arch/powerpc/net/bpf_jit.h

   1 /* bpf_jit.h: BPF JIT compiler for PPC64
   2  *
   3  * Copyright 2011 Matt Evans <matt@ozlabs.org>, IBM Corporation
   4  *
   5  * This program is free software; you can redistribute it and/or
   6  * modify it under the terms of the GNU General Public License
   7  * as published by the Free Software Foundation; version 2
   8  * of the License.
   9  */
  10 #ifndef _BPF_JIT_H
  11 #define _BPF_JIT_H
  12
  13 #define BPF_PPC_STACK_LOCALS    32
  14 #define BPF_PPC_STACK_BASIC     (48+64)
  15 #define BPF_PPC_STACK_SAVE      (18*8)
  16 #define BPF_PPC_STACKFRAME      (BPF_PPC_STACK_BASIC+BPF_PPC_STACK_LOCALS+ \
  17                                  BPF_PPC_STACK_SAVE)
  18 #define BPF_PPC_SLOWPATH_FRAME  (48+64)
  19
  20 /*
  21  * Generated code register usage:
  22  *
  23  * As normal PPC C ABI (e.g. r1=sp, r2=TOC), with:
  24  *
  25  * skb          r3      (Entry parameter)
  26  * A register   r4
  27  * X register   r5
  28  * addr param   r6
  29  * r7-r10       scratch
  30  * skb->data    r14
  31  * skb headlen  r15     (skb->len - skb->data_len)
  32  * m[0]         r16
  33  * m[...]       ...
  34  * m[15]        r31
  35  */
  36 #define r_skb           3
  37 #define r_ret           3
  38 #define r_A             4
  39 #define r_X             5
  40 #define r_addr          6
  41 #define r_scratch1      7
  42 #define r_D             14
  43 #define r_HL            15
  44 #define r_M             16
  45
  46 #ifndef __ASSEMBLY__
  47
  48 /*
  49  * Assembly helpers from arch/powerpc/net/bpf_jit.S:
  50  */
  51 #define DECLARE_LOAD_FUNC(func) \
  52         extern u8 func[], func##_negative_offset[], func##_positive_offset[]
  53
  54 DECLARE_LOAD_FUNC(sk_load_word);
  55 DECLARE_LOAD_FUNC(sk_load_half);
  56 DECLARE_LOAD_FUNC(sk_load_byte);
  57 DECLARE_LOAD_FUNC(sk_load_byte_msh);
  58
  59 #define FUNCTION_DESCR_SIZE     24
  60
  61 /*
  62  * 16-bit immediate helper macros: HA() is for use with sign-extending instrs
  63  * (e.g. LD, ADDI).  If the bottom 16 bits is "-ve", add another bit into the
  64  * top half to negate the effect (i.e. 0xffff + 1 = 0x(1)0000).
