arch/s390/net/bpf_jit_comp.c

   1 /*
   2  * BPF Jit compiler for s390.
   3  *
   4  * Copyright IBM Corp. 2012
   5  *
   6  * Author(s): Martin Schwidefsky <schwidefsky@de.ibm.com>
   7  */
   8 #include <linux/moduleloader.h>
   9 #include <linux/netdevice.h>
  10 #include <linux/filter.h>
  11 #include <asm/cacheflush.h>
  12 #include <asm/processor.h>
  13 #include <asm/facility.h>
  14
  15 /*
  16  * Conventions:
  17  *   %r2 = skb pointer
  18  *   %r3 = offset parameter
  19  *   %r4 = scratch register / length parameter
  20  *   %r5 = BPF A accumulator
  21  *   %r8 = return address
  22  *   %r9 = save register for skb pointer
  23  *   %r10 = skb->data
  24  *   %r11 = skb->len - skb->data_len (headlen)
  25  *   %r12 = BPF X accumulator
  26  *   %r13 = literal pool pointer
  27  *   0(%r15) - 63(%r15) scratch memory array with BPF_MEMWORDS
  28  */
  29 int bpf_jit_enable __read_mostly;
  30
  31 /*
  32  * assembly code in arch/x86/net/bpf_jit.S
  33  */
  34 extern u8 sk_load_word[], sk_load_half[], sk_load_byte[], sk_load_byte_msh[];
  35 extern u8 sk_load_word_ind[], sk_load_half_ind[], sk_load_byte_ind[];
  36
  37 struct bpf_jit {
  38         unsigned int seen;
  39         u8 *start;
  40         u8 *prg;
  41         u8 *mid;
  42         u8 *lit;
  43         u8 *end;
  44         u8 *base_ip;
  45         u8 *ret0_ip;
  46         u8 *exit_ip;
  47         unsigned int off_load_word;
  48         unsigned int off_load_half;
  49         unsigned int off_load_byte;
  50         unsigned int off_load_bmsh;
  51         unsigned int off_load_iword;
  52         unsigned int off_load_ihalf;
  53         unsigned int off_load_ibyte;
  54 };
  55
  56 #define BPF_SIZE_MAX    4096    /* Max size for program */
  57
  58 #define SEEN_DATAREF    1       /* might call external helpers */
  59 #define SEEN_XREG       2       /* ebx is used */
  60 #define SEEN_MEM        4       /* use mem[] for temporary storage */
  61 #define SEEN_RET0       8       /* pc_ret0 points to a valid return 0 */
  62 #define SEEN_LITERAL    16      /* code uses literals */
  63 #define SEEN_LOAD_WORD  32      /* code uses sk_load_word */
  64 #define SEEN_LOAD_HALF  64      /* code uses sk_load_half */
  65 #define SEEN_LOAD_BYTE  128     /* code uses sk_load_byte */
  66 #define SEEN_LOAD_BMSH  256     /* code uses sk_load_byte_msh */
  67 #define SEEN_LOAD_IWORD 512     /* code uses sk_load_word_ind */
  68 #define SEEN_LOAD_IHALF 1024    /* code uses sk_load_half_ind */
  69 #define SEEN_LOAD_IBYTE 2048    /* code uses sk_load_byte_ind */
  70
  71 #define EMIT2(op)                                       \
  72 ({                                                      \
  73         if (jit->prg + 2 <= jit->mid)                   \
  74                 *(u16 *) jit->prg = op;                 \
  75         jit->prg += 2;                                  \
  76 })
  77
  78 #define EMIT4(op)                                       \
  79 ({                                                      \
  80         if (jit->prg + 4 <= jit->mid)                   \
  81                 *(u32 *) jit->prg = op;                 \
  82         jit->prg += 4;                                  \
  83 })
  84
  85 #define EMIT4_DISP(op, disp)                            \
  86 ({                                                      \
  87         unsigned int __disp = (disp) & 0xfff;           \
  88         EMIT4(op | __disp);                             \
  89 })
  90
  91 #define EMIT4_IMM(op, imm)                              \
  92 ({                                                      \
  93         unsigned int __imm = (imm) & 0xffff;            \
  94         EMIT4(op | __imm);                              \
  95 })
  96
  97 #define EMIT4_PCREL(op, pcrel)                          \
  98 ({                                                      \
  99         long __pcrel = ((pcrel) >> 1) & 0xffff;         \
 100         EMIT4(op | __pcrel);                            \
 101 })
 102
 103 #define EMIT6(op1, op2)                                 \
 104 ({                                                      \
 105         if (jit->prg + 6 <= jit->mid) {                 \
 106                 *(u32 *) jit->prg = op1;                \
 107                 *(u16 *) (jit->prg + 4) = op2;          \
 108         }                                               \
