arch/mips/include/asm/hazards.h

   1 /*
   2  * This file is subject to the terms and conditions of the GNU General Public
   3  * License.  See the file "COPYING" in the main directory of this archive
   4  * for more details.
   5  *
   6  * Copyright (C) 2003, 04, 07 Ralf Baechle <ralf@linux-mips.org>
   7  * Copyright (C) MIPS Technologies, Inc.
   8  *   written by Ralf Baechle <ralf@linux-mips.org>
   9  */
  10 #ifndef _ASM_HAZARDS_H
  11 #define _ASM_HAZARDS_H
  12
  13 #ifdef __ASSEMBLY__
  14 #define ASMMACRO(name, code...) .macro name; code; .endm
  15 #else
  16
  17 #include <asm/cpu-features.h>
  18
  19 #define ASMMACRO(name, code...)                                         \
  20 __asm__(".macro " #name "; " #code "; .endm");                          \
  21                                                                         \
  22 static inline void name(void)                                           \
  23 {                                                                       \
  24         __asm__ __volatile__ (#name);                                   \
  25 }
  26
  27 /*
  28  * MIPS R2 instruction hazard barrier.   Needs to be called as a subroutine.
  29  */
  30 extern void mips_ihb(void);
  31
  32 #endif
  33
  34 ASMMACRO(_ssnop,
  35          sll    $0, $0, 1
  36         )
  37
  38 ASMMACRO(_ehb,
  39          sll    $0, $0, 3
  40         )
  41
  42 /*
  43  * TLB hazards
  44  */
  45 #if defined(CONFIG_CPU_MIPSR2) && !defined(CONFIG_CPU_CAVIUM_OCTEON)
  46
  47 /*
  48  * MIPSR2 defines ehb for hazard avoidance
  49  */
  50
  51 ASMMACRO(mtc0_tlbw_hazard,
  52          _ehb
  53         )
  54 ASMMACRO(tlbw_use_hazard,
  55          _ehb
  56         )
  57 ASMMACRO(tlb_probe_hazard,
  58          _ehb
  59         )
  60 ASMMACRO(irq_enable_hazard,
  61          _ehb
  62         )
  63 ASMMACRO(irq_disable_hazard,
  64         _ehb
  65         )
  66 ASMMACRO(back_to_back_c0_hazard,
  67          _ehb
  68         )
  69 /*
  70  * gcc has a tradition of misscompiling the previous construct using the
  71  * address of a label as argument to inline assembler.  Gas otoh has the
  72  * annoying difference between la and dla which are only usable for 32-bit
  73  * rsp. 64-bit code, so can't be used without conditional compilation.
  74  * The alterantive is switching the assembler to 64-bit code which happens
  75  * to work right even for 32-bit code ...
  76  */
  77 #define instruction_hazard()                                            \
  78 do {                                                                    \
  79         unsigned long tmp;                                              \
  80                                                                         \
  81         __asm__ __volatile__(                                           \
  82         "       .set    mips64r2                                \n"     \
  83         "       dla     %0, 1f                                  \n"     \
  84         "       jr.hb   %0                                      \n"     \
  85         "       .set    mips0                                   \n"     \
  86         "1:                                                     \n"     \
  87         : "=r" (tmp));                                                  \
  88 } while (0)
  89
  90 #elif (defined(CONFIG_CPU_MIPSR1) && !defined(CONFIG_MIPS_ALCHEMY)) || \
  91         defined(CONFIG_CPU_BMIPS)
  92
  93 /*
  94  * These are slightly complicated by the fact that we guarantee R1 kernels to
  95  * run fine on R2 processors.
  96  */
  97 ASMMACRO(mtc0_tlbw_hazard,
  98         _ssnop; _ssnop; _ehb
  99         )
 100 ASMMACRO(tlbw_use_hazard,
 101         _ssnop; _ssnop; _ssnop; _ehb
 102         )
 103 ASMMACRO(tlb_probe_hazard,
 104          _ssnop; _ssnop; _ssnop; _ehb
 105         )
 106 ASMMACRO(irq_enable_hazard,
 107          _ssnop; _ssnop; _ssnop; _ehb
 108         )
 109 ASMMACRO(irq_disable_hazard,
 110         _ssnop; _ssnop; _ssnop; _ehb
 111         )
 112 ASMMACRO(back_to_back_c0_hazard,
 113          _ssnop; _ssnop; _ssnop; _ehb
 114         )
 115 /*
 116  * gcc has a tradition of misscompiling the previous construct using the
 117  * address of a label as argument to inline assembler.  Gas otoh has the
 118  * annoying difference between la and dla which are only usable for 32-bit
 119  * rsp. 64-bit code, so can't be used without conditional compilation.
