;
int from = ctx->idx;
return to - from;
}
/* Stack must be multiples of 16B */
#define STACK_ALIGN(sz) (((sz) + 15) & ~15)
#define PROLOGUE_OFFSET 8
static int build_prologue(struct jit_ctx *ctx)
{
const struct bpf_prog *prog = ctx->prog;
const u8 r6 = bpf2a64[BPF_REG_6];
const u8 r7 = bpf2a64[BPF_REG_7];
const u8 r8 = bpf2a64[BPF_REG_8];
const u8 r9 = bpf2a64[BPF_REG_9];
const u8 fp = bpf2a64[BPF_REG_FP];
const u8 tcc = bpf2a64[TCALL_CNT];
const int idx0 = ctx->idx;
int cur_offset;
/*
* BPF prog stack layout
*
* high
* original A64_SP => 0:+-----+ BPF prologue
* |FP/LR|
* current A64_FP => -16:+-----+
* | ... | callee saved registers
* BPF fp register => -64:+-----+ <= (BPF_FP)
* | |
* | ... | BPF prog stack
* | |
* +-----+ <= (BPF_FP - prog->aux->stack_depth)
* |RSVD | JIT scratchpad
* current A64_SP => +-----+ <= (BPF_FP - ctx->stack_size)
* | |
* | ... | Function call stack
* | |
* +-----+
* low
*
*/
/* Save FP and LR registers to stay align with ARM64 AAPCS */
emit(A64_PUSH(A64_FP, A64_LR, A64_SP), ctx);
emit(A64_MOV(1, A64_FP, A64_SP), ctx);
/* Save callee-saved registers */
emit(A64_PUSH(r6, r7, A64_SP), ctx);
emit(A64_PUSH(r8, r9, A64_SP), ctx);
emit(A64_PUSH(fp, tcc, A64_SP), ctx);
/* Set up BPF prog stack base register */
emit(A64_MOV(1, fp, A64_SP), ctx);
/* Initialize tail_call_cnt */
emit(A64_MOVZ(1, tcc, 0, 0), ctx);
/* 4 byte extra for skb_copy_bits buffer */
ctx->stack_size = prog->aux->stack_depth + 4;
ctx->stack_size = STACK_ALIGN(ctx->stack_size);
/* Set up function call stack */
emit(A64_SUB_I(1, A64_SP, A64_SP, ctx->stack_size), ctx);
cur_offset = ctx->idx - idx0;
if (cur_offset != PROLOGUE_OFFSET) {
pr_err_once("PROLOGUE_OFFSET = %d, expected %d!\n",
cur_offset, PROLOGUE_OFFSET);
return -1;
}
return 0;
}
static int out_offset = -1; /* initialized on the first pass of build_body() */
static int emit_bpf_tail_call(struct jit_ctx *ctx)
{
/* bpf_tail_call(void *prog_ctx, struct bpf_array *array, u64 index) */
const u8 r2 = bpf2a64[BPF_REG_2];
const u8 r3 = bpf2a64[BPF_REG_3];
const u8 tmp = bpf2a64[TMP_REG_1];
const u8 prg = bpf2a64[TMP_REG_2];
const u8 tcc = bpf2a64[TCALL_CNT];
const int idx0 = ctx->idx;
#define cur_offset (ctx->idx - idx0)
#define jmp_offset (out_offset - (cur_offset))
size_t off;
/* if (index >= array->map.max_entries)
* goto out;
*/
off = offsetof(struct bpf_array, map.max_entries);
emit_a64_mov_i64(tmp, off, ctx);
emit(A64_LDR32(tmp, r2, tmp), ctx);
emit(A64_CMP(0, r3, tmp), ctx);
emit(A64_B_(A64_COND_GE, jmp_offset), ctx);
/* if (tail_call_cnt > MAX_TAIL_CALL_CNT)
* goto out;
* tail_call_cnt++;
*/
emit_a64_mov_i64(tmp, MAX_TAIL_CALL_CNT, ctx);
emit(A64_CMP(1, tcc, tmp), ctx);
