arch/x86/net/bpf_jit_comp.c

   1 /* bpf_jit_comp.c : BPF JIT compiler
   2  *
   3  * Copyright (C) 2011 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
  15 /*
  16  * Conventions :
  17  *  EAX : BPF A accumulator
  18  *  EBX : BPF X accumulator
  19  *  RDI : pointer to skb   (first argument given to JIT function)
  20  *  RBP : frame pointer (even if CONFIG_FRAME_POINTER=n)
  21  *  ECX,EDX,ESI : scratch registers
  22  *  r9d : skb->len - skb->data_len (headlen)
  23  *  r8  : skb->data
  24  * -8(RBP) : saved RBX value
  25  * -16(RBP)..-80(RBP) : BPF_MEMWORDS values
  26  */
  27 int bpf_jit_enable __read_mostly;
  28
  29 /*
  30  * assembly code in arch/x86/net/bpf_jit.S
  31  */
  32 extern u8 sk_load_word[], sk_load_half[], sk_load_byte[], sk_load_byte_msh[];
  33 extern u8 sk_load_word_ind[], sk_load_half_ind[], sk_load_byte_ind[];
  34
  35 static inline u8 *emit_code(u8 *ptr, u32 bytes, unsigned int len)
  36 {
  37         if (len == 1)
  38                 *ptr = bytes;
  39         else if (len == 2)
  40                 *(u16 *)ptr = bytes;
  41         else {
  42                 *(u32 *)ptr = bytes;
  43                 barrier();
  44         }
  45         return ptr + len;
  46 }
  47
  48 #define EMIT(bytes, len)        do { prog = emit_code(prog, bytes, len); } while (0)
  49
  50 #define EMIT1(b1)               EMIT(b1, 1)
  51 #define EMIT2(b1, b2)           EMIT((b1) + ((b2) << 8), 2)
  52 #define EMIT3(b1, b2, b3)       EMIT((b1) + ((b2) << 8) + ((b3) << 16), 3)
  53 #define EMIT4(b1, b2, b3, b4)   EMIT((b1) + ((b2) << 8) + ((b3) << 16) + ((b4) << 24), 4)
  54 #define EMIT1_off32(b1, off)    do { EMIT1(b1); EMIT(off, 4);} while (0)
  55
  56 #define CLEAR_A() EMIT2(0x31, 0xc0) /* xor %eax,%eax */
  57 #define CLEAR_X() EMIT2(0x31, 0xdb) /* xor %ebx,%ebx */
  58
  59 static inline bool is_imm8(int value)
  60 {
  61         return value <= 127 && value >= -128;
  62 }
  63
  64 static inline bool is_near(int offset)
  65 {
  66         return offset <= 127 && offset >= -128;
  67 }
  68
  69 #define EMIT_JMP(offset)                                                \
  70 do {                                                                    \
  71         if (offset) {                                                   \
  72                 if (is_near(offset))                                    \
  73                         EMIT2(0xeb, offset); /* jmp .+off8 */           \
  74                 else                                                    \
  75                         EMIT1_off32(0xe9, offset); /* jmp .+off32 */    \
  76         }                                                               \
  77 } while (0)
  78
  79 /* list of x86 cond jumps opcodes (. + s8)
  80  * Add 0x10 (and an extra 0x0f) to generate far jumps (. + s32)
  81  */
  82 #define X86_JB  0x72
  83 #define X86_JAE 0x73
  84 #define X86_JE  0x74
  85 #define X86_JNE 0x75
  86 #define X86_JBE 0x76
  87 #define X86_JA  0x77
  88
  89 #define EMIT_COND_JMP(op, offset)                               \
  90 do {                                                            \
  91         if (is_near(offset))                                    \
  92                 EMIT2(op, offset); /* jxx .+off8 */             \
  93         else {                                                  \
  94                 EMIT2(0x0f, op + 0x10);                         \
  95                 EMIT(offset, 4); /* jxx .+off32 */              \
  96         }                                                       \
  97 } while (0)
  98
  99 #define COND_SEL(CODE, TOP, FOP)        \
 100         case CODE:                      \
 101                 t_op = TOP;             \
 102                 f_op = FOP;             \
 103                 goto cond_branch
 104
 105
 106 #define SEEN_DATAREF 1 /* might call external helpers */
 107 #define SEEN_XREG    2 /* ebx is used */
 108 #define SEEN_MEM     4 /* use mem[] for temporary storage */
 109
 110 static inline void bpf_flush_icache(void *start, void *end)
 111 {
 112         mm_segment_t old_fs = get_fs();
 113
 114         set_fs(KERNEL_DS);
 115         smp_wmb();
 116         flush_icache_range((unsigned long)start, (unsigned long)end);
 117         set_fs(old_fs);
 118 }
 119
 120
 121 void bpf_jit_compile(struct sk_filter *fp)
 122 {
 123         u8 temp[64];
 124         u8 *prog;
 125         unsigned int proglen, oldproglen = 0;
 126         int ilen, i;
