arch/mips/kernel/r4k_switch.S

   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) 1994, 1995, 1996, 1998, 1999, 2002, 2003 Ralf Baechle
   7  * Copyright (C) 1996 David S. Miller (davem@davemloft.net)
   8  * Copyright (C) 1994, 1995, 1996, by Andreas Busse
   9  * Copyright (C) 1999 Silicon Graphics, Inc.
  10  * Copyright (C) 2000 MIPS Technologies, Inc.
  11  *    written by Carsten Langgaard, carstenl@mips.com
  12  */
  13 #include <asm/asm.h>
  14 #include <asm/cachectl.h>
  15 #include <asm/fpregdef.h>
  16 #include <asm/mipsregs.h>
  17 #include <asm/asm-offsets.h>
  18 #include <asm/pgtable-bits.h>
  19 #include <asm/regdef.h>
  20 #include <asm/stackframe.h>
  21 #include <asm/thread_info.h>
  22
  23 #include <asm/asmmacro.h>
  24
  25 /* preprocessor replaces the fp in ".set fp=64" with $30 otherwise */
  26 #undef fp
  27
  28 /*
  29  * Offset to the current process status flags, the first 32 bytes of the
  30  * stack are not used.
  31  */
  32 #define ST_OFF (_THREAD_SIZE - 32 - PT_SIZE + PT_STATUS)
  33
  34 #ifndef USE_ALTERNATE_RESUME_IMPL
  35 /*
  36  * task_struct *resume(task_struct *prev, task_struct *next,
  37  *                     struct thread_info *next_ti, s32 fp_save)
  38  */
  39         .align  5
  40         LEAF(resume)
  41         mfc0    t1, CP0_STATUS
  42         LONG_S  t1, THREAD_STATUS(a0)
  43         cpu_save_nonscratch a0
  44         LONG_S  ra, THREAD_REG31(a0)
  45
  46         /*
  47          * Check whether we need to save any FP context. FP context is saved
  48          * iff the process has used the context with the scalar FPU or the MSA
  49          * ASE in the current time slice, as indicated by _TIF_USEDFPU and
  50          * _TIF_USEDMSA respectively. switch_to will have set fp_save
  51          * accordingly to an FP_SAVE_ enum value.
  52          */
  53         beqz    a3, 2f
  54
  55         /*
  56          * We do. Clear the saved CU1 bit for prev, such that next time it is
  57          * scheduled it will start in userland with the FPU disabled. If the
  58          * task uses the FPU then it will be enabled again via the do_cpu trap.
  59          * This allows us to lazily restore the FP context.
  60          */
  61         PTR_L   t3, TASK_THREAD_INFO(a0)
  62         LONG_L  t0, ST_OFF(t3)
  63         li      t1, ~ST0_CU1
  64         and     t0, t0, t1
  65         LONG_S  t0, ST_OFF(t3)
  66
  67         /* Check whether we're saving scalar or vector context. */
  68         bgtz    a3, 1f
  69
  70         /* Save 128b MSA vector context + scalar FP control & status. */
  71         .set push
  72         SET_HARDFLOAT
  73         cfc1    t1, fcr31
  74         msa_save_all    a0
  75         .set pop        /* SET_HARDFLOAT */
  76
  77         sw      t1, THREAD_FCR31(a0)
  78         b       2f
  79
  80 1:      /* Save 32b/64b scalar FP context. */
  81         fpu_save_double a0 t0 t1                # c0_status passed in t0
  82                                                 # clobbers t1
  83 2:
  84
  85 #if defined(CONFIG_CC_STACKPROTECTOR) && !defined(CONFIG_SMP)
  86         PTR_LA  t8, __stack_chk_guard
  87         LONG_L  t9, TASK_STACK_CANARY(a1)
  88         LONG_S  t9, 0(t8)
  89 #endif
  90
  91         /*
  92          * The order of restoring the registers takes care of the race
  93          * updating $28, $29 and kernelsp without disabling ints.
  94          */
  95         move    $28, a2
  96         cpu_restore_nonscratch a1
  97
  98         PTR_ADDU        t0, $28, _THREAD_SIZE - 32
  99         set_saved_sp    t0, t1, t2
 100         mfc0    t1, CP0_STATUS          /* Do we really need this? */
 101         li      a3, 0xff01
 102         and     t1, a3
 103         LONG_L  a2, THREAD_STATUS(a1)
 104         nor     a3, $0, a3
 105         and     a2, a3
 106         or      a2, t1
 107         mtc0    a2, CP0_STATUS
 108         move    v0, a0
 109         jr      ra
 110         END(resume)
 111
 112 #endif /* USE_ALTERNATE_RESUME_IMPL */
 113
 114 /*
 115  * Save a thread's fp context.
 116  */
 117 LEAF(_save_fp)
 118 #if defined(CONFIG_64BIT) || defined(CONFIG_CPU_MIPS32_R2)
 119         mfc0    t0, CP0_STATUS
 120 #endif
 121         fpu_save_double a0 t0 t1                # clobbers t1
 122         jr      ra
 123         END(_save_fp)
 124
 125 /*
 126  * Restore a thread's fp context.
 127  */
 128 LEAF(_restore_fp)
 129 #if defined(CONFIG_64BIT) || defined(CONFIG_CPU_MIPS32_R2)
 130         mfc0    t0, CP0_STATUS
 131 #endif
 132         fpu_restore_double a0 t0 t1             # clobbers t1
 133         jr      ra
 134         END(_restore_fp)
 135
 136 #ifdef CONFIG_CPU_HAS_MSA
 137
 138 /*
 139  * Save a thread's MSA vector context.
 140  */
 141 LEAF(_save_msa)
 142         msa_save_all    a0
 143         jr      ra
 144         END(_save_msa)
 145
 146 /*
 147  * Restore a thread's MSA vector context.
