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_positive_offset[], sk_load_half_positive_offset[];
  34 extern u8 sk_load_byte_positive_offset[], sk_load_byte_msh_positive_offset[];
  35 extern u8 sk_load_word_negative_offset[], sk_load_half_negative_offset[];
  36 extern u8 sk_load_byte_negative_offset[], sk_load_byte_msh_negative_offset[];
  37
  38 static inline u8 *emit_code(u8 *ptr, u32 bytes, unsigned int len)
  39 {
  40         if (len == 1)
  41                 *ptr = bytes;
  42         else if (len == 2)
  43                 *(u16 *)ptr = bytes;
  44         else {
  45                 *(u32 *)ptr = bytes;
  46                 barrier();
  47         }
  48         return ptr + len;
  49 }
  50
  51 #define EMIT(bytes, len)        do { prog = emit_code(prog, bytes, len); } while (0)
  52
  53 #define EMIT1(b1)               EMIT(b1, 1)
  54 #define EMIT2(b1, b2)           EMIT((b1) + ((b2) << 8), 2)
  55 #define EMIT3(b1, b2, b3)       EMIT((b1) + ((b2) << 8) + ((b3) << 16), 3)
  56 #define EMIT4(b1, b2, b3, b4)   EMIT((b1) + ((b2) << 8) + ((b3) << 16) + ((b4) << 24), 4)
  57 #define EMIT1_off32(b1, off)    do { EMIT1(b1); EMIT(off, 4);} while (0)
  58
  59 #define CLEAR_A() EMIT2(0x31, 0xc0) /* xor %eax,%eax */
  60 #define CLEAR_X() EMIT2(0x31, 0xdb) /* xor %ebx,%ebx */
  61
  62 static inline bool is_imm8(int value)
  63 {
  64         return value <= 127 && value >= -128;
  65 }
  66
  67 static inline bool is_near(int offset)
  68 {
  69         return offset <= 127 && offset >= -128;
  70 }
  71
  72 #define EMIT_JMP(offset)                                                \
  73 do {                                                                    \
  74         if (offset) {                                                   \
  75                 if (is_near(offset))                                    \
  76                         EMIT2(0xeb, offset); /* jmp .+off8 */           \
  77                 else                                                    \
  78                         EMIT1_off32(0xe9, offset); /* jmp .+off32 */    \
  79         }                                                               \
  80 } while (0)
  81
  82 /* list of x86 cond jumps opcodes (. + s8)
  83  * Add 0x10 (and an extra 0x0f) to generate far jumps (. + s32)
  84  */
  85 #define X86_JB  0x72
  86 #define X86_JAE 0x73
  87 #define X86_JE  0x74
  88 #define X86_JNE 0x75
  89 #define X86_JBE 0x76
  90 #define X86_JA  0x77
  91
  92 #define EMIT_COND_JMP(op, offset)                               \
  93 do {                                                            \
  94         if (is_near(offset))                                    \
  95                 EMIT2(op, offset); /* jxx .+off8 */             \
  96         else {                                                  \
  97                 EMIT2(0x0f, op + 0x10);                         \
  98                 EMIT(offset, 4); /* jxx .+off32 */              \
  99         }                                                       \
 100 } while (0)
 101
 102 #define COND_SEL(CODE, TOP, FOP)        \
 103         case CODE:                      \
 104                 t_op = TOP;             \
 105                 f_op = FOP;             \
 106                 goto cond_branch
 107
 108
 109 #define SEEN_DATAREF 1 /* might call external helpers */
 110 #define SEEN_XREG    2 /* ebx is used */
 111 #define SEEN_MEM     4 /* use mem[] for temporary storage */
 112
 113 static inline void bpf_flush_icache(void *start, void *end)
 114 {
 115         mm_segment_t old_fs = get_fs();
 116
 117         set_fs(KERNEL_DS);
 118         smp_wmb();
 119         flush_icache_range((unsigned long)start, (unsigned long)end);
 120         set_fs(old_fs);
 121 }
 122
 123 #define CHOOSE_LOAD_FUNC(K, func) \
 124         ((int)K < 0 ? ((int)K >= SKF_LL_OFF ? func##_negative_offset : func) : func##_positive_offset)
 125
 126 void bpf_jit_compile(struct sk_filter *fp)
 127 {
 128         u8 temp[64];
 129         u8 *prog;
 130         unsigned int proglen, oldproglen = 0;
 131         int ilen, i;
 132         int t_offset, f_offset;
 133         u8 t_op, f_op, seen = 0, pass;
 134         u8 *image = NULL;
 135         u8 *func;
 136         int pc_ret0 = -1; /* bpf index of first RET #0 instruction (if any) */
 137         unsigned int cleanup_addr; /* epilogue code offset */
 138         unsigned int *addrs;
 139         const struct sock_filter *filter = fp->insns;
