linux/arch/x86/net/bpf_jit_comp.c
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   1/* bpf_jit_comp.c : BPF JIT compiler
   2 *
   3 * Copyright (C) 2011 Eric Dumazet (eric.dumazet@gmail.com)
   4 *
   5 * This program is free software; you can redistribute it and/or
   6 * modify it under the terms of the GNU General Public License
   7 * as published by the Free Software Foundation; version 2
   8 * of the License.
   9 */
  10#include <linux/moduleloader.h>
  11#include <asm/cacheflush.h>
  12#include <linux/netdevice.h>
  13#include <linux/filter.h>
  14
  15/*
  16 * Conventions :
  17 *  EAX : BPF A accumulator
  18 *  EBX : BPF X accumulator
  19 *  RDI : pointer to skb   (first argument given to JIT function)
  20 *  RBP : frame pointer (even if CONFIG_FRAME_POINTER=n)
  21 *  ECX,EDX,ESI : scratch registers
  22 *  r9d : skb->len - skb->data_len (headlen)
  23 *  r8  : skb->data
  24 * -8(RBP) : saved RBX value
  25 * -16(RBP)..-80(RBP) : BPF_MEMWORDS values
  26 */
  27int bpf_jit_enable __read_mostly;
  28
  29/*
  30 * assembly code in arch/x86/net/bpf_jit.S
  31 */
  32extern u8 sk_load_word[], sk_load_half[], sk_load_byte[], sk_load_byte_msh[];
  33extern u8 sk_load_word_positive_offset[], sk_load_half_positive_offset[];
  34extern u8 sk_load_byte_positive_offset[], sk_load_byte_msh_positive_offset[];
  35extern u8 sk_load_word_negative_offset[], sk_load_half_negative_offset[];
  36extern u8 sk_load_byte_negative_offset[], sk_load_byte_msh_negative_offset[];
  37
  38static inline u8 *emit_code(u8 *ptr, u32 bytes, unsigned int len)
  39{
  40        if (len == 1)
  41                *ptr = bytes;
  42        else if (len == 2)
  43                *(u16 *)ptr = bytes;
  44        else {
  45                *(u32 *)ptr = bytes;
  46                barrier();
  47        }
  48        return ptr + len;
  49}
  50
  51#define EMIT(bytes, len)        do { prog = emit_code(prog, bytes, len); } while (0)
  52
  53#define EMIT1(b1)               EMIT(b1, 1)
  54#define EMIT2(b1, b2)           EMIT((b1) + ((b2) << 8), 2)
  55#define EMIT3(b1, b2, b3)       EMIT((b1) + ((b2) << 8) + ((b3) << 16), 3)
  56#define EMIT4(b1, b2, b3, b4)   EMIT((b1) + ((b2) << 8) + ((b3) << 16) + ((b4) << 24), 4)
  57#define EMIT1_off32(b1, off)    do { EMIT1(b1); EMIT(off, 4);} while (0)
  58
  59#define CLEAR_A() EMIT2(0x31, 0xc0) /* xor %eax,%eax */
  60#define CLEAR_X() EMIT2(0x31, 0xdb) /* xor %ebx,%ebx */
  61
  62static inline bool is_imm8(int value)
  63{
  64        return value <= 127 && value >= -128;
  65}
  66
  67static inline bool is_near(int offset)
  68{
  69        return offset <= 127 && offset >= -128;
  70}
  71
  72#define EMIT_JMP(offset)                                                \
  73do {                                                                    \
  74        if (offset) {                                                   \
  75                if (is_near(offset))                                    \
  76                        EMIT2(0xeb, offset); /* jmp .+off8 */           \
  77                else                                                    \
  78                        EMIT1_off32(0xe9, offset); /* jmp .+off32 */    \
  79        }                                                               \
  80} while (0)
  81
  82/* list of x86 cond jumps opcodes (. + s8)
  83 * Add 0x10 (and an extra 0x0f) to generate far jumps (. + s32)
  84 */
  85#define X86_JB  0x72
  86#define X86_JAE 0x73
  87#define X86_JE  0x74
  88#define X86_JNE 0x75
  89#define X86_JBE 0x76
  90#define X86_JA  0x77
  91
  92#define EMIT_COND_JMP(op, offset)                               \
  93do {                                                            \
  94        if (is_near(offset))                                    \
  95                EMIT2(op, offset); /* jxx .+off8 */             \
  96        else {                                                  \
  97                EMIT2(0x0f, op + 0x10);                         \
  98                EMIT(offset, 4); /* jxx .+off32 */              \
  99        }                                                       \
 100} while (0)
 101
 102#define COND_SEL(CODE, TOP, FOP)        \
 103        case CODE:                      \
 104                t_op = TOP;             \
 105                f_op = FOP;             \
 106                goto cond_branch
 107
 108
 109#define SEEN_DATAREF 1 /* might call external helpers */
 110#define SEEN_XREG    2 /* ebx is used */
 111#define SEEN_MEM     4 /* use mem[] for temporary storage */
