diff options
Diffstat (limited to 'arch/arm/net/bpf_jit_32.c')
| -rw-r--r-- | arch/arm/net/bpf_jit_32.c | 915 |
1 files changed, 915 insertions, 0 deletions
diff --git a/arch/arm/net/bpf_jit_32.c b/arch/arm/net/bpf_jit_32.c new file mode 100644 index 000000000000..62135849f48b --- /dev/null +++ b/arch/arm/net/bpf_jit_32.c @@ -0,0 +1,915 @@ +/* + * Just-In-Time compiler for BPF filters on 32bit ARM + * + * Copyright (c) 2011 Mircea Gherzan <mgherzan@gmail.com> + * + * 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 <linux/bitops.h> +#include <linux/compiler.h> +#include <linux/errno.h> +#include <linux/filter.h> +#include <linux/moduleloader.h> +#include <linux/netdevice.h> +#include <linux/string.h> +#include <linux/slab.h> +#include <asm/cacheflush.h> +#include <asm/hwcap.h> + +#include "bpf_jit_32.h" + +/* + * ABI: + * + * r0 scratch register + * r4 BPF register A + * r5 BPF register X + * r6 pointer to the skb + * r7 skb->data + * r8 skb_headlen(skb) + */ + +#define r_scratch ARM_R0 +/* r1-r3 are (also) used for the unaligned loads on the non-ARMv7 slowpath */ +#define r_off ARM_R1 +#define r_A ARM_R4 +#define r_X ARM_R5 +#define r_skb ARM_R6 +#define r_skb_data ARM_R7 +#define r_skb_hl ARM_R8 + +#define SCRATCH_SP_OFFSET 0 +#define SCRATCH_OFF(k) (SCRATCH_SP_OFFSET + (k)) + +#define SEEN_MEM ((1 << BPF_MEMWORDS) - 1) +#define SEEN_MEM_WORD(k) (1 << (k)) +#define SEEN_X (1 << BPF_MEMWORDS) +#define SEEN_CALL (1 << (BPF_MEMWORDS + 1)) +#define SEEN_SKB (1 << (BPF_MEMWORDS + 2)) +#define SEEN_DATA (1 << (BPF_MEMWORDS + 3)) + +#define FLAG_NEED_X_RESET (1 << 0) + +struct jit_ctx { + const struct sk_filter *skf; + unsigned idx; + unsigned prologue_bytes; + int ret0_fp_idx; + u32 seen; + u32 flags; + u32 *offsets; + u32 *target; +#if __LINUX_ARM_ARCH__ < 7 + u16 epilogue_bytes; + u16 imm_count; + u32 *imms; +#endif +}; + +int bpf_jit_enable __read_mostly; + +static u64 jit_get_skb_b(struct sk_buff *skb, unsigned offset) +{ + u8 ret; + int err; + + err = skb_copy_bits(skb, offset, &ret, 1); + + return (u64)err << 32 | ret; +} + +static u64 jit_get_skb_h(struct sk_buff *skb, unsigned offset) +{ + u16 ret; + int err; + + err = skb_copy_bits(skb, offset, &ret, 2); + + return (u64)err << 32 | ntohs(ret); +} + +static u64 jit_get_skb_w(struct sk_buff *skb, unsigned offset) +{ + u32 ret; + int err; + + err = skb_copy_bits(skb, offset, &ret, 4); + + return (u64)err << 32 | ntohl(ret); +} + +/* + * Wrapper that handles both OABI and EABI and assures Thumb2 interworking + * (where the assembly routines like __aeabi_uidiv could cause problems). + */ +static u32 jit_udiv(u32 dividend, u32 divisor) +{ + return dividend / divisor; +} + +static inline void _emit(int cond, u32 inst, struct jit_ctx *ctx) +{ + if (ctx->target != NULL) + ctx->target[ctx->idx] = inst | (cond << 