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   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, 2004 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
  14 #ifdef __ASSEMBLY__
  15 #define ASMMACRO(name, code...) .macro name; code; .endm
  16 #else
  17
  18 #define ASMMACRO(name, code...)                                         \
  19 __asm__(".macro " #name "; " #code "; .endm");                          \
  20                                                                         \
  21 static inline void name(void)                                           \
  22 {                                                                       \
  23         __asm__ __volatile__ (#name);                                   \
  24 }
  25
  26 #endif
  27
  28 ASMMACRO(_ssnop,
  29          sll    $0, $0, 1
  30         )
  31
  32 ASMMACRO(_ehb,
  33          sll    $0, $0, 3
  34         )
  35
  36 /*
  37  * TLB hazards
  38  */
  39 #if defined(CONFIG_CPU_MIPSR2)
  40
  41 /*
  42  * MIPSR2 defines ehb for hazard avoidance
  43  */
  44
  45 ASMMACRO(mtc0_tlbw_hazard,
  46          _ehb
  47         )
  48 ASMMACRO(tlbw_use_hazard,
  49          _ehb
  50         )
  51 ASMMACRO(tlb_probe_hazard,
  52          _ehb
  53         )
  54 ASMMACRO(irq_enable_hazard,
  55          _ehb
  56         )
  57 ASMMACRO(irq_disable_hazard,
  58         _ehb
  59         )
  60 ASMMACRO(back_to_back_c0_hazard,
  61          _ehb
  62         )
  63 /*
  64  * gcc has a tradition of misscompiling the previous construct using the
  65  * address of a label as argument to inline assembler.  Gas otoh has the
  66  * annoying difference between la and dla which are only usable for 32-bit
  67  * rsp. 64-bit code, so can't be used without conditional compilation.
  68  * The alterantive is switching the assembler to 64-bit code which happens
  69  * to work right even for 32-bit code ...
  70  */
  71 #define instruction_hazard()                                            \
  72 do {                                                                    \
  73         unsigned long tmp;                                              \
  74                                                                         \
  75         __asm__ __volatile__(                                           \
  76         "       .set    mips64r2                                \n"     \
  77         "       dla     %0, 1f                                  \n"     \
  78         "       jr.hb   %0                                      \n"     \
  79         "       .set    mips0                                   \n"     \
  80         "1:                                                     \n"     \
  81         : "=r" (tmp));                                                  \
  82 } while (0)
  83
  84 #elif defined(CONFIG_CPU_R10000)
  85
  86 /*
  87  * R10000 rocks - all hazards handled in hardware, so this becomes a nobrainer.
  88  */
  89
  90 ASMMACRO(mtc0_tlbw_hazard,
  91         )
  92 ASMMACRO(tlbw_use_hazard,
  93         )
  94 ASMMACRO(tlb_probe_hazard,
  95         )
  96 ASMMACRO(irq_enable_hazard,
  97         )
  98 ASMMACRO(irq_disable_hazard,
  99         )
 100 ASMMACRO(back_to_back_c0_hazard,
 101         )
 102 #define instruction_hazard() do { } while (0)
 103
 104 #elif defined(CONFIG_CPU_RM9000)
 105
 106 /*
 107  * RM9000 hazards.  When the JTLB is updated by tlbwi or tlbwr, a subsequent
 108  * use of the JTLB for instructions should not occur for 4 cpu cycles and use
 109  * for data translations should not occur for 3 cpu cycles.
 110  */
 111
 112 ASMMACRO(mtc0_tlbw_hazard,
 113          _ssnop; _ssnop; _ssnop; _ssnop
 114         )
 115 ASMMACRO(tlbw_use_hazard,
 116          _ssnop; _ssnop; _ssnop; _ssnop
 117         )
 118 ASMMACRO(tlb_probe_hazard,
 119          _ssnop; _ssnop; _ssnop; _ssnop
 120         )
 121 ASMMACRO(irq_enable_hazard,
 122         )
 123 ASMMACRO(irq_disable_hazard,
 124         )
 125 ASMMACRO(back_to_back_c0_hazard,
 126         )
 127 #define instruction_hazard() do { } while (0)
 128
 129 #elif defined(CONFIG_CPU_SB1)
 130
 131 /*
 132  * Mostly like R4000 for historic reasons
 133  */
 134 ASMMACRO(mtc0_tlbw_hazard,
 135         )
 136 ASMMACRO(tlbw_use_hazard,
 137         )
 138 ASMMACRO(tlb_probe_hazard,
 139         )
 140 ASMMACRO(irq_enable_hazard,
 141         )
 142 ASMMACRO(irq_disable_hazard,
 143          _ssnop; _ssnop; _ssnop
 144         )
 145 ASMMACRO(back_to_back_c0_hazard,
 146         )
 147 #define instruction_hazard() do { } while (0)
 148
 149 #else
 150
 151 /*
 152  * Finally the catchall case for all other processors including R4000, R4400,
 153  * R4600, R4700, R5000, RM7000, NEC VR41xx etc.
 154  *
 155  * The taken branch will result in a two cycle penalty for the two killed
 156  * instructions on R4000 / R4400.  Other processors only have a single cycle
 157  * hazard so this is nice trick to have an optimal code for a range of
 158  * processors.
 159  */
 160 ASMMACRO(mtc0_tlbw_hazard,
 161         nop; nop
 162         )
 163 ASMMACRO(tlbw_use_hazard,
 164         nop; nop; nop
 165         )
 166 ASMMACRO(tlb_probe_hazard,
 167          nop; nop; nop
 168         )
 169 ASMMACRO(irq_enable_hazard,
 170         )
 171 ASMMACRO(irq_disable_hazard,
 172         nop; nop; nop
 173         )
 174 ASMMACRO(back_to_back_c0_hazard,
 175          _ssnop; _ssnop; _ssnop;
 176         )
 177 #define instruction_hazard() do { } while (0)
 178
 179 #endif
 180
 181
 182 /* FPU hazards */
 183
 184 #if defined(CONFIG_CPU_SB1)
 185 ASMMACRO(enable_fpu_hazard,
 186          .set   push;
 187          .set   mips64;
 188          .set   noreorder;
 189          _ssnop;
 190          bnezl  $0,.+4;
 191          _ssnop;
 192          .set   pop
 193 )
 194 ASMMACRO(disable_fpu_hazard,
 195 )
 196
 197 #elif defined(CONFIG_CPU_MIPSR2)
 198 ASMMACRO(enable_fpu_hazard,
 199          _ehb
 200 )
 201 ASMMACRO(disable_fpu_hazard,
 202          _ehb
 203 )
 204 #else
 205 ASMMACRO(enable_fpu_hazard,
 206          nop; nop; nop; nop
 207 )
 208 ASMMACRO(disable_fpu_hazard,
 209          _ehb
 210 )
 211 #endif
 212
 213 #endif /* _ASM_HAZARDS_H */