| /* bpf_jit_comp.c : BPF JIT compiler |
| * |
| * Copyright (C) 2011-2013 Eric Dumazet (eric.dumazet@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/moduleloader.h> |
| #include <asm/cacheflush.h> |
| #include <linux/netdevice.h> |
| #include <linux/filter.h> |
| #include <linux/if_vlan.h> |
| |
| /* |
| * Conventions : |
| * EAX : BPF A accumulator |
| * EBX : BPF X accumulator |
| * RDI : pointer to skb (first argument given to JIT function) |
| * RBP : frame pointer (even if CONFIG_FRAME_POINTER=n) |
| * ECX,EDX,ESI : scratch registers |
| * r9d : skb->len - skb->data_len (headlen) |
| * r8 : skb->data |
| * -8(RBP) : saved RBX value |
| * -16(RBP)..-80(RBP) : BPF_MEMWORDS values |
| */ |
| int bpf_jit_enable __read_mostly; |
| |
| /* |
| * assembly code in arch/x86/net/bpf_jit.S |
| */ |
| extern u8 sk_load_word[], sk_load_half[], sk_load_byte[], sk_load_byte_msh[]; |
| extern u8 sk_load_word_positive_offset[], sk_load_half_positive_offset[]; |
| extern u8 sk_load_byte_positive_offset[], sk_load_byte_msh_positive_offset[]; |
| extern u8 sk_load_word_negative_offset[], sk_load_half_negative_offset[]; |
| extern u8 sk_load_byte_negative_offset[], sk_load_byte_msh_negative_offset[]; |
| |
| static inline u8 *emit_code(u8 *ptr, u32 bytes, unsigned int len) |
| { |
| if (len == 1) |
| *ptr = bytes; |
| else if (len == 2) |
| *(u16 *)ptr = bytes; |
| else { |
| *(u32 *)ptr = bytes; |
| barrier(); |
| } |
| return ptr + len; |
| } |
| |
| #define EMIT(bytes, len) do { prog = emit_code(prog, bytes, len); } while (0) |
| |
| #define EMIT1(b1) EMIT(b1, 1) |
| #define EMIT2(b1, b2) EMIT((b1) + ((b2) << 8), 2) |
| #define EMIT3(b1, b2, b3) EMIT((b1) + ((b2) << 8) + ((b3) << 16), 3) |
| #define EMIT4(b1, b2, b3, b4) EMIT((b1) + ((b2) << 8) + ((b3) << 16) + ((b4) << 24), 4) |
| #define EMIT1_off32(b1, off) do { EMIT1(b1); EMIT(off, 4);} while (0) |
| |
| #define CLEAR_A() EMIT2(0x31, 0xc0) /* xor %eax,%eax */ |
| #define CLEAR_X() EMIT2(0x31, 0xdb) /* xor %ebx,%ebx */ |
| |
| static inline bool is_imm8(int value) |
| { |
| return value <= 127 && value >= -128; |
| } |
| |
| static inline bool is_near(int offset) |
| { |
| return offset <= 127 && offset >= -128; |
| } |
| |
| #define EMIT_JMP(offset) \ |
| do { \ |
| if (offset) { \ |
| if (is_near(offset)) \ |
| EMIT2(0xeb, offset); /* jmp .+off8 */ \ |
| else \ |
| EMIT1_off32(0xe9, offset); /* jmp .+off32 */ \ |
| } \ |
| } while (0) |
| |
| /* list of x86 cond jumps opcodes (. + s8) |
| * Add 0x10 (and an extra 0x0f) to generate far jumps (. + s32) |
| */ |
| #define X86_JB 0x72 |
| #define X86_JAE 0x73 |
| #define X86_JE 0x74 |
| #define X86_JNE 0x75 |
| #define X86_JBE 0x76 |
| #define X86_JA 0x77 |
| |
