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/if_vlan.h>
  11 #include <linux/filter.h>
  12 #include <linux/random.h>
  13 #include <linux/init.h>
  14 #include <asm/cacheflush.h>
  15 #include <asm/facility.h>
  16 #include <asm/dis.h>
  17
  18 /*
  19  * Conventions:
  20  *   %r2 = skb pointer
  21  *   %r3 = offset parameter
  22  *   %r4 = scratch register / length parameter
  23  *   %r5 = BPF A accumulator
  24  *   %r8 = return address
  25  *   %r9 = save register for skb pointer
  26  *   %r10 = skb->data
  27  *   %r11 = skb->len - skb->data_len (headlen)
  28  *   %r12 = BPF X accumulator
  29  *   %r13 = literal pool pointer
  30  *   0(%r15) - 63(%r15) scratch memory array with BPF_MEMWORDS
  31  */
  32 int bpf_jit_enable __read_mostly;
  33
  34 /*
  35  * assembly code in arch/x86/net/bpf_jit.S
  36  */
  37 extern u8 sk_load_word[], sk_load_half[], sk_load_byte[], sk_load_byte_msh[];
  38 extern u8 sk_load_word_ind[], sk_load_half_ind[], sk_load_byte_ind[];
  39
  40 struct bpf_jit {
  41         unsigned int seen;
  42         u8 *start;
  43         u8 *prg;
  44         u8 *mid;
  45         u8 *lit;
  46         u8 *end;
  47         u8 *base_ip;
  48         u8 *ret0_ip;
  49         u8 *exit_ip;
  50         unsigned int off_load_word;
  51         unsigned int off_load_half;
  52         unsigned int off_load_byte;
  53         unsigned int off_load_bmsh;
  54         unsigned int off_load_iword;
  55         unsigned int off_load_ihalf;
  56         unsigned int off_load_ibyte;
  57 };
  58
  59 #define BPF_SIZE_MAX    4096    /* Max size for program */
  60
  61 #define SEEN_DATAREF    1       /* might call external helpers */
  62 #define SEEN_XREG       2       /* ebx is used */
  63 #define SEEN_MEM        4       /* use mem[] for temporary storage */
  64 #define SEEN_RET0       8       /* pc_ret0 points to a valid return 0 */
  65 #define SEEN_LITERAL    16      /* code uses literals */
  66 #define SEEN_LOAD_WORD  32      /* code uses sk_load_word */
  67 #define SEEN_LOAD_HALF  64      /* code uses sk_load_half */
  68 #define SEEN_LOAD_BYTE  128     /* code uses sk_load_byte */
  69 #define SEEN_LOAD_BMSH  256     /* code uses sk_load_byte_msh */
  70 #define SEEN_LOAD_IWORD 512     /* code uses sk_load_word_ind */
  71 #define SEEN_LOAD_IHALF 1024    /* code uses sk_load_half_ind */
  72 #define SEEN_LOAD_IBYTE 2048    /* code uses sk_load_byte_ind */
  73
  74 #define EMIT2(op)                                       \
  75 ({                                                      \
  76         if (jit->prg + 2 <= jit->mid)                   \
  77                 *(u16 *) jit->prg = op;                 \
  78         jit->prg += 2;                                  \
  79 })
  80
  81 #define EMIT4(op)                                       \
  82 ({                                                      \
  83         if (jit->prg + 4 <= jit->mid)                   \
  84                 *(u32 *) jit->prg = op;                 \
  85         jit->prg += 4;                                  \
  86 })
  87
  88 #define EMIT4_DISP(op, disp)                            \
  89 ({                                                      \
  90         unsigned int __disp = (disp) & 0xfff;           \
  91         EMIT4(op | __disp);                             \
  92 })
  93
  94 #define EMIT4_IMM(op, imm)                              \
  95 ({                                                      \
  96         unsigned int __imm = (imm) & 0xffff;            \
  97         EMIT4(op | __imm);                              \
  98 })
  99
 100 #define EMIT4_PCREL(op, pcrel)                          \
 101 ({                                                      \
 102         long __pcrel = ((pcrel) >> 1) & 0xffff;         \
 103         EMIT4(op | __pcrel);                            \
 104 })
 105
 106 #define EMIT6(op1, op2)                                 \
 107 ({                                                      \
 108         if (jit->prg + 6 <= jit->mid) {                 \
 109                 *(u32 *) jit->prg = op1;                \
 110                 *(u16 *) (jit->prg + 4) = op2;          \
 111         }                                               \
 112         jit->prg += 6;                                  \
 113 })
 114
 115 #define EMIT6_DISP(op1, op2, disp)                      \
 116 ({                                                      \
 117         unsigned int __disp = (disp) & 0xfff;           \
 118         EMIT6(op1 | __disp, op2);                       \
 119 })
 120
 121 #define EMIT6_IMM(op, imm)                              \
 122 ({                                                      \
 123         unsigned int __imm = (imm);                     \
 124         EMIT6(op | (__imm >> 16), __imm & 0xffff);      \
 125 })
 126