 109         jit->prg += 6;                                  \
 110 })
 111
 112 #define EMIT6_DISP(op1, op2, disp)                      \
 113 ({                                                      \
 114         unsigned int __disp = (disp) & 0xfff;           \
 115         EMIT6(op1 | __disp, op2);                       \
 116 })
 117
 118 #define EMIT6_IMM(op, imm)                              \
 119 ({                                                      \
 120         unsigned int __imm = (imm);                     \
 121         EMIT6(op | (__imm >> 16), __imm & 0xffff);      \
 122 })
 123
 124 #define EMIT_CONST(val)                                 \
 125 ({                                                      \
 126         unsigned int ret;                               \
 127         ret = (unsigned int) (jit->lit - jit->base_ip); \
 128         jit->seen |= SEEN_LITERAL;                      \
 129         if (jit->lit + 4 <= jit->end)                   \
 130                 *(u32 *) jit->lit = val;                \
 131         jit->lit += 4;                                  \
 132         ret;                                            \
 133 })
 134
 135 #define EMIT_FN_CONST(bit, fn)                          \
 136 ({                                                      \
 137         unsigned int ret;                               \
 138         ret = (unsigned int) (jit->lit - jit->base_ip); \
 139         if (jit->seen & bit) {                          \
 140                 jit->seen |= SEEN_LITERAL;              \
 141                 if (jit->lit + 8 <= jit->end)           \
 142                         *(void **) jit->lit = fn;       \
 143                 jit->lit += 8;                          \
 144         }                                               \
 145         ret;                                            \
 146 })
 147
 148 static void bpf_jit_prologue(struct bpf_jit *jit)
 149 {
 150         /* Save registers and create stack frame if necessary */
 151         if (jit->seen & SEEN_DATAREF) {
 152                 /* stmg %r8,%r15,88(%r15) */
 153                 EMIT6(0xeb8ff058, 0x0024);
 154                 /* lgr %r14,%r15 */
 155                 EMIT4(0xb90400ef);
 156                 /* ahi %r15,<offset> */
 157                 EMIT4_IMM(0xa7fa0000, (jit->seen & SEEN_MEM) ? -112 : -80);
 158                 /* stg %r14,152(%r15) */
 159                 EMIT6(0xe3e0f098, 0x0024);
 160         } else if ((jit->seen & SEEN_XREG) && (jit->seen & SEEN_LITERAL))
 161                 /* stmg %r12,%r13,120(%r15) */
 162                 EMIT6(0xebcdf078, 0x0024);
 163         else if (jit->seen & SEEN_XREG)
 164                 /* stg %r12,120(%r15) */
 165                 EMIT6(0xe3c0f078, 0x0024);
 166         else if (jit->seen & SEEN_LITERAL)
 167                 /* stg %r13,128(%r15) */
 168                 EMIT6(0xe3d0f080, 0x0024);
 169
 170         /* Setup literal pool */
 171         if (jit->seen & SEEN_LITERAL) {
 172                 /* basr %r13,0 */
 173                 EMIT2(0x0dd0);
 174                 jit->base_ip = jit->prg;
 175         }
 176         jit->off_load_word = EMIT_FN_CONST(SEEN_LOAD_WORD, sk_load_word);
 177         jit->off_load_half = EMIT_FN_CONST(SEEN_LOAD_HALF, sk_load_half);
 178         jit->off_load_byte = EMIT_FN_CONST(SEEN_LOAD_BYTE, sk_load_byte);
 179         jit->off_load_bmsh = EMIT_FN_CONST(SEEN_LOAD_BMSH, sk_load_byte_msh);
 180         jit->off_load_iword = EMIT_FN_CONST(SEEN_LOAD_IWORD, sk_load_word_ind);
 181         jit->off_load_ihalf = EMIT_FN_CONST(SEEN_LOAD_IHALF, sk_load_half_ind);
 182         jit->off_load_ibyte = EMIT_FN_CONST(SEEN_LOAD_IBYTE, sk_load_byte_ind);
 183
 184         /* Filter needs to access skb data */
 185         if (jit->seen & SEEN_DATAREF) {
 186                 /* l %r11,<len>(%r2) */
 187                 EMIT4_DISP(0x58b02000, offsetof(struct sk_buff, len));
 188                 /* s %r11,<data_len>(%r2) */
 189                 EMIT4_DISP(0x5bb02000, offsetof(struct sk_buff, data_len));
 190                 /* lg %r10,<data>(%r2) */
 191                 EMIT6_DISP(0xe3a02000, 0x0004,
 192                            offsetof(struct sk_buff, data));
 193         }
 194 }
 195
 196 static void bpf_jit_epilogue(struct bpf_jit *jit)
 197 {
 198         /* Return 0 */