| #define EMIT_COND_JMP(op, offset) \ |
| do { \ |
| if (is_near(offset)) \ |
| EMIT2(op, offset); /* jxx .+off8 */ \ |
| else { \ |
| EMIT2(0x0f, op + 0x10); \ |
| EMIT(offset, 4); /* jxx .+off32 */ \ |
| } \ |
| } while (0) |
| |
| #define COND_SEL(CODE, TOP, FOP) \ |
| case CODE: \ |
| t_op = TOP; \ |
| f_op = FOP; \ |
| goto cond_branch |
| |
| |
| #define SEEN_DATAREF 1 /* might call external helpers */ |
| #define SEEN_XREG 2 /* ebx is used */ |
| #define SEEN_MEM 4 /* use mem[] for temporary storage */ |
| |
| static inline void bpf_flush_icache(void *start, void *end) |
| { |
| mm_segment_t old_fs = get_fs(); |
| |
| set_fs(KERNEL_DS); |
| smp_wmb(); |
| flush_icache_range((unsigned long)start, (unsigned long)end); |
| set_fs(old_fs); |
| } |
| |
| #define CHOOSE_LOAD_FUNC(K, func) \ |
| ((int)K < 0 ? ((int)K >= SKF_LL_OFF ? func##_negative_offset : func) : func##_positive_offset) |
| |
| /* Helper to find the offset of pkt_type in sk_buff |
| * We want to make sure its still a 3bit field starting at a byte boundary. |
| */ |
| #define PKT_TYPE_MAX 7 |
| static int pkt_type_offset(void) |
| { |
| struct sk_buff skb_probe = { |
| .pkt_type = ~0, |
| }; |
| char *ct = (char *)&skb_probe; |
| unsigned int off; |
| |
| for (off = 0; off < sizeof(struct sk_buff); off++) { |
| if (ct[off] == PKT_TYPE_MAX) |
| return off; |
| } |
| pr_err_once("Please fix pkt_type_offset(), as pkt_type couldn't be found\n"); |
| return -1; |
| } |
| |
| void bpf_jit_compile(struct sk_filter *fp) |
| { |
| u8 temp[64]; |
| u8 *prog; |
| unsigned int proglen, oldproglen = 0; |
| int ilen, i; |
| int t_offset, f_offset; |
| u8 t_op, f_op, seen = 0, pass; |
| u8 *image = NULL; |
| u8 *func; |
| int pc_ret0 = -1; /* bpf index of first RET #0 instruction (if any) */ |
| unsigned int cleanup_addr; /* epilogue code offset */ |
| unsigned int *addrs; |
| const struct sock_filter *filter = fp->insns; |
| int flen = fp->len; |
| |
| if (!bpf_jit_enable) |
| return; |
| |
| addrs = kmalloc(flen * sizeof(*addrs), GFP_KERNEL); |
| if (addrs == NULL) |
| return; |
| |
| /* Before first pass, make a rough estimation of addrs[] |
| * each bpf instruction is translated to less than 64 bytes |
| */ |
| for (proglen = 0, i = 0; i < flen; i++) { |
| proglen += 64; |
| addrs[i] = proglen; |
| } |
| cleanup_addr = proglen; /* epilogue address */ |
| |
| for (pass = 0; pass < 10; pass++) { |
| u8 seen_or_pass0 = (pass == 0) ? (SEEN_XREG | SEEN_DATAREF | SEEN_MEM) : seen; |
| /* no prologue/epilogue for trivial filters (RET something) */ |
| proglen = 0; |
| prog = temp; |
| |
| if (seen_or_pass0) { |
| EMIT4(0x55, 0x48, 0x89, 0xe5); /* push %rbp; mov %rsp,%rbp */ |
| EMIT4(0x48, 0x83, 0xec, 96); /* subq $96,%rsp */ |