28); + + ctx->idx++; +} + +/* + * Emit an instruction that will be executed unconditionally. + */ +static inline void emit(u32 inst, struct jit_ctx *ctx) +{ + _emit(ARM_COND_AL, inst, ctx); +} + +static u16 saved_regs(struct jit_ctx *ctx) +{ + u16 ret = 0; + + if ((ctx->skf->len > 1) || + (ctx->skf->insns[0].code == BPF_S_RET_A)) + ret |= 1 << r_A; + +#ifdef CONFIG_FRAME_POINTER + ret |= (1 << ARM_FP) | (1 << ARM_IP) | (1 << ARM_LR) | (1 << ARM_PC); +#else + if (ctx->seen & SEEN_CALL) + ret |= 1 << ARM_LR; +#endif + if (ctx->seen & (SEEN_DATA | SEEN_SKB)) + ret |= 1 << r_skb; + if (ctx->seen & SEEN_DATA) + ret |= (1 << r_skb_data) | (1 << r_skb_hl); + if (ctx->seen & SEEN_X) + ret |= 1 << r_X; + + return ret; +} + +static inline int mem_words_used(struct jit_ctx *ctx) +{ + /* yes, we do waste some stack space IF there are "holes" in the set" */ + return fls(ctx->seen & SEEN_MEM); +} + +static inline bool is_load_to_a(u16 inst) +{ + switch (inst) { + case BPF_S_LD_W_LEN: + case BPF_S_LD_W_ABS: + case BPF_S_LD_H_ABS: + case BPF_S_LD_B_ABS: + case BPF_S_ANC_CPU: + case BPF_S_ANC_IFINDEX: + case BPF_S_ANC_MARK: + case BPF_S_ANC_PROTOCOL: + case BPF_S_ANC_RXHASH: + case BPF_S_ANC_QUEUE: + return true; + default: + return false; + } +} + +static void build_prologue(struct jit_ctx *ctx) +{ + u16 reg_set = saved_regs(ctx); + u16 first_inst = ctx->skf->insns[0].code; + u16 off; + +#ifdef CONFIG_FRAME_POINTER + emit(ARM_MOV_R(ARM_IP, ARM_SP), ctx); + emit(ARM_PUSH(reg_set), ctx); + emit(ARM_SUB_I(ARM_FP, ARM_IP, 4), ctx); +#else + if (reg_set) + emit(ARM_PUSH(reg_set), ctx); +#endif + + if (ctx->seen & (SEEN_DATA | SEEN_SKB)) + emit(ARM_MOV_R(r_skb, ARM_R0), ctx); + + if (ctx->seen & SEEN_DATA) { + off = offsetof(struct sk_buff, data); + emit(ARM_LDR_I(r_skb_data, r_skb, off), ctx); + /* headlen = len - data_len */ + off = offsetof(struct sk_buff, len); + emit(ARM_LDR_I(r_skb_hl, r_skb, off), ctx); + off = offsetof(struct sk_buff, data_len); + emit(ARM_LDR_I(r_scratch, r_skb, off), ctx); + emit(ARM_SUB_R(r_skb_hl, r_skb_hl, r_scratch), ctx); + } + + if (ctx->flags & FLAG_NEED_X_RESET) + emit(ARM_MOV_I(r_X, 0), ctx); + + /* do not leak kernel data to userspace */ + if ((first_inst != BPF_S_RET_K) && !(is_load_to_a(first_inst))) + emit(ARM_MOV_I(r_A, 0), ctx); + + /* stack space for the BPF_MEM words */ + if (ctx->seen & SEEN_MEM) + emit(ARM_SUB_I(ARM_SP, ARM_SP, mem_words_used(ctx) * 4), ctx); +} + +static void build_epilogue(struct jit_ctx *ctx) +{ + u16 reg_set = saved_regs(ctx); + + if (ctx->seen & SEEN_MEM) + emit(ARM_ADD_I(ARM_SP, ARM_SP, mem_words_used(ctx) * 4), ctx); + + reg_set &= ~(1 << ARM_LR); + +#ifdef CONFIG_FRAME_POINTER + /* the first instruction of the prologue was: mov ip, sp */ + reg_set &= ~(1 << ARM_IP); + reg_set |= (1 << ARM_SP); + emit(ARM_LDM(ARM_SP, reg_set), ctx); +#else + if (reg_set) { + if (ctx->seen & SEEN_CALL) + reg_set |= 1 << ARM_PC; + emit(ARM_POP(reg_set), ctx); + } + + if (!