 199         if (jit->seen & SEEN_RET0) {
 200                 jit->ret0_ip = jit->prg;
 201                 /* lghi %r2,0 */
 202                 EMIT4(0xa7290000);
 203         }
 204         jit->exit_ip = jit->prg;
 205         /* Restore registers */
 206         if (jit->seen & SEEN_DATAREF)
 207                 /* lmg %r8,%r15,<offset>(%r15) */
 208                 EMIT6_DISP(0xeb8ff000, 0x0004,
 209                            (jit->seen & SEEN_MEM) ? 200 : 168);
 210         else if ((jit->seen & SEEN_XREG) && (jit->seen & SEEN_LITERAL))
 211                 /* lmg %r12,%r13,120(%r15) */
 212                 EMIT6(0xebcdf078, 0x0004);
 213         else if (jit->seen & SEEN_XREG)
 214                 /* lg %r12,120(%r15) */
 215                 EMIT6(0xe3c0f078, 0x0004);
 216         else if (jit->seen & SEEN_LITERAL)
 217                 /* lg %r13,128(%r15) */
 218                 EMIT6(0xe3d0f080, 0x0004);
 219         /* br %r14 */
 220         EMIT2(0x07fe);
 221 }
 222
 223 /*
 224  * make sure we dont leak kernel information to user
 225  */
 226 static void bpf_jit_noleaks(struct bpf_jit *jit, struct sock_filter *filter)
 227 {
 228         /* Clear temporary memory if (seen & SEEN_MEM) */
 229         if (jit->seen & SEEN_MEM)
 230                 /* xc 0(64,%r15),0(%r15) */
 231                 EMIT6(0xd73ff000, 0xf000);
 232         /* Clear X if (seen & SEEN_XREG) */
 233         if (jit->seen & SEEN_XREG)
 234                 /* lhi %r12,0 */
 235                 EMIT4(0xa7c80000);
 236         /* Clear A if the first register does not set it. */
 237         switch (filter[0].code) {
 238         case BPF_S_LD_W_ABS:
 239         case BPF_S_LD_H_ABS:
 240         case BPF_S_LD_B_ABS:
 241         case BPF_S_LD_W_LEN:
 242         case BPF_S_LD_W_IND:
 243         case BPF_S_LD_H_IND:
 244         case BPF_S_LD_B_IND:
 245         case BPF_S_LDX_B_MSH:
 246         case BPF_S_LD_IMM:
 247         case BPF_S_LD_MEM:
 248         case BPF_S_MISC_TXA:
 249         case BPF_S_ANC_PROTOCOL:
 250         case BPF_S_ANC_PKTTYPE:
 251         case BPF_S_ANC_IFINDEX:
 252         case BPF_S_ANC_MARK:
 253         case BPF_S_ANC_QUEUE:
 254         case BPF_S_ANC_HATYPE:
 255         case BPF_S_ANC_RXHASH:
 256         case BPF_S_ANC_CPU:
 257         case BPF_S_RET_K:
 258                 /* first instruction sets A register */
 259                 break;
 260         default: /* A = 0 */
 261                 /* lhi %r5,0 */
 262                 EMIT4(0xa7580000);
 263         }
 264 }
 265
 266 static int bpf_jit_insn(struct bpf_jit *jit, struct sock_filter *filter,
 267                         unsigned int *addrs, int i, int last)
 268 {
 269         unsigned int K;
 270         int offset;
 271         unsigned int mask;
 272
 273         K = filter->k;
 274         switch (filter->code) {
 275         case BPF_S_ALU_ADD_X: /* A += X */
 276                 jit->seen |= SEEN_XREG;
 277                 /* ar %r5,%r12 */
 278                 EMIT2(0x1a5c);
 279                 break;
 280         case BPF_S_ALU_ADD_K: /* A += K */
 281                 if (!K)
 282                         break;
 283                 if (K <= 16383)
 284                         /* ahi %r5,<K> */
 285                         EMIT4_IMM(0xa75a0000, K);
 286                 else if (test_facility(21))
 287                         /* alfi %r5,<K> */
 288                         EMIT6_IMM(0xc25b0000, K);
 289                 else
 290                         /* a %r5,<d(K)>(%r13) */
 291                         EMIT4_DISP(0x5a50d000, EMIT_CONST(K));
 292                 break;
 293         case BPF_S_ALU_SUB_X: /* A -= X */
 294                 jit->seen |= SEEN_XREG;
 295                 /* sr %r5,%r12 */
 296                 EMIT2(0x1b5c);
 297                 break;
 298         case BPF_S_ALU_SUB_K: /* A -= K */
 299                 if (!K)
 300                         break;
 301                 if (K <= 16384)
 302                         /* ahi %r5,-K */
 303                         EMIT4_IMM(0xa75a0000, -K);
 304                 else if (test_facility(21))
 305                         /* alfi %r5,-K */
 306                         EMIT6_IMM(0xc25b0000, -K);
 307                 else
 308                         /* s %r5,<d(K)>(%r13) */
 309                         EMIT4_DISP(0x5b50d000, EMIT_CONST(K));
 310                 break;