 127 #define EMIT_CONST(val)                                 \
 128 ({                                                      \
 129         unsigned int ret;                               \
 130         ret = (unsigned int) (jit->lit - jit->base_ip); \
 131         jit->seen |= SEEN_LITERAL;                      \
 132         if (jit->lit + 4 <= jit->end)                   \
 133                 *(u32 *) jit->lit = val;                \
 134         jit->lit += 4;                                  \
 135         ret;                                            \
 136 })
 137
 138 #define EMIT_FN_CONST(bit, fn)                          \
 139 ({                                                      \
 140         unsigned int ret;                               \
 141         ret = (unsigned int) (jit->lit - jit->base_ip); \
 142         if (jit->seen & bit) {                          \
 143                 jit->seen |= SEEN_LITERAL;              \
 144                 if (jit->lit + 8 <= jit->end)           \
 145                         *(void **) jit->lit = fn;       \
 146                 jit->lit += 8;                          \
 147         }                                               \
 148         ret;                                            \
 149 })
 150
 151 static void bpf_jit_prologue(struct bpf_jit *jit)
 152 {
 153         /* Save registers and create stack frame if necessary */
 154         if (jit->seen & SEEN_DATAREF) {
 155                 /* stmg %r8,%r15,88(%r15) */
 156                 EMIT6(0xeb8ff058, 0x0024);
 157                 /* lgr %r14,%r15 */
 158                 EMIT4(0xb90400ef);
 159                 /* aghi %r15,<offset> */
 160                 EMIT4_IMM(0xa7fb0000, (jit->seen & SEEN_MEM) ? -112 : -80);
 161                 /* stg %r14,152(%r15) */
 162                 EMIT6(0xe3e0f098, 0x0024);
 163         } else if ((jit->seen & SEEN_XREG) && (jit->seen & SEEN_LITERAL))
 164                 /* stmg %r12,%r13,120(%r15) */
 165                 EMIT6(0xebcdf078, 0x0024);
 166         else if (jit->seen & SEEN_XREG)
 167                 /* stg %r12,120(%r15) */
 168                 EMIT6(0xe3c0f078, 0x0024);
 169         else if (jit->seen & SEEN_LITERAL)
 170                 /* stg %r13,128(%r15) */
 171                 EMIT6(0xe3d0f080, 0x0024);
 172
 173         /* Setup literal pool */
 174         if (jit->seen & SEEN_LITERAL) {
 175                 /* basr %r13,0 */
 176                 EMIT2(0x0dd0);
 177                 jit->base_ip = jit->prg;
 178         }
 179         jit->off_load_word = EMIT_FN_CONST(SEEN_LOAD_WORD, sk_load_word);
 180         jit->off_load_half = EMIT_FN_CONST(SEEN_LOAD_HALF, sk_load_half);
 181         jit->off_load_byte = EMIT_FN_CONST(SEEN_LOAD_BYTE, sk_load_byte);
 182         jit->off_load_bmsh = EMIT_FN_CONST(SEEN_LOAD_BMSH, sk_load_byte_msh);
 183         jit->off_load_iword = EMIT_FN_CONST(SEEN_LOAD_IWORD, sk_load_word_ind);
 184         jit->off_load_ihalf = EMIT_FN_CONST(SEEN_LOAD_IHALF, sk_load_half_ind);
 185         jit->off_load_ibyte = EMIT_FN_CONST(SEEN_LOAD_IBYTE, sk_load_byte_ind);
 186
 187         /* Filter needs to access skb data */
 188         if (jit->seen & SEEN_DATAREF) {
 189                 /* l %r11,<len>(%r2) */
 190                 EMIT4_DISP(0x58b02000, offsetof(struct sk_buff, len));
 191                 /* s %r11,<data_len>(%r2) */
 192                 EMIT4_DISP(0x5bb02000, offsetof(struct sk_buff, data_len));
 193                 /* lg %r10,<data>(%r2) */
 194                 EMIT6_DISP(0xe3a02000, 0x0004,
 195                            offsetof(struct sk_buff, data));
 196         }
 197 }
 198
 199 static void bpf_jit_epilogue(struct bpf_jit *jit)
 200 {
 201         /* Return 0 */
 202         if (jit->seen & SEEN_RET0) {
 203                 jit->ret0_ip = jit->prg;
 204                 /* lghi %r2,0 */
 205                 EMIT4(0xa7290000);
 206         }
 207         jit->exit_ip = jit->prg;
 208         /* Restore registers */
 209         if (jit->seen & SEEN_DATAREF)
 210                 /* lmg %r8,%r15,<offset>(%r15) */
 211                 EMIT6_DISP(0xeb8ff000, 0x0004,
 212                            (jit->seen & SEEN_MEM) ? 200 : 168);
 213         else if ((jit->seen & SEEN_XREG) && (jit->seen & SEEN_LITERAL))
 214                 /* lmg %r12,%r13,120(%r15) */
 215                 EMIT6(0xebcdf078, 0x0004);
 216         else if (jit->seen & SEEN_XREG)
 217                 /* lg %r12,120(%r15) */
 218                 EMIT6(0xe3c0f078, 0x0004);
 219         else if (jit->seen & SEEN_LITERAL)
 220                 /* lg %r13,128(%r15) */
 221                 EMIT6(0xe3d0f080, 0x0004);
 222         /* br %r14 */
 223         EMIT2(0x07fe);
 224 }
 225
 226 /* Helper to find the offset of pkt_type in sk_buff
 227  * Make sure its still a 3bit field starting at the MSBs within a byte.