(ctx->seen & SEEN_CALL)) + emit(ARM_BX(ARM_LR), ctx); +#endif +} + +static int16_t imm8m(u32 x) +{ + u32 rot; + + for (rot = 0; rot < 16; rot++) + if ((x & ~ror32(0xff, 2 * rot)) == 0) + return rol32(x, 2 * rot) | (rot << 8); + + return -1; +} + +#if __LINUX_ARM_ARCH__ < 7 + +static u16 imm_offset(u32 k, struct jit_ctx *ctx) +{ + unsigned i = 0, offset; + u16 imm; + + /* on the "fake" run we just count them (duplicates included) */ + if (ctx->target == NULL) { + ctx->imm_count++; + return 0; + } + + while ((i < ctx->imm_count) && ctx->imms[i]) { + if (ctx->imms[i] == k) + break; + i++; + } + + if (ctx->imms[i] == 0) + ctx->imms[i] = k; + + /* constants go just after the epilogue */ + offset = ctx->offsets[ctx->skf->len]; + offset += ctx->prologue_bytes; + offset += ctx->epilogue_bytes; + offset += i * 4; + + ctx->target[offset / 4] = k; + + /* PC in ARM mode == address of the instruction + 8 */ + imm = offset - (8 + ctx->idx * 4); + + return imm; +} + +#endif /* __LINUX_ARM_ARCH__ */ + +/* + * Move an immediate that's not an imm8m to a core register. + */ +static inline void emit_mov_i_no8m(int rd, u32 val, struct jit_ctx *ctx) +{ +#if __LINUX_ARM_ARCH__ < 7 + emit(ARM_LDR_I(rd, ARM_PC, imm_offset(val, ctx)), ctx); +#else + emit(ARM_MOVW(rd, val & 0xffff), ctx); + if (val > 0xffff) + emit(ARM_MOVT(rd, val >> 16), ctx); +#endif +} + +static inline void emit_mov_i(int rd, u32 val, struct jit_ctx *ctx) +{ + int imm12 = imm8m(val); + + if (imm12 >= 0) + emit(ARM_MOV_I(rd, imm12), ctx); + else + emit_mov_i_no8m(rd, val, ctx); +} + +#if __LINUX_ARM_ARCH__ < 6 + +static void emit_load_be32(u8 cond, u8 r_res, u8 r_addr, struct jit_ctx *ctx) +{ + _emit(cond, ARM_LDRB_I(ARM_R3, r_addr, 1), ctx); + _emit(cond, ARM_LDRB_I(ARM_R1, r_addr, 0), ctx); + _emit(cond, ARM_LDRB_I(ARM_R2, r_addr, 3), ctx); + _emit(cond, ARM_LSL_I(ARM_R3, ARM_R3, 16), ctx); + _emit(cond, ARM_LDRB_I(ARM_R0, r_addr, 2), ctx); + _emit(cond, ARM_ORR_S(ARM_R3, ARM_R3, ARM_R1, SRTYPE_LSL, 24), ctx); + _emit(cond, ARM_ORR_R(ARM_R3, ARM_R3, ARM_R2), ctx); + _emit(cond, ARM_ORR_S(r_res, ARM_R3, ARM_R0, SRTYPE_LSL, 8), ctx); +} + +static void emit_load_be16(u8 cond, u8 r_res, u8 r_addr, struct jit_ctx *ctx) +{ + _emit(cond, ARM_LDRB_I(ARM_R1, r_addr, 0), ctx); + _emit(cond, ARM_LDRB_I(ARM_R2, r_addr, 1), ctx); + _emit(cond, ARM_ORR_S(r_res, ARM_R2, ARM_R1, SRTYPE_LSL, 8), ctx); +} + +static inline void emit_swap16(u8 r_dst, u8 r_src, struct jit_ctx *ctx) +{ + emit(ARM_LSL_R(ARM_R1, r_src, 8), ctx); + emit(ARM_ORR_S(r_dst, ARM_R1, r_src, SRTYPE_LSL, 8), ctx); + emit(ARM_LSL_I(r_dst, r_dst, 8), ctx); + emit(ARM_LSL_R(r_dst, r_dst, 8), ctx); +} + +#else /* ARMv6+ */ + +static