arch/x86/net/bpf_jit_comp.c

   1 /* bpf_jit_comp.c : BPF JIT compiler
   2  *
   3  * Copyright (C) 2011-2013 Eric Dumazet ([email protected])
   4  *
   5  * This program is free software; you can redistribute it and/or
   6  * modify it under the terms of the GNU General Public License
   7  * as published by the Free Software Foundation; version 2
   8  * of the License.
   9  */
  10 #include <linux/moduleloader.h>
  11 #include <asm/cacheflush.h>
  12 #include <linux/netdevice.h>
  13 #include <linux/filter.h>
  14 #include <linux/if_vlan.h>
  15 #include <linux/random.h>
  16
  17 /*
  18  * Conventions :
  19  *  EAX : BPF A accumulator
  20  *  EBX : BPF X accumulator
  21  *  RDI : pointer to skb   (first argument given to JIT function)
  22  *  RBP : frame pointer (even if CONFIG_FRAME_POINTER=n)
  23  *  ECX,EDX,ESI : scratch registers
  24  *  r9d : skb->len - skb->data_len (headlen)
  25  *  r8  : skb->data
  26  * -8(RBP) : saved RBX value
  27  * -16(RBP)..-80(RBP) : BPF_MEMWORDS values
  28  */
  29 int bpf_jit_enable __read_mostly;
  30
  31 /*
  32  * assembly code in arch/x86/net/bpf_jit.S
  33  */
  34 extern u8 sk_load_word[], sk_load_half[], sk_load_byte[], sk_load_byte_msh[];
  35 extern u8 sk_load_word_positive_offset[], sk_load_half_positive_offset[];
  36 extern u8 sk_load_byte_positive_offset[], sk_load_byte_msh_positive_offset[];
  37 extern u8 sk_load_word_negative_offset[], sk_load_half_negative_offset[];
  38 extern u8 sk_load_byte_negative_offset[], sk_load_byte_msh_negative_offset[];
  39
  40 static inline u8 *emit_code(u8 *ptr, u32 bytes, unsigned int len)
  41 {
  42         if (len == 1)
  43                 *ptr = bytes;
  44         else if (len == 2)
  45                 *(u16 *)ptr = bytes;
  46         else {
  47                 *(u32 *)ptr = bytes;
  48                 barrier();
  49         }
  50         return ptr + len;
  51 }
  52
  53 #define EMIT(bytes, len)        do { prog = emit_code(prog, bytes, len); } while (0)
  54
  55 #define EMIT1(b1)               EMIT(b1, 1)
  56 #define EMIT2(b1, b2)           EMIT((b1) + ((b2) << 8), 2)
  57 #define EMIT3(b1, b2, b3)       EMIT((b1) + ((b2) << 8) + ((b3) << 16), 3)
  58 #define EMIT4(b1, b2, b3, b4)   EMIT((b1) + ((b2) << 8) + ((b3) << 16) + ((b4) << 24), 4)
  59 #define EMIT1_off32(b1, off)    do { EMIT1(b1); EMIT(off, 4);} while (0)
  60
  61 #define CLEAR_A() EMIT2(0x31, 0xc0) /* xor %eax,%eax */
  62 #define CLEAR_X() EMIT2(0x31, 0xdb) /* xor %ebx,%ebx */
  63
  64 static inline bool is_imm8(int value)
  65 {
  66         return value <= 127 && value >= -128;
  67 }
  68
  69 static inline bool is_near(int offset)
  70 {
  71         return offset <= 127 && offset >= -128;
  72 }
  73
  74 #define EMIT_JMP(offset)                                                \
  75 do {                                                                    \
  76         if (offset) {                                                   \
  77                 if (is_near(offset))                                    \
  78                         EMIT2(0xeb, offset); /* jmp .+off8 */           \
  79                 else                                                    \
  80                         EMIT1_off32(0xe9, offset); /* jmp .+off32 */    \
  81         }                                                               \
  82 } while (0)
  83
  84 /* list of x86 cond jumps opcodes (. + s8)
  85  * Add 0x10 (and an extra 0x0f) to generate far jumps (. + s32)
  86  */
  87 #define X86_JB  0x72
  88 #define X86_JAE 0x73
  89 #define X86_JE  0x74
  90 #define X86_JNE 0x75
  91 #define X86_JBE 0x76
  92 #define X86_JA  0x77
  93
  94 #define EMIT_COND_JMP(op, offset)                               \
  95 do {                                                            \
  96         if (is_near(offset))                                    \
  97                 EMIT2(op, offset); /* jxx .+off8 */             \
  98         else {                                                  \
  99                 EMIT2(0x0f, op + 0x10);                         \
 100                 EMIT(offset, 4); /* jxx .+off32 */              \
 101         }                                                       \
 102 } while (0)
 103
 104 #define COND_SEL(CODE, TOP, FOP)        \
 105         case CODE:                      \
 106                 t_op = TOP;             \
 107                 f_op = FOP;             \
 108                 goto cond_branch
 109
 110
 111 #define SEEN_DATAREF 1 /* might call external helpers */
 112 #define SEEN_XREG    2 /* ebx is used */
 113 #define SEEN_MEM     4 /* use mem[] for temporary storage */
 114
 115 static inline void bpf_flush_icache(void *start, void *end)
 116 {
 117         mm_segment_t old_fs = get_fs();
 118
 119         set_fs(KERNEL_DS);
 120         smp_wmb();
 121         flush_icache_range((unsigned long)start, (unsigned long)end);
 122         set_fs(old_fs);
 123 }
 124
 125 #define CHOOSE_LOAD_FUNC(K, func) \
 126         ((int)K < 0 ? ((int)K >= SKF_LL_OFF ? func##_negative_offset : func) : func##_positive_offset)
 127
 128 /* Helper to find the offset of pkt_type in sk_buff
 129  * We want to make sure its still a 3bit field starting at a byte boundary.