emit(A64_B_(A64_COND_GT, jmp_offset), ctx);
emit(A64_ADD_I(1, tcc, tcc, 1), ctx);
/* prog = array->ptrs[index];
* if (prog == NULL)
* goto out;
*/
off = offsetof(struct bpf_array, ptrs);
emit_a64_mov_i64(tmp, off, ctx);
emit(A64_ADD(1, tmp, r2, tmp), ctx);
emit(A64_LSL(1, prg, r3, 3), ctx);
emit(A64_LDR64(prg, tmp, prg), ctx);
emit(A64_CBZ(1, prg, jmp_offset), ctx);
/* goto *(prog->bpf_func + prologue_size); */
off = offsetof(struct bpf_prog, bpf_func);
emit_a64_mov_i64(tmp, off, ctx);
emit(A64_LDR64(tmp, prg, tmp), ctx);
emit(A64_ADD_I(1, tmp, tmp, sizeof(u32) * PROLOGUE_OFFSET), ctx);
emit(A64_BR(tmp), ctx);
/* out: */
if (out_offset == -1)
out_offset = cur_offset;
if (cur_offset != out_offset) {
pr_err_once("tail_call out_offset = %d, expected %d!\n",
cur_offset, out_offset);
return -1;
}
return 0;
#undef cur_offset
#undef jmp_offset
}
static void build_epilogue(struct jit_ctx *ctx)
{
const u8 r0 = bpf2a64[BPF_REG_0];
const u8 r6 = bpf2a64[BPF_REG_6];
const u8 r7 = bpf2a64[BPF_REG_7];
const u8 r8 = bpf2a64[BPF_REG_8];
const u8 r9 = bpf2a64[BPF_REG_9];
const u8 fp = bpf2a64[BPF_REG_FP];
/* We're done with BPF stack */
emit(A64_ADD_I(1, A64_SP, A64_SP, ctx->stack_size), ctx);
/* Restore fs (x25) and x26 */
emit(A64_POP(fp, A64_R(26), A64_SP), ctx);
/* Restore callee-saved register */
emit(A64_POP(r8, r9, A64_SP), ctx);
emit(A64_POP(r6, r7, A64_SP), ctx);
/* Restore FP/LR registers */
emit(A64_POP(A64_FP, A64_LR, A64_SP), ctx);
/* Set return value */
emit(A64_MOV(1, A64_R(0), r0), ctx);
emit(A64_RET(A64_LR), ctx);
}
/* JITs an eBPF instruction.
* Returns:
* 0 - successfully JITed an 8-byte eBPF instruction.
* >0 - successfully JITed a 16-byte eBPF instruction.
* <0 - failed to JIT.
*/
static int build_insn(const struct bpf_insn *insn, struct jit_ctx *ctx)
{
const u8 code = insn->code;
const u8 dst = bpf2a64[insn->dst_reg];
const u8 src = bpf2a64[insn->src_reg];
const u8 tmp = bpf2a64[TMP_REG_1];
const u8 tmp2 = bpf2a64[TMP_REG_2];
const u8 tmp3 = bpf2a64[TMP_REG_3];
const s16 off = insn->off;
const s32 imm = insn->imm;
const int i = insn - ctx->prog->insnsi;
const bool is64 = BPF_CLASS(code) == BPF_ALU64;
const bool isdw = BPF_SIZE(code) == BPF_DW;
u8 jmp_cond;
s32 jmp_offset;
#define check_imm(bits, imm) do { \
if ((((imm) > 0) && ((imm) >> (bits))) || \
(((imm) < 0) && (~(imm) >> (bits)))) { \
pr_info("[%2d] imm=%d(0x%x) out of range\n", \
i, imm, imm); \
return -EINVAL; \
} \
} while (0)
#define check_imm19(imm) check_imm(19, imm)
#define check_imm26(imm) check_imm(26, imm)
switch (code) {
/* dst = src */
case BPF_ALU | BPF_MOV | BPF_X:
case BPF_ALU64 | BPF_MOV | BPF_X:
emit(A64_MOV(is64, dst, src), ctx);
break;
/* dst = dst OP src */
case BPF_ALU | BPF_ADD | BPF_X:
case BPF_ALU64 | BPF_ADD | BPF_X:
emit(A64_ADD(is64, dst, dst, src), ctx);
break;
case BPF_ALU | BPF_SUB | BPF_X:
case BPF_ALU64 | BPF_SUB | BPF_X:
emit(A64_SUB(is64, dst, dst, src), ctx);
break;
case BPF_ALU | BPF_AND | BPF_X:
case BPF_ALU64 | BPF_AND | BPF_X:
emit(A64_AND(is64, dst, dst, src), ctx);
break;
case BPF_ALU | BPF_OR | BPF_X:
case BPF_ALU64 | BPF_OR | BPF_X:
emit(A64_ORR(is64, dst, dst, src), ctx);
break;
case BPF_ALU | BPF_XOR | BPF_X:
case BPF_ALU64 | BPF_XOR | BPF_X:
emit(A64_EOR(is64, dst, dst, src), ctx);
break;
case BPF_ALU | BPF_MUL | BPF_X:
case BPF_ALU64 | BPF_MUL | BPF_X:
emit(A64_MUL(is64, dst, dst, src), ctx);
break;
case BPF_ALU | BPF_DIV | BPF_X:
case BPF_ALU64 | BPF_DIV | BPF_X:
case BPF_ALU | BPF_MOD | BPF_X:
case BPF_ALU64 | BPF_MOD | BPF_X:
{
const u8 r0 = bpf2a64[BPF_REG_0];
/* if (src == 0) return 0 */
jmp_offset = 3; /* skip ahead to else path */
check_imm19(jmp_offset);
emit(A64_CBNZ(is64, src, jmp_offset), ctx);
emit(A64_MOVZ(1, r0, 0, 0), ctx);
jmp_offset = epilogue_offset(ctx);
check_imm26(jmp_offset);
emit(A64_B(jmp_offset), ctx);
/* else */
switch (BPF_OP(code)) {
case BPF_DIV:
emit(A64_UDIV(is64, dst, dst, src), ctx);
break;
case BPF_MOD:
emit(A64_UDIV(is64, tmp, dst, src), ctx);
emit(A64_MUL(is64, tmp, tmp, src), ctx);
emit(A64_SUB(is64, dst, dst, tmp), ctx);
break;
}
break;
}
case BPF_ALU | BPF_LSH | BPF_X:
case BPF_ALU64 | BPF_LSH | BPF_X:
emit(A64_LSLV(is64, dst, dst, src), ctx);
break;
case BPF_ALU | BPF_RSH | BPF_X:
case BPF_ALU64 | BPF_RSH | BPF_X:
emit(A64_LSRV(is64, dst, dst, src), ctx);
break;
case BPF_ALU | BPF_ARSH | BPF_X:
case BPF_ALU64 | BPF_ARSH | BPF_X:
emit(A64_ASRV(is64, dst, dst, src), ctx);
break;
/* dst = -dst */
case BPF_ALU | BPF_NEG:
case BPF_ALU64 | BPF_NEG:
emit(A64_NEG(is64, dst, dst), ctx);
break;
/* dst = BSWAP##imm(dst) */
case BPF_ALU | BPF_END | BPF_FROM_LE:
case BPF_ALU | BPF_END | BPF_FROM_BE:
#ifdef CONFIG_CPU_BIG_ENDIAN
if (BPF_SRC(code) == BPF_FROM_BE)
goto emit_bswap_uxt;
#else /* !CONFIG_CPU_BIG_ENDIAN */
if (BPF_SRC(code) == BPF_FROM_LE)
goto emit_bswap_uxt;
#endif
switch (imm) {
case 16:
emit(A64_REV16(is64, dst, dst), ctx);
/* zero-extend 16 bits into 64 bits */
emit(A64_UXTH(is64, dst, dst), ctx);
break;
case 32:
emit(A64_REV32(is64, dst, dst), ctx);
/* upper 32 bits already cleared */
break;
case 64:
emit(A64_REV64(dst, dst), ctx);
break;
}
break;
emit_bswap_uxt:
switch (imm) {
case 16:
/* zero-extend 16 bits into 64 bits */
emit(A64_UXTH(is64, dst, dst), ctx);
break;
case 32:
/* zero-extend 32 bits into 64 bits */
emit(A64_UXTW(is64, dst, dst), ctx);
break;
case 64:
/* nop */
break;
}
break;
/* dst = imm */
case BPF_ALU | BPF_MOV | BPF_K:
case BPF_ALU64 | BPF_MOV | BPF_K:
emit_a64_mov_i(is64, dst, imm, ctx);
break;
/* dst = dst OP imm */
case BPF_ALU | BPF_ADD | BPF_K:
case BPF_ALU64 | BPF_ADD | BPF_K:
emit_a64_mov_i(is64, tmp, imm, ctx);
emit(A64_ADD(is64, dst, dst, tmp), ctx);
break;
case BPF_ALU | BPF_SUB | BPF_K:
case BPF_ALU64 | BPF_SUB | BPF_K:
emit_a64_mov_i(is64, tmp, imm, ctx);
emit(A64_SUB(is64, dst, dst, tmp), ctx);
break;
case BPF_ALU | BPF_AND | BPF_K:
case BPF_ALU64 | BPF_AND | BPF_K:
emit_a64_mov_i(is64, tmp, imm, ctx);
emit(A64_AND(is64, dst, dst, tmp), ctx);
break;
case BPF_ALU | BPF_OR | BPF_K:
case BPF_ALU64 | BPF_OR | BPF_K:
emit_a64_mov_i(is64, tmp, imm, ctx);
emit(A64_ORR(is64, dst, dst, tmp), ctx);
break;
case BPF_ALU | BPF_XOR | BPF_K:
case BPF_ALU64 | BPF_XOR | BPF_K:
emit_a64_mov_i(is64, tmp, imm, ctx);
emit(A64_EOR(is64, dst, dst, tmp), ctx);
break;
case BPF_ALU | BPF_MUL | BPF_K:
case BPF_ALU64 | BPF_MUL | BPF_K:
emit_a64_mov_i(is64, tmp, imm, ctx);
emit(A64_MUL(is64, dst, dst, tmp), ctx);
break;
case BPF_ALU | BPF_DIV | BPF_K:
case BPF_ALU64 | BPF_DIV | BPF_K:
emit_a64_mov_i(is64, tmp, imm, ctx);
emit(A64_UDIV(is64, dst, dst, tmp), ctx);
break;
case BPF_ALU | BPF_MOD | BPF_K:
case BPF_ALU64 | BPF_MOD | BPF_K:
emit_a64_mov_i(is64, tmp2, imm, ctx);
emit(A64_UDIV(is64, tmp, dst, tmp2), ctx);
emit(A64_MUL(is64, tmp, tmp, tmp2), ctx);
emit(A64_SUB(is64, dst, dst, tmp), ctx);
break;
case BPF_ALU | BPF_LSH | BPF_K:
case BPF_ALU64 | BPF_LSH | BPF_K:
emit(A64_LSL(is64, dst, dst, imm), ctx);
break;
case BPF_ALU | BPF_RSH | BPF_K:
case BPF_ALU64 | BPF_RSH | BPF_K:
emit(A64_LSR(is64, dst, dst, imm), ctx);
break;
case BPF_ALU | BPF_ARSH | BPF_K:
case BPF_ALU64 | BPF_ARSH | BPF_K:
emit(A64_ASR(is64, dst, dst, imm), ctx);
break;
/* JUMP off */
case BPF_JMP | BPF_JA:
jmp_offset = bpf2a64_offset(i + off, i, ctx);
check_imm26(jmp_offset);
emit(A64_B(jmp_offset), ctx);
break;
/* IF (dst COND src) JUMP off */
case BPF_JMP | BPF_JEQ | BPF_X:
case BPF_JMP | BPF_JGT | BPF_X:
case BPF_JMP | BPF_JLT | BPF_X:
case BPF_JMP | BPF_JGE | BPF_X:
case BPF_JMP | BPF_JLE | BPF_X:
case BPF_JMP | BPF_JNE | BPF_X:
case BPF_JMP | BPF_JSGT | BPF_X:
case BPF_JMP | BPF_JSLT | BPF_X:
case BPF_JMP | BPF_JSGE | BPF_X:
case BPF_JMP | BPF_JSLE | BPF_X:
emit(A64_CMP(1, dst, src), ctx);
emit_cond_jmp:
jmp_offset = bpf2a64_offset(i + off, i, ctx);
check_imm19(jmp_offset);
switch (BPF_OP(code)) {
case BPF_JEQ:
jmp_cond = A64_COND_EQ;
break;
case BPF_JGT:
jmp_cond = A64_COND_HI;
break;
case BPF_JLT:
jmp_cond = A64_COND_CC;
break;
case BPF_JGE:
jmp_cond = A64_COND_CS;
break;
case BPF_JLE:
jmp_cond = A64_COND_LS;
break;
case BPF_JSET:
case BPF_JNE:
jmp_cond = A64_COND_NE;
break;
case BPF_JSGT:
jmp_cond = A64_COND_GT;
break;
case BPF_JSLT:
jmp_cond = A64_COND_LT;
break;
case BPF_JSGE:
jmp_cond = A64_COND_GE;
break;
case BPF_JSLE:
jmp_cond = A64_COND_LE;
break;
default:
return -EFAULT;
}
emit(A64_B_(jmp_cond, jmp_offset), ctx);
break;
case BPF_JMP | BPF_JSET | BPF_X:
emit(A64_TST(1, dst, src), ctx);
goto emit_cond_jmp;
/* IF (dst COND imm) JUMP off */
case BPF_JMP | BPF_JEQ | BPF_K:
case BPF_JMP | BPF_JGT | BPF_K:
case BPF_JMP | BPF_JLT | BPF_K:
case BPF_JMP | BPF_JGE | BPF_K:
case BPF_JMP | BPF_JLE | BPF_K:
case BPF_JMP | BPF_JNE | BPF_K:
case BPF_JMP | BPF_JSGT | BPF_K:
case BPF_JMP | BPF_JSLT | BPF_K:
case BPF_JMP | BPF_JSGE | BPF_K:
case BPF_JMP | BPF_JSLE | BPF_K:
emit_a64_mov_i(1, tmp, imm, ctx);
emit(A64_CMP(1, dst, tmp), ctx);
goto emit_cond_jmp;
case BPF_JMP | BPF_JSET | BPF_K:
emit_a64_mov_i(1, tmp, imm, ctx);
emit(A64_TST(1, dst, tmp), ctx);
goto emit_cond_jmp;
/* function call */
case BPF_JMP | BPF_CALL:
{
const u8 r0 = bpf2a64[BPF_REG_0];
const u64 func = (u64)__bpf_call_base + imm;
emit_a64_mov_i64(tmp, func, ctx);
emit(A64_BLR(tmp), ctx);
emit(A64_MOV(1, r0, A64_R(0)), ctx);
break;
}
/* tail call */
case BPF_JMP | BPF_TAIL_CALL:
if (emit_bpf_tail_call(ctx))
return -EFAULT;
break;
/* function return */
case BPF_JMP | BPF_EXIT:
/* Optimization: when last instruction is EXIT,
simply fallthrough to epilogue. */
if (i == ctx->prog->len - 1)
break;
jmp_offset = epilogue_offset(ctx);
check_imm26(jmp_offset);
emit(A64_B(jmp_offset), ctx);
break;
/* dst = imm64 */
case BPF_LD | BPF_IMM | BPF_DW:
{
const struct bpf_insn insn1 = insn[1];
u64 imm64;
imm64 = (u64)insn1.imm << 32 | (u32)imm;
emit_a64_mov_i64(dst, imm64, ctx);
return 1;
}
/* LDX: dst = *(size *)(src + off) */
case BPF_LDX | BPF_MEM | BPF_W:
case BPF_LDX | BPF_MEM | BPF_H:
case BPF_LDX | BPF_MEM | BPF_B:
case BPF_LDX | BPF_MEM | BPF_DW:
emit_a64_mov_i(1, tmp, off, ctx);
switch (BPF_SIZE(code)) {
case BPF_W:
emit(A64_LDR32(dst, src, tmp), ctx);
break;
case BPF_H:
emit(A64_LDRH(dst, src, tmp), ctx);
break;
case BPF_B:
emit(A64_LDRB(dst, src, tmp), ctx);
break;
case BPF_DW:
emit(A64_LDR64(dst, src, tmp), ctx);
break;
}
break;
/* ST: *(size *)(dst + off) = imm */
case BPF_ST | BPF_MEM | BPF_W:
case BPF_ST | BPF_MEM | BPF_H:
case BPF_ST | BPF_MEM | BPF_B:
case BPF_ST | BPF_MEM | BPF_DW:
/* Load imm to a register then store it */
emit_a64_mov_i(1, tmp2, off, ctx);
emit_a64_mov_i(1, tmp, imm, ctx);
switch (BPF_SIZE(code)) {
case BPF_W:
emit(A64_STR32(tmp, dst, tmp2), ctx);
break;
case BPF_H:
emit(A64_STRH(tmp, dst, tmp2), ctx);
break;
case BPF_B:
emit(A64_STRB(tmp, dst, tmp2), ctx);
break;
case BPF_DW:
emit(A64_STR64(tmp, dst, tmp2), ctx);
break;
}
break;