 228  */
 229 #define PKT_TYPE_MAX 0xe0
 230 static int pkt_type_offset;
 231
 232 static int __init bpf_pkt_type_offset_init(void)
 233 {
 234         struct sk_buff skb_probe = {
 235                 .pkt_type = ~0,
 236         };
 237         char *ct = (char *)&skb_probe;
 238         int off;
 239
 240         pkt_type_offset = -1;
 241         for (off = 0; off < sizeof(struct sk_buff); off++) {
 242                 if (!ct[off])
 243                         continue;
 244                 if (ct[off] == PKT_TYPE_MAX)
 245                         pkt_type_offset = off;
 246                 else {
 247                         /* Found non matching bit pattern, fix needed. */
 248                         WARN_ON_ONCE(1);
 249                         pkt_type_offset = -1;
 250                         return -1;
 251                 }
 252         }
 253         return 0;
 254 }
 255 device_initcall(bpf_pkt_type_offset_init);
 256
 257 /*
 258  * make sure we dont leak kernel information to user
 259  */
 260 static void bpf_jit_noleaks(struct bpf_jit *jit, struct sock_filter *filter)
 261 {
 262         /* Clear temporary memory if (seen & SEEN_MEM) */
 263         if (jit->seen & SEEN_MEM)
 264                 /* xc 0(64,%r15),0(%r15) */
 265                 EMIT6(0xd73ff000, 0xf000);
 266         /* Clear X if (seen & SEEN_XREG) */
 267         if (jit->seen & SEEN_XREG)
 268                 /* lhi %r12,0 */
 269                 EMIT4(0xa7c80000);
 270         /* Clear A if the first register does not set it. */
 271         switch (filter[0].code) {
 272         case BPF_S_LD_W_ABS:
 273         case BPF_S_LD_H_ABS:
 274         case BPF_S_LD_B_ABS:
 275         case BPF_S_LD_W_LEN:
 276         case BPF_S_LD_W_IND:
 277         case BPF_S_LD_H_IND:
 278         case BPF_S_LD_B_IND:
 279         case BPF_S_LD_IMM:
 280         case BPF_S_LD_MEM:
 281         case BPF_S_MISC_TXA:
 282         case BPF_S_ANC_PROTOCOL:
 283         case BPF_S_ANC_PKTTYPE:
 284         case BPF_S_ANC_IFINDEX:
 285         case BPF_S_ANC_MARK:
 286         case BPF_S_ANC_QUEUE:
 287         case BPF_S_ANC_HATYPE:
 288         case BPF_S_ANC_RXHASH:
 289         case BPF_S_ANC_CPU:
 290         case BPF_S_ANC_VLAN_TAG:
 291         case BPF_S_ANC_VLAN_TAG_PRESENT:
 292         case BPF_S_RET_K:
 293                 /* first instruction sets A register */
 294                 break;
 295         default: /* A = 0 */
 296                 /* lhi %r5,0 */
 297                 EMIT4(0xa7580000);
 298         }
 299 }
 300
 301 static int bpf_jit_insn(struct bpf_jit *jit, struct sock_filter *filter,
 302                         unsigned int *addrs, int i, int last)
 303 {
 304         unsigned int K;
 305         int offset;
 306         unsigned int mask;
 307
 308         K = filter->k;
 309         switch (filter->code) {
 310         case BPF_S_ALU_ADD_X: /* A += X */
 311                 jit->seen |= SEEN_XREG;
 312                 /* ar %r5,%r12 */
 313                 EMIT2(0x1a5c);
 314                 break;
 315         case BPF_S_ALU_ADD_K: /* A += K */
 316                 if (!K)
 317                         break;
 318                 if (K <= 16383)
 319                         /* ahi %r5,<K> */
 320                         EMIT4_IMM(0xa75a0000, K);
 321                 else if (test_facility(21))
 322                         /* alfi %r5,<K> */
 323                         EMIT6_IMM(0xc25b0000, K);
 324                 else
 325                         /* a %r5,<d(K)>(%r13) */
 326                         EMIT4_DISP(0x5a50d000, EMIT_CONST(K));
 327                 break;
 328         case BPF_S_ALU_SUB_X: /* A -= X */
 329                 jit->seen |= SEEN_XREG;
 330                 /* sr %r5,%r12 */
 331                 EMIT2(0x1b5c);
 332                 break;
 333         case BPF_S_ALU_SUB_K: /* A -= K */
 334                 if (!K)
 335                         break;
 336                 if (K <= 16384)
 337                         /* ahi %r5,-K */
 338                         EMIT4_IMM(0xa75a0000, -K);
 339                 else if (test_facility(21))
 340                         /* alfi %r5,-K */
 341                         EMIT6_IMM(0xc25b0000, -K);
 342                 else
 343                         /* s %r5,<d(K)>(%r13) */
 344                         EMIT4_DISP(0x5b50d000, EMIT_CONST(K));
 345                 break;
 346         case BPF_S_ALU_MUL_X: /* A *= X */
 347                 jit->seen |= SEEN_XREG;
 348                 /* msr %r5,%r12 */
 349                 EMIT4(0xb252005c);
 350                 break;
 351         case BPF_S_ALU_MUL_K: /* A *= K */
 352                 if (K <= 16383)
 353                         /* mhi %r5,K */
 354                         EMIT4_IMM(0xa75c0000, K);
 355                 else if (test_facility(34))
 356                         /* msfi %r5,<K> */
 357                         EMIT6_IMM(0xc2510000, K);
 358                 else
 359                         /* ms %r5,<d(K)>(%r13) */
 360                         EMIT4_DISP(0x7150d000, EMIT_CONST(K));
 361                 break;