 130  */
 131 #define PKT_TYPE_MAX 7
 132 static int pkt_type_offset(void)
 133 {
 134         struct sk_buff skb_probe = {
 135                 .pkt_type = ~0,
 136         };
 137         char *ct = (char *)&skb_probe;
 138         unsigned int off;
 139
 140         for (off = 0; off < sizeof(struct sk_buff); off++) {
 141                 if (ct[off] == PKT_TYPE_MAX)
 142                         return off;
 143         }
 144         pr_err_once("Please fix pkt_type_offset(), as pkt_type couldn't be found\n");
 145         return -1;
 146 }
 147
 148 struct bpf_binary_header {
 149         unsigned int    pages;
 150         /* Note : for security reasons, bpf code will follow a randomly
 151          * sized amount of int3 instructions
 152          */
 153         u8              image[];
 154 };
 155
 156 static struct bpf_binary_header *bpf_alloc_binary(unsigned int proglen,
 157                                                   u8 **image_ptr)
 158 {
 159         unsigned int sz, hole;
 160         struct bpf_binary_header *header;
 161
 162         /* Most of BPF filters are really small,
 163          * but if some of them fill a page, allow at least
 164          * 128 extra bytes to insert a random section of int3
 165          */
 166         sz = round_up(proglen + sizeof(*header) + 128, PAGE_SIZE);
 167         header = module_alloc(sz);
 168         if (!header)
 169                 return NULL;
 170
 171         memset(header, 0xcc, sz); /* fill whole space with int3 instructions */
 172
 173         header->pages = sz / PAGE_SIZE;
 174         hole = sz - (proglen + sizeof(*header));
 175
 176         /* insert a random number of int3 instructions before BPF code */
 177         *image_ptr = &header->image[prandom_u32() % hole];
 178         return header;
 179 }
 180
 181 void bpf_jit_compile(struct sk_filter *fp)
 182 {
 183         u8 temp[64];
 184         u8 *prog;
 185         unsigned int proglen, oldproglen = 0;
 186         int ilen, i;
 187         int t_offset, f_offset;
 188         u8 t_op, f_op, seen = 0, pass;
 189         u8 *image = NULL;
 190         struct bpf_binary_header *header = NULL;
 191         u8 *func;
 192         int pc_ret0 = -1; /* bpf index of first RET #0 instruction (if any) */
 193         unsigned int cleanup_addr; /* epilogue code offset */
 194         unsigned int *addrs;
 195         const struct sock_filter *filter = fp->insns;
 196         int flen = fp->len;
 197
 198         if (!bpf_jit_enable)
 199                 return;
 200
 201         addrs = kmalloc(flen * sizeof(*addrs), GFP_KERNEL);
 202         if (addrs == NULL)
 203                 return;
 204
 205         /* Before first pass, make a rough estimation of addrs[]
 206          * each bpf instruction is translated to less than 64 bytes
 207          */
 208         for (proglen = 0, i = 0; i < flen; i++) {
 209                 proglen += 64;
 210                 addrs[i] = proglen;
 211         }
 212         cleanup_addr = proglen; /* epilogue address */
 213
 214         for (pass = 0; pass < 10; pass++) {
 215                 u8 seen_or_pass0 = (pass == 0) ? (SEEN_XREG | SEEN_DATAREF | SEEN_MEM) : seen;
 216                 /* no prologue/epilogue for trivial filters (RET something) */
 217                 proglen = 0;
 218                 prog = temp;
 219
 220                 if (seen_or_pass0) {
 221                         EMIT4(0x55, 0x48, 0x89, 0xe5); /* push %rbp; mov %rsp,%rbp */
 222                         EMIT4(0x48, 0x83, 0xec, 96);    /* subq  $96,%rsp       */
 223                         /* note : must save %rbx in case bpf_error is hit */
 224                         if (seen_or_pass0 & (SEEN_XREG | SEEN_DATAREF))
 225                                 EMIT4(0x48, 0x89, 0x5d, 0xf8); /* mov %rbx, -8(%rbp) */
 226                         if (seen_or_pass0 & SEEN_XREG)
 227                                 CLEAR_X(); /* make sure we dont leek kernel memory */
 228
 229                         /*
 230                          * If this filter needs to access skb data,
 231                          * loads r9 and r8 with :
 232                          *  r9 = skb->len - skb->data_len
 233                          *  r8 = skb->data
 234                          */
 235                         if (seen_or_pass0 & SEEN_DATAREF) {
 236                                 if (offsetof(struct sk_buff, len) <= 127)
 237                                         /* mov    off8(%rdi),%r9d */
 238                                         EMIT4(0x44, 0x8b, 0x4f, offsetof(struct sk_buff, len));
 239                                 else {
 240                                         /* mov    off32(%rdi),%r9d */
 241                                         EMIT3(0x44, 0x8b, 0x8f);
 242                                         EMIT(offsetof(struct sk_buff, len), 4);
 243                                 }
 244                                 if (is_imm8(offsetof(struct sk_buff, data_len)))
 245                                         /* sub    off8(%rdi),%r9d */
 246                                         EMIT4(0x44, 0x2b, 0x4f, offsetof(struct sk_buff, data_len));
 247                                 else {
 248                                         EMIT3(0x44, 0x2b, 0x8f);
 249                                         EMIT(offsetof(struct sk_buff, data_len), 4);
 250                                 }
 251
 252                                 if (is_imm8(offsetof(struct sk_buff, data)))