 140         int flen = fp->len;
 141
 142         if (!bpf_jit_enable)
 143                 return;
 144
 145         addrs = kmalloc(flen * sizeof(*addrs), GFP_KERNEL);
 146         if (addrs == NULL)
 147                 return;
 148
 149         /* Before first pass, make a rough estimation of addrs[]
 150          * each bpf instruction is translated to less than 64 bytes
 151          */
 152         for (proglen = 0, i = 0; i < flen; i++) {
 153                 proglen += 64;
 154                 addrs[i] = proglen;
 155         }
 156         cleanup_addr = proglen; /* epilogue address */
 157
 158         for (pass = 0; pass < 10; pass++) {
 159                 u8 seen_or_pass0 = (pass == 0) ? (SEEN_XREG | SEEN_DATAREF | SEEN_MEM) : seen;
 160                 /* no prologue/epilogue for trivial filters (RET something) */
 161                 proglen = 0;
 162                 prog = temp;
 163
 164                 if (seen_or_pass0) {
 165                         EMIT4(0x55, 0x48, 0x89, 0xe5); /* push %rbp; mov %rsp,%rbp */
 166                         EMIT4(0x48, 0x83, 0xec, 96);    /* subq  $96,%rsp       */
 167                         /* note : must save %rbx in case bpf_error is hit */
 168                         if (seen_or_pass0 & (SEEN_XREG | SEEN_DATAREF))
 169                                 EMIT4(0x48, 0x89, 0x5d, 0xf8); /* mov %rbx, -8(%rbp) */
 170                         if (seen_or_pass0 & SEEN_XREG)
 171                                 CLEAR_X(); /* make sure we dont leek kernel memory */
 172
 173                         /*
 174                          * If this filter needs to access skb data,
 175                          * loads r9 and r8 with :
 176                          *  r9 = skb->len - skb->data_len
 177                          *  r8 = skb->data
 178                          */
 179                         if (seen_or_pass0 & SEEN_DATAREF) {
 180                                 if (offsetof(struct sk_buff, len) <= 127)
 181                                         /* mov    off8(%rdi),%r9d */
 182                                         EMIT4(0x44, 0x8b, 0x4f, offsetof(struct sk_buff, len));
 183                                 else {
 184                                         /* mov    off32(%rdi),%r9d */
 185                                         EMIT3(0x44, 0x8b, 0x8f);
 186                                         EMIT(offsetof(struct sk_buff, len), 4);
 187                                 }
 188                                 if (is_imm8(offsetof(struct sk_buff, data_len)))
 189                                         /* sub    off8(%rdi),%r9d */
 190                                         EMIT4(0x44, 0x2b, 0x4f, offsetof(struct sk_buff, data_len));
 191                                 else {
 192                                         EMIT3(0x44, 0x2b, 0x8f);
 193                                         EMIT(offsetof(struct sk_buff, data_len), 4);
 194                                 }
 195
 196                                 if (is_imm8(offsetof(struct sk_buff, data)))
 197                                         /* mov off8(%rdi),%r8 */
 198                                         EMIT4(0x4c, 0x8b, 0x47, offsetof(struct sk_buff, data));
 199                                 else {
 200                                         /* mov off32(%rdi),%r8 */
 201                                         EMIT3(0x4c, 0x8b, 0x87);
 202                                         EMIT(offsetof(struct sk_buff, data), 4);
 203                                 }
 204                         }
 205                 }
 206
 207                 switch (filter[0].code) {
 208                 case BPF_S_RET_K:
 209                 case BPF_S_LD_W_LEN:
 210                 case BPF_S_ANC_PROTOCOL:
 211                 case BPF_S_ANC_IFINDEX:
 212                 case BPF_S_ANC_MARK:
 213                 case BPF_S_ANC_RXHASH:
 214                 case BPF_S_ANC_CPU:
 215                 case BPF_S_ANC_QUEUE:
 216                 case BPF_S_LD_W_ABS:
 217                 case BPF_S_LD_H_ABS:
 218                 case BPF_S_LD_B_ABS:
 219                         /* first instruction sets A register (or is RET 'constant') */
 220                         break;
 221                 default:
 222                         /* make sure we dont leak kernel information to user */
 223                         CLEAR_A(); /* A = 0 */
 224                 }
 225
