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 extern u8 sk_load_word[], sk_load_half[], sk_load_byte[], sk_load_byte_msh[];
  52
  53 #define FUNCTION_DESCR_SIZE     24
  54
  55 /*
  56  * 16-bit immediate helper macros: HA() is for use with sign-extending instrs
  57  * (e.g. LD, ADDI).  If the bottom 16 bits is "-ve", add another bit into the
  58  * top half to negate the effect (i.e. 0xffff + 1 = 0x(1)0000).
  59  */
  60 #define IMM_H(i)                ((uintptr_t)(i)>>16)
  61 #define IMM_HA(i)               (((uintptr_t)(i)>>16) +                       \
  62                                  (((uintptr_t)(i) & 0x8000) >> 15))
  63 #define IMM_L(i)                ((uintptr_t)(i) & 0xffff)
  64
  65 #define PLANT_INSTR(d, idx, instr)                                            \
  66         do { if (d) { (d)[idx] = instr; } idx++; } while (0)
  67 #define EMIT(instr)             PLANT_INSTR(image, ctx->idx, instr)
  68
  69 #define PPC_NOP()               EMIT(PPC_INST_NOP)
  70 #define PPC_BLR()               EMIT(PPC_INST_BLR)
  71 #define PPC_BLRL()              EMIT(PPC_INST_BLRL)
  72 #define PPC_MTLR(r)             EMIT(PPC_INST_MTLR | __PPC_RT(r))
  73 #define PPC_ADDI(d, a, i)       EMIT(PPC_INST_ADDI | __PPC_RT(d) |            \
  74                                      __PPC_RA(a) | IMM_L(i))
  75 #define PPC_MR(d, a)            PPC_OR(d, a, a)
  76 #define PPC_LI(r, i)            PPC_ADDI(r, 0, i)
  77 #define PPC_ADDIS(d, a, i)      EMIT(PPC_INST_ADDIS |                         \
  78                                      __PPC_RS(d) | __PPC_RA(a) | IMM_L(i))
  79 #define PPC_LIS(r, i)           PPC_ADDIS(r, 0, i)
  80 #define PPC_STD(r, base, i)     EMIT(PPC_INST_STD | __PPC_RS(r) |             \
  81                                      __PPC_RA(base) | ((i) & 0xfffc))
  82
  83 #define PPC_LD(r, base, i)      EMIT(PPC_INST_LD | __PPC_RT(r) |              \
  84                                      __PPC_RA(base) | IMM_L(i))
  85 #define PPC_LWZ(r, base, i)     EMIT(PPC_INST_LWZ | __PPC_RT(r) |             \
  86                                      __PPC_RA(base) | IMM_L(i))
  87 #define PPC_LHZ(r, base, i)     EMIT(PPC_INST_LHZ | __PPC_RT(r) |             \
  88                                      __PPC_RA(base) | IMM_L(i))
  89 /* Convenience helpers for the above with 'far' offsets: */
  90 #define PPC_LD_OFFS(r, base, i) do { if ((i) < 32768) PPC_LD(r, base, i);     \
  91                 else {  PPC_ADDIS(r, base, IMM_HA(i));                        \
  92                         PPC_LD(r, r, IMM_L(i)); } } while(0)
  93
  94 #define PPC_LWZ_OFFS(r, base, i) do { if ((i) < 32768) PPC_LWZ(r, base, i);   \
  95                 else {  PPC_ADDIS(r, base, IMM_HA(i));                        \
  96                         PPC_LWZ(r, r, IMM_L(i)); } } while(0)
  97
  98 #define PPC_LHZ_OFFS(r, base, i) do { if ((i) < 32768) PPC_LHZ(r, base, i);   \
  99                 else {  PPC_ADDIS(r, base, IMM_HA(i));                        \
 100                         PPC_LHZ(r, r, IMM_L(i)); } } while(0)
 101
 102 #define PPC_CMPWI(a, i)         EMIT(PPC_INST_CMPWI | __PPC_RA(a) | IMM_L(i))
 103 #define PPC_CMPDI(a, i)         EMIT(PPC_INST_CMPDI | __PPC_RA(a) | IMM_L(i))
 104 #define PPC_CMPLWI(a, i)        EMIT(PPC_INST_CMPLWI | __PPC_RA(a) | IMM_L(i))
 105 #define PPC_CMPLW(a, b)         EMIT(PPC_INST_CMPLW | __PPC_RA(a) | __PPC_RB(b))
 106
 107 #define PPC_SUB(d, a, b)        EMIT(PPC_INST_SUB | __PPC_RT(d) |             \
 108                                      __PPC_RB(a) | __PPC_RA(b))
 109 #define PPC_ADD(d, a, b)        EMIT(PPC_INST_ADD | __PPC_RT(d) |             \