| /* note : must save %rbx in case bpf_error is hit */ |
| if (seen_or_pass0 & (SEEN_XREG | SEEN_DATAREF)) |
| EMIT4(0x48, 0x89, 0x5d, 0xf8); /* mov %rbx, -8(%rbp) */ |
| if (seen_or_pass0 & SEEN_XREG) |
| CLEAR_X(); /* make sure we dont leek kernel memory */ |
| |
| /* |
| * If this filter needs to access skb data, |
| * loads r9 and r8 with : |
| * r9 = skb->len - skb->data_len |
| * r8 = skb->data |
| */ |
| if (seen_or_pass0 & SEEN_DATAREF) { |
| if (offsetof(struct sk_buff, len) <= 127) |
| /* mov off8(%rdi),%r9d */ |
| EMIT4(0x44, 0x8b, 0x4f, offsetof(struct sk_buff, len)); |
| else { |
| /* mov off32(%rdi),%r9d */ |
| EMIT3(0x44, 0x8b, 0x8f); |
| EMIT(offsetof(struct sk_buff, len), 4); |
| } |
| if (is_imm8(offsetof(struct sk_buff, data_len))) |
| /* sub off8(%rdi),%r9d */ |
| EMIT4(0x44, 0x2b, 0x4f, offsetof(struct sk_buff, data_len)); |
| else { |
| EMIT3(0x44, 0x2b, 0x8f); |
| EMIT(offsetof(struct sk_buff, data_len), 4); |
| } |
| |
| if (is_imm8(offsetof(struct sk_buff, data))) |
| /* mov off8(%rdi),%r8 */ |
| EMIT4(0x4c, 0x8b, 0x47, offsetof(struct sk_buff, data)); |
| else { |
| /* mov off32(%rdi),%r8 */ |
| EMIT3(0x4c, 0x8b, 0x87); |
| EMIT(offsetof(struct sk_buff, data), 4); |
| } |
| } |
| } |
| |
| switch (filter[0].code) { |
| case BPF_S_RET_K: |
| case BPF_S_LD_W_LEN: |
| case BPF_S_ANC_PROTOCOL: |
| case BPF_S_ANC_IFINDEX: |
| case BPF_S_ANC_MARK: |
| case BPF_S_ANC_RXHASH: |
| case BPF_S_ANC_CPU: |
| case BPF_S_ANC_VLAN_TAG: |
| case BPF_S_ANC_VLAN_TAG_PRESENT: |
| case BPF_S_ANC_QUEUE: |
| case BPF_S_ANC_PKTTYPE: |
| case BPF_S_LD_W_ABS: |
| case BPF_S_LD_H_ABS: |
| case BPF_S_LD_B_ABS: |
| /* first instruction sets A register (or is RET 'constant') */ |
| break; |
| default: |
| /* make sure we dont leak kernel information to user */ |
| CLEAR_A(); /* A = 0 */ |
| } |
| |
| for (i = 0; i < flen; i++) { |
| unsigned int K = filter[i].k; |
| |
| switch (filter[i].code) { |
| case BPF_S_ALU_ADD_X: /* A += X; */ |
| seen |= SEEN_XREG; |
| EMIT2(0x01, 0xd8); /* add %ebx,%eax */ |
| break; |
| case BPF_S_ALU_ADD_K: /* A += K; */ |
| if (!K) |
| break; |
| if (is_imm8(K)) |
| EMIT3(0x83, 0xc0, K); /* add imm8,%eax */ |
| else |
| EMIT1_off32(0x05, K); /* add imm32,%eax */ |
| break; |
| case BPF_S_ALU_SUB_X: /* A -= X; */ |
| seen |= SEEN_XREG; |
| EMIT2(0x29, 0xd8); /* sub %ebx,%eax */ |
| break; |
| case BPF_S_ALU_SUB_K: /* A -= K */ |
| if (!K) |
| break; |
| if (is_imm8(K)) |
| EMIT3(0x83, 0xe8, K); /* sub imm8,%eax */ |
| else |
| EMIT1_off32(0x2d, K); /* sub imm32,%eax */ |
| break; |
| case BPF_S_ALU_MUL_X: /* A *= X; */ |
| seen |= SEEN_XREG; |
| EMIT3(0x0f, 0xaf, 0xc3); /* imul %ebx,%eax */ |
| break; |
| case BPF_S_ALU_MUL_K: /* A *= K */ |