 226                 for (i = 0; i < flen; i++) {
 227                         unsigned int K = filter[i].k;
 228
 229                         switch (filter[i].code) {
 230                         case BPF_S_ALU_ADD_X: /* A += X; */
 231                                 seen |= SEEN_XREG;
 232                                 EMIT2(0x01, 0xd8);              /* add %ebx,%eax */
 233                                 break;
 234                         case BPF_S_ALU_ADD_K: /* A += K; */
 235                                 if (!K)
 236                                         break;
 237                                 if (is_imm8(K))
 238                                         EMIT3(0x83, 0xc0, K);   /* add imm8,%eax */
 239                                 else
 240                                         EMIT1_off32(0x05, K);   /* add imm32,%eax */
 241                                 break;
 242                         case BPF_S_ALU_SUB_X: /* A -= X; */
 243                                 seen |= SEEN_XREG;
 244                                 EMIT2(0x29, 0xd8);              /* sub    %ebx,%eax */
 245                                 break;
 246                         case BPF_S_ALU_SUB_K: /* A -= K */
 247                                 if (!K)
 248                                         break;
 249                                 if (is_imm8(K))
 250                                         EMIT3(0x83, 0xe8, K); /* sub imm8,%eax */
 251                                 else
 252                                         EMIT1_off32(0x2d, K); /* sub imm32,%eax */
 253                                 break;
 254                         case BPF_S_ALU_MUL_X: /* A *= X; */
 255                                 seen |= SEEN_XREG;
 256                                 EMIT3(0x0f, 0xaf, 0xc3);        /* imul %ebx,%eax */
 257                                 break;
 258                         case BPF_S_ALU_MUL_K: /* A *= K */
 259                                 if (is_imm8(K))
 260                                         EMIT3(0x6b, 0xc0, K); /* imul imm8,%eax,%eax */
 261                                 else {
 262                                         EMIT2(0x69, 0xc0);              /* imul imm32,%eax */
 263                                         EMIT(K, 4);
 264                                 }
 265                                 break;
 266                         case BPF_S_ALU_DIV_X: /* A /= X; */
 267                                 seen |= SEEN_XREG;
 268                                 EMIT2(0x85, 0xdb);      /* test %ebx,%ebx */
 269                                 if (pc_ret0 > 0) {
 270                                         /* addrs[pc_ret0 - 1] is start address of target
 271                                          * (addrs[i] - 4) is the address following this jmp
 272                                          * ("xor %edx,%edx; div %ebx" being 4 bytes long)
 273                                          */
 274                                         EMIT_COND_JMP(X86_JE, addrs[pc_ret0 - 1] -
 275                                                                 (addrs[i] - 4));
 276                                 } else {
 277                                         EMIT_COND_JMP(X86_JNE, 2 + 5);
 278                                         CLEAR_A();
 279                                         EMIT1_off32(0xe9, cleanup_addr - (addrs[i] - 4)); /* jmp .+off32 */
 280                                 }
 281                                 EMIT4(0x31, 0xd2, 0xf7, 0xf3); /* xor %edx,%edx; div %ebx */
 282                                 break;
 283                         case BPF_S_ALU_DIV_K: /* A = reciprocal_divide(A, K); */
 284                                 EMIT3(0x48, 0x69, 0xc0); /* imul imm32,%rax,%rax */
 285                                 EMIT(K, 4);
 286                                 EMIT4(0x48, 0xc1, 0xe8, 0x20); /* shr $0x20,%rax */
 287                                 break;
 288                         case BPF_S_ALU_AND_X:
 289                                 seen |= SEEN_XREG;
 290                                 EMIT2(0x21, 0xd8);              /* and %ebx,%eax */
 291                                 break;
 292                         case BPF_S_ALU_AND_K:
 293                                 if (K >= 0xFFFFFF00) {
 294                                         EMIT2(0x24, K & 0xFF); /* and imm8,%al */
 295                                 } else if (K >= 0xFFFF0000) {
