arch/powerpc/net/bpf_jit64.h

   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    ] 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 /* Ensure this is quadword aligned */
  36 #define BPF_PPC_STACKFRAME      (STACK_FRAME_MIN_SIZE + MAX_BPF_STACK + \
  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 */
  48 static 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
  80 DECLARE_LOAD_FUNC(sk_load_word);
  81 DECLARE_LOAD_FUNC(sk_load_half);
  82 DECLARE_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 /*
  90  * WARNING: These can use TMP_REG_2 if the offset is not at word boundary,
  91  * so ensure that it isn't in use already.
  92  */
  93 #define PPC_BPF_LL(r, base, i) do {                                           \
  94                                 if ((i) % 4) {                                \
  95                                         PPC_LI(b2p[TMP_REG_2], (i));          \
  96                                         PPC_LDX(r, base, b2p[TMP_REG_2]);     \
  97                                 } else                                        \
  98                                         PPC_LD(r, base, i);                   \
  99                                 } while(0)
 100 #define PPC_BPF_STL(r, base, i) do {                                          \
 101                                 if ((i) % 4) {                                \
 102                                         PPC_LI(b2p[TMP_REG_2], (i));          \
 103                                         PPC_STDX(r, base, b2p[TMP_REG_2]);    \
 104                                 } else                                        \
 105                                         PPC_STD(r, base, i);                  \
 106                                 } while(0)
 107 #define PPC_BPF_STLU(r, base, i) do { PPC_STDU(r, base, i); } while(0)
 108
 109 #define SEEN_FUNC       0x1000 /* might call external helpers */
 110 #define SEEN_STACK      0x2000 /* uses BPF stack */
 111 #define SEEN_SKB        0x4000 /* uses sk_buff */
 112 #define SEEN_TAILCALL   0x8000 /* uses tail calls */
 113
 114 struct codegen_context {
 115         /*
 116          * This is used to track register usage as well
 117          * as calls to external helpers.
 118          * - register usage is tracked with corresponding
 119          *   bits (r3-r10 and r25-r31)
 120          * - rest of the bits can be used to track other
 121          *   things -- for now, we use bits 16 to 23
 122          *   encoded in SEEN_* macros above
 123          */
 124         unsigned int seen;
 125         unsigned int idx;
 126 };
 127
 128 #endif /* !__ASSEMBLY__ */
 129
 130 #endif