 253                                         /* mov off8(%rdi),%r8 */
 254                                         EMIT4(0x4c, 0x8b, 0x47, offsetof(struct sk_buff, data));
 255                                 else {
 256                                         /* mov off32(%rdi),%r8 */
 257                                         EMIT3(0x4c, 0x8b, 0x87);
 258                                         EMIT(offsetof(struct sk_buff, data), 4);
 259                                 }
 260                         }
 261                 }
 262
 263                 switch (filter[0].code) {
 264                 case BPF_S_RET_K:
 265                 case BPF_S_LD_W_LEN:
 266                 case BPF_S_ANC_PROTOCOL:
 267                 case BPF_S_ANC_IFINDEX:
 268                 case BPF_S_ANC_MARK:
 269                 case BPF_S_ANC_RXHASH:
 270                 case BPF_S_ANC_CPU:
 271                 case BPF_S_ANC_VLAN_TAG:
 272                 case BPF_S_ANC_VLAN_TAG_PRESENT:
 273                 case BPF_S_ANC_QUEUE:
 274                 case BPF_S_ANC_PKTTYPE:
 275                 case BPF_S_LD_W_ABS:
 276                 case BPF_S_LD_H_ABS:
 277                 case BPF_S_LD_B_ABS:
 278                         /* first instruction sets A register (or is RET 'constant') */
 279                         break;
 280                 default:
 281                         /* make sure we dont leak kernel information to user */
 282                         CLEAR_A(); /* A = 0 */
 283                 }
 284
 285                 for (i = 0; i < flen; i++) {
 286                         unsigned int K = filter[i].k;
 287
 288                         switch (filter[i].code) {
 289                         case BPF_S_ALU_ADD_X: /* A += X; */
 290                                 seen |= SEEN_XREG;
 291                                 EMIT2(0x01, 0xd8);              /* add %ebx,%eax */
 292                                 break;
 293                         case BPF_S_ALU_ADD_K: /* A += K; */
 294                                 if (!K)
 295                                         break;
 296                                 if (is_imm8(K))
 297                                         EMIT3(0x83, 0xc0, K);   /* add imm8,%eax */
 298                                 else
 299                                         EMIT1_off32(0x05, K);   /* add imm32,%eax */
 300                                 break;
 301                         case BPF_S_ALU_SUB_X: /* A -= X; */
 302                                 seen |= SEEN_XREG;
 303                                 EMIT2(0x29, 0xd8);              /* sub    %ebx,%eax */
 304                                 break;
 305                         case BPF_S_ALU_SUB_K: /* A -= K */
 306                                 if (!K)
 307                                         break;
 308                                 if (is_imm8(K))
 309                                         EMIT3(0x83, 0xe8, K); /* sub imm8,%eax */
 310                                 else
 311                                         EMIT1_off32(0x2d, K); /* sub imm32,%eax */
 312                                 break;
 313                         case BPF_S_ALU_MUL_X: /* A *= X; */
 314                                 seen |= SEEN_XREG;
 315                                 EMIT3(0x0f, 0xaf, 0xc3);        /* imul %ebx,%eax */
 316                                 break;
 317                         case BPF_S_ALU_MUL_K: /* A *= K */
 318                                 if (is_imm8(K))
 319                                         EMIT3(0x6b, 0xc0, K); /* imul imm8,%eax,%eax */
 320                                 else {
 321                                         EMIT2(0x69, 0xc0);              /* imul imm32,%eax */
 322                                         EMIT(K, 4);
 323                                 }
 324                                 break;
 325                         case BPF_S_ALU_DIV_X: /* A /= X; */
 326                                 seen |= SEEN_XREG;
 327                                 EMIT2(0x85, 0xdb);      /* test %ebx,%ebx */
 328                                 if (pc_ret0 > 0) {
 329                                         /* addrs[pc_ret0 - 1] is start address of target
 330                                          * (addrs[i] - 4) is the address following this jmp
 331                                          * ("xor %edx,%edx; div %ebx" being 4 bytes long)
 332                                          */
 333                                         EMIT_COND_JMP(X86_JE, addrs[pc_ret0 - 1] -
 334                                                                 (addrs[i] - 4));
 335                                 } else {
 336                                         EMIT_COND_JMP(X86_JNE, 2 + 5);
 337                                         CLEAR_A();
 338                                         EMIT1_off32(0xe9, cleanup_addr - (addrs[i] - 4)); /* jmp .+off32 */
 339                                 }
 340                                 EMIT4(0x31, 0xd2, 0xf7, 0xf3); /* xor %edx,%edx; div %ebx */
 341                                 break;
 342                         case BPF_S_ALU_MOD_X: /* A %= X; */
 343                                 seen |= SEEN_XREG;
 344                                 EMIT2(0x85, 0xdb);      /* test %ebx,%ebx */
 345                                 if (pc_ret0 > 0) {
 346                                         /* addrs[pc_ret0 - 1] is start address of target