| if (is_imm8(K)) |
| EMIT3(0x6b, 0xc0, K); /* imul imm8,%eax,%eax */ |
| else { |
| EMIT2(0x69, 0xc0); /* imul imm32,%eax */ |
| EMIT(K, 4); |
| } |
| break; |
| case BPF_S_ALU_DIV_X: /* A /= X; */ |
| seen |= SEEN_XREG; |
| EMIT2(0x85, 0xdb); /* test %ebx,%ebx */ |
| if (pc_ret0 > 0) { |
| /* addrs[pc_ret0 - 1] is start address of target |
| * (addrs[i] - 4) is the address following this jmp |
| * ("xor %edx,%edx; div %ebx" being 4 bytes long) |
| */ |
| EMIT_COND_JMP(X86_JE, addrs[pc_ret0 - 1] - |
| (addrs[i] - 4)); |
| } else { |
| EMIT_COND_JMP(X86_JNE, 2 + 5); |
| CLEAR_A(); |
| EMIT1_off32(0xe9, cleanup_addr - (addrs[i] - 4)); /* jmp .+off32 */ |
| } |
| EMIT4(0x31, 0xd2, 0xf7, 0xf3); /* xor %edx,%edx; div %ebx */ |
| break; |
| case BPF_S_ALU_MOD_X: /* A %= X; */ |
| seen |= SEEN_XREG; |
| EMIT2(0x85, 0xdb); /* test %ebx,%ebx */ |
| if (pc_ret0 > 0) { |
| /* addrs[pc_ret0 - 1] is start address of target |
| * (addrs[i] - 6) is the address following this jmp |
| * ("xor %edx,%edx; div %ebx;mov %edx,%eax" being 6 bytes long) |
| */ |
| EMIT_COND_JMP(X86_JE, addrs[pc_ret0 - 1] - |
| (addrs[i] - 6)); |
| } else { |
| EMIT_COND_JMP(X86_JNE, 2 + 5); |
| CLEAR_A(); |
| EMIT1_off32(0xe9, cleanup_addr - (addrs[i] - 6)); /* jmp .+off32 */ |
| } |
| EMIT2(0x31, 0xd2); /* xor %edx,%edx */ |
| EMIT2(0xf7, 0xf3); /* div %ebx */ |
| EMIT2(0x89, 0xd0); /* mov %edx,%eax */ |
| break; |
| case BPF_S_ALU_MOD_K: /* A %= K; */ |
| EMIT2(0x31, 0xd2); /* xor %edx,%edx */ |
| EMIT1(0xb9);EMIT(K, 4); /* mov imm32,%ecx */ |
| EMIT2(0xf7, 0xf1); /* div %ecx */ |
| EMIT2(0x89, 0xd0); /* mov %edx,%eax */ |
| break; |
| case BPF_S_ALU_DIV_K: /* A = reciprocal_divide(A, K); */ |
| EMIT3(0x48, 0x69, 0xc0); /* imul imm32,%rax,%rax */ |
| EMIT(K, 4); |
| EMIT4(0x48, 0xc1, 0xe8, 0x20); /* shr $0x20,%rax */ |
| break; |
| case BPF_S_ALU_AND_X: |
| seen |= SEEN_XREG; |
| EMIT2(0x21, 0xd8); /* and %ebx,%eax */ |
| break; |
| case BPF_S_ALU_AND_K: |
| if (K >= 0xFFFFFF00) { |
| EMIT2(0x24, K & 0xFF); /* and imm8,%al */ |
| } else if (K >= 0xFFFF0000) { |
| EMIT2(0x66, 0x25); /* and imm16,%ax */ |
| EMIT(K, 2); |
| } else { |
| EMIT1_off32(0x25, K); /* and imm32,%eax */ |
| } |
| break; |
| case BPF_S_ALU_OR_X: |
| seen |= SEEN_XREG; |
| EMIT2(0x09, 0xd8); /* or %ebx,%eax */ |
| break; |
| case BPF_S_ALU_OR_K: |
| if (is_imm8(K)) |
| EMIT3(0x83, 0xc8, K); /* or imm8,%eax */ |
| else |
| EMIT1_off32(0x0d, K); /* or imm32,%eax */ |
| break; |
| case BPF_S_ANC_ALU_XOR_X: /* A ^= X; */ |
| case BPF_S_ALU_XOR_X: |
| seen |= SEEN_XREG; |
| EMIT2(0x31, 0xd8); /* xor %ebx,%eax */ |
| break; |
| case BPF_S_ALU_XOR_K: /* A ^= K; */ |
| if (K == 0) |
| break; |
| if (is_imm8(K)) |
| EMIT3(0x83, 0xf0, K); /* xor imm8,%eax */ |