 362         case BPF_S_ALU_DIV_X: /* A /= X */
 363                 jit->seen |= SEEN_XREG | SEEN_RET0;
 364                 /* ltr %r12,%r12 */
 365                 EMIT2(0x12cc);
 366                 /* jz <ret0> */
 367                 EMIT4_PCREL(0xa7840000, (jit->ret0_ip - jit->prg));
 368                 /* lhi %r4,0 */
 369                 EMIT4(0xa7480000);
 370                 /* dlr %r4,%r12 */
 371                 EMIT4(0xb997004c);
 372                 break;
 373         case BPF_S_ALU_DIV_K: /* A /= K */
 374                 if (K == 1)
 375                         break;
 376                 /* lhi %r4,0 */
 377                 EMIT4(0xa7480000);
 378                 /* dl %r4,<d(K)>(%r13) */
 379                 EMIT6_DISP(0xe340d000, 0x0097, EMIT_CONST(K));
 380                 break;
 381         case BPF_S_ALU_MOD_X: /* A %= X */
 382                 jit->seen |= SEEN_XREG | SEEN_RET0;
 383                 /* ltr %r12,%r12 */
 384                 EMIT2(0x12cc);
 385                 /* jz <ret0> */
 386                 EMIT4_PCREL(0xa7840000, (jit->ret0_ip - jit->prg));
 387                 /* lhi %r4,0 */
 388                 EMIT4(0xa7480000);
 389                 /* dlr %r4,%r12 */
 390                 EMIT4(0xb997004c);
 391                 /* lr %r5,%r4 */
 392                 EMIT2(0x1854);
 393                 break;
 394         case BPF_S_ALU_MOD_K: /* A %= K */
 395                 if (K == 1) {
 396                         /* lhi %r5,0 */
 397                         EMIT4(0xa7580000);
 398                         break;
 399                 }
 400                 /* lhi %r4,0 */
 401                 EMIT4(0xa7480000);
 402                 /* dl %r4,<d(K)>(%r13) */
 403                 EMIT6_DISP(0xe340d000, 0x0097, EMIT_CONST(K));
 404                 /* lr %r5,%r4 */
 405                 EMIT2(0x1854);
 406                 break;
 407         case BPF_S_ALU_AND_X: /* A &= X */
 408                 jit->seen |= SEEN_XREG;
 409                 /* nr %r5,%r12 */
 410                 EMIT2(0x145c);
 411                 break;
 412         case BPF_S_ALU_AND_K: /* A &= K */
 413                 if (test_facility(21))
 414                         /* nilf %r5,<K> */
 415                         EMIT6_IMM(0xc05b0000, K);
 416                 else
 417                         /* n %r5,<d(K)>(%r13) */
 418                         EMIT4_DISP(0x5450d000, EMIT_CONST(K));
 419                 break;
 420         case BPF_S_ALU_OR_X: /* A |= X */
 421                 jit->seen |= SEEN_XREG;
 422                 /* or %r5,%r12 */
 423                 EMIT2(0x165c);
 424                 break;
 425         case BPF_S_ALU_OR_K: /* A |= K */
 426                 if (test_facility(21))
 427                         /* oilf %r5,<K> */
 428                         EMIT6_IMM(0xc05d0000, K);
 429                 else
 430                         /* o %r5,<d(K)>(%r13) */
 431                         EMIT4_DISP(0x5650d000, EMIT_CONST(K));
 432                 break;
 433         case BPF_S_ANC_ALU_XOR_X: /* A ^= X; */
 434         case BPF_S_ALU_XOR_X:
 435                 jit->seen |= SEEN_XREG;
 436                 /* xr %r5,%r12 */
 437                 EMIT2(0x175c);
 438                 break;
 439         case BPF_S_ALU_XOR_K: /* A ^= K */
 440                 if (!K)
 441                         break;
 442                 /* x %r5,<d(K)>(%r13) */
 443                 EMIT4_DISP(0x5750d000, EMIT_CONST(K));
 444                 break;
 445         case BPF_S_ALU_LSH_X: /* A <<= X; */
 446                 jit->seen |= SEEN_XREG;
 447                 /* sll %r5,0(%r12) */
 448                 EMIT4(0x8950c000);
 449                 break;
 450         case BPF_S_ALU_LSH_K: /* A <<= K */
 451                 if (K == 0)
 452                         break;
 453                 /* sll %r5,K */
 454                 EMIT4_DISP(0x89500000, K);
 455                 break;
 456         case BPF_S_ALU_RSH_X: /* A >>= X; */
 457                 jit->seen |= SEEN_XREG;
 458                 /* srl %r5,0(%r12) */
 459                 EMIT4(0x8850c000);
 460                 break;
 461         case BPF_S_ALU_RSH_K: /* A >>= K; */
 462                 if (K == 0)
 463                         break;
 464                 /* srl %r5,K */
 465                 EMIT4_DISP(0x88500000, K);
 466                 break;
 467         case BPF_S_ALU_NEG: /* A = -A */
 468                 /* lnr %r5,%r5 */
 469                 EMIT2(0x1155);
 470                 break;
 471         case BPF_S_JMP_JA: /* ip += K */
 472                 offset = addrs[i + K] + jit->start - jit->prg;
 473                 EMIT4_PCREL(0xa7f40000, offset);
 474                 break;
 475         case BPF_S_JMP_JGT_K: /* ip += (A > K) ? jt : jf */
 476                 mask = 0x200000; /* jh */
 477                 goto kbranch;
 478         case BPF_S_JMP_JGE_K: /* ip += (A >= K) ? jt : jf */
 479                 mask = 0xa00000; /* jhe */
 480                 goto kbranch;
 481         case BPF_S_JMP_JEQ_K: /* ip += (A == K) ? jt : jf */
 482                 mask = 0x800000; /* je */