  65  */
  66 #define IMM_H(i)                ((uintptr_t)(i)>>16)
  67 #define IMM_HA(i)               (((uintptr_t)(i)>>16) +                       \
  68                                  (((uintptr_t)(i) & 0x8000) >> 15))
  69 #define IMM_L(i)                ((uintptr_t)(i) & 0xffff)
  70
  71 #define PLANT_INSTR(d, idx, instr)                                            \
  72         do { if (d) { (d)[idx] = instr; } idx++; } while (0)
  73 #define EMIT(instr)             PLANT_INSTR(image, ctx->idx, instr)
  74
  75 #define PPC_NOP()               EMIT(PPC_INST_NOP)
  76 #define PPC_BLR()               EMIT(PPC_INST_BLR)
  77 #define PPC_BLRL()              EMIT(PPC_INST_BLRL)
  78 #define PPC_MTLR(r)             EMIT(PPC_INST_MTLR | ___PPC_RT(r))
  79 #define PPC_ADDI(d, a, i)       EMIT(PPC_INST_ADDI | ___PPC_RT(d) |           \
  80                                      ___PPC_RA(a) | IMM_L(i))
  81 #define PPC_MR(d, a)            PPC_OR(d, a, a)
  82 #define PPC_LI(r, i)            PPC_ADDI(r, 0, i)
  83 #define PPC_ADDIS(d, a, i)      EMIT(PPC_INST_ADDIS |                         \
  84                                      ___PPC_RS(d) | ___PPC_RA(a) | IMM_L(i))
  85 #define PPC_LIS(r, i)           PPC_ADDIS(r, 0, i)
  86 #define PPC_STD(r, base, i)     EMIT(PPC_INST_STD | ___PPC_RS(r) |            \
  87                                      ___PPC_RA(base) | ((i) & 0xfffc))
  88
  89 #define PPC_LD(r, base, i)      EMIT(PPC_INST_LD | ___PPC_RT(r) |             \
  90                                      ___PPC_RA(base) | IMM_L(i))
  91 #define PPC_LWZ(r, base, i)     EMIT(PPC_INST_LWZ | ___PPC_RT(r) |            \
  92                                      ___PPC_RA(base) | IMM_L(i))
  93 #define PPC_LHZ(r, base, i)     EMIT(PPC_INST_LHZ | ___PPC_RT(r) |            \
  94                                      ___PPC_RA(base) | IMM_L(i))
  95 /* Convenience helpers for the above with 'far' offsets: */
  96 #define PPC_LD_OFFS(r, base, i) do { if ((i) < 32768) PPC_LD(r, base, i);     \
  97                 else {  PPC_ADDIS(r, base, IMM_HA(i));                        \
  98                         PPC_LD(r, r, IMM_L(i)); } } while(0)
  99
 100 #define PPC_LWZ_OFFS(r, base, i) do { if ((i) < 32768) PPC_LWZ(r, base, i);   \
 101                 else {  PPC_ADDIS(r, base, IMM_HA(i));                        \
 102                         PPC_LWZ(r, r, IMM_L(i)); } } while(0)
 103
 104 #define PPC_LHZ_OFFS(r, base, i) do { if ((i) < 32768) PPC_LHZ(r, base, i);   \
 105                 else {  PPC_ADDIS(r, base, IMM_HA(i));                        \
 106                         PPC_LHZ(r, r, IMM_L(i)); } } while(0)
 107
 108 #define PPC_CMPWI(a, i)         EMIT(PPC_INST_CMPWI | ___PPC_RA(a) | IMM_L(i))
 109 #define PPC_CMPDI(a, i)         EMIT(PPC_INST_CMPDI | ___PPC_RA(a) | IMM_L(i))
 110 #define PPC_CMPLWI(a, i)        EMIT(PPC_INST_CMPLWI | ___PPC_RA(a) | IMM_L(i))
 111 #define PPC_CMPLW(a, b)         EMIT(PPC_INST_CMPLW | ___PPC_RA(a) | ___PPC_RB(b))
 112
 113 #define PPC_SUB(d, a, b)        EMIT(PPC_INST_SUB | ___PPC_RT(d) |            \
 114                                      ___PPC_RB(a) | ___PPC_RA(b))
 115 #define PPC_ADD(d, a, b)        EMIT(PPC_INST_ADD | ___PPC_RT(d) |            \
 116                                      ___PPC_RA(a) | ___PPC_RB(b))
 117 #define PPC_MUL(d, a, b)        EMIT(PPC_INST_MULLW | ___PPC_RT(d) |          \
 118                                      ___PPC_RA(a) | ___PPC_RB(b))
 119 #define PPC_MULHWU(d, a, b)     EMIT(PPC_INST_MULHWU | ___PPC_RT(d) |         \
 120                                      ___PPC_RA(a) | ___PPC_RB(b))
