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    ] 6*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 */
  32 #define BPF_PPC_STACK_SAVE      (6*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 TMP_REG_1       (MAX_BPF_JIT_REG + 0)
  43 #define TMP_REG_2       (MAX_BPF_JIT_REG + 1)
  44
  45 /* BPF to ppc register mappings */
  46 static const int b2p[] = {
  47         /* function return value */
  48         [BPF_REG_0] = 8,
  49         /* function arguments */
  50         [BPF_REG_1] = 3,
  51         [BPF_REG_2] = 4,
  52         [BPF_REG_3] = 5,
  53         [BPF_REG_4] = 6,
  54         [BPF_REG_5] = 7,
  55         /* non volatile registers */
  56         [BPF_REG_6] = 27,
  57         [BPF_REG_7] = 28,
  58         [BPF_REG_8] = 29,
  59         [BPF_REG_9] = 30,
  60         /* frame pointer aka BPF_REG_10 */
  61         [BPF_REG_FP] = 31,
  62         /* eBPF jit internal registers */
  63         [BPF_REG_AX] = 2,
  64         [TMP_REG_1] = 9,
  65         [TMP_REG_2] = 10
  66 };
  67
  68 /* PPC NVR range -- update this if we ever use NVRs below r27 */
  69 #define BPF_PPC_NVR_MIN         27
  70
  71 /*
  72  * WARNING: These can use TMP_REG_2 if the offset is not at word boundary,
  73  * so ensure that it isn't in use already.
  74  */
  75 #define PPC_BPF_LL(r, base, i) do {                                           \
  76                                 if ((i) % 4) {                                \
  77                                         PPC_LI(b2p[TMP_REG_2], (i));          \
  78                                         PPC_LDX(r, base, b2p[TMP_REG_2]);     \
  79                                 } else                                        \
  80                                         PPC_LD(r, base, i);                   \
  81                                 } while(0)
  82 #define PPC_BPF_STL(r, base, i) do {                                          \
  83                                 if ((i) % 4) {                                \
  84                                         PPC_LI(b2p[TMP_REG_2], (i));          \
  85                                         PPC_STDX(r, base, b2p[TMP_REG_2]);    \
  86                                 } else                                        \
  87                                         PPC_STD(r, base, i);                  \
  88                                 } while(0)
  89 #define PPC_BPF_STLU(r, base, i) do { PPC_STDU(r, base, i); } while(0)
  90
  91 #define SEEN_FUNC       0x1000 /* might call external helpers */
  92 #define SEEN_STACK      0x2000 /* uses BPF stack */
  93 #define SEEN_TAILCALL   0x4000 /* uses tail calls */
  94
  95 struct codegen_context {
  96         /*
  97          * This is used to track register usage as well
  98          * as calls to external helpers.
  99          * - register usage is tracked with corresponding
 100          *   bits (r3-r10 and r27-r31)
 101          * - rest of the bits can be used to track other
 102          *   things -- for now, we use bits 16 to 23
 103          *   encoded in SEEN_* macros above
 104          */
 105         unsigned int seen;
 106         unsigned int idx;
 107         unsigned int stack_size;
 108 };
 109
 110 #endif /* !__ASSEMBLY__ */
 111
 112 #endif