 311         case BPF_S_ALU_MUL_X: /* A *= X */
 312                 jit->seen |= SEEN_XREG;
 313                 /* msr %r5,%r12 */
 314                 EMIT4(0xb252005c);
 315                 break;
 316         case BPF_S_ALU_MUL_K: /* A *= K */
 317                 if (K <= 16383)
 318                         /* mhi %r5,K */
 319                         EMIT4_IMM(0xa75c0000, K);
 320                 else if (test_facility(34))
 321                         /* msfi %r5,<K> */
 322                         EMIT6_IMM(0xc2510000, K);
 323                 else
 324                         /* ms %r5,<d(K)>(%r13) */
 325                         EMIT4_DISP(0x7150d000, EMIT_CONST(K));
 326                 break;
 327         case BPF_S_ALU_DIV_X: /* A /= X */
 328                 jit->seen |= SEEN_XREG | SEEN_RET0;
 329                 /* ltr %r12,%r12 */
 330                 EMIT2(0x12cc);
 331                 /* jz <ret0> */
 332                 EMIT4_PCREL(0xa7840000, (jit->ret0_ip - jit->prg));
 333                 /* lhi %r4,0 */
 334                 EMIT4(0xa7480000);
 335                 /* dr %r4,%r12 */
 336                 EMIT2(0x1d4c);
 337                 break;
 338         case BPF_S_ALU_DIV_K: /* A = reciprocal_divide(A, K) */
 339                 /* m %r4,<d(K)>(%r13) */
 340                 EMIT4_DISP(0x5c40d000, EMIT_CONST(K));
 341                 /* lr %r5,%r4 */
 342                 EMIT2(0x1854);
 343                 break;
 344         case BPF_S_ALU_AND_X: /* A &= X */
 345                 jit->seen |= SEEN_XREG;
 346                 /* nr %r5,%r12 */
 347                 EMIT2(0x145c);
 348                 break;
 349         case BPF_S_ALU_AND_K: /* A &= K */
 350                 if (test_facility(21))
 351                         /* nilf %r5,<K> */
 352                         EMIT6_IMM(0xc05b0000, K);
 353                 else
 354                         /* n %r5,<d(K)>(%r13) */
 355                         EMIT4_DISP(0x5450d000, EMIT_CONST(K));
 356                 break;
 357         case BPF_S_ALU_OR_X: /* A |= X */
 358                 jit->seen |= SEEN_XREG;
 359                 /* or %r5,%r12 */
 360                 EMIT2(0x165c);
 361                 break;
 362         case BPF_S_ALU_OR_K: /* A |= K */
 363                 if (test_facility(21))
 364                         /* oilf %r5,<K> */
 365                         EMIT6_IMM(0xc05d0000, K);
 366                 else
 367                         /* o %r5,<d(K)>(%r13) */
 368                         EMIT4_DISP(0x5650d000, EMIT_CONST(K));
 369                 break;
 370         case BPF_S_ANC_ALU_XOR_X: /* A ^= X; */
 371                 jit->seen |= SEEN_XREG;
 372                 /* xr %r5,%r12 */
 373                 EMIT2(0x175c);
 374                 break;
 375         case BPF_S_ALU_LSH_X: /* A <<= X; */
 376                 jit->seen |= SEEN_XREG;
 377                 /* sll %r5,0(%r12) */
 378                 EMIT4(0x8950c000);
 379                 break;
 380         case BPF_S_ALU_LSH_K: /* A <<= K */
 381                 if (K == 0)
 382                         break;
 383                 /* sll %r5,K */
 384                 EMIT4_DISP(0x89500000, K);
 385                 break;
 386         case BPF_S_ALU_RSH_X: /* A >>= X; */
 387                 jit->seen |= SEEN_XREG;
 388                 /* srl %r5,0(%r12) */
 389                 EMIT4(0x8850c000);
 390                 break;
 391         case BPF_S_ALU_RSH_K: /* A >>= K; */
 392                 if (K == 0)
 393                         break;
 394                 /* srl %r5,K */
 395                 EMIT4_DISP(0x88500000, K);
 396                 break;
 397         case BPF_S_ALU_NEG: /* A = -A */
 398                 /* lnr %r5,%r5 */
 399                 EMIT2(0x1155);
 400                 break;
 401         case BPF_S_JMP_JA: /* ip += K */
 402                 offset = addrs[i + K] + jit->start - jit->prg;
 403                 EMIT4_PCREL(0xa7f40000, offset);
 404                 break;
 405         case BPF_S_JMP_JGT_K: /* ip += (A > K) ? jt : jf */
 406                 mask = 0x200000; /* jh */
 407                 goto kbranch;
 408         case BPF_S_JMP_JGE_K: /* ip += (A >= K) ? jt : jf */
 409                 mask = 0xa00000; /* jhe */
 410                 goto kbranch;
 411         case BPF_S_JMP_JEQ_K: /* ip += (A == K) ? jt : jf */
 412                 mask = 0x800000; /* je */