 112
 113static inline void bpf_flush_icache(void *start, void *end)
 114{
 115        mm_segment_t old_fs = get_fs();
 116
 117        set_fs(KERNEL_DS);
 118        smp_wmb();
 119        flush_icache_range((unsigned long)start, (unsigned long)end);
 120        set_fs(old_fs);
 121}
 122
 123#define CHOOSE_LOAD_FUNC(K, func) \
 124        ((int)K < 0 ? ((int)K >= SKF_LL_OFF ? func##_negative_offset : func) : func##_positive_offset)
 125
 126void bpf_jit_compile(struct sk_filter *fp)
 127{
 128        u8 temp[64];
 129        u8 *prog;
 130        unsigned int proglen, oldproglen = 0;
 131        int ilen, i;
 132        int t_offset, f_offset;
 133        u8 t_op, f_op, seen = 0, pass;
 134        u8 *image = NULL;
 135        u8 *func;
 136        int pc_ret0 = -1; /* bpf index of first RET #0 instruction (if any) */
 137        unsigned int cleanup_addr; /* epilogue code offset */
 138        unsigned int *addrs;
 139        const struct sock_filter *filter = fp->insns;
 140        int flen = fp->len;
 141
 142        if (!bpf_jit_enable)
 143                return;
 144
 145        addrs = kmalloc(flen * sizeof(*addrs), GFP_KERNEL);
 146        if (addrs == NULL)
 147                return;
 148
 149        /* Before first pass, make a rough estimation of addrs[]
 150         * each bpf instruction is translated to less than 64 bytes
 151         */
 152        for (proglen = 0, i = 0; i < flen; i++) {
 153                proglen += 64;
 154                addrs[i] = proglen;
 155        }
 156        cleanup_addr = proglen; /* epilogue address */
 157
 158        for (pass = 0; pass < 10; pass++) {
 159                u8 seen_or_pass0 = (pass == 0) ? (SEEN_XREG | SEEN_DATAREF | SEEN_MEM) : seen;
 160                /* no prologue/epilogue for trivial filters (RET something) */
 161                proglen = 0;
 162                prog = temp;
 163
 164                if (seen_or_pass0) {
 165                        EMIT4(0x55, 0x48, 0x89, 0xe5); /* push %rbp; mov %rsp,%rbp */
 166                        EMIT4(0x48, 0x83, 0xec, 96);    /* subq  $96,%rsp       */
 167                        /* note : must save %rbx in case bpf_error is hit */
 168                        if (seen_or_pass0 & (SEEN_XREG | SEEN_DATAREF))
 169                                EMIT4(0x48, 0x89, 0x5d, 0xf8); /* mov %rbx, -8(%rbp) */
 170                        if (seen_or_pass0 & SEEN_XREG)
 171                                CLEAR_X(); /* make sure we dont leek kernel memory */
 172
 173                        /*
 174                         * If this filter needs to access skb data,
 175                         * loads r9 and r8 with :
 176                         *  r9 = skb->len - skb->data_len
 177                         *  r8 = skb->data
 178                         */
 179                        if (seen_or_pass0 & SEEN_DATAREF) {
 180                                if (offsetof(struct sk_buff, len) <= 127)
 181                                        /* mov    off8(%rdi),%r9d */
 182                                        EMIT4(0x44, 0x8b, 0x4f, offsetof(struct sk_buff, len));
 183                                else {
 184                                        /* mov    off32(%rdi),%r9d */
 185                                        EMIT3(0x44, 0x8b, 0x8f);
 186                                        EMIT(offsetof(struct sk_buff, len), 4);
 187                                }
 188                                if (is_imm8(offsetof(struct sk_buff, data_len)))
 189                                        /* sub    off8(%rdi),%r9d */
 190                                        EMIT4(0x44, 0x2b, 0x4f, offsetof(struct sk_buff, data_len));
 191                                else {
 192                                        EMIT3(0x44, 0x2b, 0x8f);
 193                                        EMIT(offsetof(struct sk_buff, data_len), 4);
 194                                }
 195
 196                                if (is_imm8(offsetof(struct sk_buff, data)))
 197                                        /* mov off8(%rdi),%r8 */
 198                                        EMIT4(0x4c, 0x8b, 0x47, offsetof(struct sk_buff, data));
 199                                else {
 200                                        /* mov off32(%rdi),%r8 */
 201                                        EMIT3(0x4c, 0x8b, 0x87);
 202                                        EMIT(offsetof(struct sk_buff, data), 4);
 203                                }
 204                        }
 205                }
 206