 127         int t_offset, f_offset;
 128         u8 t_op, f_op, seen = 0, pass;
 129         u8 *image = NULL;
 130         u8 *func;
 131         int pc_ret0 = -1; /* bpf index of first RET #0 instruction (if any) */
 132         unsigned int cleanup_addr; /* epilogue code offset */
 133         unsigned int *addrs;
 134         const struct sock_filter *filter = fp->insns;
 135         int flen = fp->len;
 136
 137         if (!bpf_jit_enable)
 138                 return;
 139
 140         addrs = kmalloc(flen * sizeof(*addrs), GFP_KERNEL);
 141         if (addrs == NULL)
 142                 return;
 143
 144         /* Before first pass, make a rough estimation of addrs[]
 145          * each bpf instruction is translated to less than 64 bytes
 146          */
 147         for (proglen = 0, i = 0; i < flen; i++) {
 148                 proglen += 64;
 149                 addrs[i] = proglen;
 150         }
 151         cleanup_addr = proglen; /* epilogue address */
 152
 153         for (pass = 0; pass < 10; pass++) {
 154                 u8 seen_or_pass0 = (pass == 0) ? (SEEN_XREG | SEEN_DATAREF | SEEN_MEM) : seen;
 155                 /* no prologue/epilogue for trivial filters (RET something) */
 156                 proglen = 0;
 157                 prog = temp;
 158
 159                 if (seen_or_pass0) {
 160                         EMIT4(0x55, 0x48, 0x89, 0xe5); /* push %rbp; mov %rsp,%rbp */
 161                         EMIT4(0x48, 0x83, 0xec, 96);    /* subq  $96,%rsp       */
 162                         /* note : must save %rbx in case bpf_error is hit */
 163                         if (seen_or_pass0 & (SEEN_XREG | SEEN_DATAREF))
 164                                 EMIT4(0x48, 0x89, 0x5d, 0xf8); /* mov %rbx, -8(%rbp) */
 165                         if (seen_or_pass0 & SEEN_XREG)
 166                                 CLEAR_X(); /* make sure we dont leek kernel memory */
 167
 168                         /*
 169                          * If this filter needs to access skb data,
 170                          * loads r9 and r8 with :
 171                          *  r9 = skb->len - skb->data_len
 172                          *  r8 = skb->data
 173                          */
 174                         if (seen_or_pass0 & SEEN_DATAREF) {
 175                                 if (offsetof(struct sk_buff, len) <= 127)
 176                                         /* mov    off8(%rdi),%r9d */
 177                                         EMIT4(0x44, 0x8b, 0x4f, offsetof(struct sk_buff, len));
 178                                 else {
 179                                         /* mov    off32(%rdi),%r9d */
 180                                         EMIT3(0x44, 0x8b, 0x8f);
 181                                         EMIT(offsetof(struct sk_buff, len), 4);
 182                                 }
 183                                 if (is_imm8(offsetof(struct sk_buff, data_len)))
 184                                         /* sub    off8(%rdi),%r9d */
 185                                         EMIT4(0x44, 0x2b, 0x4f, offsetof(struct sk_buff, data_len));
 186                                 else {
 187                                         EMIT3(0x44, 0x2b, 0x8f);
 188                                         EMIT(offsetof(struct sk_buff, data_len), 4);
 189                                 }
 190
 191                                 if (is_imm8(offsetof(struct sk_buff, data)))
 192                                         /* mov off8(%rdi),%r8 */
 193                                         EMIT4(0x4c, 0x8b, 0x47, offsetof(struct sk_buff, data));
 194                                 else {
 195                                         /* mov off32(%rdi),%r8 */
 196                                         EMIT3(0x4c, 0x8b, 0x87);
 197                                         EMIT(offsetof(struct sk_buff, data), 4);
 198                                 }
 199                         }
 200                 }
 201
 202                 switch (filter[0].code) {
 203                 case BPF_S_RET_K:
 204                 case BPF_S_LD_W_LEN:
 205                 case BPF_S_ANC_PROTOCOL:
 206                 case BPF_S_ANC_IFINDEX:
 207                 case BPF_S_ANC_MARK:
 208                 case BPF_S_ANC_RXHASH:
 209                 case BPF_S_ANC_CPU:
 210                 case BPF_S_ANC_QUEUE:
 211                 case BPF_S_LD_W_ABS:
 212                 case BPF_S_LD_H_ABS:
 213                 case BPF_S_LD_B_ABS:
 214                         /* first instruction sets A register (or is RET 'constant') */
 215                         break;
 216                 default:
 217                         /* make sure we dont leak kernel information to user */
 218                         CLEAR_A(); /* A = 0 */
 219                 }
 220
 221                 for (i = 0; i < flen; i++) {
 222                         unsigned int K = filter[i].k;
 223
 224                         switch (filter[i].code) {
 225                         case BPF_S_ALU_ADD_X: /* A += X; */
 226                                 seen |= SEEN_XREG;
 227                                 EMIT2(0x01, 0xd8);              /* add %ebx,%eax */
 228                                 break;
 229                         case BPF_S_ALU_ADD_K: /* A += K; */
 230                                 if (!K)
 231                                         break;
 232                                 if (is_imm8(K))
 233                                         EMIT3(0x83, 0xc0, K);   /* add imm8,%eax */
 234                                 else
 235                                         EMIT1_off32(0x05, K);   /* add imm32,%eax */
 236                                 break;
 237                         case BPF_S_ALU_SUB_X: /* A -= X; */
 238                                 seen |= SEEN_XREG;
 239                                 EMIT2(0x29, 0xd8);              /* sub    %ebx,%eax */
 240                                 break;
 241                         case BPF_S_ALU_SUB_K: /* A -= K */
 242                                 if (!K)
 243                                         break;
 244                                 if (is_imm8(K))
 245                                         EMIT3(0x83, 0xe8, K); /* sub imm8,%eax */
 246                                 else
 247                                         EMIT1_off32(0x2d, K); /* sub imm32,%eax */
 248                                 break;
 249                         case BPF_S_ALU_MUL_X: /* A *= X; */
 250                                 seen |= SEEN_XREG;
 251                                 EMIT3(0x0f, 0xaf, 0xc3);        /* imul %ebx,%eax */
 252                                 break;
 253                         case BPF_S_ALU_MUL_K: /* A *= K */
 254                                 if (is_imm8(K))
 255                                         EMIT3(0x6b, 0xc0, K); /* imul imm8,%eax,%eax */
 256                                 else {
 257                                         EMIT2(0x69, 0xc0);              /* imul imm32,%eax */
 258                                         EMIT(K, 4);
 259                                 }
 260                                 break;
 261                         case BPF_S_ALU_DIV_X: /* A /= X; */
 262                                 seen |= SEEN_XREG;
 263                                 EMIT2(0x85, 0xdb);      /* test %ebx,%ebx */
 264                                 if (pc_ret0 > 0) {
 265                                         /* addrs[pc_ret0 - 1] is start address of target
 266                                          * (addrs[i] - 4) is the address following this jmp
 267                                          * ("xor %edx,%edx; div %ebx" being 4 bytes long)
 268                                          */
 269                                         EMIT_COND_JMP(X86_JE, addrs[pc_ret0 - 1] -
 270                                                                 (addrs[i] - 4));
 271                                 } else {
 272                                         EMIT_COND_JMP(X86_JNE, 2 + 5);
 273                                         CLEAR_A();
 274                                         EMIT1_off32(0xe9, cleanup_addr - (addrs[i] - 4)); /* jmp .+off32 */
 275                                 }
 276                                 EMIT4(0x31, 0xd2, 0xf7, 0xf3); /* xor %edx,%edx; div %ebx */
 277                                 break;
 278                         case BPF_S_ALU_DIV_K: /* A = reciprocal_divide(A, K); */
 279                                 EMIT3(0x48, 0x69, 0xc0); /* imul imm32,%rax,%rax */
 280                                 EMIT(K, 4);
 281                                 EMIT4(0x48, 0xc1, 0xe8, 0x20); /* shr $0x20,%rax */
 282                                 break;
 283                         case BPF_S_ALU_AND_X:
 284                                 seen |= SEEN_XREG;