 296                                         EMIT2(0x66, 0x25);      /* and imm16,%ax */
 297                                         EMIT(K, 2);
 298                                 } else {
 299                                         EMIT1_off32(0x25, K);   /* and imm32,%eax */
 300                                 }
 301                                 break;
 302                         case BPF_S_ALU_OR_X:
 303                                 seen |= SEEN_XREG;
 304                                 EMIT2(0x09, 0xd8);              /* or %ebx,%eax */
 305                                 break;
 306                         case BPF_S_ALU_OR_K:
 307                                 if (is_imm8(K))
 308                                         EMIT3(0x83, 0xc8, K); /* or imm8,%eax */
 309                                 else
 310                                         EMIT1_off32(0x0d, K);   /* or imm32,%eax */
 311                                 break;
 312                         case BPF_S_ANC_ALU_XOR_X: /* A ^= X; */
 313                                 seen |= SEEN_XREG;
 314                                 EMIT2(0x31, 0xd8);              /* xor %ebx,%eax */
 315                                 break;
 316                         case BPF_S_ALU_LSH_X: /* A <<= X; */
 317                                 seen |= SEEN_XREG;
 318                                 EMIT4(0x89, 0xd9, 0xd3, 0xe0);  /* mov %ebx,%ecx; shl %cl,%eax */
 319                                 break;
 320                         case BPF_S_ALU_LSH_K:
 321                                 if (K == 0)
 322                                         break;
 323                                 else if (K == 1)
 324                                         EMIT2(0xd1, 0xe0); /* shl %eax */
 325                                 else
 326                                         EMIT3(0xc1, 0xe0, K);
 327                                 break;
 328                         case BPF_S_ALU_RSH_X: /* A >>= X; */
 329                                 seen |= SEEN_XREG;
 330                                 EMIT4(0x89, 0xd9, 0xd3, 0xe8);  /* mov %ebx,%ecx; shr %cl,%eax */
 331                                 break;
 332                         case BPF_S_ALU_RSH_K: /* A >>= K; */
 333                                 if (K == 0)
 334                                         break;
 335                                 else if (K == 1)
 336                                         EMIT2(0xd1, 0xe8); /* shr %eax */
 337                                 else
 338                                         EMIT3(0xc1, 0xe8, K);
 339                                 break;
 340                         case BPF_S_ALU_NEG:
 341                                 EMIT2(0xf7, 0xd8);              /* neg %eax */
 342                                 break;
 343                         case BPF_S_RET_K:
 344                                 if (!K) {
 345                                         if (pc_ret0 == -1)
 346                                                 pc_ret0 = i;
 347                                         CLEAR_A();
 348                                 } else {
 349                                         EMIT1_off32(0xb8, K);   /* mov $imm32,%eax */
 350                                 }
 351                                 /* fallinto */
 352                         case BPF_S_RET_A:
 353                                 if (seen_or_pass0) {
 354                                         if (i != flen - 1) {
 355                                                 EMIT_JMP(cleanup_addr - addrs[i]);
 356                                                 break;
 357                                         }
 358                                         if (seen_or_pass0 & SEEN_XREG)
 359                                                 EMIT4(0x48, 0x8b, 0x5d, 0xf8);  /* mov  -8(%rbp),%rbx */
 360                                         EMIT1(0xc9);            /* leaveq */
 361                                 }
 362                                 EMIT1(0xc3);            /* ret */
 363                                 break;
 364                         case BPF_S_MISC_TAX: /* X = A */
 365                                 seen |= SEEN_XREG;
 366                                 EMIT2(0x89, 0xc3);      /* mov    %eax,%ebx */
 367                                 break;
 368                         case BPF_S_MISC_TXA: /* A = X */
 369                                 seen |= SEEN_XREG;