 483 kbranch:        /* Emit compare if the branch targets are different */
 484                 if (filter->jt != filter->jf) {
 485                         if (K <= 16383)
 486                                 /* chi %r5,<K> */
 487                                 EMIT4_IMM(0xa75e0000, K);
 488                         else if (test_facility(21))
 489                                 /* clfi %r5,<K> */
 490                                 EMIT6_IMM(0xc25f0000, K);
 491                         else
 492                                 /* c %r5,<d(K)>(%r13) */
 493                                 EMIT4_DISP(0x5950d000, EMIT_CONST(K));
 494                 }
 495 branch:         if (filter->jt == filter->jf) {
 496                         if (filter->jt == 0)
 497                                 break;
 498                         /* j <jt> */
 499                         offset = addrs[i + filter->jt] + jit->start - jit->prg;
 500                         EMIT4_PCREL(0xa7f40000, offset);
 501                         break;
 502                 }
 503                 if (filter->jt != 0) {
 504                         /* brc  <mask>,<jt> */
 505                         offset = addrs[i + filter->jt] + jit->start - jit->prg;
 506                         EMIT4_PCREL(0xa7040000 | mask, offset);
 507                 }
 508                 if (filter->jf != 0) {
 509                         /* brc  <mask^15>,<jf> */
 510                         offset = addrs[i + filter->jf] + jit->start - jit->prg;
 511                         EMIT4_PCREL(0xa7040000 | (mask ^ 0xf00000), offset);
 512                 }
 513                 break;
 514         case BPF_S_JMP_JSET_K: /* ip += (A & K) ? jt : jf */
 515                 mask = 0x700000; /* jnz */
 516                 /* Emit test if the branch targets are different */
 517                 if (filter->jt != filter->jf) {
 518                         if (K > 65535) {
 519                                 /* lr %r4,%r5 */
 520                                 EMIT2(0x1845);
 521                                 /* n %r4,<d(K)>(%r13) */
 522                                 EMIT4_DISP(0x5440d000, EMIT_CONST(K));
 523                         } else
 524                                 /* tmll %r5,K */
 525                                 EMIT4_IMM(0xa7510000, K);
 526                 }
 527                 goto branch;
 528         case BPF_S_JMP_JGT_X: /* ip += (A > X) ? jt : jf */
 529                 mask = 0x200000; /* jh */
 530                 goto xbranch;
 531         case BPF_S_JMP_JGE_X: /* ip += (A >= X) ? jt : jf */
 532                 mask = 0xa00000; /* jhe */
 533                 goto xbranch;
 534         case BPF_S_JMP_JEQ_X: /* ip += (A == X) ? jt : jf */
 535                 mask = 0x800000; /* je */
 536 xbranch:        /* Emit compare if the branch targets are different */
 537                 if (filter->jt != filter->jf) {
 538                         jit->seen |= SEEN_XREG;
 539                         /* cr %r5,%r12 */
 540                         EMIT2(0x195c);
 541                 }
 542                 goto branch;
 543         case BPF_S_JMP_JSET_X: /* ip += (A & X) ? jt : jf */
 544                 mask = 0x700000; /* jnz */
 545                 /* Emit test if the branch targets are different */
 546                 if (filter->jt != filter->jf) {
 547                         jit->seen |= SEEN_XREG;
 548                         /* lr %r4,%r5 */
 549                         EMIT2(0x1845);
 550                         /* nr %r4,%r12 */
 551                         EMIT2(0x144c);
 552                 }
 553                 goto branch;
 554         case BPF_S_LD_W_ABS: /* A = *(u32 *) (skb->data+K) */
 555                 jit->seen |= SEEN_DATAREF | SEEN_RET0 | SEEN_LOAD_WORD;
 556                 offset = jit->off_load_word;
 557                 goto load_abs;
 558         case BPF_S_LD_H_ABS: /* A = *(u16 *) (skb->data+K) */
 559                 jit->seen |= SEEN_DATAREF | SEEN_RET0 | SEEN_LOAD_HALF;
 560                 offset = jit->off_load_half;
 561                 goto load_abs;
 562         case BPF_S_LD_B_ABS: /* A = *(u8 *) (skb->data+K) */
 563                 jit->seen |= SEEN_DATAREF | SEEN_RET0 | SEEN_LOAD_BYTE;
 564                 offset = jit->off_load_byte;
 565 load_abs:       if ((int) K < 0)
 566                         goto out;
 567 call_fn:        /* lg %r1,<d(function)>(%r13) */
 568                 EMIT6_DISP(0xe310d000, 0x0004, offset);
 569                 /* l %r3,<d(K)>(%r13) */
 570                 EMIT4_DISP(0x5830d000, EMIT_CONST(K));
 571                 /* basr %r8,%r1 */
 572                 EMIT2(0x0d81);
 573                 /* jnz <ret0> */
 574                 EMIT4_PCREL(0xa7740000, (jit->ret0_ip - jit->prg));
 575                 break;
 576         case BPF_S_LD_W_IND: /* A = *(u32 *) (skb->data+K+X) */
 577                 jit->seen |= SEEN_DATAREF | SEEN_RET0 | SEEN_LOAD_IWORD;
 578                 offset = jit->off_load_iword;
 579                 goto call_fn;
 580         case BPF_S_LD_H_IND: /* A = *(u16 *) (skb->data+K+X) */