 285                                 EMIT2(0x21, 0xd8);              /* and %ebx,%eax */
 286                                 break;
 287                         case BPF_S_ALU_AND_K:
 288                                 if (K >= 0xFFFFFF00) {
 289                                         EMIT2(0x24, K & 0xFF); /* and imm8,%al */
 290                                 } else if (K >= 0xFFFF0000) {
 291                                         EMIT2(0x66, 0x25);      /* and imm16,%ax */
 292                                         EMIT(K, 2);
 293                                 } else {
 294                                         EMIT1_off32(0x25, K);   /* and imm32,%eax */
 295                                 }
 296                                 break;
 297                         case BPF_S_ALU_OR_X:
 298                                 seen |= SEEN_XREG;
 299                                 EMIT2(0x09, 0xd8);              /* or %ebx,%eax */
 300                                 break;
 301                         case BPF_S_ALU_OR_K:
 302                                 if (is_imm8(K))
 303                                         EMIT3(0x83, 0xc8, K); /* or imm8,%eax */
 304                                 else
 305                                         EMIT1_off32(0x0d, K);   /* or imm32,%eax */
 306                                 break;
 307                         case BPF_S_ALU_LSH_X: /* A <<= X; */
 308                                 seen |= SEEN_XREG;
 309                                 EMIT4(0x89, 0xd9, 0xd3, 0xe0);  /* mov %ebx,%ecx; shl %cl,%eax */
 310                                 break;
 311                         case BPF_S_ALU_LSH_K:
 312                                 if (K == 0)
 313                                         break;
 314                                 else if (K == 1)
 315                                         EMIT2(0xd1, 0xe0); /* shl %eax */
 316                                 else
 317                                         EMIT3(0xc1, 0xe0, K);
 318                                 break;
 319                         case BPF_S_ALU_RSH_X: /* A >>= X; */
 320                                 seen |= SEEN_XREG;
 321                                 EMIT4(0x89, 0xd9, 0xd3, 0xe8);  /* mov %ebx,%ecx; shr %cl,%eax */
 322                                 break;
 323                         case BPF_S_ALU_RSH_K: /* A >>= K; */
 324                                 if (K == 0)
 325                                         break;
 326                                 else if (K == 1)
 327                                         EMIT2(0xd1, 0xe8); /* shr %eax */
 328                                 else
 329                                         EMIT3(0xc1, 0xe8, K);
 330                                 break;
 331                         case BPF_S_ALU_NEG:
 332                                 EMIT2(0xf7, 0xd8);              /* neg %eax */
 333                                 break;
 334                         case BPF_S_RET_K:
 335                                 if (!K) {
 336                                         if (pc_ret0 == -1)
 337                                                 pc_ret0 = i;
 338                                         CLEAR_A();
 339                                 } else {
 340                                         EMIT1_off32(0xb8, K);   /* mov $imm32,%eax */
 341                                 }
 342                                 /* fallinto */
 343                         case BPF_S_RET_A:
 344                                 if (seen_or_pass0) {
 345                                         if (i != flen - 1) {
 346                                                 EMIT_JMP(cleanup_addr - addrs[i]);
 347                                                 break;
 348                                         }
 349                                         if (seen_or_pass0 & SEEN_XREG)
 350                                                 EMIT4(0x48, 0x8b, 0x5d, 0xf8);  /* mov  -8(%rbp),%rbx */
 351                                         EMIT1(0xc9);            /* leaveq */
 352                                 }
 353                                 EMIT1(0xc3);            /* ret */
 354                                 break;
 355                         case BPF_S_MISC_TAX: /* X = A */
 356                                 seen |= SEEN_XREG;
 357                                 EMIT2(0x89, 0xc3);      /* mov    %eax,%ebx */
 358                                 break;