 207                switch (filter[0].code) {
 208                case BPF_S_RET_K:
 209                case BPF_S_LD_W_LEN:
 210                case BPF_S_ANC_PROTOCOL:
 211                case BPF_S_ANC_IFINDEX:
 212                case BPF_S_ANC_MARK:
 213                case BPF_S_ANC_RXHASH:
 214                case BPF_S_ANC_CPU:
 215                case BPF_S_ANC_QUEUE:
 216                case BPF_S_LD_W_ABS:
 217                case BPF_S_LD_H_ABS:
 218                case BPF_S_LD_B_ABS:
 219                        /* first instruction sets A register (or is RET 'constant') */
 220                        break;
 221                default:
 222                        /* make sure we dont leak kernel information to user */
 223                        CLEAR_A(); /* A = 0 */
 224                }
 225
 226                for (i = 0; i < flen; i++) {
 227                        unsigned int K = filter[i].k;
 228
 229                        switch (filter[i].code) {
 230                        case BPF_S_ALU_ADD_X: /* A += X; */
 231                                seen |= SEEN_XREG;
 232                                EMIT2(0x01, 0xd8);              /* add %ebx,%eax */
 233                                break;
 234                        case BPF_S_ALU_ADD_K: /* A += K; */
 235                                if (!K)
 236                                        break;
 237                                if (is_imm8(K))
 238                                        EMIT3(0x83, 0xc0, K);   /* add imm8,%eax */
 239                                else
 240                                        EMIT1_off32(0x05, K);   /* add imm32,%eax */
 241                                break;
 242                        case BPF_S_ALU_SUB_X: /* A -= X; */
 243                                seen |= SEEN_XREG;
 244                                EMIT2(0x29, 0xd8);              /* sub    %ebx,%eax */
 245                                break;
 246                        case BPF_S_ALU_SUB_K: /* A -= K */
 247                                if (!K)
 248                                        break;
 249                                if (is_imm8(K))
 250                                        EMIT3(0x83, 0xe8, K); /* sub imm8,%eax */
 251                                else
 252                                        EMIT1_off32(0x2d, K); /* sub imm32,%eax */
 253                                break;
 254                        case BPF_S_ALU_MUL_X: /* A *= X; */
 255                                seen |= SEEN_XREG;
 256                                EMIT3(0x0f, 0xaf, 0xc3);        /* imul %ebx,%eax */
 257                                break;
 258                        case BPF_S_ALU_MUL_K: /* A *= K */
 259                                if (is_imm8(K))
 260                                        EMIT3(0x6b, 0xc0, K); /* imul imm8,%eax,%eax */
 261                                else {
 262                                        EMIT2(0x69, 0xc0);              /* imul imm32,%eax */
 263                                        EMIT(K, 4);
 264                                }
 265                                break;
 266                        case BPF_S_ALU_DIV_X: /* A /= X; */
 267                                seen |= SEEN_XREG;
 268                                EMIT2(0x85, 0xdb);      /* test %ebx,%ebx */
 269                                if (pc_ret0 > 0) {
 270                                        /* addrs[pc_ret0 - 1] is start address of target
 271                                         * (addrs[i] - 4) is the address following this jmp
 272                                         * ("xor %edx,%edx; div %ebx" being 4 bytes long)
 273                                         */
 274                                        EMIT_COND_JMP(X86_JE, addrs[pc_ret0 - 1] -
 275                                                                (addrs[i] - 4));
 276                                } else {
 277                                        EMIT_COND_JMP(X86_JNE, 2 + 5);
 278                                        CLEAR_A();
 279                                        EMIT1_off32(0xe9, cleanup_addr - (addrs[i] - 4)); /* jmp .+off32 */
 280                                }
 281                                EMIT4(0x31, 0xd2, 0xf7, 0xf3); /* xor %edx,%edx; div %ebx */
 282                                break;
 283                        case BPF_S_ALU_DIV_K: /* A = reciprocal_divide(A, K); */
 284                                EMIT3(0x48, 0x69, 0xc0); /* imul imm32,%rax,%rax */