 370                                 EMIT2(0x89, 0xd8);      /* mov    %ebx,%eax */
 371                                 break;
 372                         case BPF_S_LD_IMM: /* A = K */
 373                                 if (!K)
 374                                         CLEAR_A();
 375                                 else
 376                                         EMIT1_off32(0xb8, K); /* mov $imm32,%eax */
 377                                 break;
 378                         case BPF_S_LDX_IMM: /* X = K */
 379                                 seen |= SEEN_XREG;
 380                                 if (!K)
 381                                         CLEAR_X();
 382                                 else
 383                                         EMIT1_off32(0xbb, K); /* mov $imm32,%ebx */
 384                                 break;
 385                         case BPF_S_LD_MEM: /* A = mem[K] : mov off8(%rbp),%eax */
 386                                 seen |= SEEN_MEM;
 387                                 EMIT3(0x8b, 0x45, 0xf0 - K*4);
 388                                 break;
 389                         case BPF_S_LDX_MEM: /* X = mem[K] : mov off8(%rbp),%ebx */
 390                                 seen |= SEEN_XREG | SEEN_MEM;
 391                                 EMIT3(0x8b, 0x5d, 0xf0 - K*4);
 392                                 break;
 393                         case BPF_S_ST: /* mem[K] = A : mov %eax,off8(%rbp) */
 394                                 seen |= SEEN_MEM;
 395                                 EMIT3(0x89, 0x45, 0xf0 - K*4);
 396                                 break;
 397                         case BPF_S_STX: /* mem[K] = X : mov %ebx,off8(%rbp) */
 398                                 seen |= SEEN_XREG | SEEN_MEM;
 399                                 EMIT3(0x89, 0x5d, 0xf0 - K*4);
 400                                 break;
 401                         case BPF_S_LD_W_LEN: /* A = skb->len; */
 402                                 BUILD_BUG_ON(FIELD_SIZEOF(struct sk_buff, len) != 4);
 403                                 if (is_imm8(offsetof(struct sk_buff, len)))
 404                                         /* mov    off8(%rdi),%eax */
 405                                         EMIT3(0x8b, 0x47, offsetof(struct sk_buff, len));
 406                                 else {
 407                                         EMIT2(0x8b, 0x87);
 408                                         EMIT(offsetof(struct sk_buff, len), 4);
 409                                 }
 410                                 break;
 411                         case BPF_S_LDX_W_LEN: /* X = skb->len; */
 412                                 seen |= SEEN_XREG;
 413                                 if (is_imm8(offsetof(struct sk_buff, len)))
 414                                         /* mov off8(%rdi),%ebx */
 415                                         EMIT3(0x8b, 0x5f, offsetof(struct sk_buff, len));
 416                                 else {
 417                                         EMIT2(0x8b, 0x9f);
 418                                         EMIT(offsetof(struct sk_buff, len), 4);
 419                                 }
 420                                 break;
 421                         case BPF_S_ANC_PROTOCOL: /* A = ntohs(skb->protocol); */
 422                                 BUILD_BUG_ON(FIELD_SIZEOF(struct sk_buff, protocol) != 2);
 423                                 if (is_imm8(offsetof(struct sk_buff, protocol))) {
 424                                         /* movzwl off8(%rdi),%eax */
 425                                         EMIT4(0x0f, 0xb7, 0x47, offsetof(struct sk_buff, protocol));
 426                                 } else {
 427                                         EMIT3(0x0f, 0xb7, 0x87); /* movzwl off32(%rdi),%eax */
 428                                         EMIT(offsetof(struct sk_buff, protocol), 4);
 429                                 }
 430                                 EMIT2(0x86, 0xc4); /* ntohs() : xchg   %al,%ah */
 431                                 break;
 432                         case BPF_S_ANC_IFINDEX:
 433                                 if (is_imm8(offsetof(struct sk_buff, dev))) {
 434                                         /* movq off8(%rdi),%rax */
 435                                         EMIT4(0x48, 0x8b, 0x47, offsetof(struct sk_buff, dev));
 436                                 } else {
 437                                         EMIT3(0x48, 0x8b, 0x87); /* movq off32(%rdi),%rax */