| else |
| EMIT1_off32(0x35, K); /* xor imm32,%eax */ |
| break; |
| case BPF_S_ALU_LSH_X: /* A <<= X; */ |
| seen |= SEEN_XREG; |
| EMIT4(0x89, 0xd9, 0xd3, 0xe0); /* mov %ebx,%ecx; shl %cl,%eax */ |
| break; |
| case BPF_S_ALU_LSH_K: |
| if (K == 0) |
| break; |
| else if (K == 1) |
| EMIT2(0xd1, 0xe0); /* shl %eax */ |
| else |
| EMIT3(0xc1, 0xe0, K); |
| break; |
| case BPF_S_ALU_RSH_X: /* A >>= X; */ |
| seen |= SEEN_XREG; |
| EMIT4(0x89, 0xd9, 0xd3, 0xe8); /* mov %ebx,%ecx; shr %cl,%eax */ |
| break; |
| case BPF_S_ALU_RSH_K: /* A >>= K; */ |
| if (K == 0) |
| break; |
| else if (K == 1) |
| EMIT2(0xd1, 0xe8); /* shr %eax */ |
| else |
| EMIT3(0xc1, 0xe8, K); |
| break; |
| case BPF_S_ALU_NEG: |
| EMIT2(0xf7, 0xd8); /* neg %eax */ |
| break; |
| case BPF_S_RET_K: |
| if (!K) { |
| if (pc_ret0 == -1) |
| pc_ret0 = i; |
| CLEAR_A(); |
| } else { |
| EMIT1_off32(0xb8, K); /* mov $imm32,%eax */ |
| } |
| /* fallinto */ |
| case BPF_S_RET_A: |
| if (seen_or_pass0) { |
| if (i != flen - 1) { |
| EMIT_JMP(cleanup_addr - addrs[i]); |
| break; |
| } |
| if (seen_or_pass0 & SEEN_XREG) |
| EMIT4(0x48, 0x8b, 0x5d, 0xf8); /* mov -8(%rbp),%rbx */ |
| EMIT1(0xc9); /* leaveq */ |
| } |
| EMIT1(0xc3); /* ret */ |
| break; |
| case BPF_S_MISC_TAX: /* X = A */ |
| seen |= SEEN_XREG; |
| EMIT2(0x89, 0xc3); /* mov %eax,%ebx */ |
| break; |
| case BPF_S_MISC_TXA: /* A = X */ |
| seen |= SEEN_XREG; |
| EMIT2(0x89, 0xd8); /* mov %ebx,%eax */ |
| break; |
| case BPF_S_LD_IMM: /* A = K */ |
| if (!K) |
| CLEAR_A(); |
| else |
| EMIT1_off32(0xb8, K); /* mov $imm32,%eax */ |
| break; |
| case BPF_S_LDX_IMM: /* X = K */ |
| seen |= SEEN_XREG; |
| if (!K) |
| CLEAR_X(); |
| else |
| EMIT1_off32(0xbb, K); /* mov $imm32,%ebx */ |
| break; |
| case BPF_S_LD_MEM: /* A = mem[K] : mov off8(%rbp),%eax */ |
| seen |= SEEN_MEM; |
| EMIT3(0x8b, 0x45, 0xf0 - K*4); |
| break; |
| case BPF_S_LDX_MEM: /* X = mem[K] : mov off8(%rbp),%ebx */ |
| seen |= SEEN_XREG | SEEN_MEM; |
| EMIT3(0x8b, 0x5d, 0xf0 - K*4); |
| break; |
| case BPF_S_ST: /* mem[K] = A : mov %eax,off8(%rbp) */ |
| seen |= SEEN_MEM; |
| EMIT3(0x89, 0x45, 0xf0 - K*4); |
| break; |
| case BPF_S_STX: /* mem[K] = X : mov %ebx,off8(%rbp) */ |
| seen |= SEEN_XREG | SEEN_MEM; |
| EMIT3(0x89, 0x5d, 0xf0 - K*4); |
| break; |
| case BPF_S_LD_W_LEN: /* A = skb->len; */ |
| BUILD_BUG_ON(FIELD_SIZEOF(struct sk_buff, len) != 4); |
| if (is_imm8(offsetof(struct sk_buff, len))) |
| /* mov off8(%rdi),%eax */ |
| EMIT3(0x8b, 0x47, offsetof(struct sk_buff, len)); |
| else { |
| EMIT2(0x8b, 0x87); |
| EMIT(offsetof(struct sk_buff, len), 4); |
| } |
| break; |
| case BPF_S_LDX_W_LEN: /* X = skb->len; */ |
| seen |= SEEN_XREG; |