 359                         case BPF_S_MISC_TXA: /* A = X */
 360                                 seen |= SEEN_XREG;
 361                                 EMIT2(0x89, 0xd8);      /* mov    %ebx,%eax */
 362                                 break;
 363                         case BPF_S_LD_IMM: /* A = K */
 364                                 if (!K)
 365                                         CLEAR_A();
 366                                 else
 367                                         EMIT1_off32(0xb8, K); /* mov $imm32,%eax */
 368                                 break;
 369                         case BPF_S_LDX_IMM: /* X = K */
 370                                 seen |= SEEN_XREG;
 371                                 if (!K)
 372                                         CLEAR_X();
 373                                 else
 374                                         EMIT1_off32(0xbb, K); /* mov $imm32,%ebx */
 375                                 break;
 376                         case BPF_S_LD_MEM: /* A = mem[K] : mov off8(%rbp),%eax */
 377                                 seen |= SEEN_MEM;
 378                                 EMIT3(0x8b, 0x45, 0xf0 - K*4);
 379                                 break;
 380                         case BPF_S_LDX_MEM: /* X = mem[K] : mov off8(%rbp),%ebx */
 381                                 seen |= SEEN_XREG | SEEN_MEM;
 382                                 EMIT3(0x8b, 0x5d, 0xf0 - K*4);
 383                                 break;
 384                         case BPF_S_ST: /* mem[K] = A : mov %eax,off8(%rbp) */
 385                                 seen |= SEEN_MEM;
 386                                 EMIT3(0x89, 0x45, 0xf0 - K*4);
 387                                 break;
 388                         case BPF_S_STX: /* mem[K] = X : mov %ebx,off8(%rbp) */
 389                                 seen |= SEEN_XREG | SEEN_MEM;
 390                                 EMIT3(0x89, 0x5d, 0xf0 - K*4);
 391                                 break;
 392                         case BPF_S_LD_W_LEN: /* A = skb->len; */
 393                                 BUILD_BUG_ON(FIELD_SIZEOF(struct sk_buff, len) != 4);
 394                                 if (is_imm8(offsetof(struct sk_buff, len)))
 395                                         /* mov    off8(%rdi),%eax */
 396                                         EMIT3(0x8b, 0x47, offsetof(struct sk_buff, len));
 397                                 else {
 398                                         EMIT2(0x8b, 0x87);
 399                                         EMIT(offsetof(struct sk_buff, len), 4);
 400                                 }
 401                                 break;
 402                         case BPF_S_LDX_W_LEN: /* X = skb->len; */
 403                                 seen |= SEEN_XREG;
 404                                 if (is_imm8(offsetof(struct sk_buff, len)))
 405                                         /* mov off8(%rdi),%ebx */
 406                                         EMIT3(0x8b, 0x5f, offsetof(struct sk_buff, len));
 407                                 else {
 408                                         EMIT2(0x8b, 0x9f);
 409                                         EMIT(offsetof(struct sk_buff, len), 4);
 410                                 }
 411                                 break;
 412                         case BPF_S_ANC_PROTOCOL: /* A = ntohs(skb->protocol); */
 413                                 BUILD_BUG_ON(FIELD_SIZEOF(struct sk_buff, protocol) != 2);
 414                                 if (is_imm8(offsetof(struct sk_buff, protocol))) {
 415                                         /* movzwl off8(%rdi),%eax */
 416                                         EMIT4(0x0f, 0xb7, 0x47, offsetof(struct sk_buff, protocol));
 417                                 } else {
 418                                         EMIT3(0x0f, 0xb7, 0x87); /* movzwl off32(%rdi),%eax */
 419                                         EMIT(offsetof(struct sk_buff, protocol), 4);
 420                                 }
 421                                 EMIT2(0x86, 0xc4); /* ntohs() : xchg   %al,%ah */
 422                                 break;
 423                         case BPF_S_ANC_IFINDEX:
 424                                 if (is_imm8(offsetof(struct sk_buff, dev))) {
 425                                         /* movq off8(%rdi),%rax */