 581                 jit->seen |= SEEN_DATAREF | SEEN_RET0 | SEEN_LOAD_IHALF;
 582                 offset = jit->off_load_ihalf;
 583                 goto call_fn;
 584         case BPF_S_LD_B_IND: /* A = *(u8 *) (skb->data+K+X) */
 585                 jit->seen |= SEEN_DATAREF | SEEN_RET0 | SEEN_LOAD_IBYTE;
 586                 offset = jit->off_load_ibyte;
 587                 goto call_fn;
 588         case BPF_S_LDX_B_MSH:
 589                 /* X = (*(u8 *)(skb->data+K) & 0xf) << 2 */
 590                 jit->seen |= SEEN_RET0;
 591                 if ((int) K < 0) {
 592                         /* j <ret0> */
 593                         EMIT4_PCREL(0xa7f40000, (jit->ret0_ip - jit->prg));
 594                         break;
 595                 }
 596                 jit->seen |= SEEN_DATAREF | SEEN_LOAD_BMSH;
 597                 offset = jit->off_load_bmsh;
 598                 goto call_fn;
 599         case BPF_S_LD_W_LEN: /* A = skb->len; */
 600                 BUILD_BUG_ON(FIELD_SIZEOF(struct sk_buff, len) != 4);
 601                 /* l %r5,<d(len)>(%r2) */
 602                 EMIT4_DISP(0x58502000, offsetof(struct sk_buff, len));
 603                 break;
 604         case BPF_S_LDX_W_LEN: /* X = skb->len; */
 605                 jit->seen |= SEEN_XREG;
 606                 /* l %r12,<d(len)>(%r2) */
 607                 EMIT4_DISP(0x58c02000, offsetof(struct sk_buff, len));
 608                 break;
 609         case BPF_S_LD_IMM: /* A = K */
 610                 if (K <= 16383)
 611                         /* lhi %r5,K */
 612                         EMIT4_IMM(0xa7580000, K);
 613                 else if (test_facility(21))
 614                         /* llilf %r5,<K> */
 615                         EMIT6_IMM(0xc05f0000, K);
 616                 else
 617                         /* l %r5,<d(K)>(%r13) */
 618                         EMIT4_DISP(0x5850d000, EMIT_CONST(K));
 619                 break;
 620         case BPF_S_LDX_IMM: /* X = K */
 621                 jit->seen |= SEEN_XREG;
 622                 if (K <= 16383)
 623                         /* lhi %r12,<K> */
 624                         EMIT4_IMM(0xa7c80000, K);
 625                 else if (test_facility(21))
 626                         /* llilf %r12,<K> */
 627                         EMIT6_IMM(0xc0cf0000, K);
 628                 else
 629                         /* l %r12,<d(K)>(%r13) */
 630                         EMIT4_DISP(0x58c0d000, EMIT_CONST(K));
 631                 break;
 632         case BPF_S_LD_MEM: /* A = mem[K] */
 633                 jit->seen |= SEEN_MEM;
 634                 /* l %r5,<K>(%r15) */
 635                 EMIT4_DISP(0x5850f000,
 636                            (jit->seen & SEEN_DATAREF) ? 160 + K*4 : K*4);
 637                 break;
 638         case BPF_S_LDX_MEM: /* X = mem[K] */
 639                 jit->seen |= SEEN_XREG | SEEN_MEM;
 640                 /* l %r12,<K>(%r15) */
 641                 EMIT4_DISP(0x58c0f000,
 642                            (jit->seen & SEEN_DATAREF) ? 160 + K*4 : K*4);
 643                 break;
 644         case BPF_S_MISC_TAX: /* X = A */
 645                 jit->seen |= SEEN_XREG;
 646                 /* lr %r12,%r5 */
 647                 EMIT2(0x18c5);
 648                 break;
 649         case BPF_S_MISC_TXA: /* A = X */
 650                 jit->seen |= SEEN_XREG;
 651                 /* lr %r5,%r12 */
 652                 EMIT2(0x185c);
 653                 break;
 654         case BPF_S_RET_K:
 655                 if (K == 0) {
 656                         jit->seen |= SEEN_RET0;
 657                         if (last)
 658                                 break;
 659                         /* j <ret0> */
 660                         EMIT4_PCREL(0xa7f40000, jit->ret0_ip - jit->prg);
 661                 } else {
 662                         if (K <= 16383)
 663                                 /* lghi %r2,K */
 664                                 EMIT4_IMM(0xa7290000, K);
 665                         else
 666                                 /* llgf %r2,<K>(%r13) */
 667                                 EMIT6_DISP(0xe320d000, 0x0016, EMIT_CONST(K));
 668                         /* j <exit> */
 669                         if (last && !(jit->seen & SEEN_RET0))
 670                                 break;
 671                         EMIT4_PCREL(0xa7f40000, jit->exit_ip - jit->prg);
 672                 }
 673                 break;
 674         case BPF_S_RET_A:
 675                 /* llgfr %r2,%r5 */
 676                 EMIT4(0xb9160025);
 677                 /* j <exit> */
 678                 EMIT4_PCREL(0xa7f40000, jit->exit_ip - jit->prg);
 679                 break;
 680         case BPF_S_ST: /* mem[K] = A */
 681                 jit->seen |= SEEN_MEM;
 682                 /* st %r5,<K>(%r15) */
 683                 EMIT4_DISP(0x5050f000,
 684                            (jit->seen & SEEN_DATAREF) ? 160 + K*4 : K*4);
 685                 break;
 686         case BPF_S_STX: /* mem[K] = X : mov %ebx,off8(%rbp) */
 687                 jit->seen |= SEEN_XREG | SEEN_MEM;