 413 kbranch:        /* Emit compare if the branch targets are different */
 414                 if (filter->jt != filter->jf) {
 415                         if (K <= 16383)
 416                                 /* chi %r5,<K> */
 417                                 EMIT4_IMM(0xa75e0000, K);
 418                         else if (test_facility(21))
 419                                 /* clfi %r5,<K> */
 420                                 EMIT6_IMM(0xc25f0000, K);
 421                         else
 422                                 /* c %r5,<d(K)>(%r13) */
 423                                 EMIT4_DISP(0x5950d000, EMIT_CONST(K));
 424                 }
 425 branch:         if (filter->jt == filter->jf) {
 426                         if (filter->jt == 0)
 427                                 break;
 428                         /* j <jt> */
 429                         offset = addrs[i + filter->jt] + jit->start - jit->prg;
 430                         EMIT4_PCREL(0xa7f40000, offset);
 431                         break;
 432                 }
 433                 if (filter->jt != 0) {
 434                         /* brc  <mask>,<jt> */
 435                         offset = addrs[i + filter->jt] + jit->start - jit->prg;
 436                         EMIT4_PCREL(0xa7040000 | mask, offset);
 437                 }
 438                 if (filter->jf != 0) {
 439                         /* brc  <mask^15>,<jf> */
 440                         offset = addrs[i + filter->jf] + jit->start - jit->prg;
 441                         EMIT4_PCREL(0xa7040000 | (mask ^ 0xf00000), offset);
 442                 }
 443                 break;
 444         case BPF_S_JMP_JSET_K: /* ip += (A & K) ? jt : jf */
 445                 mask = 0x700000; /* jnz */
 446                 /* Emit test if the branch targets are different */
 447                 if (filter->jt != filter->jf) {
 448                         if (K > 65535) {
 449                                 /* lr %r4,%r5 */
 450                                 EMIT2(0x1845);
 451                                 /* n %r4,<d(K)>(%r13) */
 452                                 EMIT4_DISP(0x5440d000, EMIT_CONST(K));
 453                         } else
 454                                 /* tmll %r5,K */
 455                                 EMIT4_IMM(0xa7510000, K);
 456                 }
 457                 goto branch;
 458         case BPF_S_JMP_JGT_X: /* ip += (A > X) ? jt : jf */
 459                 mask = 0x200000; /* jh */
 460                 goto xbranch;
 461         case BPF_S_JMP_JGE_X: /* ip += (A >= X) ? jt : jf */
 462                 mask = 0xa00000; /* jhe */
 463                 goto xbranch;
 464         case BPF_S_JMP_JEQ_X: /* ip += (A == X) ? jt : jf */
 465                 mask = 0x800000; /* je */
 466 xbranch:        /* Emit compare if the branch targets are different */
 467                 if (filter->jt != filter->jf) {
 468                         jit->seen |= SEEN_XREG;
 469                         /* cr %r5,%r12 */
 470                         EMIT2(0x195c);
 471                 }
 472                 goto branch;
 473         case BPF_S_JMP_JSET_X: /* ip += (A & X) ? jt : jf */
 474                 mask = 0x700000; /* jnz */
 475                 /* Emit test if the branch targets are different */
 476                 if (filter->jt != filter->jf) {
 477                         jit->seen |= SEEN_XREG;
 478                         /* lr %r4,%r5 */
 479                         EMIT2(0x1845);
 480                         /* nr %r4,%r12 */
 481                         EMIT2(0x144c);
 482                 }
 483                 goto branch;
 484         case BPF_S_LD_W_ABS: /* A = *(u32 *) (skb->data+K) */
 485                 jit->seen |= SEEN_DATAREF | SEEN_RET0 | SEEN_LOAD_WORD;
 486                 offset = jit->off_load_word;
 487                 goto load_abs;
 488         case BPF_S_LD_H_ABS: /* A = *(u16 *) (skb->data+K) */
 489                 jit->seen |= SEEN_DATAREF | SEEN_RET0 | SEEN_LOAD_HALF;
 490                 offset = jit->off_load_half;
 491                 goto load_abs;
 492         case BPF_S_LD_B_ABS: /* A = *(u8 *) (skb->data+K) */
 493                 jit->seen |= SEEN_DATAREF | SEEN_RET0 | SEEN_LOAD_BYTE;
 494                 offset = jit->off_load_byte;
 495 load_abs:       if ((int) K < 0)
 496                         goto out;
