include/asm-mips/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)
  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)
  91
  92 /*
  93  * These are slightly complicated by the fact that we guarantee R1 kernels to
  94  * run fine on R2 processors.
  95  */
  96 ASMMACRO(mtc0_tlbw_hazard,
  97         _ssnop; _ssnop; _ehb
  98         )
  99 ASMMACRO(tlbw_use_hazard,
 100         _ssnop; _ssnop; _ssnop; _ehb
 101         )
 102 ASMMACRO(tlb_probe_hazard,
 103          _ssnop; _ssnop; _ssnop; _ehb
 104         )
 105 ASMMACRO(irq_enable_hazard,
 106          _ssnop; _ssnop; _ssnop; _ehb
 107         )
 108 ASMMACRO(irq_disable_hazard,
 109         _ssnop; _ssnop; _ssnop; _ehb
 110         )
 111 ASMMACRO(back_to_back_c0_hazard,
 112          _ssnop; _ssnop; _ssnop; _ehb
 113         )
 114 /*
 115  * gcc has a tradition of misscompiling the previous construct using the
 116  * address of a label as argument to inline assembler.  Gas otoh has the
 117  * annoying difference between la and dla which are only usable for 32-bit
 118  * rsp. 64-bit code, so can't be used without conditional compilation.
 119  * The alterantive is switching the assembler to 64-bit code which happens
 120  * to work right even for 32-bit code ...
 121  */
 122 #define __instruction_hazard()                                          \
 123 do {                                                                    \
 124         unsigned long tmp;                                              \
 125                                                                         \
 126         __asm__ __volatile__(                                           \
 127         "       .set    mips64r2                                \n"     \
 128         "       dla     %0, 1f                                  \n"     \
 129         "       jr.hb   %0                                      \n"     \
 130         "       .set    mips0                                   \n"     \
 131         "1:                                                     \n"     \
 132         : "=r" (tmp));                                                  \
 133 } while (0)
 134
 135 #define instruction_hazard()                                            \
 136 do {                                                                    \
 137         if (cpu_has_mips_r2)                                            \
 138                 __instruction_hazard();                                 \
 139 } while (0)
 140
 141 #elif defined(CONFIG_CPU_R10000)
 142
 143 /*
 144  * R10000 rocks - all hazards handled in hardware, so this becomes a nobrainer.
 145  */
 146
 147 ASMMACRO(mtc0_tlbw_hazard,
 148         )
 149 ASMMACRO(tlbw_use_hazard,
 150         )
 151 ASMMACRO(tlb_probe_hazard,
 152         )
 153 ASMMACRO(irq_enable_hazard,
 154         )
 155 ASMMACRO(irq_disable_hazard,
 156         )
 157 ASMMACRO(back_to_back_c0_hazard,
 158         )
 159 #define instruction_hazard() do { } while (0)
 160
 161 #elif defined(CONFIG_CPU_RM9000)
 162
 163 /*
 164  * RM9000 hazards.  When the JTLB is updated by tlbwi or tlbwr, a subsequent
 165  * use of the JTLB for instructions should not occur for 4 cpu cycles and use
 166  * for data translations should not occur for 3 cpu cycles.
 167  */
 168
 169 ASMMACRO(mtc0_tlbw_hazard,
 170          _ssnop; _ssnop; _ssnop; _ssnop
 171         )
 172 ASMMACRO(tlbw_use_hazard,
 173          _ssnop; _ssnop; _ssnop; _ssnop
 174         )
 175 ASMMACRO(tlb_probe_hazard,
 176          _ssnop; _ssnop; _ssnop; _ssnop
 177         )
 178 ASMMACRO(irq_enable_hazard,
 179         )
 180 ASMMACRO(irq_disable_hazard,
 181         )
 182 ASMMACRO(back_to_back_c0_hazard,
 183         )
 184 #define instruction_hazard() do { } while (0)
 185
 186 #elif defined(CONFIG_CPU_SB1)
 187
 188 /*
 189  * Mostly like R4000 for historic reasons
 190  */
 191 ASMMACRO(mtc0_tlbw_hazard,
 192         )
 193 ASMMACRO(tlbw_use_hazard,
 194         )
 195 ASMMACRO(tlb_probe_hazard,
 196         )
 197 ASMMACRO(irq_enable_hazard,
 198         )
 199 ASMMACRO(irq_disable_hazard,
 200          _ssnop; _ssnop; _ssnop
 201         )
 202 ASMMACRO(back_to_back_c0_hazard,
 203         )
 204 #define instruction_hazard() do { } while (0)
 205
 206 #else
 207
 208 /*
 209  * Finally the catchall case for all other processors including R4000, R4400,
 210  * R4600, R4700, R5000, RM7000, NEC VR41xx etc.
 211  *
 212  * The taken branch will result in a two cycle penalty for the two killed
 213  * instructions on R4000 / R4400.  Other processors only have a single cycle
 214  * hazard so this is nice trick to have an optimal code for a range of
 215  * processors.
 216  */
 217 ASMMACRO(mtc0_tlbw_hazard,
 218         nop; nop
 219         )
 220 ASMMACRO(tlbw_use_hazard,
 221         nop; nop; nop
 222         )
 223 ASMMACRO(tlb_probe_hazard,
 224          nop; nop; nop
 225         )
 226 ASMMACRO(irq_enable_hazard,
 227          _ssnop; _ssnop; _ssnop;
 228         )
 229 ASMMACRO(irq_disable_hazard,
 230         nop; nop; nop
 231         )
 232 ASMMACRO(back_to_back_c0_hazard,
 233          _ssnop; _ssnop; _ssnop;
 234         )
 235 #define instruction_hazard() do { } while (0)
 236
 237 #endif
 238
 239
 240 /* FPU hazards */
 241
 242 #if defined(CONFIG_CPU_SB1)
 243 ASMMACRO(enable_fpu_hazard,
 244          .set   push;
 245          .set   mips64;
 246          .set   noreorder;
 247          _ssnop;
 248          bnezl  $0, .+4;
 249          _ssnop;
 250          .set   pop
 251 )
 252 ASMMACRO(disable_fpu_hazard,
 253 )
 254
 255 #elif defined(CONFIG_CPU_MIPSR2)
 256 ASMMACRO(enable_fpu_hazard,
 257          _ehb
 258 )
 259 ASMMACRO(disable_fpu_hazard,
 260          _ehb
 261 )
 262 #else
 263 ASMMACRO(enable_fpu_hazard,
 264          nop; nop; nop; nop
 265 )
 266 ASMMACRO(disable_fpu_hazard,
 267          _ehb
 268 )
 269 #endif
 270
 271 #endif /* _ASM_HAZARDS_H */