 688                 /* st %r12,<K>(%r15) */
 689                 EMIT4_DISP(0x50c0f000,
 690                            (jit->seen & SEEN_DATAREF) ? 160 + K*4 : K*4);
 691                 break;
 692         case BPF_S_ANC_PROTOCOL: /* A = ntohs(skb->protocol); */
 693                 BUILD_BUG_ON(FIELD_SIZEOF(struct sk_buff, protocol) != 2);
 694                 /* lhi %r5,0 */
 695                 EMIT4(0xa7580000);
 696                 /* icm  %r5,3,<d(protocol)>(%r2) */
 697                 EMIT4_DISP(0xbf532000, offsetof(struct sk_buff, protocol));
 698                 break;
 699         case BPF_S_ANC_IFINDEX: /* if (!skb->dev) return 0;
 700                                  * A = skb->dev->ifindex */
 701                 BUILD_BUG_ON(FIELD_SIZEOF(struct net_device, ifindex) != 4);
 702                 jit->seen |= SEEN_RET0;
 703                 /* lg %r1,<d(dev)>(%r2) */
 704                 EMIT6_DISP(0xe3102000, 0x0004, offsetof(struct sk_buff, dev));
 705                 /* ltgr %r1,%r1 */
 706                 EMIT4(0xb9020011);
 707                 /* jz <ret0> */
 708                 EMIT4_PCREL(0xa7840000, jit->ret0_ip - jit->prg);
 709                 /* l %r5,<d(ifindex)>(%r1) */
 710                 EMIT4_DISP(0x58501000, offsetof(struct net_device, ifindex));
 711                 break;
 712         case BPF_S_ANC_MARK: /* A = skb->mark */
 713                 BUILD_BUG_ON(FIELD_SIZEOF(struct sk_buff, mark) != 4);
 714                 /* l %r5,<d(mark)>(%r2) */
 715                 EMIT4_DISP(0x58502000, offsetof(struct sk_buff, mark));
 716                 break;
 717         case BPF_S_ANC_QUEUE: /* A = skb->queue_mapping */
 718                 BUILD_BUG_ON(FIELD_SIZEOF(struct sk_buff, queue_mapping) != 2);
 719                 /* lhi %r5,0 */
 720                 EMIT4(0xa7580000);
 721                 /* icm  %r5,3,<d(queue_mapping)>(%r2) */
 722                 EMIT4_DISP(0xbf532000, offsetof(struct sk_buff, queue_mapping));
 723                 break;
 724         case BPF_S_ANC_HATYPE:  /* if (!skb->dev) return 0;
 725                                  * A = skb->dev->type */
 726                 BUILD_BUG_ON(FIELD_SIZEOF(struct net_device, type) != 2);
 727                 jit->seen |= SEEN_RET0;
 728                 /* lg %r1,<d(dev)>(%r2) */
 729                 EMIT6_DISP(0xe3102000, 0x0004, offsetof(struct sk_buff, dev));
 730                 /* ltgr %r1,%r1 */
 731                 EMIT4(0xb9020011);
 732                 /* jz <ret0> */
 733                 EMIT4_PCREL(0xa7840000, jit->ret0_ip - jit->prg);
 734                 /* lhi %r5,0 */
 735                 EMIT4(0xa7580000);
 736                 /* icm  %r5,3,<d(type)>(%r1) */
 737                 EMIT4_DISP(0xbf531000, offsetof(struct net_device, type));
 738                 break;
 739         case BPF_S_ANC_RXHASH: /* A = skb->hash */
 740                 BUILD_BUG_ON(FIELD_SIZEOF(struct sk_buff, hash) != 4);
 741                 /* l %r5,<d(hash)>(%r2) */
 742                 EMIT4_DISP(0x58502000, offsetof(struct sk_buff, hash));
 743                 break;
 744         case BPF_S_ANC_VLAN_TAG:
 745         case BPF_S_ANC_VLAN_TAG_PRESENT:
 746                 BUILD_BUG_ON(FIELD_SIZEOF(struct sk_buff, vlan_tci) != 2);
 747                 BUILD_BUG_ON(VLAN_TAG_PRESENT != 0x1000);
 748                 /* lhi %r5,0 */
 749                 EMIT4(0xa7580000);
 750                 /* icm  %r5,3,<d(vlan_tci)>(%r2) */
 751                 EMIT4_DISP(0xbf532000, offsetof(struct sk_buff, vlan_tci));
 752                 if (filter->code == BPF_S_ANC_VLAN_TAG) {
 753                         /* nill %r5,0xefff */
 754                         EMIT4_IMM(0xa5570000, ~VLAN_TAG_PRESENT);
 755                 } else {
 756                         /* nill %r5,0x1000 */
 757                         EMIT4_IMM(0xa5570000, VLAN_TAG_PRESENT);
 758                         /* srl %r5,12 */
 759                         EMIT4_DISP(0x88500000, 12);
 760                 }
 761                 break;
 762         case BPF_S_ANC_PKTTYPE:
 763                 if (pkt_type_offset < 0)
 764                         goto out;
 765                 /* lhi %r5,0 */
 766                 EMIT4(0xa7580000);
 767                 /* ic %r5,<d(pkt_type_offset)>(%r2) */
 768                 EMIT4_DISP(0x43502000, pkt_type_offset);
 769                 /* srl %r5,5 */
 770                 EMIT4_DISP(0x88500000, 5);
 771                 break;
 772         case BPF_S_ANC_CPU: /* A = smp_processor_id() */
 773 #ifdef CONFIG_SMP
 774                 /* l %r5,<d(cpu_nr)> */
 775                 EMIT4_DISP(0x58500000, offsetof(struct _lowcore, cpu_nr));
 776 #else
 777                 /* lhi %r5,0 */
 778                 EMIT4(0xa7580000);
 779 #endif
 780                 break;
 781         default: /* too complex, give up */
 782                 goto out;
 783         }
 784         addrs[i] = jit->prg - jit->start;
 785         return 0;
 786 out:
 787         return -1;
 788 }
 789
 790 /*
 791  * Note: for security reasons, bpf code will follow a randomly
 792  *       sized amount of illegal instructions.