 121 #define PPC_MULI(d, a, i)       EMIT(PPC_INST_MULLI | ___PPC_RT(d) |          \
 122                                      ___PPC_RA(a) | IMM_L(i))
 123 #define PPC_DIVWU(d, a, b)      EMIT(PPC_INST_DIVWU | ___PPC_RT(d) |          \
 124                                      ___PPC_RA(a) | ___PPC_RB(b))
 125 #define PPC_AND(d, a, b)        EMIT(PPC_INST_AND | ___PPC_RA(d) |            \
 126                                      ___PPC_RS(a) | ___PPC_RB(b))
 127 #define PPC_ANDI(d, a, i)       EMIT(PPC_INST_ANDI | ___PPC_RA(d) |           \
 128                                      ___PPC_RS(a) | IMM_L(i))
 129 #define PPC_AND_DOT(d, a, b)    EMIT(PPC_INST_ANDDOT | ___PPC_RA(d) |         \
 130                                      ___PPC_RS(a) | ___PPC_RB(b))
 131 #define PPC_OR(d, a, b)         EMIT(PPC_INST_OR | ___PPC_RA(d) |             \
 132                                      ___PPC_RS(a) | ___PPC_RB(b))
 133 #define PPC_ORI(d, a, i)        EMIT(PPC_INST_ORI | ___PPC_RA(d) |            \
 134                                      ___PPC_RS(a) | IMM_L(i))
 135 #define PPC_ORIS(d, a, i)       EMIT(PPC_INST_ORIS | ___PPC_RA(d) |           \
 136                                      ___PPC_RS(a) | IMM_L(i))
 137 #define PPC_XOR(d, a, b)        EMIT(PPC_INST_XOR | ___PPC_RA(d) |            \
 138                                      ___PPC_RS(a) | ___PPC_RB(b))
 139 #define PPC_XORI(d, a, i)       EMIT(PPC_INST_XORI | ___PPC_RA(d) |           \
 140                                      ___PPC_RS(a) | IMM_L(i))
 141 #define PPC_XORIS(d, a, i)      EMIT(PPC_INST_XORIS | ___PPC_RA(d) |          \
 142                                      ___PPC_RS(a) | IMM_L(i))
 143 #define PPC_SLW(d, a, s)        EMIT(PPC_INST_SLW | ___PPC_RA(d) |            \
 144                                      ___PPC_RS(a) | ___PPC_RB(s))
 145 #define PPC_SRW(d, a, s)        EMIT(PPC_INST_SRW | ___PPC_RA(d) |            \
 146                                      ___PPC_RS(a) | ___PPC_RB(s))
 147 /* slwi = rlwinm Rx, Ry, n, 0, 31-n */
 148 #define PPC_SLWI(d, a, i)       EMIT(PPC_INST_RLWINM | ___PPC_RA(d) |         \
 149                                      ___PPC_RS(a) | __PPC_SH(i) |             \
 150                                      __PPC_MB(0) | __PPC_ME(31-(i)))
 151 /* srwi = rlwinm Rx, Ry, 32-n, n, 31 */
 152 #define PPC_SRWI(d, a, i)       EMIT(PPC_INST_RLWINM | ___PPC_RA(d) |         \
 153                                      ___PPC_RS(a) | __PPC_SH(32-(i)) |        \
 154                                      __PPC_MB(i) | __PPC_ME(31))
 155 /* sldi = rldicr Rx, Ry, n, 63-n */
 156 #define PPC_SLDI(d, a, i)       EMIT(PPC_INST_RLDICR | ___PPC_RA(d) |         \
 157                                      ___PPC_RS(a) | __PPC_SH(i) |             \
 158                                      __PPC_MB(63-(i)) | (((i) & 0x20) >> 4))
 159 #define PPC_NEG(d, a)           EMIT(PPC_INST_NEG | ___PPC_RT(d) | ___PPC_RA(a))
 160
 161 /* Long jump; (unconditional 'branch') */
 162 #define PPC_JMP(dest)           EMIT(PPC_INST_BRANCH |                        \
 163                                      (((dest) - (ctx->idx * 4)) & 0x03fffffc))
 164 /* "cond" here covers BO:BI fields. */
 165 #define PPC_BCC_SHORT(cond, dest)       EMIT(PPC_INST_BRANCH_COND |           \
 166                                              (((cond) & 0x3ff) << 16) |       \
 167                                              (((dest) - (ctx->idx * 4)) &     \
 168                                               0xfffc))
 169 #define PPC_LI32(d, i)          do { PPC_LI(d, IMM_L(i));                     \
 170                 if ((u32)(uintptr_t)(i) >= 32768) {                           \