void emit_load_be32(u8 cond, u8 r_res, u8 r_addr, struct jit_ctx *ctx) +{ + _emit(cond, ARM_LDR_I(r_res, r_addr, 0), ctx); +#ifdef __LITTLE_ENDIAN + _emit(cond, ARM_REV(r_res, r_res), ctx); +#endif +} + +static void emit_load_be16(u8 cond, u8 r_res, u8 r_addr, struct jit_ctx *ctx) +{ + _emit(cond, ARM_LDRH_I(r_res, r_addr, 0), ctx); +#ifdef __LITTLE_ENDIAN + _emit(cond, ARM_REV16(r_res, r_res), ctx); +#endif +} + +static inline void emit_swap16(u8 r_dst __maybe_unused, + u8 r_src __maybe_unused, + struct jit_ctx *ctx __maybe_unused) +{ +#ifdef __LITTLE_ENDIAN + emit(ARM_REV16(r_dst, r_src), ctx); +#endif +} + +#endif /* __LINUX_ARM_ARCH__ < 6 */ + + +/* Compute the immediate value for a PC-relative branch. */ +static inline u32 b_imm(unsigned tgt, struct jit_ctx *ctx) +{ + u32 imm; + + if (ctx->target == NULL) + return 0; + /* + * BPF allows only forward jumps and the offset of the target is + * still the one computed during the first pass. + */ + imm = ctx->offsets[tgt] + ctx->prologue_bytes - (ctx->idx * 4 + 8); + + return imm >> 2; +} + +#define OP_IMM3(op, r1, r2, imm_val, ctx) \ + do { \ + imm12 = imm8m(imm_val); \ + if (imm12 < 0) { \ + emit_mov_i_no8m(r_scratch, imm_val, ctx); \ + emit(op ## _R((r1), (r2), r_scratch), ctx); \ + } else { \ + emit(op ## _I((r1), (r2), imm12), ctx); \ + } \ + } while (0) + +static inline void emit_err_ret(u8 cond, struct jit_ctx *ctx) +{ + if (ctx->ret0_fp_idx >= 0) { + _emit(cond, ARM_B(b_imm(ctx->ret0_fp_idx, ctx)), ctx); + /* NOP to keep the size constant between passes */ + emit(ARM_MOV_R(ARM_R0, ARM_R0), ctx); + } else { + _emit(cond, ARM_MOV_I(ARM_R0, 0), ctx); + _emit(cond, ARM_B(b_imm(ctx->skf->len, ctx)), ctx); + } +} + +static inline void emit_blx_r(u8 tgt_reg, struct jit_ctx *ctx) +{ +#if __LINUX_ARM_ARCH__ < 5 + emit(ARM_MOV_R(ARM_LR, ARM_PC), ctx); + + if (elf_hwcap & HWCAP_THUMB) + emit(ARM_BX(tgt_reg), ctx); + else + emit(ARM_MOV_R(ARM_PC, tgt_reg), ctx); +#else + emit(ARM_BLX_R(tgt_reg), ctx); +#endif +} + +static inline void emit_udiv(u8 rd, u8 rm, u8 rn, struct jit_ctx *ctx) +{ +#if __LINUX_ARM_ARCH__ == 7 + if (elf_hwcap & HWCAP_IDIVA) { + emit(ARM_UDIV(rd, rm, rn), ctx); + return; + } +#endif + if (rm != ARM_R0) + emit(ARM_MOV_R(ARM_R0, rm), ctx); + if (rn != ARM_R1) + emit(ARM_MOV_R(ARM_R1, rn), ctx); + + ctx->seen |= SEEN_CALL; + emit_mov_i(ARM_R3, (u32)jit_udiv, ctx); + emit_blx_r(ARM_R3, ctx); + + if (rd != ARM_R0) + emit(ARM_MOV_R(rd, ARM_R0), ctx); +} + +static inline void update_on_xread(struct jit_ctx *ctx) +{ + if (!