 110                                      __PPC_RA(a) | __PPC_RB(b))
 111 #define PPC_MUL(d, a, b)        EMIT(PPC_INST_MULLW | __PPC_RT(d) |           \
 112                                      __PPC_RA(a) | __PPC_RB(b))
 113 #define PPC_MULHWU(d, a, b)     EMIT(PPC_INST_MULHWU | __PPC_RT(d) |          \
 114                                      __PPC_RA(a) | __PPC_RB(b))
 115 #define PPC_MULI(d, a, i)       EMIT(PPC_INST_MULLI | __PPC_RT(d) |           \
 116                                      __PPC_RA(a) | IMM_L(i))
 117 #define PPC_DIVWU(d, a, b)      EMIT(PPC_INST_DIVWU | __PPC_RT(d) |           \
 118                                      __PPC_RA(a) | __PPC_RB(b))
 119 #define PPC_AND(d, a, b)        EMIT(PPC_INST_AND | __PPC_RA(d) |             \
 120                                      __PPC_RS(a) | __PPC_RB(b))
 121 #define PPC_ANDI(d, a, i)       EMIT(PPC_INST_ANDI | __PPC_RA(d) |            \
 122                                      __PPC_RS(a) | IMM_L(i))
 123 #define PPC_AND_DOT(d, a, b)    EMIT(PPC_INST_ANDDOT | __PPC_RA(d) |          \
 124                                      __PPC_RS(a) | __PPC_RB(b))
 125 #define PPC_OR(d, a, b)         EMIT(PPC_INST_OR | __PPC_RA(d) |              \
 126                                      __PPC_RS(a) | __PPC_RB(b))
 127 #define PPC_ORI(d, a, i)        EMIT(PPC_INST_ORI | __PPC_RA(d) |             \
 128                                      __PPC_RS(a) | IMM_L(i))
 129 #define PPC_ORIS(d, a, i)       EMIT(PPC_INST_ORIS | __PPC_RA(d) |            \
 130                                      __PPC_RS(a) | IMM_L(i))
 131 #define PPC_SLW(d, a, s)        EMIT(PPC_INST_SLW | __PPC_RA(d) |             \
 132                                      __PPC_RS(a) | __PPC_RB(s))
 133 #define PPC_SRW(d, a, s)        EMIT(PPC_INST_SRW | __PPC_RA(d) |             \
 134                                      __PPC_RS(a) | __PPC_RB(s))
 135 /* slwi = rlwinm Rx, Ry, n, 0, 31-n */
 136 #define PPC_SLWI(d, a, i)       EMIT(PPC_INST_RLWINM | __PPC_RA(d) |          \
 137                                      __PPC_RS(a) | __PPC_SH(i) |              \
 138                                      __PPC_MB(0) | __PPC_ME(31-(i)))
 139 /* srwi = rlwinm Rx, Ry, 32-n, n, 31 */
 140 #define PPC_SRWI(d, a, i)       EMIT(PPC_INST_RLWINM | __PPC_RA(d) |          \
 141                                      __PPC_RS(a) | __PPC_SH(32-(i)) |         \
 142                                      __PPC_MB(i) | __PPC_ME(31))
 143 /* sldi = rldicr Rx, Ry, n, 63-n */
 144 #define PPC_SLDI(d, a, i)       EMIT(PPC_INST_RLDICR | __PPC_RA(d) |          \
 145                                      __PPC_RS(a) | __PPC_SH(i) |              \
 146                                      __PPC_MB(63-(i)) | (((i) & 0x20) >> 4))
 147 #define PPC_NEG(d, a)           EMIT(PPC_INST_NEG | __PPC_RT(d) | __PPC_RA(a))
 148
 149 /* Long jump; (unconditional 'branch') */
 150 #define PPC_JMP(dest)           EMIT(PPC_INST_BRANCH |                        \
 151                                      (((dest) - (ctx->idx * 4)) & 0x03fffffc))
 152 /* "cond" here covers BO:BI fields. */
 153 #define PPC_BCC_SHORT(cond, dest)       EMIT(PPC_INST_BRANCH_COND |           \
 154                                              (((cond) & 0x3ff) << 16) |       \
 155                                              (((dest) - (ctx->idx * 4)) &     \
 156                                               0xfffc))
 157 #define PPC_LI32(d, i)          do { PPC_LI(d, IMM_L(i));                     \
 158                 if ((u32)(uintptr_t)(i) >= 32768) {                           \
