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  *
  20  *              [       prev sp         ] <-------------
  21  *              [   nv gpr save area    ] 8*8           |
  22  * fp (r31) --> [   ebpf stack space    ] 512           |
  23  *              [  local/tmp var space  ] 16            |
  24  *              [     frame header      ] 32/112        |
  25  * sp (r1) ---> [    stack pointer      ] --------------
  26  */
  27
  28 /* for bpf JIT code internal usage */
  29 #define BPF_PPC_STACK_LOCALS    16
  30 /* for gpr non volatile registers BPG_REG_6 to 10, plus skb cache registers */
  31 #define BPF_PPC_STACK_SAVE      (8*8)
  32 /* Ensure this is quadword aligned */
  33 #define BPF_PPC_STACKFRAME      (STACK_FRAME_MIN_SIZE + BPF_PPC_STACK_LOCALS + \
  34                                  MAX_BPF_STACK + BPF_PPC_STACK_SAVE)
  35
  36 #ifndef __ASSEMBLY__
  37
  38 /* BPF register usage */
  39 #define SKB_HLEN_REG    (MAX_BPF_REG + 0)
  40 #define SKB_DATA_REG    (MAX_BPF_REG + 1)
  41 #define TMP_REG_1       (MAX_BPF_REG + 2)
  42 #define TMP_REG_2       (MAX_BPF_REG + 3)
  43
  44 /* BPF to ppc register mappings */
  45 static const int b2p[] = {
  46         /* function return value */
  47         [BPF_REG_0] = 8,
  48         /* function arguments */
  49         [BPF_REG_1] = 3,
  50         [BPF_REG_2] = 4,
  51         [BPF_REG_3] = 5,
  52         [BPF_REG_4] = 6,
  53         [BPF_REG_5] = 7,
  54         /* non volatile registers */
  55         [BPF_REG_6] = 27,
  56         [BPF_REG_7] = 28,
  57         [BPF_REG_8] = 29,
  58         [BPF_REG_9] = 30,
  59         /* frame pointer aka BPF_REG_10 */
  60         [BPF_REG_FP] = 31,
  61         /* eBPF jit internal registers */
  62         [SKB_HLEN_REG] = 25,
  63         [SKB_DATA_REG] = 26,
  64         [TMP_REG_1] = 9,
  65         [TMP_REG_2] = 10
  66 };
  67
  68 /* Assembly helpers */
  69 #define DECLARE_LOAD_FUNC(func) u64 func(u64 r3, u64 r4);                       \
  70                                 u64 func##_negative_offset(u64 r3, u64 r4);     \
  71                                 u64 func##_positive_offset(u64 r3, u64 r4);
  72
  73 DECLARE_LOAD_FUNC(sk_load_word);
  74 DECLARE_LOAD_FUNC(sk_load_half);
  75 DECLARE_LOAD_FUNC(sk_load_byte);
  76
  77 #define CHOOSE_LOAD_FUNC(imm, func)                                             \
  78                         (imm < 0 ?                                              \
  79                         (imm >= SKF_LL_OFF ? func##_negative_offset : func) :   \
  80                         func##_positive_offset)
  81
  82 #define SEEN_FUNC       0x1000 /* might call external helpers */
  83 #define SEEN_STACK      0x2000 /* uses BPF stack */
  84 #define SEEN_SKB        0x4000 /* uses sk_buff */
  85
  86 struct codegen_context {
  87         /*
  88          * This is used to track register usage as well
  89          * as calls to external helpers.
  90          * - register usage is tracked with corresponding
  91          *   bits (r3-r10 and r25-r31)
  92          * - rest of the bits can be used to track other
  93          *   things -- for now, we use bits 16 to 23
  94          *   encoded in SEEN_* macros above
  95          */
  96         unsigned int seen;
  97         unsigned int idx;
  98 };
  99
 100 #endif /* !__ASSEMBLY__ */
 101
 102 #endif