(ctx->seen & SEEN_X)) + ctx->flags |= FLAG_NEED_X_RESET; + + ctx->seen |= SEEN_X; +} + +static int build_body(struct jit_ctx *ctx) +{ + void *load_func[] = {jit_get_skb_b, jit_get_skb_h, jit_get_skb_w}; + const struct sk_filter *prog = ctx->skf; + const struct sock_filter *inst; + unsigned i, load_order, off, condt; + int imm12; + u32 k; + + for (i = 0; i < prog->len; i++) { + inst = &(prog->insns[i]); + /* K as an immediate value operand */ + k = inst->k; + + /* compute offsets only in the fake pass */ + if (ctx->target == NULL) + ctx->offsets[i] = ctx->idx * 4; + + switch (inst->code) { + case BPF_S_LD_IMM: + emit_mov_i(r_A, k, ctx); + break; + case BPF_S_LD_W_LEN: + ctx->seen |= SEEN_SKB; + BUILD_BUG_ON(FIELD_SIZEOF(struct sk_buff, len) != 4); + emit(ARM_LDR_I(r_A, r_skb, + offsetof(struct sk_buff, len)), ctx); + break; + case BPF_S_LD_MEM: + /* A = scratch[k] */ + ctx->seen |= SEEN_MEM_WORD(k); + emit(ARM_LDR_I(r_A, ARM_SP, SCRATCH_OFF(k)), ctx); + break; + case BPF_S_LD_W_ABS: + load_order = 2; + goto load; + case BPF_S_LD_H_ABS: + load_order = 1; + goto load; + case BPF_S_LD_B_ABS: + load_order = 0; +load: + /* the interpreter will deal with the negative K */ + if ((int)k < 0) + return -ENOTSUPP; + emit_mov_i(r_off, k, ctx); +load_common: + ctx->seen |= SEEN_DATA | SEEN_CALL; + + if (load_order > 0) { + emit(ARM_SUB_I(r_scratch, r_skb_hl, + 1 << load_order), ctx); + emit(ARM_CMP_R(r_scratch, r_off), ctx); + condt = ARM_COND_HS; + } else { + emit(ARM_CMP_R(r_skb_hl, r_off), ctx); + condt = ARM_COND_HI; + } + + _emit(condt, ARM_ADD_R(r_scratch, r_off, r_skb_data), + ctx); + + if (load_order == 0) + _emit(condt, ARM_LDRB_I(r_A, r_scratch, 0), + ctx); + else if (load_order == 1) + emit_load_be16(condt, r_A, r_scratch, ctx); + else if (load_order == 2) + emit_load_be32(condt, r_A, r_scratch, ctx); + + _emit(condt, ARM_B(b_imm(i + 1, ctx)), ctx); + + /* the slowpath */ + emit_mov_i(ARM_R3, (u32)load_func[load_order], ctx); + emit(ARM_MOV_R(ARM_R0, r_skb), ctx); + /* the offset is already in R1 */ + emit_blx_r(ARM_R3, ctx); + /* check the result of skb_copy_bits */ + emit(ARM_CMP_I(ARM_R1, 0), ctx); + emit_err_ret(ARM_COND_NE, ctx); + emit(ARM_MOV_R(r_A, ARM_R0), ctx); + break; + case BPF_S_LD_W_IND: + load_order = 2; + goto load_ind; + case BPF_S_LD_H_IND: + load_order = 1; + goto load_ind; + case BPF_S_LD_B_IND: + load_order = 0; +load_ind: + OP_IMM3(ARM_ADD, r_off, r_X, k, ctx); + goto load_common; + case BPF_S_LDX_IMM: + ctx->seen |= SEEN_X; + emit_mov_i(r_X, k, ctx); + break; + case BPF_S_LDX_W_LEN: + ctx->seen |= SEEN_X | SEEN_SKB; + emit(ARM_LDR_I(r_X, r_skb, + offsetof(struct sk_buff, len)), ctx); + break; + case BPF_S_LDX_MEM: + ctx->seen |= SEEN_X | SEEN_MEM_WORD(k); + emit(ARM_LDR_I(r_X, ARM_SP, SCRATCH_OFF(k)), ctx); + break; + case BPF_S_LDX_B_MSH: + /* x = ((*(frame + k)) & 0xf) << 2; */ + ctx->seen |= SEEN_X | SEEN_DATA | SEEN_CALL; + /* the interpreter should deal with the negative K */ + if (k < 0) + return -1; + /* offset in r1: we might have to take the slow path */ + emit_mov_i(r_off, k, ctx); + emit(ARM_CMP_R(r_skb_hl, r_off), ctx); + + /* load