 347                                          * (addrs[i] - 6) is the address following this jmp
 348                                          * ("xor %edx,%edx; div %ebx;mov %edx,%eax" being 6 bytes long)
 349                                          */
 350                                         EMIT_COND_JMP(X86_JE, addrs[pc_ret0 - 1] -
 351                                                                 (addrs[i] - 6));
 352                                 } else {
 353                                         EMIT_COND_JMP(X86_JNE, 2 + 5);
 354                                         CLEAR_A();
 355                                         EMIT1_off32(0xe9, cleanup_addr - (addrs[i] - 6)); /* jmp .+off32 */
 356                                 }
 357                                 EMIT2(0x31, 0xd2);      /* xor %edx,%edx */
 358                                 EMIT2(0xf7, 0xf3);      /* div %ebx */
 359                                 EMIT2(0x89, 0xd0);      /* mov %edx,%eax */
 360                                 break;
 361                         case BPF_S_ALU_MOD_K: /* A %= K; */
 362                                 if (K == 1) {
 363                                         CLEAR_A();
 364                                         break;
 365                                 }
 366                                 EMIT2(0x31, 0xd2);      /* xor %edx,%edx */
 367                                 EMIT1(0xb9);EMIT(K, 4); /* mov imm32,%ecx */
 368                                 EMIT2(0xf7, 0xf1);      /* div %ecx */
 369                                 EMIT2(0x89, 0xd0);      /* mov %edx,%eax */
 370                                 break;
 371                         case BPF_S_ALU_DIV_K: /* A /= K */
 372                                 if (K == 1)
 373                                         break;
 374                                 EMIT2(0x31, 0xd2);      /* xor %edx,%edx */
 375                                 EMIT1(0xb9);EMIT(K, 4); /* mov imm32,%ecx */
 376                                 EMIT2(0xf7, 0xf1);      /* div %ecx */
 377                                 break;
 378                         case BPF_S_ALU_AND_X:
 379                                 seen |= SEEN_XREG;
 380                                 EMIT2(0x21, 0xd8);              /* and %ebx,%eax */
 381                                 break;
 382                         case BPF_S_ALU_AND_K:
 383                                 if (K >= 0xFFFFFF00) {
 384                                         EMIT2(0x24, K & 0xFF); /* and imm8,%al */
 385                                 } else if (K >= 0xFFFF0000) {
 386                                         EMIT2(0x66, 0x25);      /* and imm16,%ax */
 387                                         EMIT(K, 2);
 388                                 } else {
 389                                         EMIT1_off32(0x25, K);   /* and imm32,%eax */
 390                                 }
 391                                 break;
 392                         case BPF_S_ALU_OR_X:
 393                                 seen |= SEEN_XREG;
 394                                 EMIT2(0x09, 0xd8);              /* or %ebx,%eax */
 395                                 break;
 396                         case BPF_S_ALU_OR_K:
 397                                 if (is_imm8(K))
 398                                         EMIT3(0x83, 0xc8, K); /* or imm8,%eax */
 399                                 else
 400                                         EMIT1_off32(0x0d, K);   /* or imm32,%eax */
 401                                 break;
 402                         case BPF_S_ANC_ALU_XOR_X: /* A ^= X; */
 403                         case BPF_S_ALU_XOR_X:
 404                                 seen |= SEEN_XREG;
 405                                 EMIT2(0x31, 0xd8);              /* xor %ebx,%eax */
 406                                 break;
 407                         case BPF_S_ALU_XOR_K: /* A ^= K; */
 408                                 if (K == 0)
 409                                         break;
 410                                 if (is_imm8(K))
 411                                         EMIT3(0x83, 0xf0, K);   /* xor imm8,%eax */
 412                                 else
 413                                         EMIT1_off32(0x35, K);   /* xor imm32,%eax */
 414                                 break;
 415                         case BPF_S_ALU_LSH_X: /* A <<= X; */
 416                                 seen |= SEEN_XREG;
 417                                 EMIT4(0x89, 0xd9, 0xd3, 0xe0);  /* mov %ebx,%ecx; shl %cl,%eax */
 418                                 break;
 419                         case BPF_S_ALU_LSH_K:
 420                                 if (K == 0)
 421                                         break;
 422                                 else if (K == 1)
 423                                         EMIT2(0xd1, 0xe0); /* shl %eax */
 424                                 else
 425                                         EMIT3(0xc1, 0xe0, K);
 426                                 break;
 427                         case BPF_S_ALU_RSH_X: /* A >>= X; */
 428                                 seen |= SEEN_XREG;
 429                                 EMIT4(0x89, 0xd9, 0xd3, 0xe8);  /* mov %ebx,%ecx; shr %cl,%eax */
 430                                 break;
 431                         case BPF_S_ALU_RSH_K: /* A >>= K; */
 432                                 if (K == 0)
 433                                         break;
 434                                 else if (K == 1)
