arch/x86/net/bpf_jit_comp.c

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