 426                                         EMIT4(0x48, 0x8b, 0x47, offsetof(struct sk_buff, dev));
 427                                 } else {
 428                                         EMIT3(0x48, 0x8b, 0x87); /* movq off32(%rdi),%rax */
 429                                         EMIT(offsetof(struct sk_buff, dev), 4);
 430                                 }
 431                                 EMIT3(0x48, 0x85, 0xc0);        /* test %rax,%rax */
 432                                 EMIT_COND_JMP(X86_JE, cleanup_addr - (addrs[i] - 6));
 433                                 BUILD_BUG_ON(FIELD_SIZEOF(struct net_device, ifindex) != 4);
 434                                 EMIT2(0x8b, 0x80);      /* mov off32(%rax),%eax */
 435                                 EMIT(offsetof(struct net_device, ifindex), 4);
 436                                 break;
 437                         case BPF_S_ANC_MARK:
 438                                 BUILD_BUG_ON(FIELD_SIZEOF(struct sk_buff, mark) != 4);
 439                                 if (is_imm8(offsetof(struct sk_buff, mark))) {
 440                                         /* mov off8(%rdi),%eax */
 441                                         EMIT3(0x8b, 0x47, offsetof(struct sk_buff, mark));
 442                                 } else {
 443                                         EMIT2(0x8b, 0x87);
 444                                         EMIT(offsetof(struct sk_buff, mark), 4);
 445                                 }
 446                                 break;
 447                         case BPF_S_ANC_RXHASH:
 448                                 BUILD_BUG_ON(FIELD_SIZEOF(struct sk_buff, rxhash) != 4);
 449                                 if (is_imm8(offsetof(struct sk_buff, rxhash))) {
 450                                         /* mov off8(%rdi),%eax */
 451                                         EMIT3(0x8b, 0x47, offsetof(struct sk_buff, rxhash));
 452                                 } else {
 453                                         EMIT2(0x8b, 0x87);
 454                                         EMIT(offsetof(struct sk_buff, rxhash), 4);
 455                                 }
 456                                 break;
 457                         case BPF_S_ANC_QUEUE:
 458                                 BUILD_BUG_ON(FIELD_SIZEOF(struct sk_buff, queue_mapping) != 2);
 459                                 if (is_imm8(offsetof(struct sk_buff, queue_mapping))) {
 460                                         /* movzwl off8(%rdi),%eax */
 461                                         EMIT4(0x0f, 0xb7, 0x47, offsetof(struct sk_buff, queue_mapping));
 462                                 } else {
 463                                         EMIT3(0x0f, 0xb7, 0x87); /* movzwl off32(%rdi),%eax */
 464                                         EMIT(offsetof(struct sk_buff, queue_mapping), 4);
 465                                 }
 466                                 break;
 467                         case BPF_S_ANC_CPU:
 468 #ifdef CONFIG_SMP
 469                                 EMIT4(0x65, 0x8b, 0x04, 0x25); /* mov %gs:off32,%eax */
 470                                 EMIT((u32)(unsigned long)&cpu_number, 4); /* A = smp_processor_id(); */
 471 #else
 472                                 CLEAR_A();
 473 #endif
 474                                 break;
 475                         case BPF_S_LD_W_ABS:
 476                                 func = sk_load_word;
 477 common_load:                    seen |= SEEN_DATAREF;
 478                                 if ((int)K < 0) {
 479                                         /* Abort the JIT because __load_pointer() is needed. */
 480                                         goto out;
 481                                 }
 482                                 t_offset = func - (image + addrs[i]);
 483                                 EMIT1_off32(0xbe, K); /* mov imm32,%esi */
 484                                 EMIT1_off32(0xe8, t_offset); /* call */
 485                                 break;
 486                         case BPF_S_LD_H_ABS:
 487                                 func = sk_load_half;
 488                                 goto common_load;
 489                         case BPF_S_LD_B_ABS:
 490                                 func = sk_load_byte;
 491                                 goto common_load;
 492                         case BPF_S_LDX_B_MSH:
 493                                 if ((int)K < 0) {