 497 call_fn:        /* lg %r1,<d(function)>(%r13) */
 498                 EMIT6_DISP(0xe310d000, 0x0004, offset);
 499                 /* l %r3,<d(K)>(%r13) */
 500                 EMIT4_DISP(0x5830d000, EMIT_CONST(K));
 501                 /* basr %r8,%r1 */
 502                 EMIT2(0x0d81);
 503                 /* jnz <ret0> */
 504                 EMIT4_PCREL(0xa7740000, (jit->ret0_ip - jit->prg));
 505                 break;
 506         case BPF_S_LD_W_IND: /* A = *(u32 *) (skb->data+K+X) */
 507                 jit->seen |= SEEN_DATAREF | SEEN_RET0 | SEEN_LOAD_IWORD;
 508                 offset = jit->off_load_iword;
 509                 goto call_fn;
 510         case BPF_S_LD_H_IND: /* A = *(u16 *) (skb->data+K+X) */
 511                 jit->seen |= SEEN_DATAREF | SEEN_RET0 | SEEN_LOAD_IHALF;
 512                 offset = jit->off_load_ihalf;
 513                 goto call_fn;
 514         case BPF_S_LD_B_IND: /* A = *(u8 *) (skb->data+K+X) */
 515                 jit->seen |= SEEN_DATAREF | SEEN_RET0 | SEEN_LOAD_IBYTE;
 516                 offset = jit->off_load_ibyte;
 517                 goto call_fn;
 518         case BPF_S_LDX_B_MSH:
 519                 /* X = (*(u8 *)(skb->data+K) & 0xf) << 2 */
 520                 jit->seen |= SEEN_RET0;
 521                 if ((int) K < 0) {
 522                         /* j <ret0> */
 523                         EMIT4_PCREL(0xa7f40000, (jit->ret0_ip - jit->prg));
 524                         break;
 525                 }
 526                 jit->seen |= SEEN_DATAREF | SEEN_LOAD_BMSH;
 527                 offset = jit->off_load_bmsh;
 528                 goto call_fn;
 529         case BPF_S_LD_W_LEN: /* A = skb->len; */
 530                 BUILD_BUG_ON(FIELD_SIZEOF(struct sk_buff, len) != 4);
 531                 /* l %r5,<d(len)>(%r2) */
 532                 EMIT4_DISP(0x58502000, offsetof(struct sk_buff, len));
 533                 break;
 534         case BPF_S_LDX_W_LEN: /* X = skb->len; */
 535                 jit->seen |= SEEN_XREG;
 536                 /* l %r12,<d(len)>(%r2) */
 537                 EMIT4_DISP(0x58c02000, offsetof(struct sk_buff, len));
 538                 break;
 539         case BPF_S_LD_IMM: /* A = K */
 540                 if (K <= 16383)
 541                         /* lhi %r5,K */
 542                         EMIT4_IMM(0xa7580000, K);
 543                 else if (test_facility(21))
 544                         /* llilf %r5,<K> */
 545                         EMIT6_IMM(0xc05f0000, K);
 546                 else
 547                         /* l %r5,<d(K)>(%r13) */
 548                         EMIT4_DISP(0x5850d000, EMIT_CONST(K));
 549                 break;
 550         case BPF_S_LDX_IMM: /* X = K */
 551                 jit->seen |= SEEN_XREG;
 552                 if (K <= 16383)
 553                         /* lhi %r12,<K> */
 554                         EMIT4_IMM(0xa7c80000, K);
 555                 else if (test_facility(21))
 556                         /* llilf %r12,<K> */
 557                         EMIT6_IMM(0xc0cf0000, K);
 558                 else
 559                         /* l %r12,<d(K)>(%r13) */
 560                         EMIT4_DISP(0x58c0d000, EMIT_CONST(K));
 561                 break;
 562         case BPF_S_LD_MEM: /* A = mem[K] */
 563                 jit->seen |= SEEN_MEM;
 564                 /* l %r5,<K>(%r15) */
 565                 EMIT4_DISP(0x5850f000,
 566                            (jit->seen & SEEN_DATAREF) ? 160 + K*4 : K*4);
 567                 break;
 568         case BPF_S_LDX_MEM: /* X = mem[K] */
 569                 jit->seen |= SEEN_XREG | SEEN_MEM;
 570                 /* l %r12,<K>(%r15) */
 571                 EMIT4_DISP(0x58c0f000,
 572                            (jit->seen & SEEN_DATAREF) ? 160 + K*4 : K*4);
 573                 break;
 574         case BPF_S_MISC_TAX: /* X = A */
 575                 jit->seen |= SEEN_XREG;
 576                 /* lr %r12,%r5 */
 577                 EMIT2(0x18c5);
 578                 break;
 579         case BPF_S_MISC_TXA: /* A = X */
 580                 jit->seen |= SEEN_XREG;
 581                 /* lr %r5,%r12 */
 582                 EMIT2(0x185c);
 583                 break;
 584         case BPF_S_RET_K:
 585                 if (K == 0) {
 586                         jit->seen |= SEEN_RET0;
 587                         if (last)