 171                         PPC_ADDIS(d, d, IMM_HA(i));                           \
 172                 } } while(0)
 173 #define PPC_LI64(d, i)          do {                                          \
 174                 if (!((uintptr_t)(i) & 0xffffffff00000000ULL))                \
 175                         PPC_LI32(d, i);                                       \
 176                 else {                                                        \
 177                         PPC_LIS(d, ((uintptr_t)(i) >> 48));                   \
 178                         if ((uintptr_t)(i) & 0x0000ffff00000000ULL)           \
 179                                 PPC_ORI(d, d,                                 \
 180                                         ((uintptr_t)(i) >> 32) & 0xffff);     \
 181                         PPC_SLDI(d, d, 32);                                   \
 182                         if ((uintptr_t)(i) & 0x00000000ffff0000ULL)           \
 183                                 PPC_ORIS(d, d,                                \
 184                                          ((uintptr_t)(i) >> 16) & 0xffff);    \
 185                         if ((uintptr_t)(i) & 0x000000000000ffffULL)           \
 186                                 PPC_ORI(d, d, (uintptr_t)(i) & 0xffff);       \
 187                 } } while (0);
 188
 189 static inline bool is_nearbranch(int offset)
 190 {
 191         return (offset < 32768) && (offset >= -32768);
 192 }
 193
 194 /*
 195  * The fly in the ointment of code size changing from pass to pass is
 196  * avoided by padding the short branch case with a NOP.  If code size differs
 197  * with different branch reaches we will have the issue of code moving from
 198  * one pass to the next and will need a few passes to converge on a stable
 199  * state.
 200  */
 201 #define PPC_BCC(cond, dest)     do {                                          \
 202                 if (is_nearbranch((dest) - (ctx->idx * 4))) {                 \
 203                         PPC_BCC_SHORT(cond, dest);                            \
 204                         PPC_NOP();                                            \
 205                 } else {                                                      \
 206                         /* Flip the 'T or F' bit to invert comparison */      \
 207                         PPC_BCC_SHORT(cond ^ COND_CMP_TRUE, (ctx->idx+2)*4);  \
 208                         PPC_JMP(dest);                                        \
 209                 } } while(0)
 210
 211 /* To create a branch condition, select a bit of cr0... */
 212 #define CR0_LT          0
 213 #define CR0_GT          1
 214 #define CR0_EQ          2
 215 /* ...and modify BO[3] */
 216 #define COND_CMP_TRUE   0x100
 217 #define COND_CMP_FALSE  0x000
 218 /* Together, they make all required comparisons: */
 219 #define COND_GT         (CR0_GT | COND_CMP_TRUE)
 220 #define COND_GE         (CR0_LT | COND_CMP_FALSE)
 221 #define COND_EQ         (CR0_EQ | COND_CMP_TRUE)
 222 #define COND_NE         (CR0_EQ | COND_CMP_FALSE)
 223 #define COND_LT         (CR0_LT | COND_CMP_TRUE)
 224
 225 #define SEEN_DATAREF 0x10000 /* might call external helpers */
 226 #define SEEN_XREG    0x20000 /* X reg is used */
 227 #define SEEN_MEM     0x40000 /* SEEN_MEM+(1<<n) = use mem[n] for temporary
 228                               * storage */
 229 #define SEEN_MEM_MSK 0x0ffff
 230
 231 struct codegen_context {
 232         unsigned int seen;
 233         unsigned int idx;
 234         int pc_ret0; /* bpf index of first RET #0 instruction (if any) */
 235 };
 236
 237 #endif
 238
 239 #endif