 438                                         EMIT(offsetof(struct sk_buff, dev), 4);
 439                                 }
 440                                 EMIT3(0x48, 0x85, 0xc0);        /* test %rax,%rax */
 441                                 EMIT_COND_JMP(X86_JE, cleanup_addr - (addrs[i] - 6));
 442                                 BUILD_BUG_ON(FIELD_SIZEOF(struct net_device, ifindex) != 4);
 443                                 EMIT2(0x8b, 0x80);      /* mov off32(%rax),%eax */
 444                                 EMIT(offsetof(struct net_device, ifindex), 4);
 445                                 break;
 446                         case BPF_S_ANC_MARK:
 447                                 BUILD_BUG_ON(FIELD_SIZEOF(struct sk_buff, mark) != 4);
 448                                 if (is_imm8(offsetof(struct sk_buff, mark))) {
 449                                         /* mov off8(%rdi),%eax */
 450                                         EMIT3(0x8b, 0x47, offsetof(struct sk_buff, mark));
 451                                 } else {
 452                                         EMIT2(0x8b, 0x87);
 453                                         EMIT(offsetof(struct sk_buff, mark), 4);
 454                                 }
 455                                 break;
 456                         case BPF_S_ANC_RXHASH:
 457                                 BUILD_BUG_ON(FIELD_SIZEOF(struct sk_buff, rxhash) != 4);
 458                                 if (is_imm8(offsetof(struct sk_buff, rxhash))) {
 459                                         /* mov off8(%rdi),%eax */
 460                                         EMIT3(0x8b, 0x47, offsetof(struct sk_buff, rxhash));
 461                                 } else {
 462                                         EMIT2(0x8b, 0x87);
 463                                         EMIT(offsetof(struct sk_buff, rxhash), 4);
 464                                 }
 465                                 break;
 466                         case BPF_S_ANC_QUEUE:
 467                                 BUILD_BUG_ON(FIELD_SIZEOF(struct sk_buff, queue_mapping) != 2);
 468                                 if (is_imm8(offsetof(struct sk_buff, queue_mapping))) {
 469                                         /* movzwl off8(%rdi),%eax */
 470                                         EMIT4(0x0f, 0xb7, 0x47, offsetof(struct sk_buff, queue_mapping));
 471                                 } else {
 472                                         EMIT3(0x0f, 0xb7, 0x87); /* movzwl off32(%rdi),%eax */
 473                                         EMIT(offsetof(struct sk_buff, queue_mapping), 4);
 474                                 }
 475                                 break;
 476                         case BPF_S_ANC_CPU:
 477 #ifdef CONFIG_SMP
 478                                 EMIT4(0x65, 0x8b, 0x04, 0x25); /* mov %gs:off32,%eax */
 479                                 EMIT((u32)(unsigned long)&cpu_number, 4); /* A = smp_processor_id(); */
 480 #else
 481                                 CLEAR_A();
 482 #endif
 483                                 break;
 484                         case BPF_S_LD_W_ABS:
 485                                 func = CHOOSE_LOAD_FUNC(K, sk_load_word);
 486 common_load:                    seen |= SEEN_DATAREF;
 487                                 t_offset = func - (image + addrs[i]);
 488                                 EMIT1_off32(0xbe, K); /* mov imm32,%esi */
 489                                 EMIT1_off32(0xe8, t_offset); /* call */
 490                                 break;
 491                         case BPF_S_LD_H_ABS:
 492                                 func = CHOOSE_LOAD_FUNC(K, sk_load_half);
 493                                 goto common_load;
 494                         case BPF_S_LD_B_ABS:
 495                                 func = CHOOSE_LOAD_FUNC(K, sk_load_byte);
 496                                 goto common_load;
 497                         case BPF_S_LDX_B_MSH:
 498                                 func = CHOOSE_LOAD_FUNC(K, sk_load_byte_msh);
 499                                 seen |= SEEN_DATAREF | SEEN_XREG;
 500                                 t_offset = func - (image + addrs[i]);
 501                                 EMIT1_off32(0xbe, K);   /* mov imm32,%esi */
 502                                 EMIT1_off32(0xe8, t_offset); /* call sk_load_byte_msh */
 503                                 break;