 435                                         EMIT2(0xd1, 0xe8); /* shr %eax */
 436                                 else
 437                                         EMIT3(0xc1, 0xe8, K);
 438                                 break;
 439                         case BPF_S_ALU_NEG:
 440                                 EMIT2(0xf7, 0xd8);              /* neg %eax */
 441                                 break;
 442                         case BPF_S_RET_K:
 443                                 if (!K) {
 444                                         if (pc_ret0 == -1)
 445                                                 pc_ret0 = i;
 446                                         CLEAR_A();
 447                                 } else {
 448                                         EMIT1_off32(0xb8, K);   /* mov $imm32,%eax */
 449                                 }
 450                                 /* fallinto */
 451                         case BPF_S_RET_A:
 452                                 if (seen_or_pass0) {
 453                                         if (i != flen - 1) {
 454                                                 EMIT_JMP(cleanup_addr - addrs[i]);
 455                                                 break;
 456                                         }
 457                                         if (seen_or_pass0 & SEEN_XREG)
 458                                                 EMIT4(0x48, 0x8b, 0x5d, 0xf8);  /* mov  -8(%rbp),%rbx */
 459                                         EMIT1(0xc9);            /* leaveq */
 460                                 }
 461                                 EMIT1(0xc3);            /* ret */
 462                                 break;
 463                         case BPF_S_MISC_TAX: /* X = A */
 464                                 seen |= SEEN_XREG;
 465                                 EMIT2(0x89, 0xc3);      /* mov    %eax,%ebx */
 466                                 break;
 467                         case BPF_S_MISC_TXA: /* A = X */
 468                                 seen |= SEEN_XREG;
 469                                 EMIT2(0x89, 0xd8);      /* mov    %ebx,%eax */
 470                                 break;
 471                         case BPF_S_LD_IMM: /* A = K */
 472                                 if (!K)
 473                                         CLEAR_A();
 474                                 else
 475                                         EMIT1_off32(0xb8, K); /* mov $imm32,%eax */
 476                                 break;
 477                         case BPF_S_LDX_IMM: /* X = K */
 478                                 seen |= SEEN_XREG;
 479                                 if (!K)
 480                                         CLEAR_X();
 481                                 else
 482                                         EMIT1_off32(0xbb, K); /* mov $imm32,%ebx */
 483                                 break;
 484                         case BPF_S_LD_MEM: /* A = mem[K] : mov off8(%rbp),%eax */
 485                                 seen |= SEEN_MEM;
 486                                 EMIT3(0x8b, 0x45, 0xf0 - K*4);
 487                                 break;
 488                         case BPF_S_LDX_MEM: /* X = mem[K] : mov off8(%rbp),%ebx */
 489                                 seen |= SEEN_XREG | SEEN_MEM;
 490                                 EMIT3(0x8b, 0x5d, 0xf0 - K*4);
 491                                 break;
 492                         case BPF_S_ST: /* mem[K] = A : mov %eax,off8(%rbp) */
 493                                 seen |= SEEN_MEM;
 494                                 EMIT3(0x89, 0x45, 0xf0 - K*4);
 495                                 break;
 496                         case BPF_S_STX: /* mem[K] = X : mov %ebx,off8(%rbp) */
 497                                 seen |= SEEN_XREG | SEEN_MEM;
 498                                 EMIT3(0x89, 0x5d, 0xf0 - K*4);
 499                                 break;
 500                         case BPF_S_LD_W_LEN: /* A = skb->len; */
 501                                 BUILD_BUG_ON(FIELD_SIZEOF(struct sk_buff, len) != 4);
 502                                 if (is_imm8(offsetof(struct sk_buff, len)))
 503                                         /* mov    off8(%rdi),%eax */
 504                                         EMIT3(0x8b, 0x47, offsetof(struct sk_buff, len));
 505                                 else {
 506                                         EMIT2(0x8b, 0x87);
 507                                         EMIT(offsetof(struct sk_buff, len), 4);
 508                                 }
 509                                 break;
 510                         case BPF_S_LDX_W_LEN: /* X = skb->len; */
 511                                 seen |= SEEN_XREG;
 512                                 if (is_imm8(offsetof(struct sk_buff, len)))
 513                                         /* mov off8(%rdi),%ebx */
 514                                         EMIT3(0x8b, 0x5f, offsetof(struct sk_buff, len));
 515                                 else {
 516                                         EMIT2(0x8b, 0x9f);
 517                                         EMIT(offsetof(struct sk_buff, len), 4);
 518                                 }
 519                                 break;
 520                         case BPF_S_ANC_PROTOCOL: /* A = ntohs(skb->protocol); */
 521                                 BUILD_BUG_ON(FIELD_SIZEOF(struct sk_buff, protocol) != 2);