 148  */
 149 LEAF(_restore_msa)
 150         msa_restore_all a0
 151         jr      ra
 152         END(_restore_msa)
 153
 154 LEAF(_init_msa_upper)
 155         msa_init_all_upper
 156         jr      ra
 157         END(_init_msa_upper)
 158
 159 #endif
 160
 161 /*
 162  * Load the FPU with signalling NANS.  This bit pattern we're using has
 163  * the property that no matter whether considered as single or as double
 164  * precision represents signaling NANS.
 165  *
 166  * We initialize fcr31 to rounding to nearest, no exceptions.
 167  */
 168
 169 #define FPU_DEFAULT  0x00000000
 170
 171         .set push
 172         SET_HARDFLOAT
 173
 174 LEAF(_init_fpu)
 175         mfc0    t0, CP0_STATUS
 176         li      t1, ST0_CU1
 177         or      t0, t1
 178         mtc0    t0, CP0_STATUS
 179         enable_fpu_hazard
 180
 181         li      t1, FPU_DEFAULT
 182         ctc1    t1, fcr31
 183
 184         li      t1, -1                          # SNaN
 185
 186 #ifdef CONFIG_64BIT
 187         sll     t0, t0, 5
 188         bgez    t0, 1f                          # 16 / 32 register mode?
 189
 190         dmtc1   t1, $f1
 191         dmtc1   t1, $f3
 192         dmtc1   t1, $f5
 193         dmtc1   t1, $f7
 194         dmtc1   t1, $f9
 195         dmtc1   t1, $f11
 196         dmtc1   t1, $f13
 197         dmtc1   t1, $f15
 198         dmtc1   t1, $f17
 199         dmtc1   t1, $f19
 200         dmtc1   t1, $f21
 201         dmtc1   t1, $f23
 202         dmtc1   t1, $f25
 203         dmtc1   t1, $f27
 204         dmtc1   t1, $f29
 205         dmtc1   t1, $f31
 206 1:
 207 #endif
 208
 209 #ifdef CONFIG_CPU_MIPS32
 210         mtc1    t1, $f0
 211         mtc1    t1, $f1
 212         mtc1    t1, $f2
 213         mtc1    t1, $f3
 214         mtc1    t1, $f4
 215         mtc1    t1, $f5
 216         mtc1    t1, $f6
 217         mtc1    t1, $f7
 218         mtc1    t1, $f8
 219         mtc1    t1, $f9
 220         mtc1    t1, $f10
 221         mtc1    t1, $f11
 222         mtc1    t1, $f12
 223         mtc1    t1, $f13
 224         mtc1    t1, $f14
 225         mtc1    t1, $f15
 226         mtc1    t1, $f16
 227         mtc1    t1, $f17
 228         mtc1    t1, $f18
 229         mtc1    t1, $f19
 230         mtc1    t1, $f20
 231         mtc1    t1, $f21
 232         mtc1    t1, $f22
 233         mtc1    t1, $f23
 234         mtc1    t1, $f24
 235         mtc1    t1, $f25
 236         mtc1    t1, $f26
 237         mtc1    t1, $f27
 238         mtc1    t1, $f28
 239         mtc1    t1, $f29
 240         mtc1    t1, $f30
 241         mtc1    t1, $f31
 242
 243 #ifdef CONFIG_CPU_MIPS32_R2
 244         .set    push
 245         .set    mips32r2
 246         .set    fp=64
 247         sll     t0, t0, 5                       # is Status.FR set?
 248         bgez    t0, 1f                          # no: skip setting upper 32b
 249
 250         mthc1   t1, $f0
 251         mthc1   t1, $f1
 252         mthc1   t1, $f2
 253         mthc1   t1, $f3
 254         mthc1   t1, $f4
 255         mthc1   t1, $f5
 256         mthc1   t1, $f6
 257         mthc1   t1, $f7
 258         mthc1   t1, $f8
 259         mthc1   t1, $f9
 260         mthc1   t1, $f10
 261         mthc1   t1, $f11
 262         mthc1   t1, $f12
 263         mthc1   t1, $f13
 264         mthc1   t1, $f14
 265         mthc1   t1, $f15
 266         mthc1   t1, $f16
 267         mthc1   t1, $f17
 268         mthc1   t1, $f18
 269         mthc1   t1, $f19
 270         mthc1   t1, $f20
 271         mthc1   t1, $f21
 272         mthc1   t1, $f22
 273         mthc1   t1, $f23
 274         mthc1   t1, $f24
 275         mthc1   t1, $f25
 276         mthc1   t1, $f26
 277         mthc1   t1, $f27
 278         mthc1   t1, $f28
 279         mthc1   t1, $f29
 280         mthc1   t1, $f30
 281         mthc1   t1, $f31
 282 1:      .set    pop
 283 #endif /* CONFIG_CPU_MIPS32_R2 */
 284 #else
 285         .set    arch=r4000
 286         dmtc1   t1, $f0
 287         dmtc1   t1, $f2
 288         dmtc1   t1, $f4
 289         dmtc1   t1, $f6
 290         dmtc1   t1, $f8
 291         dmtc1   t1, $f10
 292         dmtc1   t1, $f12
 293         dmtc1   t1, $f14
 294         dmtc1   t1, $f16
 295         dmtc1   t1, $f18
 296         dmtc1   t1, $f20
 297         dmtc1   t1, $f22
 298         dmtc1   t1, $f24
 299         dmtc1   t1, $f26
 300         dmtc1   t1, $f28
 301         dmtc1   t1, $f30
 302 #endif
 303         jr      ra
 304         END(_init_fpu)
 305
 306         .set pop        /* SET_HARDFLOAT */