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linux/arch/arm64/net/bpf_jit_comp.c
Zi Shen Lim 42ff712bc0 arm64: bpf: add extra pass to handle faulty codegen 
Code generation functions in arch/arm64/kernel/insn.c previously
BUG_ON invalid parameters. Following change of that behavior, now we
need to handle the error case where AARCH64_BREAK_FAULT is returned.

Instead of error-handling on every emit() in JIT, we add a new
validation pass at the end of JIT compilation. There's no point in
running JITed code at run-time only to trap due to AARCH64_BREAK_FAULT.
Instead, we drop this failed JIT compilation and allow the system to
gracefully fallback on the BPF interpreter.

Signed-off-by: Zi Shen Lim <zlim.lnx@gmail.com>
Suggested-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
2016-01-17 19:15:26 -05:00

849 lines
21 KiB
C
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/*
* 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/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 "bpf_jit.h"
int bpf_jit_enable __read_mostly;
#define TMP_REG_1 (MAX_BPF_REG + 0)
#define TMP_REG_2 (MAX_BPF_REG + 1)
/* 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 register for internal BPF JIT */
[TMP_REG_1] = A64_R(23),
[TMP_REG_2] = A64_R(24),
};
struct jit_ctx {
const struct bpf_prog *prog;
int idx;
int tmp_used;
int epilogue_offset;
int *offset;
u32 *image;
};
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)
{
u32 *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 _STACK_SIZE \
(MAX_BPF_STACK \
+ 4 /* extra for skb_copy_bits buffer */)
#define STACK_SIZE STACK_ALIGN(_STACK_SIZE)
static void build_prologue(struct jit_ctx *ctx)
{
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 tmp1 = bpf2a64[TMP_REG_1];
const u8 tmp2 = bpf2a64[TMP_REG_2];
/*
* BPF prog stack layout
*
* high
* original A64_SP => 0:+-----+ BPF prologue
* |FP/LR|
* current A64_FP => -16:+-----+
* | ... | callee saved registers
* +-----+
* | | x25/x26
* BPF fp register => -80:+-----+ <= (BPF_FP)
* | |
* | ... | BPF prog stack
* | |
* +-----+ <= (BPF_FP - MAX_BPF_STACK)
* |RSVD | JIT scratchpad
* current A64_SP => +-----+ <= (BPF_FP - 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 register */
emit(A64_PUSH(r6, r7, A64_SP), ctx);
emit(A64_PUSH(r8, r9, A64_SP), ctx);
if (ctx->tmp_used)
emit(A64_PUSH(tmp1, tmp2, A64_SP), ctx);
/* Save fp (x25) and x26. SP requires 16 bytes alignment */
emit(A64_PUSH(fp, A64_R(26), A64_SP), ctx);
/* Set up BPF prog stack base register (x25) */
emit(A64_MOV(1, fp, A64_SP), ctx);
/* Set up function call stack */
emit(A64_SUB_I(1, A64_SP, A64_SP, STACK_SIZE), ctx);
}
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];
const u8 tmp1 = bpf2a64[TMP_REG_1];
const u8 tmp2 = bpf2a64[TMP_REG_2];
/* We're done with BPF stack */
emit(A64_ADD_I(1, A64_SP, A64_SP, STACK_SIZE), ctx);
/* Restore fs (x25) and x26 */
emit(A64_POP(fp, A64_R(26), A64_SP), ctx);
/* Restore callee-saved register */
if (ctx->tmp_used)
emit(A64_POP(tmp1, tmp2, A64_SP), ctx);
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 s16 off = insn->off;
const s32 imm = insn->imm;
const int i = insn - ctx->prog->insnsi;
const bool is64 = BPF_CLASS(code) == BPF_ALU64;
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:
ctx->tmp_used = 1;
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:
ctx->tmp_used = 1;
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:
ctx->tmp_used = 1;
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:
ctx->tmp_used = 1;
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:
ctx->tmp_used = 1;
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:
ctx->tmp_used = 1;
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:
ctx->tmp_used = 1;
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:
ctx->tmp_used = 1;
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:
ctx->tmp_used = 1;
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_JGE | BPF_X:
case BPF_JMP | BPF_JNE | BPF_X:
case BPF_JMP | BPF_JSGT | BPF_X:
case BPF_JMP | BPF_JSGE | 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_JGE:
jmp_cond = A64_COND_CS;
break;
case BPF_JNE:
jmp_cond = A64_COND_NE;
break;
case BPF_JSGT:
jmp_cond = A64_COND_GT;
break;
case BPF_JSGE:
jmp_cond = A64_COND_GE;
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_JGE | BPF_K:
case BPF_JMP | BPF_JNE | BPF_K:
case BPF_JMP | BPF_JSGT | BPF_K:
case BPF_JMP | BPF_JSGE | BPF_K:
ctx->tmp_used = 1;
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:
ctx->tmp_used = 1;
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;
ctx->tmp_used = 1;
emit_a64_mov_i64(tmp, func, ctx);
emit(A64_PUSH(A64_FP, A64_LR, A64_SP), ctx);
emit(A64_MOV(1, A64_FP, A64_SP), ctx);
emit(A64_BLR(tmp), ctx);
emit(A64_MOV(1, r0, A64_R(0)), ctx);
emit(A64_POP(A64_FP, A64_LR, A64_SP), ctx);
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;
if (insn1.code != 0 || insn1.src_reg != 0 ||
insn1.dst_reg != 0 || insn1.off != 0) {
/* Note: verifier in BPF core must catch invalid
* instructions.
*/
pr_err_once("Invalid BPF_LD_IMM64 instruction\n");
return -EINVAL;
}
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:
ctx->tmp_used = 1;
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 */
ctx->tmp_used = 1;
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:
ctx->tmp_used = 1;
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:
goto notyet;
/* 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, STACK_SIZE), ctx);
emit_a64_mov_i64(r5, (unsigned long)bpf_load_pointer, ctx);
emit(A64_PUSH(A64_FP, A64_LR, A64_SP), ctx);
emit(A64_MOV(1, A64_FP, A64_SP), ctx);
emit(A64_BLR(r5), ctx);
emit(A64_MOV(1, r0, A64_R(0)), ctx);
emit(A64_POP(A64_FP, A64_LR, A64_SP), 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;
}
notyet:
pr_info_once("*** NOT YET: opcode %02x ***\n", code);
return -EFAULT;
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 (ctx->image == NULL)
ctx->offset[i] = ctx->idx;
if (ret > 0) {
i++;
continue;
}
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);
}
void bpf_jit_compile(struct bpf_prog *prog)
{
/* Nothing to do here. We support Internal BPF. */
}
void bpf_int_jit_compile(struct bpf_prog *prog)
{
struct bpf_binary_header *header;
struct jit_ctx ctx;
int image_size;
u8 *image_ptr;
if (!bpf_jit_enable)
return;
if (!prog || !prog->len)
return;
memset(&ctx, 0, sizeof(ctx));
ctx.prog = prog;
ctx.offset = kcalloc(prog->len, sizeof(int), GFP_KERNEL);
if (ctx.offset == NULL)
return;
/* 1. Initial fake pass to compute ctx->idx. */
/* Fake pass to fill in ctx->offset and ctx->tmp_used. */
if (build_body(&ctx))
goto out;
build_prologue(&ctx);
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)
goto out;
/* 2. Now, the actual pass. */
ctx.image = (u32 *)image_ptr;
ctx.idx = 0;
build_prologue(&ctx);
if (build_body(&ctx)) {
bpf_jit_binary_free(header);
goto out;
}
build_epilogue(&ctx);
/* 3. Extra pass to validate JITed code. */
if (validate_code(&ctx)) {
bpf_jit_binary_free(header);
goto out;
}
/* 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);
set_memory_ro((unsigned long)header, header->pages);
prog->bpf_func = (void *)ctx.image;
prog->jited = 1;
out:
kfree(ctx.offset);
}
void bpf_jit_free(struct bpf_prog *prog)
{
unsigned long addr = (unsigned long)prog->bpf_func & PAGE_MASK;
struct bpf_binary_header *header = (void *)addr;
if (!prog->jited)
goto free_filter;
set_memory_rw(addr, header->pages);
bpf_jit_binary_free(header);
free_filter:
bpf_prog_unlock_free(prog);
}
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