LXR linux/arch/s390/net/bpf_jit

   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 */
  32int bpf_jit_enable __read_mostly;
  33
  34/*
  35 * assembly code in arch/x86/net/bpf_jit.S
  36 */
  37extern u8 sk_load_word[], sk_load_half[], sk_load_byte[], sk_load_byte_msh[];
  38extern u8 sk_load_word_ind[], sk_load_half_ind[], sk_load_byte_ind[];
  39
  40struct 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
 151static 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
 199static 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
 230static int pkt_type_offset;
 231
 232static 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}
 255device_initcall(bpf_pkt_type_offset_init);
 256
 257/*
 258 * make sure we dont leak kernel information to user
 259 */
 260static 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
 301static 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 */
 483kbranch:        /* 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                }
 495branch:         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 */
 536xbranch:        /* 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;
 565load_abs:       if ((int) K < 0)
 566                        goto out;
 567call_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;
 786out:
 787        return -1;
 788}
 789
 790/*
 791 * Note: for security reasons, bpf code will follow a randomly
 792 *       sized amount of illegal instructions.
 793 */
 794struct bpf_binary_header {
 795        unsigned int pages;
 796        u8 image[];
 797};
 798
 799static 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
 822void 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        }
 881out:
 882        kfree(addrs);
 883}
 884
 885void 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
 896free_filter:
 897        kfree(fp);
 898}
 899