 588                                 break;
 589                         /* j <ret0> */
 590                         EMIT4_PCREL(0xa7f40000, jit->ret0_ip - jit->prg);
 591                 } else {
 592                         if (K <= 16383)
 593                                 /* lghi %r2,K */
 594                                 EMIT4_IMM(0xa7290000, K);
 595                         else
 596                                 /* llgf %r2,<K>(%r13) */
 597                                 EMIT6_DISP(0xe320d000, 0x0016, EMIT_CONST(K));
 598                         /* j <exit> */
 599                         if (last && !(jit->seen & SEEN_RET0))
 600                                 break;
 601                         EMIT4_PCREL(0xa7f40000, jit->exit_ip - jit->prg);
 602                 }
 603                 break;
 604         case BPF_S_RET_A:
 605                 /* llgfr %r2,%r5 */
 606                 EMIT4(0xb9160025);
 607                 /* j <exit> */
 608                 EMIT4_PCREL(0xa7f40000, jit->exit_ip - jit->prg);
 609                 break;
 610         case BPF_S_ST: /* mem[K] = A */
 611                 jit->seen |= SEEN_MEM;
 612                 /* st %r5,<K>(%r15) */
 613                 EMIT4_DISP(0x5050f000,
 614                            (jit->seen & SEEN_DATAREF) ? 160 + K*4 : K*4);
 615                 break;
 616         case BPF_S_STX: /* mem[K] = X : mov %ebx,off8(%rbp) */
 617                 jit->seen |= SEEN_XREG | SEEN_MEM;
 618                 /* st %r12,<K>(%r15) */
 619                 EMIT4_DISP(0x50c0f000,
 620                            (jit->seen & SEEN_DATAREF) ? 160 + K*4 : K*4);
 621                 break;
 622         case BPF_S_ANC_PROTOCOL: /* A = ntohs(skb->protocol); */
 623                 BUILD_BUG_ON(FIELD_SIZEOF(struct sk_buff, protocol) != 2);
 624                 /* lhi %r5,0 */
 625                 EMIT4(0xa7580000);
 626                 /* icm  %r5,3,<d(protocol)>(%r2) */
 627                 EMIT4_DISP(0xbf532000, offsetof(struct sk_buff, protocol));
 628                 break;
 629         case BPF_S_ANC_IFINDEX: /* if (!skb->dev) return 0;
 630                                  * A = skb->dev->ifindex */
 631                 BUILD_BUG_ON(FIELD_SIZEOF(struct net_device, ifindex) != 4);
 632                 jit->seen |= SEEN_RET0;
 633                 /* lg %r1,<d(dev)>(%r2) */
 634                 EMIT6_DISP(0xe3102000, 0x0004, offsetof(struct sk_buff, dev));
 635                 /* ltgr %r1,%r1 */
 636                 EMIT4(0xb9020011);
 637                 /* jz <ret0> */
 638                 EMIT4_PCREL(0xa7840000, jit->ret0_ip - jit->prg);
 639                 /* l %r5,<d(ifindex)>(%r1) */
 640                 EMIT4_DISP(0x58501000, offsetof(struct net_device, ifindex));
 641                 break;
 642         case BPF_S_ANC_MARK: /* A = skb->mark */
 643                 BUILD_BUG_ON(FIELD_SIZEOF(struct sk_buff, mark) != 4);
 644                 /* l %r5,<d(mark)>(%r2) */
 645                 EMIT4_DISP(0x58502000, offsetof(struct sk_buff, mark));
 646                 break;
 647         case BPF_S_ANC_QUEUE: /* A = skb->queue_mapping */
 648                 BUILD_BUG_ON(FIELD_SIZEOF(struct sk_buff, queue_mapping) != 2);
 649                 /* lhi %r5,0 */
 650                 EMIT4(0xa7580000);
 651                 /* icm  %r5,3,<d(queue_mapping)>(%r2) */
 652                 EMIT4_DISP(0xbf532000, offsetof(struct sk_buff, queue_mapping));
 653                 break;
 654         case BPF_S_ANC_HATYPE:  /* if (!skb->dev) return 0;
 655                                  * A = skb->dev->type */
 656                 BUILD_BUG_ON(FIELD_SIZEOF(struct net_device, type) != 2);
 657                 jit->seen |= SEEN_RET0;
 658                 /* lg %r1,<d(dev)>(%r2) */
 659                 EMIT6_DISP(0xe3102000, 0x0004, offsetof(struct sk_buff, dev));
 660                 /* ltgr %r1,%r1 */
 661                 EMIT4(0xb9020011);
 662                 /* jz <ret0> */
 663                 EMIT4_PCREL(0xa7840000, jit->ret0_ip - jit->prg);
 664                 /* lhi %r5,0 */
 665                 EMIT4(0xa7580000);
 666                 /* icm  %r5,3,<d(type)>(%r1) */
 667                 EMIT4_DISP(0xbf531000, offsetof(struct net_device, type));
 668                 break;
 669         case BPF_S_ANC_RXHASH: /* A = skb->rxhash */
 670                 BUILD_BUG_ON(FIELD_SIZEOF(struct sk_buff, rxhash) != 4);