 522                                 if (is_imm8(offsetof(struct sk_buff, protocol))) {
 523                                         /* movzwl off8(%rdi),%eax */
 524                                         EMIT4(0x0f, 0xb7, 0x47, offsetof(struct sk_buff, protocol));
 525                                 } else {
 526                                         EMIT3(0x0f, 0xb7, 0x87); /* movzwl off32(%rdi),%eax */
 527                                         EMIT(offsetof(struct sk_buff, protocol), 4);
 528                                 }
 529                                 EMIT2(0x86, 0xc4); /* ntohs() : xchg   %al,%ah */
 530                                 break;
 531                         case BPF_S_ANC_IFINDEX:
 532                                 if (is_imm8(offsetof(struct sk_buff, dev))) {
 533                                         /* movq off8(%rdi),%rax */
 534                                         EMIT4(0x48, 0x8b, 0x47, offsetof(struct sk_buff, dev));
 535                                 } else {
 536                                         EMIT3(0x48, 0x8b, 0x87); /* movq off32(%rdi),%rax */
 537                                         EMIT(offsetof(struct sk_buff, dev), 4);
 538                                 }
 539                                 EMIT3(0x48, 0x85, 0xc0);        /* test %rax,%rax */
 540                                 EMIT_COND_JMP(X86_JE, cleanup_addr - (addrs[i] - 6));
 541                                 BUILD_BUG_ON(FIELD_SIZEOF(struct net_device, ifindex) != 4);
 542                                 EMIT2(0x8b, 0x80);      /* mov off32(%rax),%eax */
 543                                 EMIT(offsetof(struct net_device, ifindex), 4);
 544                                 break;
 545                         case BPF_S_ANC_MARK:
 546                                 BUILD_BUG_ON(FIELD_SIZEOF(struct sk_buff, mark) != 4);
 547                                 if (is_imm8(offsetof(struct sk_buff, mark))) {
 548                                         /* mov off8(%rdi),%eax */
 549                                         EMIT3(0x8b, 0x47, offsetof(struct sk_buff, mark));
 550                                 } else {
 551                                         EMIT2(0x8b, 0x87);
 552                                         EMIT(offsetof(struct sk_buff, mark), 4);
 553                                 }
 554                                 break;
 555                         case BPF_S_ANC_RXHASH:
 556                                 BUILD_BUG_ON(FIELD_SIZEOF(struct sk_buff, rxhash) != 4);
 557                                 if (is_imm8(offsetof(struct sk_buff, rxhash))) {
 558                                         /* mov off8(%rdi),%eax */
 559                                         EMIT3(0x8b, 0x47, offsetof(struct sk_buff, rxhash));
 560                                 } else {
 561                                         EMIT2(0x8b, 0x87);
 562                                         EMIT(offsetof(struct sk_buff, rxhash), 4);
 563                                 }
 564                                 break;
 565                         case BPF_S_ANC_QUEUE:
 566                                 BUILD_BUG_ON(FIELD_SIZEOF(struct sk_buff, queue_mapping) != 2);
 567                                 if (is_imm8(offsetof(struct sk_buff, queue_mapping))) {
 568                                         /* movzwl off8(%rdi),%eax */
 569                                         EMIT4(0x0f, 0xb7, 0x47, offsetof(struct sk_buff, queue_mapping));
 570                                 } else {
 571                                         EMIT3(0x0f, 0xb7, 0x87); /* movzwl off32(%rdi),%eax */
 572                                         EMIT(offsetof(struct sk_buff, queue_mapping), 4);
 573                                 }
 574                                 break;
 575                         case BPF_S_ANC_CPU:
 576 #ifdef CONFIG_SMP
 577                                 EMIT4(0x65, 0x8b, 0x04, 0x25); /* mov %gs:off32,%eax */
 578                                 EMIT((u32)(unsigned long)&cpu_number, 4); /* A = smp_processor_id(); */
 579 #else
 580                                 CLEAR_A();
 581 #endif
 582                                 break;
 583                         case BPF_S_ANC_VLAN_TAG:
 584                         case BPF_S_ANC_VLAN_TAG_PRESENT:
 585                                 BUILD_BUG_ON(FIELD_SIZEOF(struct sk_buff, vlan_tci) != 2);
 586                                 if (is_imm8(offsetof(struct sk_buff, vlan_tci))) {
 587                                         /* movzwl off8(%rdi),%eax */
 588                                         EMIT4(0x0f, 0xb7, 0x47, offsetof(struct sk_buff, vlan_tci));
 589                                 } else {
 590                                         EMIT3(0x0f, 0xb7, 0x87); /* movzwl off32(%rdi),%eax */
 591                                         EMIT(offsetof(struct sk_buff, vlan_tci), 4);
 592                                 }
 593                                 BUILD_BUG_ON(VLAN_TAG_PRESENT != 0x1000);
 594                                 if (filter[i].code == BPF_S_ANC_VLAN_TAG) {
 595                                         EMIT3(0x80, 0xe4, 0xef); /* and    $0xef,%ah */
 596                                 } else {
 597                                         EMIT3(0xc1, 0xe8, 0x0c); /* shr    $0xc,%eax */
 598                                         EMIT3(0x83, 0xe0, 0x01); /* and    $0x1,%eax */
 599                                 }
 600                                 break;