 494                                         /* Abort the JIT because __load_pointer() is needed. */
 495                                         goto out;
 496                                 }
 497                                 seen |= SEEN_DATAREF | SEEN_XREG;
 498                                 t_offset = sk_load_byte_msh - (image + addrs[i]);
 499                                 EMIT1_off32(0xbe, K);   /* mov imm32,%esi */
 500                                 EMIT1_off32(0xe8, t_offset); /* call sk_load_byte_msh */
 501                                 break;
 502                         case BPF_S_LD_W_IND:
 503                                 func = sk_load_word_ind;
 504 common_load_ind:                seen |= SEEN_DATAREF | SEEN_XREG;
 505                                 t_offset = func - (image + addrs[i]);
 506                                 EMIT1_off32(0xbe, K);   /* mov imm32,%esi   */
 507                                 EMIT1_off32(0xe8, t_offset);    /* call sk_load_xxx_ind */
 508                                 break;
 509                         case BPF_S_LD_H_IND:
 510                                 func = sk_load_half_ind;
 511                                 goto common_load_ind;
 512                         case BPF_S_LD_B_IND:
 513                                 func = sk_load_byte_ind;
 514                                 goto common_load_ind;
 515                         case BPF_S_JMP_JA:
 516                                 t_offset = addrs[i + K] - addrs[i];
 517                                 EMIT_JMP(t_offset);
 518                                 break;
 519                         COND_SEL(BPF_S_JMP_JGT_K, X86_JA, X86_JBE);
 520                         COND_SEL(BPF_S_JMP_JGE_K, X86_JAE, X86_JB);
 521                         COND_SEL(BPF_S_JMP_JEQ_K, X86_JE, X86_JNE);
 522                         COND_SEL(BPF_S_JMP_JSET_K,X86_JNE, X86_JE);
 523                         COND_SEL(BPF_S_JMP_JGT_X, X86_JA, X86_JBE);
 524                         COND_SEL(BPF_S_JMP_JGE_X, X86_JAE, X86_JB);
 525                         COND_SEL(BPF_S_JMP_JEQ_X, X86_JE, X86_JNE);
 526                         COND_SEL(BPF_S_JMP_JSET_X,X86_JNE, X86_JE);
 527
 528 cond_branch:                    f_offset = addrs[i + filter[i].jf] - addrs[i];
 529                                 t_offset = addrs[i + filter[i].jt] - addrs[i];
 530
 531                                 /* same targets, can avoid doing the test :) */
 532                                 if (filter[i].jt == filter[i].jf) {
 533                                         EMIT_JMP(t_offset);
 534                                         break;
 535                                 }
 536
 537                                 switch (filter[i].code) {
 538                                 case BPF_S_JMP_JGT_X:
 539                                 case BPF_S_JMP_JGE_X:
 540                                 case BPF_S_JMP_JEQ_X:
 541                                         seen |= SEEN_XREG;
 542                                         EMIT2(0x39, 0xd8); /* cmp %ebx,%eax */
 543                                         break;
 544                                 case BPF_S_JMP_JSET_X:
 545                                         seen |= SEEN_XREG;
 546                                         EMIT2(0x85, 0xd8); /* test %ebx,%eax */
 547                                         break;
 548                                 case BPF_S_JMP_JEQ_K:
 549                                         if (K == 0) {
 550                                                 EMIT2(0x85, 0xc0); /* test   %eax,%eax */
 551                                                 break;
 552                                         }
 553                                 case BPF_S_JMP_JGT_K:
 554                                 case BPF_S_JMP_JGE_K:
 555                                         if (K <= 127)
 556                                                 EMIT3(0x83, 0xf8, K); /* cmp imm8,%eax */
 557                                         else
 558                                                 EMIT1_off32(0x3d, K); /* cmp imm32,%eax */
 559                                         break;
 560                                 case BPF_S_JMP_JSET_K:
 561                                         if (K <= 0xFF)
 562                                                 EMIT2(0xa8, K); /* test imm8,%al */
 563                                         else if (!(K & 0xFFFF00FF))