/* STX: *(size *)(dst + off) = src */
case BPF_STX | BPF_MEM | BPF_W:
case BPF_STX | BPF_MEM | BPF_H:
case BPF_STX | BPF_MEM | BPF_B:
case BPF_STX | BPF_MEM | BPF_DW:
emit_a64_mov_i(1, tmp, off, ctx);
switch (BPF_SIZE(code)) {
case BPF_W:
emit(A64_STR32(src, dst, tmp), ctx);
break;
case BPF_H:
emit(A64_STRH(src, dst, tmp), ctx);
break;
case BPF_B:
emit(A64_STRB(src, dst, tmp), ctx);
break;
case BPF_DW:
emit(A64_STR64(src, dst, tmp), ctx);
break;
}
break;
/* STX XADD: lock *(u32 *)(dst + off) += src */
case BPF_STX | BPF_XADD | BPF_W:
/* STX XADD: lock *(u64 *)(dst + off) += src */
case BPF_STX | BPF_XADD | BPF_DW:
emit_a64_mov_i(1, tmp, off, ctx);
emit(A64_ADD(1, tmp, tmp, dst), ctx);
emit(A64_PRFM(tmp, PST, L1, STRM), ctx);
emit(A64_LDXR(isdw, tmp2, tmp), ctx);
emit(A64_ADD(isdw, tmp2, tmp2, src), ctx);
emit(A64_STXR(isdw, tmp2, tmp, tmp3), ctx);
jmp_offset = -3;
check_imm19(jmp_offset);
emit(A64_CBNZ(0, tmp3, jmp_offset), ctx);
break;
/* R0 = ntohx(*(size *)(((struct sk_buff *)R6)->data + imm)) */
case BPF_LD | BPF_ABS | BPF_W:
case BPF_LD | BPF_ABS | BPF_H:
case BPF_LD | BPF_ABS | BPF_B:
/* R0 = ntohx(*(size *)(((struct sk_buff *)R6)->data + src + imm)) */
case BPF_LD | BPF_IND | BPF_W:
case BPF_LD | BPF_IND | BPF_H:
case BPF_LD | BPF_IND | BPF_B:
{
const u8 r0 = bpf2a64[BPF_REG_0]; /* r0 = return value */
const u8 r6 = bpf2a64[BPF_REG_6]; /* r6 = pointer to sk_buff */
const u8 fp = bpf2a64[BPF_REG_FP];
const u8 r1 = bpf2a64[BPF_REG_1]; /* r1: struct sk_buff *skb */
const u8 r2 = bpf2a64[BPF_REG_2]; /* r2: int k */
const u8 r3 = bpf2a64[BPF_REG_3]; /* r3: unsigned int size */
const u8 r4 = bpf2a64[BPF_REG_4]; /* r4: void *buffer */
const u8 r5 = bpf2a64[BPF_REG_5]; /* r5: void *(*func)(...) */
int size;
emit(A64_MOV(1, r1, r6), ctx);
emit_a64_mov_i(0, r2, imm, ctx);
if (BPF_MODE(code) == BPF_IND)
emit(A64_ADD(0, r2, r2, src), ctx);
switch (BPF_SIZE(code)) {
case BPF_W:
size = 4;
break;
case BPF_H:
size = 2;
break;
case BPF_B:
size = 1;
break;
default:
return -EINVAL;
}
emit_a64_mov_i64(r3, size, ctx);
emit(A64_SUB_I(1, r4, fp, ctx->stack_size), ctx);
emit_a64_mov_i64(r5, (unsigned long)bpf_load_pointer, ctx);
emit(A64_BLR(r5), ctx);
emit(A64_MOV(1, r0, A64_R(0)), ctx);
jmp_offset = epilogue_offset(ctx);
check_imm19(jmp_offset);
emit(A64_CBZ(1, r0, jmp_offset), ctx);
emit(A64_MOV(1, r5, r0), ctx);
switch (BPF_SIZE(code)) {
case BPF_W:
emit(A64_LDR32(r0, r5, A64_ZR), ctx);
#ifndef CONFIG_CPU_BIG_ENDIAN
emit(A64_REV32(0, r0, r0), ctx);
#endif
break;
case BPF_H:
emit(A64_LDRH(r0, r5, A64_ZR), ctx);
#ifndef CONFIG_CPU_BIG_ENDIAN
emit(A64_REV16(0, r0, r0), ctx);
#endif
break;
case BPF_B:
emit(A64_LDRB(r0, r5, A64_ZR), ctx);
break;
}
break;
}
default:
pr_err_once("unknown opcode %02x\n", code);
return -EINVAL;
}
return 0;
}
static int build_body(struct jit_ctx *ctx)
{
const struct bpf_prog *prog = ctx->prog;
int i;
for (i = 0; i < prog->len; i++) {
const struct bpf_insn *insn = &prog->insnsi[i];
int ret;
ret = build_insn(insn, ctx);
if (ret > 0) {
i++;
if (ctx->image == NULL)
ctx->offset[i] = ctx->idx;
continue;
}
if (ctx->image == NULL)
ctx->offset[i] = ctx->idx;
if (ret)
return ret;
}
return 0;
}
static int validate_code(struct jit_ctx *ctx)
{
int i;
for (i = 0; i < ctx->idx; i++) {
u32 a64_insn = le32_to_cpu(ctx->image[i]);
if (a64_insn == AARCH64_BREAK_FAULT)
return -1;
}
return 0;
}
static inline void bpf_flush_icache(void *start, void *end)
{
flush_icache_range((unsigned long)start, (unsigned long)end);
}
struct bpf_prog *bpf_int_jit_compile(struct bpf_prog *prog)
{
struct bpf_prog *tmp, *orig_prog = prog;
struct bpf_binary_header *header;
bool tmp_blinded = false;
struct jit_ctx ctx;
int image_size;
u8 *image_ptr;
if (!prog->jit_requested)
return orig_prog;
tmp = bpf_jit_blind_constants(prog);
/* If blinding was requested and we failed during blinding,
* we must fall back to the interpreter.
*/
if (IS_ERR(tmp))
return orig_prog;
if (tmp != prog) {
tmp_blinded = true;
prog = tmp;
}
memset(&ctx, 0, sizeof(ctx));
ctx.prog = prog;
ctx.offset = kcalloc(prog->len, sizeof(int), GFP_KERNEL);
if (ctx.offset == NULL) {
prog = orig_prog;
goto out;
}
/* 1. Initial fake pass to compute ctx->idx. */
/* Fake pass to fill in ctx->offset. */
if (build_body(&ctx)) {
prog = orig_prog;
goto out_off;
}
if (build_prologue(&ctx)) {
prog = orig_prog;
goto out_off;
}
ctx.epilogue_offset = ctx.idx;
build_epilogue(&ctx);
/* Now we know the actual image size. */
image_size = sizeof(u32) * ctx.idx;
header = bpf_jit_binary_alloc(image_size, &image_ptr,
sizeof(u32), jit_fill_hole);
if (header == NULL) {
prog = orig_prog;
goto out_off;
}
/* 2. Now, the actual pass. */
ctx.image = (__le32 *)image_ptr;
ctx.idx = 0;
build_prologue(&ctx);
if (build_body(&ctx)) {
bpf_jit_binary_free(header);
prog = orig_prog;
goto out_off;
}
build_epilogue(&ctx);
/* 3. Extra pass to validate JITed code. */
if (validate_code(&ctx)) {
bpf_jit_binary_free(header);
prog = orig_prog;
goto out_off;
}
/* And we're done. */
if (bpf_jit_enable > 1)
bpf_jit_dump(prog->len, image_size, 2, ctx.image);
bpf_flush_icache(header, ctx.image + ctx.idx);
bpf_jit_binary_lock_ro(header);
prog->bpf_func = (void *)ctx.image;
prog->jited = 1;
prog->jited_len = image_size;
out_off:
kfree(ctx.offset);
out:
if (tmp_blinded)
bpf_jit_prog_release_other(prog, prog == orig_prog ?
tmp : orig_prog);
return prog;
}
Reference in New Issue View Git Blame Copy Permalink