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