 285                                EMIT(K, 4);
 286                                EMIT4(0x48, 0xc1, 0xe8, 0x20); /* shr $0x20,%rax */
 287                                break;
 288                        case BPF_S_ALU_AND_X:
 289                                seen |= SEEN_XREG;
 290                                EMIT2(0x21, 0xd8);              /* and %ebx,%eax */
 291                                break;
 292                        case BPF_S_ALU_AND_K:
 293                                if (K >= 0xFFFFFF00) {
 294                                        EMIT2(0x24, K & 0xFF); /* and imm8,%al */
 295                                } else if (K >= 0xFFFF0000) {
 296                                        EMIT2(0x66, 0x25);      /* and imm16,%ax */
 297                                        EMIT(K, 2);
 298                                } else {
 299                                        EMIT1_off32(0x25, K);   /* and imm32,%eax */
 300                                }
 301                                break;
 302                        case BPF_S_ALU_OR_X:
 303                                seen |= SEEN_XREG;
 304                                EMIT2(0x09, 0xd8);              /* or %ebx,%eax */
 305                                break;
 306                        case BPF_S_ALU_OR_K:
 307                                if (is_imm8(K))
 308                                        EMIT3(0x83, 0xc8, K); /* or imm8,%eax */
 309                                else
 310                                        EMIT1_off32(0x0d, K);   /* or imm32,%eax */
 311                                break;
 312                        case BPF_S_ANC_ALU_XOR_X: /* A ^= X; */
 313                                seen |= SEEN_XREG;
 314                                EMIT2(0x31, 0xd8);              /* xor %ebx,%eax */
 315                                break;
 316                        case BPF_S_ALU_LSH_X: /* A <<= X; */
 317                                seen |= SEEN_XREG;
 318                                EMIT4(0x89, 0xd9, 0xd3, 0xe0);  /* mov %ebx,%ecx; shl %cl,%eax */
 319                                break;
 320                        case BPF_S_ALU_LSH_K:
 321                                if (K == 0)
 322                                        break;
 323                                else if (K == 1)
 324                                        EMIT2(0xd1, 0xe0); /* shl %eax */
 325                                else
 326                                        EMIT3(0xc1, 0xe0, K);
 327                                break;
 328                        case BPF_S_ALU_RSH_X: /* A >>= X; */
 329                                seen |= SEEN_XREG;
 330                                EMIT4(0x89, 0xd9, 0xd3, 0xe8);  /* mov %ebx,%ecx; shr %cl,%eax */
 331                                break;
 332                        case BPF_S_ALU_RSH_K: /* A >>= K; */
 333                                if (K == 0)
 334                                        break;
 335                                else if (K == 1)
 336                                        EMIT2(0xd1, 0xe8); /* shr %eax */
 337                                else
 338                                        EMIT3(0xc1, 0xe8, K);
 339                                break;
 340                        case BPF_S_ALU_NEG:
 341                                EMIT2(0xf7, 0xd8);              /* neg %eax */
 342                                break;
 343                        case BPF_S_RET_K:
 344                                if (!K) {
 345                                        if (pc_ret0 == -1)
 346                                                pc_ret0 = i;
 347                                        CLEAR_A();
 348                                } else {
 349                                        EMIT1_off32(0xb8, K);   /* mov $imm32,%eax */
 350                                }
 351                                /* fallinto */
 352                        case BPF_S_RET_A:
 353                                if (seen_or_pass0) {
 354                                        if (i != flen - 1) {
 355                                                EMIT_JMP(cleanup_addr - addrs[i]);
 356                                                break;
 357                                        }
 358                                        if (seen_or_pass0 & SEEN_XREG)
 359                                                EMIT4(0x48, 0x8b, 0x5d, 0xf8);  /* mov  -8(%rbp),%rbx */
 360                                        EMIT1(0xc9);            /* leaveq */