 120  * The alterantive is switching the assembler to 64-bit code which happens
 121  * to work right even for 32-bit code ...
 122  */
 123 #define __instruction_hazard()                                          \
 124 do {                                                                    \
 125         unsigned long tmp;                                              \
 126                                                                         \
 127         __asm__ __volatile__(                                           \
 128         "       .set    mips64r2                                \n"     \
 129         "       dla     %0, 1f                                  \n"     \
 130         "       jr.hb   %0                                      \n"     \
 131         "       .set    mips0                                   \n"     \
 132         "1:                                                     \n"     \
 133         : "=r" (tmp));                                                  \
 134 } while (0)
 135
 136 #define instruction_hazard()                                            \
 137 do {                                                                    \
 138         if (cpu_has_mips_r2)                                            \
 139                 __instruction_hazard();                                 \
 140 } while (0)
 141
 142 #elif defined(CONFIG_MIPS_ALCHEMY) || defined(CONFIG_CPU_CAVIUM_OCTEON) || \
 143         defined(CONFIG_CPU_LOONGSON2) || defined(CONFIG_CPU_R10000) || \
 144         defined(CONFIG_CPU_R5500)
 145
 146 /*
 147  * R10000 rocks - all hazards handled in hardware, so this becomes a nobrainer.
 148  */
 149
 150 ASMMACRO(mtc0_tlbw_hazard,
 151         )
 152 ASMMACRO(tlbw_use_hazard,
 153         )
 154 ASMMACRO(tlb_probe_hazard,
 155         )
 156 ASMMACRO(irq_enable_hazard,
 157         )
 158 ASMMACRO(irq_disable_hazard,
 159         )
 160 ASMMACRO(back_to_back_c0_hazard,
 161         )
 162 #define instruction_hazard() do { } while (0)
 163
 164 #elif defined(CONFIG_CPU_SB1)
 165
 166 /*
 167  * Mostly like R4000 for historic reasons
 168  */
 169 ASMMACRO(mtc0_tlbw_hazard,
 170         )
 171 ASMMACRO(tlbw_use_hazard,
 172         )
 173 ASMMACRO(tlb_probe_hazard,
 174         )
 175 ASMMACRO(irq_enable_hazard,
 176         )
 177 ASMMACRO(irq_disable_hazard,
 178          _ssnop; _ssnop; _ssnop
 179         )
 180 ASMMACRO(back_to_back_c0_hazard,
 181         )
 182 #define instruction_hazard() do { } while (0)
 183
 184 #else
 185
 186 /*
 187  * Finally the catchall case for all other processors including R4000, R4400,
 188  * R4600, R4700, R5000, RM7000, NEC VR41xx etc.
 189  *
 190  * The taken branch will result in a two cycle penalty for the two killed
 191  * instructions on R4000 / R4400.  Other processors only have a single cycle
 192  * hazard so this is nice trick to have an optimal code for a range of
 193  * processors.
 194  */
 195 ASMMACRO(mtc0_tlbw_hazard,
 196         nop; nop
 197         )
 198 ASMMACRO(tlbw_use_hazard,
 199         nop; nop; nop
 200         )
 201 ASMMACRO(tlb_probe_hazard,
 202          nop; nop; nop
 203         )
 204 ASMMACRO(irq_enable_hazard,
 205          _ssnop; _ssnop; _ssnop;
 206         )
 207 ASMMACRO(irq_disable_hazard,
 208         nop; nop; nop
 209         )
 210 ASMMACRO(back_to_back_c0_hazard,
 211          _ssnop; _ssnop; _ssnop;
 212         )
 213 #define instruction_hazard() do { } while (0)
 214
 215 #endif
 216
 217
 218 /* FPU hazards */
 219
 220 #if defined(CONFIG_CPU_SB1)
 221 ASMMACRO(enable_fpu_hazard,
 222          .set   push;
 223          .set   mips64;
 224          .set   noreorder;
 225          _ssnop;
 226          bnezl  $0, .+4;
 227          _ssnop;
 228          .set   pop
 229 )
 230 ASMMACRO(disable_fpu_hazard,
 231 )
 232
 233 #elif defined(CONFIG_CPU_MIPSR2)
 234 ASMMACRO(enable_fpu_hazard,
 235          _ehb
 236 )
 237 ASMMACRO(disable_fpu_hazard,
 238          _ehb
 239 )
 240 #else
 241 ASMMACRO(enable_fpu_hazard,
 242          nop; nop; nop; nop
 243 )
 244 ASMMACRO(disable_fpu_hazard,
 245          _ehb
 246 )
 247 #endif
 248
 249 #endif /* _ASM_HAZARDS_H */