in r0: common with the slowpath */ + _emit(ARM_COND_HI, ARM_LDRB_R(ARM_R0, r_skb_data, + ARM_R1), ctx); + /* + * emit_mov_i() might generate one or two instructions, + * the same holds for emit_blx_r() + */ + _emit(ARM_COND_HI, ARM_B(b_imm(i + 1, ctx) - 2), ctx); + + emit(ARM_MOV_R(ARM_R0, r_skb), ctx); + /* r_off is r1 */ + emit_mov_i(ARM_R3, (u32)jit_get_skb_b, ctx); + emit_blx_r(ARM_R3, ctx); + /* check the return value of skb_copy_bits */ + emit(ARM_CMP_I(ARM_R1, 0), ctx); + emit_err_ret(ARM_COND_NE, ctx); + + emit(ARM_AND_I(r_X, ARM_R0, 0x00f), ctx); + emit(ARM_LSL_I(r_X, r_X, 2), ctx); + break; + case BPF_S_ST: + ctx->seen |= SEEN_MEM_WORD(k); + emit(ARM_STR_I(r_A, ARM_SP, SCRATCH_OFF(k)), ctx); + break; + case BPF_S_STX: + update_on_xread(ctx); + ctx->seen |= SEEN_MEM_WORD(k); + emit(ARM_STR_I(r_X, ARM_SP, SCRATCH_OFF(k)), ctx); + break; + case BPF_S_ALU_ADD_K: + /* A += K */ + OP_IMM3(ARM_ADD, r_A, r_A, k, ctx); + break; + case BPF_S_ALU_ADD_X: + update_on_xread(ctx); + emit(ARM_ADD_R(r_A, r_A, r_X), ctx); + break; + case BPF_S_ALU_SUB_K: + /* A -= K */ + OP_IMM3(ARM_SUB, r_A, r_A, k, ctx); + break; + case BPF_S_ALU_SUB_X: + update_on_xread(ctx); + emit(ARM_SUB_R(r_A, r_A, r_X), ctx); + break; + case BPF_S_ALU_MUL_K: + /* A *= K */ + emit_mov_i(r_scratch, k, ctx); + emit(ARM_MUL(r_A, r_A, r_scratch), ctx); + break; + case BPF_S_ALU_MUL_X: + update_on_xread(ctx); + emit(ARM_MUL(r_A, r_A, r_X), ctx); + break; + case BPF_S_ALU_DIV_K: + /* current k == reciprocal_value(userspace k) */ + emit_mov_i(r_scratch, k, ctx); + /* A = top 32 bits of the product */ + emit(ARM_UMULL(r_scratch, r_A, r_A, r_scratch), ctx); + break; + case BPF_S_ALU_DIV_X: + update_on_xread(ctx); + emit(ARM_CMP_I(r_X, 0), ctx); + emit_err_ret(ARM_COND_EQ, ctx); + emit_udiv(r_A, r_A, r_X, ctx); + break; + case BPF_S_ALU_OR_K: + /* A |= K */ + OP_IMM3(ARM_ORR, r_A, r_A, k, ctx); + break; + case BPF_S_ALU_OR_X: + update_on_xread(ctx); + emit(ARM_ORR_R(r_A, r_A, r_X), ctx); + break; + case BPF_S_ALU_AND_K: + /* A &= K */ + OP_IMM3(ARM_AND, r_A, r_A, k, ctx); + break; + case BPF_S_ALU_AND_X: + update_on_xread(ctx); + emit(ARM_AND_R(r_A, r_A, r_X), ctx); + break; + case BPF_S_ALU_LSH_K: + if (unlikely(k > 31)) + return -1; + emit(ARM_LSL_I(r_A, r_A, k), ctx); + break; + case BPF_S_ALU_LSH_X: + update_on_xread(ctx); + emit(ARM_LSL_R(r_A, r_A, r_X), ctx); + break; + case BPF_S_ALU_RSH_K: + if (unlikely(k > 31)) + return -1; + emit(ARM_LSR_I(r_A, r_A, k), ctx); + break; + case BPF_S_ALU_RSH_X: + update_on_xread(ctx); + emit(ARM_LSR_R(r_A, r_A, r_X), ctx); + break; + case BPF_S_ALU_NEG: + /* A = -A */ + emit(ARM_RSB_I(r_A, r_A, 0), ctx); + break; + case BPF_S_JMP_JA: + /* pc += K */ + emit(ARM_B(b_imm(i + k + 1, ctx)), ctx); + break; + case BPF_S_JMP_JEQ_K: + /* pc += (A == K) ? pc->jt : pc->jf */ + condt = ARM_COND_EQ; + goto cmp_imm; + case BPF_S_JMP_JGT_K: + /* pc += (A > K) ? pc->jt : pc->jf */ + condt = ARM_COND_HI; + goto cmp_imm; + case BPF_S_JMP_JGE_K: + /* pc += (A >= K) ? pc->jt : pc->jf */ + condt = ARM_COND_HS; +cmp_imm: + imm12 = imm8m(k); + if (imm12 < 0) { + emit_mov_i_no8m(r_scratch, k, ctx); + emit(ARM_CMP_R(r_A, r_scratch), ctx); + } else { + emit(ARM_CMP_I(r_A, imm12), ctx); + } +cond_jump: + if (inst->jt) + _emit(condt, ARM_B(b_imm(i + inst->jt + 1, + ctx)), ctx); + if (inst->jf) + _emit(condt ^ 1, ARM_B(b_imm(i + inst->jf + 1, + ctx)), ctx); + break; + case BPF_S_JMP_JEQ_X: + /* pc += (A == X) ? pc->jt : pc->jf */ + condt = ARM_COND_EQ; + goto cmp_x; + case BPF_S_JMP_JGT_X: + /* pc += (A > X) ? pc->jt : pc->jf */ + condt = ARM_COND_HI; + goto cmp_x; + case BPF_S_JMP_JGE_X: + /* pc += (A >= X) ? pc->jt : pc->jf */ + condt = ARM_COND_CS; +cmp_x: + update_on_xread(ctx); + emit(ARM_CMP_R(r_A, r_X), ctx); + goto cond_jump; + case BPF_S_JMP_JSET_K: + /* pc += (A & K) ? pc->jt : pc->jf */ + condt = ARM_COND_NE; + /* not set iff all zeroes iff Z==1 iff EQ */ + + imm12 = imm8m(k); + if (imm12 < 0) { + emit_mov_i_no8m(r_scratch, k, ctx); + emit(ARM_TST_R(r_A, r_scratch), ctx); + } else { + emit(ARM_TST_I(r_A, imm12), ctx); + } + goto cond_jump; + case BPF_S_JMP_JSET_X: + /* pc += (A & X) ? pc->jt : pc->jf */ + update_on_xread(ctx); + condt = ARM_COND_NE; + emit(ARM_TST_R(r_A, r_X), ctx); + goto cond_jump; + case BPF_S_RET_A: + emit(ARM_MOV_R(ARM_R0, r_A), ctx); + goto b_epilogue; + case BPF_S_RET_K: + if ((k == 0) && (ctx->ret0_fp_idx < 0)) + ctx->ret0_fp_idx = i; + emit_mov_i(ARM_R0, k, ctx); +b_epilogue: + if (i != ctx->skf->len - 1) + emit(ARM_B(b_imm(prog->len, ctx)), ctx); + break; + case BPF_S_MISC_TAX: + /* X = A */ + ctx->seen |= SEEN_X; + emit(ARM_MOV_R(r_X, r_A), ctx); + break; + case BPF_S_MISC_TXA: + /* A = X */ + update_on_xread(ctx); + emit(ARM_MOV_R(r_A, r_X), ctx); + break; + case BPF_S_ANC_PROTOCOL: + /* A = ntohs(skb->protocol) */ + ctx->seen |= SEEN_SKB; + BUILD_BUG_ON(FIELD_SIZEOF(struct sk_buff, + protocol) != 2); + off = offsetof(struct sk_buff, protocol); + emit(ARM_LDRH_I(r_scratch, r_skb, off), ctx); + emit_swap16(r_A, r_scratch, ctx); + break; + case BPF_S_ANC_CPU: + /* r_scratch = current_thread_info() */ + OP_IMM3(ARM_BIC, r_scratch, ARM_SP, THREAD_SIZE - 1, ctx); + /* A = current_thread_info()->cpu */ + BUILD_BUG_ON(FIELD_SIZEOF(struct thread_info, cpu) != 4); + off = offsetof(struct thread_info, cpu); + emit(ARM_LDR_I(r_A, r_scratch, off), ctx); + break; + case BPF_S_ANC_IFINDEX: + /* A = skb->dev->ifindex */ + ctx->seen |= SEEN_SKB; + off = offsetof(struct sk_buff, dev); + emit(ARM_LDR_I(r_scratch, r_skb, off), ctx); + + emit(ARM_CMP_I(r_scratch, 0), ctx); + emit_err_ret(ARM_COND_EQ, ctx); + + BUILD_BUG_ON(FIELD_SIZEOF(struct