 601                         case BPF_S_ANC_PKTTYPE:
 602                         {
 603                                 int off = pkt_type_offset();
 604
 605                                 if (off < 0)
 606                                         goto out;
 607                                 if (is_imm8(off)) {
 608                                         /* movzbl off8(%rdi),%eax */
 609                                         EMIT4(0x0f, 0xb6, 0x47, off);
 610                                 } else {
 611                                         /* movbl off32(%rdi),%eax */
 612                                         EMIT3(0x0f, 0xb6, 0x87);
 613                                         EMIT(off, 4);
 614                                 }
 615                                 EMIT3(0x83, 0xe0, PKT_TYPE_MAX); /* and    $0x7,%eax */
 616                                 break;
 617                         }
 618                         case BPF_S_LD_W_ABS:
 619                                 func = CHOOSE_LOAD_FUNC(K, sk_load_word);
 620 common_load:                    seen |= SEEN_DATAREF;
 621                                 t_offset = func - (image + addrs[i]);
 622                                 EMIT1_off32(0xbe, K); /* mov imm32,%esi */
 623                                 EMIT1_off32(0xe8, t_offset); /* call */
 624                                 break;
 625                         case BPF_S_LD_H_ABS:
 626                                 func = CHOOSE_LOAD_FUNC(K, sk_load_half);
 627                                 goto common_load;
 628                         case BPF_S_LD_B_ABS:
 629                                 func = CHOOSE_LOAD_FUNC(K, sk_load_byte);
 630                                 goto common_load;
 631                         case BPF_S_LDX_B_MSH:
 632                                 func = CHOOSE_LOAD_FUNC(K, sk_load_byte_msh);
 633                                 seen |= SEEN_DATAREF | SEEN_XREG;
 634                                 t_offset = func - (image + addrs[i]);
 635                                 EMIT1_off32(0xbe, K);   /* mov imm32,%esi */
 636                                 EMIT1_off32(0xe8, t_offset); /* call sk_load_byte_msh */
 637                                 break;
 638                         case BPF_S_LD_W_IND:
 639                                 func = sk_load_word;
 640 common_load_ind:                seen |= SEEN_DATAREF | SEEN_XREG;
 641                                 t_offset = func - (image + addrs[i]);
 642                                 if (K) {
 643                                         if (is_imm8(K)) {
 644                                                 EMIT3(0x8d, 0x73, K); /* lea imm8(%rbx), %esi */
 645                                         } else {
 646                                                 EMIT2(0x8d, 0xb3); /* lea imm32(%rbx),%esi */
 647                                                 EMIT(K, 4);
 648                                         }
 649                                 } else {
 650                                         EMIT2(0x89,0xde); /* mov %ebx,%esi */
 651                                 }
 652                                 EMIT1_off32(0xe8, t_offset);    /* call sk_load_xxx_ind */
 653                                 break;
 654                         case BPF_S_LD_H_IND:
 655                                 func = sk_load_half;
 656                                 goto common_load_ind;
 657                         case BPF_S_LD_B_IND:
 658                                 func = sk_load_byte;
 659                                 goto common_load_ind;
 660                         case BPF_S_JMP_JA:
 661                                 t_offset = addrs[i + K] - addrs[i];
 662                                 EMIT_JMP(t_offset);
 663                                 break;
 664                         COND_SEL(BPF_S_JMP_JGT_K, X86_JA, X86_JBE);
 665                         COND_SEL(BPF_S_JMP_JGE_K, X86_JAE, X86_JB);
 666                         COND_SEL(BPF_S_JMP_JEQ_K, X86_JE, X86_JNE);
 667                         COND_SEL(BPF_S_JMP_JSET_K,X86_JNE, X86_JE);
 668                         COND_SEL(BPF_S_JMP_JGT_X, X86_JA, X86_JBE);
 669                         COND_SEL(BPF_S_JMP_JGE_X, X86_JAE, X86_JB);
 670                         COND_SEL(BPF_S_JMP_JEQ_X, X86_JE, X86_JNE);
 671                         COND_SEL(BPF_S_JMP_JSET_X,X86_JNE, X86_JE);
 672
 673 cond_branch:                    f_offset = addrs[i + filter[i].jf] - addrs[i];
 674                                 t_offset = addrs[i + filter[i].jt] - addrs[i];
 675
 676                                 /* same targets, can avoid doing the test :) */
 677                                 if (filter[i].jt == filter[i].jf) {
 678                                         EMIT_JMP(t_offset);
 679                                         break;
 680                                 }
 681
 682                                 switch (filter[i].code) {
 683                                 case BPF_S_JMP_JGT_X:
 684                                 case BPF_S_JMP_JGE_X:
 685                                 case BPF_S_JMP_JEQ_X:
 686                                         seen |= SEEN_XREG;
 687                                         EMIT2(0x39, 0xd8); /* cmp %ebx,%eax */
 688                                         break;
 689                                 case BPF_S_JMP_JSET_X:
 690                                         seen |= SEEN_XREG;