 793  */
 794 struct bpf_binary_header {
 795         unsigned int pages;
 796         u8 image[];
 797 };
 798
 799 static struct bpf_binary_header *bpf_alloc_binary(unsigned int bpfsize,
 800                                                   u8 **image_ptr)
 801 {
 802         struct bpf_binary_header *header;
 803         unsigned int sz, hole;
 804
 805         /* Most BPF filters are really small, but if some of them fill a page,
 806          * allow at least 128 extra bytes for illegal instructions.
 807          */
 808         sz = round_up(bpfsize + sizeof(*header) + 128, PAGE_SIZE);
 809         header = module_alloc(sz);
 810         if (!header)
 811                 return NULL;
 812         memset(header, 0, sz);
 813         header->pages = sz / PAGE_SIZE;
 814         hole = min(sz - (bpfsize + sizeof(*header)), PAGE_SIZE - sizeof(*header));
 815         /* Insert random number of illegal instructions before BPF code
 816          * and make sure the first instruction starts at an even address.
 817          */
 818         *image_ptr = &header->image[(prandom_u32() % hole) & -2];
 819         return header;
 820 }
 821
 822 void bpf_jit_compile(struct sk_filter *fp)
 823 {
 824         struct bpf_binary_header *header = NULL;
 825         unsigned long size, prg_len, lit_len;
 826         struct bpf_jit jit, cjit;
 827         unsigned int *addrs;
 828         int pass, i;
 829
 830         if (!bpf_jit_enable)
 831                 return;
 832         addrs = kcalloc(fp->len, sizeof(*addrs), GFP_KERNEL);
 833         if (addrs == NULL)
 834                 return;
 835         memset(&jit, 0, sizeof(cjit));
 836         memset(&cjit, 0, sizeof(cjit));
 837
 838         for (pass = 0; pass < 10; pass++) {
 839                 jit.prg = jit.start;
 840                 jit.lit = jit.mid;
 841
 842                 bpf_jit_prologue(&jit);
 843                 bpf_jit_noleaks(&jit, fp->insns);
 844                 for (i = 0; i < fp->len; i++) {
 845                         if (bpf_jit_insn(&jit, fp->insns + i, addrs, i,
 846                                          i == fp->len - 1))
 847                                 goto out;
 848                 }
 849                 bpf_jit_epilogue(&jit);
 850                 if (jit.start) {
 851                         WARN_ON(jit.prg > cjit.prg || jit.lit > cjit.lit);
 852                         if (memcmp(&jit, &cjit, sizeof(jit)) == 0)
 853                                 break;
 854                 } else if (jit.prg == cjit.prg && jit.lit == cjit.lit) {
 855                         prg_len = jit.prg - jit.start;
 856                         lit_len = jit.lit - jit.mid;
 857                         size = prg_len + lit_len;
 858                         if (size >= BPF_SIZE_MAX)
 859                                 goto out;
 860                         header = bpf_alloc_binary(size, &jit.start);
 861                         if (!header)
 862                                 goto out;
 863                         jit.prg = jit.mid = jit.start + prg_len;
 864                         jit.lit = jit.end = jit.start + prg_len + lit_len;
 865                         jit.base_ip += (unsigned long) jit.start;
 866                         jit.exit_ip += (unsigned long) jit.start;
 867                         jit.ret0_ip += (unsigned long) jit.start;
 868                 }
 869                 cjit = jit;
 870         }
 871         if (bpf_jit_enable > 1) {
 872                 bpf_jit_dump(fp->len, jit.end - jit.start, pass, jit.start);
 873                 if (jit.start)
 874                         print_fn_code(jit.start, jit.mid - jit.start);
 875         }
 876         if (jit.start) {
 877                 set_memory_ro((unsigned long)header, header->pages);
 878                 fp->bpf_func = (void *) jit.start;
 879                 fp->jited = 1;
 880         }
 881 out:
 882         kfree(addrs);
 883 }
 884
 885 void bpf_jit_free(struct sk_filter *fp)
 886 {
 887         unsigned long addr = (unsigned long)fp->bpf_func & PAGE_MASK;
 888         struct bpf_binary_header *header = (void *)addr;
 889
 890         if (!fp->jited)
 891                 goto free_filter;
 892
 893         set_memory_rw(addr, header->pages);
 894         module_free(NULL, header);
 895
 896 free_filter:
 897         kfree(fp);
 898 }