 361                                }
 362                                EMIT1(0xc3);            /* ret */
 363                                break;
 364                        case BPF_S_MISC_TAX: /* X = A */
 365                                seen |= SEEN_XREG;
 366                                EMIT2(0x89, 0xc3);      /* mov    %eax,%ebx */
 367                                break;
 368                        case BPF_S_MISC_TXA: /* A = X */
 369                                seen |= SEEN_XREG;
 370                                EMIT2(0x89, 0xd8);      /* mov    %ebx,%eax */
 371                                break;
 372                        case BPF_S_LD_IMM: /* A = K */
 373                                if (!K)
 374                                        CLEAR_A();
 375                                else
 376                                        EMIT1_off32(0xb8, K); /* mov $imm32,%eax */
 377                                break;
 378                        case BPF_S_LDX_IMM: /* X = K */
 379                                seen |= SEEN_XREG;
 380                                if (!K)
 381                                        CLEAR_X();
 382                                else
 383                                        EMIT1_off32(0xbb, K); /* mov $imm32,%ebx */
 384                                break;
 385                        case BPF_S_LD_MEM: /* A = mem[K] : mov off8(%rbp),%eax */
 386                                seen |= SEEN_MEM;
 387                                EMIT3(0x8b, 0x45, 0xf0 - K*4);
 388                                break;
 389                        case BPF_S_LDX_MEM: /* X = mem[K] : mov off8(%rbp),%ebx */
 390                                seen |= SEEN_XREG | SEEN_MEM;
 391                                EMIT3(0x8b, 0x5d, 0xf0 - K*4);
 392                                break;
 393                        case BPF_S_ST: /* mem[K] = A : mov %eax,off8(%rbp) */
 394                                seen |= SEEN_MEM;
 395                                EMIT3(0x89, 0x45, 0xf0 - K*4);
 396                                break;
 397                        case BPF_S_STX: /* mem[K] = X : mov %ebx,off8(%rbp) */
 398                                seen |= SEEN_XREG | SEEN_MEM;
 399                                EMIT3(0x89, 0x5d, 0xf0 - K*4);
 400                                break;
 401                        case BPF_S_LD_W_LEN: /* A = skb->len; */
 402                                BUILD_BUG_ON(FIELD_SIZEOF(struct sk_buff, len) != 4);
 403                                if (is_imm8(offsetof(struct sk_buff, len)))
 404                                        /* mov    off8(%rdi),%eax */
 405                                        EMIT3(0x8b, 0x47, offsetof(struct sk_buff, len));
 406                                else {
 407                                        EMIT2(0x8b, 0x87);
 408                                        EMIT(offsetof(struct sk_buff, len), 4);
 409                                }
 410                                break;
 411                        case BPF_S_LDX_W_LEN: /* X = skb->len; */
 412                                seen |= SEEN_XREG;
 413                                if (is_imm8(offsetof(struct sk_buff, len)))
 414                                        /* mov off8(%rdi),%ebx */
 415                                        EMIT3(0x8b, 0x5f, offsetof(struct sk_buff, len));
 416                                else {
 417                                        EMIT2(0x8b, 0x9f);
 418                                        EMIT(offsetof(struct sk_buff, len), 4);
 419                                }
 420                                break;
 421                        case BPF_S_ANC_PROTOCOL: /* A = ntohs(skb->protocol); */
 422                                BUILD_BUG_ON(FIELD_SIZEOF(struct sk_buff, protocol) != 2);
 423                                if (is_imm8(offsetof(struct sk_buff, protocol))) {
 424                                        /* movzwl off8(%rdi),%eax */
 425                                        EMIT4(0x0f, 0xb7, 0x47, offsetof(struct sk_buff, protocol));
 426                                } else {
 427                                        EMIT3(0x0f, 0xb7, 0x87); /* movzwl off32(%rdi),%eax */
 428                                        EMIT(offsetof(struct sk_buff, protocol), 4);
 429                                }
 430                                EMIT2(0x86, 0xc4); /* ntohs() : xchg   %al,%ah */
 431                                break;