 159                         PPC_ADDIS(d, d, IMM_HA(i));                           \
 160                 } } while(0)
 161 #define PPC_LI64(d, i)          do {                                          \
 162                 if (!((uintptr_t)(i) & 0xffffffff00000000ULL))                \
 163                         PPC_LI32(d, i);                                       \
 164                 else {                                                        \
 165                         PPC_LIS(d, ((uintptr_t)(i) >> 48));                   \
 166                         if ((uintptr_t)(i) & 0x0000ffff00000000ULL)           \
 167                                 PPC_ORI(d, d,                                 \
 168                                         ((uintptr_t)(i) >> 32) & 0xffff);     \
 169                         PPC_SLDI(d, d, 32);                                   \
 170                         if ((uintptr_t)(i) & 0x00000000ffff0000ULL)           \
 171                                 PPC_ORIS(d, d,                                \
 172                                          ((uintptr_t)(i) >> 16) & 0xffff);    \
 173                         if ((uintptr_t)(i) & 0x000000000000ffffULL)           \
 174                                 PPC_ORI(d, d, (uintptr_t)(i) & 0xffff);       \
 175                 } } while (0);
 176
 177 static inline bool is_nearbranch(int offset)
 178 {
 179         return (offset < 32768) && (offset >= -32768);
 180 }
 181
 182 /*
 183  * The fly in the ointment of code size changing from pass to pass is
 184  * avoided by padding the short branch case with a NOP.  If code size differs
 185  * with different branch reaches we will have the issue of code moving from
 186  * one pass to the next and will need a few passes to converge on a stable
 187  * state.
 188  */
 189 #define PPC_BCC(cond, dest)     do {                                          \
 190                 if (is_nearbranch((dest) - (ctx->idx * 4))) {                 \
 191                         PPC_BCC_SHORT(cond, dest);                            \
 192                         PPC_NOP();                                            \
 193                 } else {                                                      \
 194                         /* Flip the 'T or F' bit to invert comparison */      \
 195                         PPC_BCC_SHORT(cond ^ COND_CMP_TRUE, (ctx->idx+2)*4);  \
 196                         PPC_JMP(dest);                                        \
 197                 } } while(0)
 198
 199 /* To create a branch condition, select a bit of cr0... */
 200 #define CR0_LT          0
 201 #define CR0_GT          1
 202 #define CR0_EQ          2
 203 /* ...and modify BO[3] */
 204 #define COND_CMP_TRUE   0x100
 205 #define COND_CMP_FALSE  0x000
 206 /* Together, they make all required comparisons: */
 207 #define COND_GT         (CR0_GT | COND_CMP_TRUE)
 208 #define COND_GE         (CR0_LT | COND_CMP_FALSE)
 209 #define COND_EQ         (CR0_EQ | COND_CMP_TRUE)
 210 #define COND_NE         (CR0_EQ | COND_CMP_FALSE)
 211 #define COND_LT         (CR0_LT | COND_CMP_TRUE)
 212
 213 #define SEEN_DATAREF 0x10000 /* might call external helpers */
 214 #define SEEN_XREG    0x20000 /* X reg is used */
 215 #define SEEN_MEM     0x40000 /* SEEN_MEM+(1<<n) = use mem[n] for temporary
 216                               * storage */
 217 #define SEEN_MEM_MSK 0x0ffff
 218
 219 struct codegen_context {
 220         unsigned int seen;
 221         unsigned int idx;
 222         int pc_ret0; /* bpf index of first RET #0 instruction (if any) */
 223 };
 224
 225 #endif
 226
 227 #endif