 504                         case BPF_S_LD_W_IND:
 505                                 func = sk_load_word;
 506 common_load_ind:                seen |= SEEN_DATAREF | SEEN_XREG;
 507                                 t_offset = func - (image + addrs[i]);
 508                                 if (K) {
 509                                         if (is_imm8(K)) {
 510                                                 EMIT3(0x8d, 0x73, K); /* lea imm8(%rbx), %esi */
 511                                         } else {
 512                                                 EMIT2(0x8d, 0xb3); /* lea imm32(%rbx),%esi */
 513                                                 EMIT(K, 4);
 514                                         }
 515                                 } else {
 516                                         EMIT2(0x89,0xde); /* mov %ebx,%esi */
 517                                 }
 518                                 EMIT1_off32(0xe8, t_offset);    /* call sk_load_xxx_ind */
 519                                 break;
 520                         case BPF_S_LD_H_IND:
 521                                 func = sk_load_half;
 522                                 goto common_load_ind;
 523                         case BPF_S_LD_B_IND:
 524                                 func = sk_load_byte;
 525                                 goto common_load_ind;
 526                         case BPF_S_JMP_JA:
 527                                 t_offset = addrs[i + K] - addrs[i];
 528                                 EMIT_JMP(t_offset);
 529                                 break;
 530                         COND_SEL(BPF_S_JMP_JGT_K, X86_JA, X86_JBE);
 531                         COND_SEL(BPF_S_JMP_JGE_K, X86_JAE, X86_JB);
 532                         COND_SEL(BPF_S_JMP_JEQ_K, X86_JE, X86_JNE);
 533                         COND_SEL(BPF_S_JMP_JSET_K,X86_JNE, X86_JE);
 534                         COND_SEL(BPF_S_JMP_JGT_X, X86_JA, X86_JBE);
 535                         COND_SEL(BPF_S_JMP_JGE_X, X86_JAE, X86_JB);
 536                         COND_SEL(BPF_S_JMP_JEQ_X, X86_JE, X86_JNE);
 537                         COND_SEL(BPF_S_JMP_JSET_X,X86_JNE, X86_JE);
 538
 539 cond_branch:                    f_offset = addrs[i + filter[i].jf] - addrs[i];
 540                                 t_offset = addrs[i + filter[i].jt] - addrs[i];
 541
 542                                 /* same targets, can avoid doing the test :) */
 543                                 if (filter[i].jt == filter[i].jf) {
 544                                         EMIT_JMP(t_offset);
 545                                         break;
 546                                 }
 547
 548                                 switch (filter[i].code) {
 549                                 case BPF_S_JMP_JGT_X:
 550                                 case BPF_S_JMP_JGE_X:
 551                                 case BPF_S_JMP_JEQ_X:
 552                                         seen |= SEEN_XREG;
 553                                         EMIT2(0x39, 0xd8); /* cmp %ebx,%eax */
 554                                         break;
 555                                 case BPF_S_JMP_JSET_X:
 556                                         seen |= SEEN_XREG;
 557                                         EMIT2(0x85, 0xd8); /* test %ebx,%eax */
 558                                         break;
 559                                 case BPF_S_JMP_JEQ_K:
 560                                         if (K == 0) {
 561                                                 EMIT2(0x85, 0xc0); /* test   %eax,%eax */
 562                                                 break;
 563                                         }
 564                                 case BPF_S_JMP_JGT_K:
 565                                 case BPF_S_JMP_JGE_K:
 566                                         if (K <= 127)
 567                                                 EMIT3(0x83, 0xf8, K); /* cmp imm8,%eax */
 568                                         else
 569                                                 EMIT1_off32(0x3d, K); /* cmp imm32,%eax */
 570                                         break;
 571                                 case BPF_S_JMP_JSET_K:
 572                                         if (K <= 0xFF)
 573                                                 EMIT2(0xa8, K); /* test imm8,%al */
 574                                         else if (!(K & 0xFFFF00FF))