 432                        case BPF_S_ANC_IFINDEX:
 433                                if (is_imm8(offsetof(struct sk_buff, dev))) {
 434                                        /* movq off8(%rdi),%rax */
 435                                        EMIT4(0x48, 0x8b, 0x47, offsetof(struct sk_buff, dev));
 436                                } else {
 437                                        EMIT3(0x48, 0x8b, 0x87); /* movq off32(%rdi),%rax */
 438                                        EMIT(offsetof(struct sk_buff, dev), 4);
 439                                }
 440                                EMIT3(0x48, 0x85, 0xc0);        /* test %rax,%rax */
 441                                EMIT_COND_JMP(X86_JE, cleanup_addr - (addrs[i] - 6));
 442                                BUILD_BUG_ON(FIELD_SIZEOF(struct net_device, ifindex) != 4);
 443                                EMIT2(0x8b, 0x80);      /* mov off32(%rax),%eax */
 444                                EMIT(offsetof(struct net_device, ifindex), 4);
 445                                break;
 446                        case BPF_S_ANC_MARK:
 447                                BUILD_BUG_ON(FIELD_SIZEOF(struct sk_buff, mark) != 4);
 448                                if (is_imm8(offsetof(struct sk_buff, mark))) {
 449                                        /* mov off8(%rdi),%eax */
 450                                        EMIT3(0x8b, 0x47, offsetof(struct sk_buff, mark));
 451                                } else {
 452                                        EMIT2(0x8b, 0x87);
 453                                        EMIT(offsetof(struct sk_buff, mark), 4);
 454                                }
 455                                break;
 456                        case BPF_S_ANC_RXHASH:
 457                                BUILD_BUG_ON(FIELD_SIZEOF(struct sk_buff, rxhash) != 4);
 458                                if (is_imm8(offsetof(struct sk_buff, rxhash))) {
 459                                        /* mov off8(%rdi),%eax */
 460                                        EMIT3(0x8b, 0x47, offsetof(struct sk_buff, rxhash));
 461                                } else {
 462                                        EMIT2(0x8b, 0x87);
 463                                        EMIT(offsetof(struct sk_buff, rxhash), 4);
 464                                }
 465                                break;
 466                        case BPF_S_ANC_QUEUE:
 467                                BUILD_BUG_ON(FIELD_SIZEOF(struct sk_buff, queue_mapping) != 2);
 468                                if (is_imm8(offsetof(struct sk_buff, queue_mapping))) {
 469                                        /* movzwl off8(%rdi),%eax */
 470                                        EMIT4(0x0f, 0xb7, 0x47, offsetof(struct sk_buff, queue_mapping));
 471                                } else {
 472                                        EMIT3(0x0f, 0xb7, 0x87); /* movzwl off32(%rdi),%eax */
 473                                        EMIT(offsetof(struct sk_buff, queue_mapping), 4);
 474                                }
 475                                break;
 476                        case BPF_S_ANC_CPU:
 477#ifdef CONFIG_SMP
 478                                EMIT4(0x65, 0x8b, 0x04, 0x25); /* mov %gs:off32,%eax */
 479                                EMIT((u32)(unsigned long)&cpu_number, 4); /* A = smp_processor_id(); */
 480#else
 481                                CLEAR_A();
 482#endif
 483                                break;
 484                        case BPF_S_LD_W_ABS:
 485                                func = CHOOSE_LOAD_FUNC(K, sk_load_word);
 486common_load:                    seen |= SEEN_DATAREF;
 487                                t_offset = func - (image + addrs[i]);
 488                                EMIT1_off32(0xbe, K); /* mov imm32,%esi */
 489                                EMIT1_off32(0xe8, t_offset); /* call */
 490                                break;
 491                        case BPF_S_LD_H_ABS:
 492                                func = CHOOSE_LOAD_FUNC(K, sk_load_half);
 493                                goto common_load;
 494                        case BPF_S_LD_B_ABS:
 495                                func = CHOOSE_LOAD_FUNC(K, sk_load_byte);
 496                                goto common_load;
 497                        case BPF_S_LDX_B_MSH:
 498                                func = CHOOSE_LOAD_FUNC(K, sk_load_byte_msh);
 499                                seen |= SEEN_DATAREF | SEEN_XREG;