 564                                                 EMIT3(0xf6, 0xc4, K >> 8); /* test imm8,%ah */
 565                                         else if (K <= 0xFFFF) {
 566                                                 EMIT2(0x66, 0xa9); /* test imm16,%ax */
 567                                                 EMIT(K, 2);
 568                                         } else {
 569                                                 EMIT1_off32(0xa9, K); /* test imm32,%eax */
 570                                         }
 571                                         break;
 572                                 }
 573                                 if (filter[i].jt != 0) {
 574                                         if (filter[i].jf && f_offset)
 575                                                 t_offset += is_near(f_offset) ? 2 : 5;
 576                                         EMIT_COND_JMP(t_op, t_offset);
 577                                         if (filter[i].jf)
 578                                                 EMIT_JMP(f_offset);
 579                                         break;
 580                                 }
 581                                 EMIT_COND_JMP(f_op, f_offset);
 582                                 break;
 583                         default:
 584                                 /* hmm, too complex filter, give up with jit compiler */
 585                                 goto out;
 586                         }
 587                         ilen = prog - temp;
 588                         if (image) {
 589                                 if (unlikely(proglen + ilen > oldproglen)) {
 590                                         pr_err("bpb_jit_compile fatal error\n");
 591                                         kfree(addrs);
 592                                         module_free(NULL, image);
 593                                         return;
 594                                 }
 595                                 memcpy(image + proglen, temp, ilen);
 596                         }
 597                         proglen += ilen;
 598                         addrs[i] = proglen;
 599                         prog = temp;
 600                 }
 601                 /* last bpf instruction is always a RET :
 602                  * use it to give the cleanup instruction(s) addr
 603                  */
 604                 cleanup_addr = proglen - 1; /* ret */
 605                 if (seen_or_pass0)
 606                         cleanup_addr -= 1; /* leaveq */
 607                 if (seen_or_pass0 & SEEN_XREG)
 608                         cleanup_addr -= 4; /* mov  -8(%rbp),%rbx */
 609
 610                 if (image) {
 611                         if (proglen != oldproglen)
 612                                 pr_err("bpb_jit_compile proglen=%u != oldproglen=%u\n", proglen, oldproglen);
 613                         break;
 614                 }
 615                 if (proglen == oldproglen) {
 616                         image = module_alloc(max_t(unsigned int,
 617                                                    proglen,
 618                                                    sizeof(struct work_struct)));
 619                         if (!image)
 620                                 goto out;
 621                 }
 622                 oldproglen = proglen;
 623         }
 624         if (bpf_jit_enable > 1)
 625                 pr_err("flen=%d proglen=%u pass=%d image=%p\n",
 626                        flen, proglen, pass, image);
 627
 628         if (image) {
 629                 if (bpf_jit_enable > 1)
 630                         print_hex_dump(KERN_ERR, "JIT code: ", DUMP_PREFIX_ADDRESS,
 631                                        16, 1, image, proglen, false);
 632
 633                 bpf_flush_icache(image, image + proglen);
 634
 635                 fp->bpf_func = (void *)image;
 636         }
 637 out:
 638         kfree(addrs);
 639         return;
 640 }
 641
 642 static void jit_free_defer(struct work_struct *arg)
 643 {
 644         module_free(NULL, arg);
 645 }
 646
 647 /* run from softirq, we must use a work_struct to call
 648  * module_free() from process context
 649  */
 650 void bpf_jit_free(struct sk_filter *fp)
 651 {
 652         if (fp->bpf_func != sk_run_filter) {
 653                 struct work_struct *work = (struct work_struct *)fp->bpf_func;
 654
 655                 INIT_WORK(work, jit_free_defer);
 656                 schedule_work(work);
 657         }
 658 }