 671                 /* l %r5,<d(rxhash)>(%r2) */
 672                 EMIT4_DISP(0x58502000, offsetof(struct sk_buff, rxhash));
 673                 break;
 674         case BPF_S_ANC_CPU: /* A = smp_processor_id() */
 675 #ifdef CONFIG_SMP
 676                 /* l %r5,<d(cpu_nr)> */
 677                 EMIT4_DISP(0x58500000, offsetof(struct _lowcore, cpu_nr));
 678 #else
 679                 /* lhi %r5,0 */
 680                 EMIT4(0xa7580000);
 681 #endif
 682                 break;
 683         default: /* too complex, give up */
 684                 goto out;
 685         }
 686         addrs[i] = jit->prg - jit->start;
 687         return 0;
 688 out:
 689         return -1;
 690 }
 691
 692 void bpf_jit_compile(struct sk_filter *fp)
 693 {
 694         unsigned long size, prg_len, lit_len;
 695         struct bpf_jit jit, cjit;
 696         unsigned int *addrs;
 697         int pass, i;
 698
 699         if (!bpf_jit_enable)
 700                 return;
 701         addrs = kmalloc(fp->len * sizeof(*addrs), GFP_KERNEL);
 702         if (addrs == NULL)
 703                 return;
 704         memset(addrs, 0, fp->len * sizeof(*addrs));
 705         memset(&jit, 0, sizeof(cjit));
 706         memset(&cjit, 0, sizeof(cjit));
 707
 708         for (pass = 0; pass < 10; pass++) {
 709                 jit.prg = jit.start;
 710                 jit.lit = jit.mid;
 711
 712                 bpf_jit_prologue(&jit);
 713                 bpf_jit_noleaks(&jit, fp->insns);
 714                 for (i = 0; i < fp->len; i++) {
 715                         if (bpf_jit_insn(&jit, fp->insns + i, addrs, i,
 716                                          i == fp->len - 1))
 717                                 goto out;
 718                 }
 719                 bpf_jit_epilogue(&jit);
 720                 if (jit.start) {
 721                         WARN_ON(jit.prg > cjit.prg || jit.lit > cjit.lit);
 722                         if (memcmp(&jit, &cjit, sizeof(jit)) == 0)
 723                                 break;
 724                 } else if (jit.prg == cjit.prg && jit.lit == cjit.lit) {
 725                         prg_len = jit.prg - jit.start;
 726                         lit_len = jit.lit - jit.mid;
 727                         size = max_t(unsigned long, prg_len + lit_len,
 728                                      sizeof(struct work_struct));
 729                         if (size >= BPF_SIZE_MAX)
 730                                 goto out;
 731                         jit.start = module_alloc(size);
 732                         if (!jit.start)
 733                                 goto out;
 734                         jit.prg = jit.mid = jit.start + prg_len;
 735                         jit.lit = jit.end = jit.start + prg_len + lit_len;
 736                         jit.base_ip += (unsigned long) jit.start;
 737                         jit.exit_ip += (unsigned long) jit.start;
 738                         jit.ret0_ip += (unsigned long) jit.start;
 739                 }
 740                 cjit = jit;
 741         }
 742         if (bpf_jit_enable > 1) {
 743                 pr_err("flen=%d proglen=%lu pass=%d image=%p\n",
 744                        fp->len, jit.end - jit.start, pass, jit.start);
 745                 if (jit.start) {
 746                         printk(KERN_ERR "JIT code:\n");
 747                         print_fn_code(jit.start, jit.mid - jit.start);
 748                         print_hex_dump(KERN_ERR, "JIT literals:\n",
 749                                        DUMP_PREFIX_ADDRESS, 16, 1,
 750                                        jit.mid, jit.end - jit.mid, false);
 751                 }
 752         }
 753         if (jit.start)
 754                 fp->bpf_func = (void *) jit.start;
 755 out:
 756         kfree(addrs);
 757 }
 758
 759 static void jit_free_defer(struct work_struct *arg)
 760 {
 761         module_free(NULL, arg);
 762 }
 763
 764 /* run from softirq, we must use a work_struct to call
 765  * module_free() from process context
 766  */
 767 void bpf_jit_free(struct sk_filter *fp)
 768 {
 769         struct work_struct *work;
 770
 771         if (fp->bpf_func == sk_run_filter)
 772                 return;
 773         work = (struct work_struct *)fp->bpf_func;
 774         INIT_WORK(work, jit_free_defer);
 775         schedule_work(work);
 776 }