 500                                t_offset = func - (image + addrs[i]);
 501                                EMIT1_off32(0xbe, K);   /* mov imm32,%esi */
 502                                EMIT1_off32(0xe8, t_offset); /* call sk_load_byte_msh */
 503                                break;
 504                        case BPF_S_LD_W_IND:
 505                                func = sk_load_word;
 506common_load_ind:                seen |= SEEN_DATAREF | SEEN_XREG;
 507                                t_offset = func - (image + addrs[i]);
 508                                if (K) {
 509                                        if (is_imm8(K)) {
 510                                                EMIT3(0x8d, 0x73, K); /* lea imm8(%rbx), %esi */
 511                                        } else {
 512                                                EMIT2(0x8d, 0xb3); /* lea imm32(%rbx),%esi */
 513                                                EMIT(K, 4);
 514                                        }
 515                                } else {
 516                                        EMIT2(0x89,0xde); /* mov %ebx,%esi */
 517                                }
 518                                EMIT1_off32(0xe8, t_offset);    /* call sk_load_xxx_ind */
 519                                break;
 520                        case BPF_S_LD_H_IND:
 521                                func = sk_load_half;
 522                                goto common_load_ind;
 523                        case BPF_S_LD_B_IND:
 524                                func = sk_load_byte;
 525                                goto common_load_ind;
 526                        case BPF_S_JMP_JA:
 527                                t_offset = addrs[i + K] - addrs[i];
 528                                EMIT_JMP(t_offset);
 529                                break;
 530                        COND_SEL(BPF_S_JMP_JGT_K, X86_JA, X86_JBE);
 531                        COND_SEL(BPF_S_JMP_JGE_K, X86_JAE, X86_JB);
 532                        COND_SEL(BPF_S_JMP_JEQ_K, X86_JE, X86_JNE);
 533                        COND_SEL(BPF_S_JMP_JSET_K,X86_JNE, X86_JE);
 534                        COND_SEL(BPF_S_JMP_JGT_X, X86_JA, X86_JBE);
 535                        COND_SEL(BPF_S_JMP_JGE_X, X86_JAE, X86_JB);
 536                        COND_SEL(BPF_S_JMP_JEQ_X, X86_JE, X86_JNE);
 537                        COND_SEL(BPF_S_JMP_JSET_X,X86_JNE, X86_JE);
 538
 539cond_branch:                    f_offset = addrs[i + filter[i].jf] - addrs[i];
 540                                t_offset = addrs[i + filter[i].jt] - addrs[i];
 541
 542                                /* same targets, can avoid doing the test :) */
 543                                if (filter[i].jt == filter[i].jf) {
 544                                        EMIT_JMP(t_offset);
 545                                        break;
 546                                }
 547
 548                                switch (filter[i].code) {
 549                                case BPF_S_JMP_JGT_X:
 550                                case BPF_S_JMP_JGE_X:
 551                                case BPF_S_JMP_JEQ_X:
 552                                        seen |= SEEN_XREG;
 553                                        EMIT2(0x39, 0xd8); /* cmp %ebx,%eax */
 554                                        break;
 555                                case BPF_S_JMP_JSET_X:
 556                                        seen |= SEEN_XREG;
 557                                        EMIT2(0x85, 0xd8); /* test %ebx,%eax */
 558                                        break;
 559                                case BPF_S_JMP_JEQ_K:
 560                                        if (K == 0) {
 561                                                EMIT2(0x85, 0xc0); /* test   %eax,%eax */
 562                                                break;
 563                                        }
 564                                case BPF_S_JMP_JGT_K:
 565                                case BPF_S_JMP_JGE_K:
 566                                        if (K <= 127)
 567                                                EMIT3(0x83, 0xf8, K); /* cmp imm8,%eax */
 568                                        else
 569                                                EMIT1_off32(0x3d, K); /* cmp imm32,%eax */
 570                                        break;
 571                                case BPF_S_JMP_JSET_K:
 572                                        if (K <= 0xFF)
 573                                                EMIT2(0xa8, K); /* test imm8,%al */