 691                                         EMIT2(0x85, 0xd8); /* test %ebx,%eax */
 692                                         break;
 693                                 case BPF_S_JMP_JEQ_K:
 694                                         if (K == 0) {
 695                                                 EMIT2(0x85, 0xc0); /* test   %eax,%eax */
 696                                                 break;
 697                                         }
 698                                 case BPF_S_JMP_JGT_K:
 699                                 case BPF_S_JMP_JGE_K:
 700                                         if (K <= 127)
 701                                                 EMIT3(0x83, 0xf8, K); /* cmp imm8,%eax */
 702                                         else
 703                                                 EMIT1_off32(0x3d, K); /* cmp imm32,%eax */
 704                                         break;
 705                                 case BPF_S_JMP_JSET_K:
 706                                         if (K <= 0xFF)
 707                                                 EMIT2(0xa8, K); /* test imm8,%al */
 708                                         else if (!(K & 0xFFFF00FF))
 709                                                 EMIT3(0xf6, 0xc4, K >> 8); /* test imm8,%ah */
 710                                         else if (K <= 0xFFFF) {
 711                                                 EMIT2(0x66, 0xa9); /* test imm16,%ax */
 712                                                 EMIT(K, 2);
 713                                         } else {
 714                                                 EMIT1_off32(0xa9, K); /* test imm32,%eax */
 715                                         }
 716                                         break;
 717                                 }
 718                                 if (filter[i].jt != 0) {
 719                                         if (filter[i].jf && f_offset)
 720                                                 t_offset += is_near(f_offset) ? 2 : 5;
 721                                         EMIT_COND_JMP(t_op, t_offset);
 722                                         if (filter[i].jf)
 723                                                 EMIT_JMP(f_offset);
 724                                         break;
 725                                 }
 726                                 EMIT_COND_JMP(f_op, f_offset);
 727                                 break;
 728                         default:
 729                                 /* hmm, too complex filter, give up with jit compiler */
 730                                 goto out;
 731                         }
 732                         ilen = prog - temp;
 733                         if (image) {
 734                                 if (unlikely(proglen + ilen > oldproglen)) {
 735                                         pr_err("bpb_jit_compile fatal error\n");
 736                                         kfree(addrs);
 737                                         module_free(NULL, header);
 738                                         return;
 739                                 }
 740                                 memcpy(image + proglen, temp, ilen);
 741                         }
 742                         proglen += ilen;
 743                         addrs[i] = proglen;
 744                         prog = temp;
 745                 }
 746                 /* last bpf instruction is always a RET :
 747                  * use it to give the cleanup instruction(s) addr
 748                  */
 749                 cleanup_addr = proglen - 1; /* ret */
 750                 if (seen_or_pass0)
 751                         cleanup_addr -= 1; /* leaveq */
 752                 if (seen_or_pass0 & SEEN_XREG)
 753                         cleanup_addr -= 4; /* mov  -8(%rbp),%rbx */
 754
 755                 if (image) {
 756                         if (proglen != oldproglen)
 757                                 pr_err("bpb_jit_compile proglen=%u != oldproglen=%u\n", proglen, oldproglen);
 758                         break;
 759                 }
 760                 if (proglen == oldproglen) {
 761                         header = bpf_alloc_binary(proglen, &image);
 762                         if (!header)
 763                                 goto out;
 764                 }
 765                 oldproglen = proglen;
 766         }
 767
 768         if (bpf_jit_enable > 1)
 769                 bpf_jit_dump(flen, proglen, pass, image);
 770
 771         if (image) {
 772                 bpf_flush_icache(header, image + proglen);
 773                 set_memory_ro((unsigned long)header, header->pages);
 774                 fp->bpf_func = (void *)image;
 775         }
 776 out:
 777         kfree(addrs);
 778         return;
 779 }
 780
 781 static void bpf_jit_free_deferred(struct work_struct *work)
 782 {
 783         struct sk_filter *fp = container_of(work, struct sk_filter, work);
 784         unsigned long addr = (unsigned long)fp->bpf_func & PAGE_MASK;
 785         struct bpf_binary_header *header = (void *)addr;
 786
 787         set_memory_rw(addr, header->pages);
 788         module_free(NULL, header);
 789         kfree(fp);
 790 }
 791
 792 void bpf_jit_free(struct sk_filter *fp)
 793 {
 794         if (fp->bpf_func != sk_run_filter) {
 795                 INIT_WORK(&fp->work, bpf_jit_free_deferred);
 796                 schedule_work(&fp->work);
 797         } else {
 798                 kfree(fp);
 799         }
 800 }