net_device, + ifindex) != 4); + off = offsetof(struct net_device, ifindex); + emit(ARM_LDR_I(r_A, r_scratch, off), ctx); + break; + case BPF_S_ANC_MARK: + ctx->seen |= SEEN_SKB; + BUILD_BUG_ON(FIELD_SIZEOF(struct sk_buff, mark) != 4); + off = offsetof(struct sk_buff, mark); + emit(ARM_LDR_I(r_A, r_skb, off), ctx); + break; + case BPF_S_ANC_RXHASH: + ctx->seen |= SEEN_SKB; + BUILD_BUG_ON(FIELD_SIZEOF(struct sk_buff, rxhash) != 4); + off = offsetof(struct sk_buff, rxhash); + emit(ARM_LDR_I(r_A, r_skb, off), ctx); + break; + case BPF_S_ANC_QUEUE: + ctx->seen |= SEEN_SKB; + BUILD_BUG_ON(FIELD_SIZEOF(struct sk_buff, + queue_mapping) != 2); + BUILD_BUG_ON(offsetof(struct sk_buff, + queue_mapping) > 0xff); + off = offsetof(struct sk_buff, queue_mapping); + emit(ARM_LDRH_I(r_A, r_skb, off), ctx); + break; + default: + return -1; + } + } + + /* compute offsets only during the first pass */ + if (ctx->target == NULL) + ctx->offsets[i] = ctx->idx * 4; + + return 0; +} + + +void bpf_jit_compile(struct sk_filter *fp) +{ + struct jit_ctx ctx; + unsigned tmp_idx; + unsigned alloc_size; + + if (!bpf_jit_enable) + return; + + memset(&ctx, 0, sizeof(ctx)); + ctx.skf = fp; + ctx.ret0_fp_idx = -1; + + ctx.offsets = kzalloc(GFP_KERNEL, 4 * (ctx.skf->len + 1)); + if (ctx.offsets == NULL) + return; + + /* fake pass to fill in the ctx->seen */ + if (unlikely(build_body(&ctx))) + goto out; + + tmp_idx = ctx.idx; + build_prologue(&ctx); + ctx.prologue_bytes = (ctx.idx - tmp_idx) * 4; + +#if __LINUX_ARM_ARCH__ < 7 + tmp_idx = ctx.idx; + build_epilogue(&ctx); + ctx.epilogue_bytes = (ctx.idx - tmp_idx) * 4; + + ctx.idx += ctx.imm_count; + if (ctx.imm_count) { + ctx.imms = kzalloc(GFP_KERNEL, 4 * ctx.imm_count); + if (ctx.imms == NULL) + goto out; + } +#else + /* there's nothing after the epilogue on ARMv7 */ + build_epilogue(&ctx); +#endif + + alloc_size = 4 * ctx.idx; + ctx.target = module_alloc(max(sizeof(struct work_struct), + alloc_size)); + if (unlikely(ctx.target == NULL)) + goto out; + + ctx.idx = 0; + build_prologue(&ctx); + build_body(&ctx); + build_epilogue(&ctx); + + flush_icache_range((u32)ctx.target, (u32)(ctx.target + ctx.idx)); + +#if __LINUX_ARM_ARCH__ < 7 + if (ctx.imm_count) + kfree(ctx.imms); +#endif + + if (bpf_jit_enable > 1) + print_hex_dump(KERN_INFO, "BPF JIT code: ", + DUMP_PREFIX_ADDRESS, 16, 4, ctx.target, + alloc_size, false); + + fp->bpf_func = (void *)ctx.target; +out: + kfree(ctx.offsets); + return; +} + +static void bpf_jit_free_worker(struct work_struct *work) +{ + module_free(NULL, work); +} + +void bpf_jit_free(struct sk_filter *fp) +{ + struct work_struct *work; + + if (fp->bpf_func != sk_run_filter) { + work = (struct work_struct *)fp->bpf_func; + + INIT_WORK(work, bpf_jit_free_worker); + schedule_work(work); + } +} |