| if (is_imm8(offsetof(struct sk_buff, len))) |
| /* mov off8(%rdi),%ebx */ |
| EMIT3(0x8b, 0x5f, offsetof(struct sk_buff, len)); |
| else { |
| EMIT2(0x8b, 0x9f); |
| EMIT(offsetof(struct sk_buff, len), 4); |
| } |
| break; |
| case BPF_S_ANC_PROTOCOL: /* A = ntohs(skb->protocol); */ |
| BUILD_BUG_ON(FIELD_SIZEOF(struct sk_buff, protocol) != 2); |
| if (is_imm8(offsetof(struct sk_buff, protocol))) { |
| /* movzwl off8(%rdi),%eax */ |
| EMIT4(0x0f, 0xb7, 0x47, offsetof(struct sk_buff, protocol)); |
| } else { |
| EMIT3(0x0f, 0xb7, 0x87); /* movzwl off32(%rdi),%eax */ |
| EMIT(offsetof(struct sk_buff, protocol), 4); |
| } |
| EMIT2(0x86, 0xc4); /* ntohs() : xchg %al,%ah */ |
| break; |
| case BPF_S_ANC_IFINDEX: |
| if (is_imm8(offsetof(struct sk_buff, dev))) { |
| /* movq off8(%rdi),%rax */ |
| EMIT4(0x48, 0x8b, 0x47, offsetof(struct sk_buff, dev)); |
| } else { |
| EMIT3(0x48, 0x8b, 0x87); /* movq off32(%rdi),%rax */ |
| EMIT(offsetof(struct sk_buff, dev), 4); |
| } |
| EMIT3(0x48, 0x85, 0xc0); /* test %rax,%rax */ |
| EMIT_COND_JMP(X86_JE, cleanup_addr - (addrs[i] - 6)); |
| BUILD_BUG_ON(FIELD_SIZEOF(struct net_device, ifindex) != 4); |
| EMIT2(0x8b, 0x80); /* mov off32(%rax),%eax */ |
| EMIT(offsetof(struct net_device, ifindex), 4); |
| break; |
| case BPF_S_ANC_MARK: |
| BUILD_BUG_ON(FIELD_SIZEOF(struct sk_buff, mark) != 4); |
| if (is_imm8(offsetof(struct sk_buff, mark))) { |
| /* mov off8(%rdi),%eax */ |
| EMIT3(0x8b, 0x47, offsetof(struct sk_buff, mark)); |
| } else { |
| EMIT2(0x8b, 0x87); |
| EMIT(offsetof(struct sk_buff, mark), 4); |
| } |
| break; |
| case BPF_S_ANC_RXHASH: |
| BUILD_BUG_ON(FIELD_SIZEOF(struct sk_buff, rxhash) != 4); |
| if (is_imm8(offsetof(struct sk_buff, rxhash))) { |
| /* mov off8(%rdi),%eax */ |
| EMIT3(0x8b, 0x47, offsetof(struct sk_buff, rxhash)); |
| } else { |
| EMIT2(0x8b, 0x87); |
| EMIT(offsetof(struct sk_buff, rxhash), 4); |
| } |
| break; |
| case BPF_S_ANC_QUEUE: |
| BUILD_BUG_ON(FIELD_SIZEOF(struct sk_buff, queue_mapping) != 2); |
| if (is_imm8(offsetof(struct sk_buff, queue_mapping))) { |
| /* movzwl off8(%rdi),%eax */ |
| EMIT4(0x0f, 0xb7, 0x47, offsetof(struct sk_buff, queue_mapping)); |
| } else { |
| EMIT3(0x0f, 0xb7, 0x87); /* movzwl off32(%rdi),%eax */ |
| EMIT(offsetof(struct sk_buff, queue_mapping), 4); |
| } |
| break; |
| case BPF_S_ANC_CPU: |
| #ifdef CONFIG_SMP |
| EMIT4(0x65, 0x8b, 0x04, 0x25); /* mov %gs:off32,%eax */ |
| EMIT((u32)(unsigned long)&cpu_number, 4); /* A = smp_processor_id(); */ |
| #else |
| CLEAR_A(); |
| #endif |
| break; |
| case BPF_S_ANC_VLAN_TAG: |
| case BPF_S_ANC_VLAN_TAG_PRESENT: |
| BUILD_BUG_ON(FIELD_SIZEOF(struct sk_buff, vlan_tci) != 2); |
| if (is_imm8(offsetof(struct sk_buff, vlan_tci))) { |
