arch/powerpc/net/bpf_jit64.h

   1 /* SPDX-License-Identifier: GPL-2.0-only */
   2 /*
   3  * bpf_jit64.h: BPF JIT compiler for PPC64
   4  *
   5  * Copyright 2016 Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
   6  *                IBM Corporation
   7  */
   8 #ifndef _BPF_JIT64_H
   9 #define _BPF_JIT64_H
  10
  11 #include "bpf_jit.h"
  12
  13 /*
  14  * Stack layout:
  15  * Ensure the top half (upto local_tmp_var) stays consistent
  16  * with our redzone usage.
  17  *
  18  *              [       prev sp         ] <-------------
  19  *              [   nv gpr save area    ] 6*8           |
  20  *              [    tail_call_cnt      ] 8             |
  21  *              [    local_tmp_var      ] 8             |
  22  * fp (r31) --> [   ebpf stack space    ] upto 512      |
  23  *              [     frame header      ] 32/112        |
  24  * sp (r1) ---> [    stack pointer      ] --------------
  25  */
  26
  27 /* for gpr non volatile registers BPG_REG_6 to 10 */
  28 #define BPF_PPC_STACK_SAVE      (6*8)
  29 /* for bpf JIT code internal usage */
  30 #define BPF_PPC_STACK_LOCALS    16
  31 /* stack frame excluding BPF stack, ensure this is quadword aligned */
  32 #define BPF_PPC_STACKFRAME      (STACK_FRAME_MIN_SIZE + \
  33                                  BPF_PPC_STACK_LOCALS + BPF_PPC_STACK_SAVE)
  34
  35 #ifndef __ASSEMBLY__
  36
  37 /* BPF register usage */
  38 #define TMP_REG_1       (MAX_BPF_JIT_REG + 0)
  39 #define TMP_REG_2       (MAX_BPF_JIT_REG + 1)
  40
  41 /* BPF to ppc register mappings */
  42 static const int b2p[] = {
  43         /* function return value */
  44         [BPF_REG_0] = 8,
  45         /* function arguments */
  46         [BPF_REG_1] = 3,
  47         [BPF_REG_2] = 4,
  48         [BPF_REG_3] = 5,
  49         [BPF_REG_4] = 6,
  50         [BPF_REG_5] = 7,
  51         /* non volatile registers */
  52         [BPF_REG_6] = 27,
  53         [BPF_REG_7] = 28,
  54         [BPF_REG_8] = 29,
  55         [BPF_REG_9] = 30,
  56         /* frame pointer aka BPF_REG_10 */
  57         [BPF_REG_FP] = 31,
  58         /* eBPF jit internal registers */
  59         [BPF_REG_AX] = 2,
  60         [TMP_REG_1] = 9,
  61         [TMP_REG_2] = 10
  62 };
  63
  64 /* PPC NVR range -- update this if we ever use NVRs below r27 */
  65 #define BPF_PPC_NVR_MIN         27
  66
  67 /*
  68  * WARNING: These can use TMP_REG_2 if the offset is not at word boundary,
  69  * so ensure that it isn't in use already.
  70  */
  71 #define PPC_BPF_LL(r, base, i) do {                                           \
  72                                 if ((i) % 4) {                                \
  73                                         EMIT(PPC_RAW_LI(b2p[TMP_REG_2], (i)));\
  74                                         EMIT(PPC_RAW_LDX(r, base,             \
  75                                                         b2p[TMP_REG_2]));     \
  76                                 } else                                        \
  77                                         EMIT(PPC_RAW_LD(r, base, i));         \
  78                                 } while(0)
  79 #define PPC_BPF_STL(r, base, i) do {                                          \
  80                                 if ((i) % 4) {                                \
  81                                         EMIT(PPC_RAW_LI(b2p[TMP_REG_2], (i)));\
  82                                         EMIT(PPC_RAW_STDX(r, base,            \
  83                                                         b2p[TMP_REG_2]));     \
  84                                 } else                                        \
  85                                         EMIT(PPC_RAW_STD(r, base, i));        \
  86                                 } while(0)
  87 #define PPC_BPF_STLU(r, base, i) do { EMIT(PPC_RAW_STDU(r, base, i)); } while(0)
  88
  89 #define SEEN_FUNC       0x1000 /* might call external helpers */
  90 #define SEEN_STACK      0x2000 /* uses BPF stack */
  91 #define SEEN_TAILCALL   0x4000 /* uses tail calls */
  92
  93 struct codegen_context {
  94         /*
  95          * This is used to track register usage as well
  96          * as calls to external helpers.
  97          * - register usage is tracked with corresponding
  98          *   bits (r3-r10 and r27-r31)
  99          * - rest of the bits can be used to track other
 100          *   things -- for now, we use bits 16 to 23
 101          *   encoded in SEEN_* macros above
 102          */
 103         unsigned int seen;
 104         unsigned int idx;
 105         unsigned int stack_size;
 106 };
 107
 108 #endif /* !__ASSEMBLY__ */
 109
 110 #endif