 574                                        else if (!(K & 0xFFFF00FF))
 575                                                EMIT3(0xf6, 0xc4, K >> 8); /* test imm8,%ah */
 576                                        else if (K <= 0xFFFF) {
 577                                                EMIT2(0x66, 0xa9); /* test imm16,%ax */
 578                                                EMIT(K, 2);
 579                                        } else {
 580                                                EMIT1_off32(0xa9, K); /* test imm32,%eax */
 581                                        }
 582                                        break;
 583                                }
 584                                if (filter[i].jt != 0) {
 585                                        if (filter[i].jf && f_offset)
 586                                                t_offset += is_near(f_offset) ? 2 : 5;
 587                                        EMIT_COND_JMP(t_op, t_offset);
 588                                        if (filter[i].jf)
 589                                                EMIT_JMP(f_offset);
 590                                        break;
 591                                }
 592                                EMIT_COND_JMP(f_op, f_offset);
 593                                break;
 594                        default:
 595                                /* hmm, too complex filter, give up with jit compiler */
 596                                goto out;
 597                        }
 598                        ilen = prog - temp;
 599                        if (image) {
 600                                if (unlikely(proglen + ilen > oldproglen)) {
 601                                        pr_err("bpb_jit_compile fatal error\n");
 602                                        kfree(addrs);
 603                                        module_free(NULL, image);
 604                                        return;
 605                                }
 606                                memcpy(image + proglen, temp, ilen);
 607                        }
 608                        proglen += ilen;
 609                        addrs[i] = proglen;
 610                        prog = temp;
 611                }
 612                /* last bpf instruction is always a RET :
 613                 * use it to give the cleanup instruction(s) addr
 614                 */
 615                cleanup_addr = proglen - 1; /* ret */
 616                if (seen_or_pass0)
 617                        cleanup_addr -= 1; /* leaveq */
 618                if (seen_or_pass0 & SEEN_XREG)
 619                        cleanup_addr -= 4; /* mov  -8(%rbp),%rbx */
 620
 621                if (image) {
 622                        if (proglen != oldproglen)
 623                                pr_err("bpb_jit_compile proglen=%u != oldproglen=%u\n", proglen, oldproglen);
 624                        break;
 625                }
 626                if (proglen == oldproglen) {
 627                        image = module_alloc(max_t(unsigned int,
 628                                                   proglen,
 629                                                   sizeof(struct work_struct)));
 630                        if (!image)
 631                                goto out;
 632                }
 633                oldproglen = proglen;
 634        }
 635        if (bpf_jit_enable > 1)
 636                pr_err("flen=%d proglen=%u pass=%d image=%p\n",
 637                       flen, proglen, pass, image);
 638
 639        if (image) {
 640                if (bpf_jit_enable > 1)
 641                        print_hex_dump(KERN_ERR, "JIT code: ", DUMP_PREFIX_ADDRESS,
 642                                       16, 1, image, proglen, false);
 643
 644                bpf_flush_icache(image, image + proglen);
 645
 646                fp->bpf_func = (void *)image;
 647        }
 648out:
 649        kfree(addrs);
 650        return;
 651}
 652
 653static void jit_free_defer(struct work_struct *arg)
 654{
 655        module_free(NULL, arg);
 656}
 657
 658/* run from softirq, we must use a work_struct to call
 659 * module_free() from process context
 660 */
 661void bpf_jit_free(struct sk_filter *fp)
 662{
 663        if (fp->bpf_func != sk_run_filter) {
 664                struct work_struct *work = (struct work_struct *)fp->bpf_func;
 665
 666                INIT_WORK(work, jit_free_defer);
 667                schedule_work(work);
 668        }
 669}
 670
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