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_MACH_ALCHEMY)
  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_MACH_ALCHEMY) || defined(CONFIG_CPU_CAVIUM_OCTEON) || \
 142       defined(CONFIG_CPU_LOONGSON2) || defined(CONFIG_CPU_R10000) || \
 143       defined(CONFIG_CPU_R5500)
 144
 145 /*
 146  * R10000 rocks - all hazards handled in hardware, so this becomes a nobrainer.
 147  */
 148
 149 ASMMACRO(mtc0_tlbw_hazard,
 150         )
 151 ASMMACRO(tlbw_use_hazard,
 152         )
 153 ASMMACRO(tlb_probe_hazard,
 154         )
 155 ASMMACRO(irq_enable_hazard,
 156         )
 157 ASMMACRO(irq_disable_hazard,
 158         )
 159 ASMMACRO(back_to_back_c0_hazard,
 160         )
 161 #define instruction_hazard() do { } while (0)
 162
 163 #elif defined(CONFIG_CPU_RM9000)
 164
 165 /*
 166  * RM9000 hazards.  When the JTLB is updated by tlbwi or tlbwr, a subsequent
 167  * use of the JTLB for instructions should not occur for 4 cpu cycles and use
 168  * for data translations should not occur for 3 cpu cycles.
 169  */
 170
 171 ASMMACRO(mtc0_tlbw_hazard,
 172          _ssnop; _ssnop; _ssnop; _ssnop
 173         )
 174 ASMMACRO(tlbw_use_hazard,
 175          _ssnop; _ssnop; _ssnop; _ssnop
 176         )
 177 ASMMACRO(tlb_probe_hazard,
 178          _ssnop; _ssnop; _ssnop; _ssnop
 179         )
 180 ASMMACRO(irq_enable_hazard,
 181         )
 182 ASMMACRO(irq_disable_hazard,
 183         )
 184 ASMMACRO(back_to_back_c0_hazard,
 185         )
 186 #define instruction_hazard() do { } while (0)
 187
 188 #elif defined(CONFIG_CPU_SB1)
 189
 190 /*
 191  * Mostly like R4000 for historic reasons
 192  */
 193 ASMMACRO(mtc0_tlbw_hazard,
 194         )
 195 ASMMACRO(tlbw_use_hazard,
 196         )
 197 ASMMACRO(tlb_probe_hazard,
 198         )
 199 ASMMACRO(irq_enable_hazard,
 200         )
 201 ASMMACRO(irq_disable_hazard,
 202          _ssnop; _ssnop; _ssnop
 203         )
 204 ASMMACRO(back_to_back_c0_hazard,
 205         )
 206 #define instruction_hazard() do { } while (0)
 207
 208 #else
 209
 210 /*
 211  * Finally the catchall case for all other processors including R4000, R4400,
 212  * R4600, R4700, R5000, RM7000, NEC VR41xx etc.
 213  *
 214  * The taken branch will result in a two cycle penalty for the two killed
 215  * instructions on R4000 / R4400.  Other processors only have a single cycle
 216  * hazard so this is nice trick to have an optimal code for a range of
 217  * processors.
 218  */
 219 ASMMACRO(mtc0_tlbw_hazard,
 220         nop; nop
 221         )
 222 ASMMACRO(tlbw_use_hazard,
 223         nop; nop; nop
 224         )
 225 ASMMACRO(tlb_probe_hazard,
 226          nop; nop; nop
 227         )
 228 ASMMACRO(irq_enable_hazard,
 229          _ssnop; _ssnop; _ssnop;
 230         )
 231 ASMMACRO(irq_disable_hazard,
 232         nop; nop; nop
 233         )
 234 ASMMACRO(back_to_back_c0_hazard,
 235          _ssnop; _ssnop; _ssnop;
 236         )
 237 #define instruction_hazard() do { } while (0)
 238
 239 #endif
 240
 241
 242 /* FPU hazards */
 243
 244 #if defined(CONFIG_CPU_SB1)
 245 ASMMACRO(enable_fpu_hazard,
 246          .set   push;
 247          .set   mips64;
 248          .set   noreorder;
 249          _ssnop;
 250          bnezl  $0, .+4;
 251          _ssnop;
 252          .set   pop
 253 )
 254 ASMMACRO(disable_fpu_hazard,
 255 )
 256
 257 #elif defined(CONFIG_CPU_MIPSR2)
 258 ASMMACRO(enable_fpu_hazard,
 259          _ehb
 260 )
 261 ASMMACRO(disable_fpu_hazard,
 262          _ehb
 263 )
 264 #else
 265 ASMMACRO(enable_fpu_hazard,
 266          nop; nop; nop; nop
 267 )
 268 ASMMACRO(disable_fpu_hazard,
 269          _ehb
 270 )
 271 #endif
 272
 273 #endif /* _ASM_HAZARDS_H */