 575                                                 EMIT3(0xf6, 0xc4, K >> 8); /* test imm8,%ah */
 576                                         else if (K <= 0xFFFF) {
 577                                                 EMIT2(0x66, 0xa9); /* test imm16,%ax */
 578                                                 EMIT(K, 2);
 579                                         } else {
 580                                                 EMIT1_off32(0xa9, K); /* test imm32,%eax */
 581                                         }
 582                                         break;
 583                                 }
 584                                 if (filter[i].jt != 0) {
 585                                         if (filter[i].jf && f_offset)
 586                                                 t_offset += is_near(f_offset) ? 2 : 5;
 587                                         EMIT_COND_JMP(t_op, t_offset);
 588                                         if (filter[i].jf)
 589                                                 EMIT_JMP(f_offset);
 590                                         break;
 591                                 }
 592                                 EMIT_COND_JMP(f_op, f_offset);
 593                                 break;
 594                         default:
 595                                 /* hmm, too complex filter, give up with jit compiler */
 596                                 goto out;
 597                         }
 598                         ilen = prog - temp;
 599                         if (image) {
 600                                 if (unlikely(proglen + ilen > oldproglen)) {
 601                                         pr_err("bpb_jit_compile fatal error\n");
 602                                         kfree(addrs);
 603                                         module_free(NULL, image);
 604                                         return;
 605                                 }
 606                                 memcpy(image + proglen, temp, ilen);
 607                         }
 608                         proglen += ilen;
 609                         addrs[i] = proglen;
 610                         prog = temp;
 611                 }
 612                 /* last bpf instruction is always a RET :
 613                  * use it to give the cleanup instruction(s) addr
 614                  */
 615                 cleanup_addr = proglen - 1; /* ret */
 616                 if (seen_or_pass0)
 617                         cleanup_addr -= 1; /* leaveq */
 618                 if (seen_or_pass0 & SEEN_XREG)
 619                         cleanup_addr -= 4; /* mov  -8(%rbp),%rbx */
 620
 621                 if (image) {
 622                         if (proglen != oldproglen)
 623                                 pr_err("bpb_jit_compile proglen=%u != oldproglen=%u\n", proglen, oldproglen);
 624                         break;
 625                 }
 626                 if (proglen == oldproglen) {
 627                         image = module_alloc(max_t(unsigned int,
 628                                                    proglen,
 629                                                    sizeof(struct work_struct)));
 630                         if (!image)
 631                                 goto out;
 632                 }
 633                 oldproglen = proglen;
 634         }
 635         if (bpf_jit_enable > 1)
 636                 pr_err("flen=%d proglen=%u pass=%d image=%p\n",
 637                        flen, proglen, pass, image);
 638
 639         if (image) {
 640                 if (bpf_jit_enable > 1)
 641                         print_hex_dump(KERN_ERR, "JIT code: ", DUMP_PREFIX_ADDRESS,
 642                                        16, 1, image, proglen, false);
 643
 644                 bpf_flush_icache(image, image + proglen);
 645
 646                 fp->bpf_func = (void *)image;
 647         }
 648 out:
 649         kfree(addrs);
 650         return;
 651 }
 652
 653 static void jit_free_defer(struct work_struct *arg)
 654 {
 655         module_free(NULL, arg);
 656 }
 657
 658 /* run from softirq, we must use a work_struct to call
 659  * module_free() from process context
 660  */
 661 void bpf_jit_free(struct sk_filter *fp)
 662 {
 663         if (fp->bpf_func != sk_run_filter) {
 664                 struct work_struct *work = (struct work_struct *)fp->bpf_func;
 665
 666                 INIT_WORK(work, jit_free_defer);
 667                 schedule_work(work);
 668         }
 669 }