| /* movzwl off8(%rdi),%eax */ |
| EMIT4(0x0f, 0xb7, 0x47, offsetof(struct sk_buff, vlan_tci)); |
| } else { |
| EMIT3(0x0f, 0xb7, 0x87); /* movzwl off32(%rdi),%eax */ |
| EMIT(offsetof(struct sk_buff, vlan_tci), 4); |
| } |
| BUILD_BUG_ON(VLAN_TAG_PRESENT != 0x1000); |
| if (filter[i].code == BPF_S_ANC_VLAN_TAG) { |
| EMIT3(0x80, 0xe4, 0xef); /* and $0xef,%ah */ |
| } else { |
| EMIT3(0xc1, 0xe8, 0x0c); /* shr $0xc,%eax */ |
| EMIT3(0x83, 0xe0, 0x01); /* and $0x1,%eax */ |
| } |
| break; |
| case BPF_S_ANC_PKTTYPE: |
| { |
| int off = pkt_type_offset(); |
| |
| if (off < 0) |
| goto out; |
| if (is_imm8(off)) { |
| /* movzbl off8(%rdi),%eax */ |
| EMIT4(0x0f, 0xb6, 0x47, off); |
| } else { |
| /* movbl off32(%rdi),%eax */ |
| EMIT3(0x0f, 0xb6, 0x87); |
| EMIT(off, 4); |
| } |
| EMIT3(0x83, 0xe0, PKT_TYPE_MAX); /* and $0x7,%eax */ |
| break; |
| } |
| case BPF_S_LD_W_ABS: |
| func = CHOOSE_LOAD_FUNC(K, sk_load_word); |
| common_load: seen |= SEEN_DATAREF; |
| t_offset = func - (image + addrs[i]); |
| EMIT1_off32(0xbe, K); /* mov imm32,%esi */ |
| EMIT1_off32(0xe8, t_offset); /* call */ |
| break; |
| case BPF_S_LD_H_ABS: |
| func = CHOOSE_LOAD_FUNC(K, sk_load_half); |
| goto common_load; |
| case BPF_S_LD_B_ABS: |
| func = CHOOSE_LOAD_FUNC(K, sk_load_byte); |
| goto common_load; |
| case BPF_S_LDX_B_MSH: |
| func = CHOOSE_LOAD_FUNC(K, sk_load_byte_msh); |
| seen |= SEEN_DATAREF | SEEN_XREG; |
| t_offset = func - (image + addrs[i]); |
| EMIT1_off32(0xbe, K); /* mov imm32,%esi */ |
| EMIT1_off32(0xe8, t_offset); /* call sk_load_byte_msh */ |
| break; |
| case BPF_S_LD_W_IND: |
| func = sk_load_word; |
| common_load_ind: seen |= SEEN_DATAREF | SEEN_XREG; |
| t_offset = func - (image + addrs[i]); |
| if (K) { |
| if (is_imm8(K)) { |
| EMIT3(0x8d, 0x73, K); /* lea imm8(%rbx), %esi */ |
| } else { |
| EMIT2(0x8d, 0xb3); /* lea imm32(%rbx),%esi */ |
| EMIT(K, 4); |
| } |
| } else { |
| EMIT2(0x89,0xde); /* mov %ebx,%esi */ |
| } |
| EMIT1_off32(0xe8, t_offset); /* call sk_load_xxx_ind */ |
| break; |
| case BPF_S_LD_H_IND: |
| func = sk_load_half; |
| goto common_load_ind; |
| case BPF_S_LD_B_IND: |
| func = sk_load_byte; |
| goto common_load_ind; |
| case BPF_S_JMP_JA: |
| t_offset = addrs[i + K] - addrs[i]; |
| EMIT_JMP(t_offset); |
| break; |
| COND_SEL(BPF_S_JMP_JGT_K, X86_JA, X86_JBE); |
| COND_SEL(BPF_S_JMP_JGE_K, X86_JAE, X86_JB); |
| COND_SEL(BPF_S_JMP_JEQ_K, X86_JE, X86_JNE); |
| COND_SEL(BPF_S_JMP_JSET_K,X86_JNE, X86_JE); |
| COND_SEL(BPF_S_JMP_JGT_X, X86_JA, X86_JBE); |
| COND_SEL(BPF_S_JMP_JGE_X, X86_JAE, X86_JB); |
| COND_SEL(BPF_S_JMP_JEQ_X, X86_JE, X86_JNE); |
| COND_SEL(BPF_S_JMP_JSET_X,X86_JNE, X86_JE); |
| |
| cond_branch: f_offset = addrs[i + filter[i].jf] - addrs[i]; |
