LXR linux/arch/powerpc/net/bpf

   1/*
   2 * bpf_jit64.h: BPF JIT compiler for PPC64
   3 *
   4 * Copyright 2016 Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
   5 *                IBM Corporation
   6 *
   7 * This program is free software; you can redistribute it and/or
   8 * modify it under the terms of the GNU General Public License
   9 * as published by the Free Software Foundation; version 2
  10 * of the License.
  11 */
  12#ifndef _BPF_JIT64_H
  13#define _BPF_JIT64_H
  14
  15#include "bpf_jit.h"
  16
  17/*
  18 * Stack layout:
  19 * Ensure the top half (upto local_tmp_var) stays consistent
  20 * with our redzone usage.
  21 *
  22 *              [       prev sp         ] <-------------
  23 *              [   nv gpr save area    ] 8*8           |
  24 *              [    tail_call_cnt      ] 8             |
  25 *              [    local_tmp_var      ] 8             |
  26 * fp (r31) --> [   ebpf stack space    ] upto 512      |
  27 *              [     frame header      ] 32/112        |
  28 * sp (r1) ---> [    stack pointer      ] --------------
  29 */
  30
  31/* for gpr non volatile registers BPG_REG_6 to 10, plus skb cache registers */
  32#define BPF_PPC_STACK_SAVE      (8*8)
  33/* for bpf JIT code internal usage */
  34#define BPF_PPC_STACK_LOCALS    16
  35/* stack frame excluding BPF stack, ensure this is quadword aligned */
  36#define BPF_PPC_STACKFRAME      (STACK_FRAME_MIN_SIZE + \
  37                                 BPF_PPC_STACK_LOCALS + BPF_PPC_STACK_SAVE)
  38
  39#ifndef __ASSEMBLY__
  40
  41/* BPF register usage */
  42#define SKB_HLEN_REG    (MAX_BPF_JIT_REG + 0)
  43#define SKB_DATA_REG    (MAX_BPF_JIT_REG + 1)
  44#define TMP_REG_1       (MAX_BPF_JIT_REG + 2)
  45#define TMP_REG_2       (MAX_BPF_JIT_REG + 3)
  46
  47/* BPF to ppc register mappings */
  48static const int b2p[] = {
  49        /* function return value */
  50        [BPF_REG_0] = 8,
  51        /* function arguments */
  52        [BPF_REG_1] = 3,
  53        [BPF_REG_2] = 4,
  54        [BPF_REG_3] = 5,
  55        [BPF_REG_4] = 6,
  56        [BPF_REG_5] = 7,
  57        /* non volatile registers */
  58        [BPF_REG_6] = 27,
  59        [BPF_REG_7] = 28,
  60        [BPF_REG_8] = 29,
  61        [BPF_REG_9] = 30,
  62        /* frame pointer aka BPF_REG_10 */
  63        [BPF_REG_FP] = 31,
  64        /* eBPF jit internal registers */
  65        [BPF_REG_AX] = 2,
  66        [SKB_HLEN_REG] = 25,
  67        [SKB_DATA_REG] = 26,
  68        [TMP_REG_1] = 9,
  69        [TMP_REG_2] = 10
  70};
  71
  72/* PPC NVR range -- update this if we ever use NVRs below r24 */
  73#define BPF_PPC_NVR_MIN         24
  74
  75/* Assembly helpers */
  76#define DECLARE_LOAD_FUNC(func) u64 func(u64 r3, u64 r4);                       \
  77                                u64 func##_negative_offset(u64 r3, u64 r4);     \
  78                                u64 func##_positive_offset(u64 r3, u64 r4);
  79
  80DECLARE_LOAD_FUNC(sk_load_word);
  81DECLARE_LOAD_FUNC(sk_load_half);
  82DECLARE_LOAD_FUNC(sk_load_byte);
  83
  84#define CHOOSE_LOAD_FUNC(imm, func)                                             \
  85                        (imm < 0 ?                                              \
  86                        (imm >= SKF_LL_OFF ? func##_negative_offset : func) :   \
  87                        func##_positive_offset)
  88
  89#define SEEN_FUNC       0x1000 /* might call external helpers */
  90#define SEEN_STACK      0x2000 /* uses BPF stack */
  91#define SEEN_SKB        0x4000 /* uses sk_buff */
  92#define SEEN_TAILCALL   0x8000 /* uses tail calls */
  93
  94struct codegen_context {
  95        /*
  96         * This is used to track register usage as well
  97         * as calls to external helpers.
  98         * - register usage is tracked with corresponding
  99         *   bits (r3-r10 and r25-r31)
 100         * - rest of the bits can be used to track other
 101         *   things -- for now, we use bits 16 to 23
 102         *   encoded in SEEN_* macros above
 103         */
 104        unsigned int seen;
 105        unsigned int idx;
 106        unsigned int stack_size;
 107};
 108
 109#endif /* !__ASSEMBLY__ */
 110
 111#endif
 112