| t_offset = addrs[i + filter[i].jt] - addrs[i]; |
| |
| /* same targets, can avoid doing the test :) */ |
| if (filter[i].jt == filter[i].jf) { |
| EMIT_JMP(t_offset); |
| break; |
| } |
| |
| switch (filter[i].code) { |
| case BPF_S_JMP_JGT_X: |
| case BPF_S_JMP_JGE_X: |
| case BPF_S_JMP_JEQ_X: |
| seen |= SEEN_XREG; |
| EMIT2(0x39, 0xd8); /* cmp %ebx,%eax */ |
| break; |
| case BPF_S_JMP_JSET_X: |
| seen |= SEEN_XREG; |
| EMIT2(0x85, 0xd8); /* test %ebx,%eax */ |
| break; |
| case BPF_S_JMP_JEQ_K: |
| if (K == 0) { |
| EMIT2(0x85, 0xc0); /* test %eax,%eax */ |
| break; |
| } |
| case BPF_S_JMP_JGT_K: |
| case BPF_S_JMP_JGE_K: |
| if (K <= 127) |
| EMIT3(0x83, 0xf8, K); /* cmp imm8,%eax */ |
| else |
| EMIT1_off32(0x3d, K); /* cmp imm32,%eax */ |
| break; |
| case BPF_S_JMP_JSET_K: |
| if (K <= 0xFF) |
| EMIT2(0xa8, K); /* test imm8,%al */ |
| else if (!(K & 0xFFFF00FF)) |
| EMIT3(0xf6, 0xc4, K >> 8); /* test imm8,%ah */ |
| else if (K <= 0xFFFF) { |
| EMIT2(0x66, 0xa9); /* test imm16,%ax */ |
| EMIT(K, 2); |
| } else { |
| EMIT1_off32(0xa9, K); /* test imm32,%eax */ |
| } |
| break; |
| } |
| if (filter[i].jt != 0) { |
| if (filter[i].jf && f_offset) |
| t_offset += is_near(f_offset) ? 2 : 5; |
| EMIT_COND_JMP(t_op, t_offset); |
| if (filter[i].jf) |
| EMIT_JMP(f_offset); |
| break; |
| } |
| EMIT_COND_JMP(f_op, f_offset); |
| break; |
| default: |
| /* hmm, too complex filter, give up with jit compiler */ |
| goto out; |
| } |
| ilen = prog - temp; |
| if (image) { |
| if (unlikely(proglen + ilen > oldproglen)) { |
| pr_err("bpb_jit_compile fatal error\n"); |
| kfree(addrs); |
| module_free(NULL, image); |
| return; |
| } |
| memcpy(image + proglen, temp, ilen); |
| } |
| proglen += ilen; |
| addrs[i] = proglen; |
| prog = temp; |
| } |
| /* last bpf instruction is always a RET : |
| * use it to give the cleanup instruction(s) addr |
| */ |
| cleanup_addr = proglen - 1; /* ret */ |
| if (seen_or_pass0) |
| cleanup_addr -= 1; /* leaveq */ |
| if (seen_or_pass0 & SEEN_XREG) |
| cleanup_addr -= 4; /* mov -8(%rbp),%rbx */ |
| |
| if (image) { |
| if (proglen != oldproglen) |
| pr_err("bpb_jit_compile proglen=%u != oldproglen=%u\n", proglen, oldproglen); |
| break; |
| } |
| if (proglen == oldproglen) { |
| image = module_alloc(proglen); |
| if (!image) |
| goto out; |
| } |
| oldproglen = proglen; |
| } |
| |
| if (bpf_jit_enable > 1) |
| bpf_jit_dump(flen, proglen, pass, image); |
| |
| if (image) { |
| bpf_flush_icache(image, image + proglen); |
| fp->bpf_func = (void *)image; |
| } |
| out: |
| kfree(addrs); |
| return; |
| } |
| |
| void bpf_jit_free(struct sk_filter *fp) |
| { |
| if (fp->bpf_func != sk_run_filter) |
| module_free(NULL, fp->bpf_func); |
| } |