arch/powerpc/kernel/fpu.S

   1 /*
   2  *  FPU support code, moved here from head.S so that it can be used
   3  *  by chips which use other head-whatever.S files.
   4  *
   5  *    Copyright (C) 1995-1996 Gary Thomas (gdt@linuxppc.org)
   6  *    Copyright (C) 1996 Cort Dougan <cort@cs.nmt.edu>
   7  *    Copyright (C) 1996 Paul Mackerras.
   8  *    Copyright (C) 1997 Dan Malek (dmalek@jlc.net).
   9  *
  10  *  This program is free software; you can redistribute it and/or
  11  *  modify it under the terms of the GNU General Public License
  12  *  as published by the Free Software Foundation; either version
  13  *  2 of the License, or (at your option) any later version.
  14  *
  15  */
  16
  17 #include <asm/reg.h>
  18 #include <asm/page.h>
  19 #include <asm/mmu.h>
  20 #include <asm/pgtable.h>
  21 #include <asm/cputable.h>
  22 #include <asm/cache.h>
  23 #include <asm/thread_info.h>
  24 #include <asm/ppc_asm.h>
  25 #include <asm/asm-offsets.h>
  26 #include <asm/ptrace.h>
  27
  28 #ifdef CONFIG_VSX
  29 #define __REST_32FPVSRS(n,c,base)                                       \
  30 BEGIN_FTR_SECTION                                                       \
  31         b       2f;                                                     \
  32 END_FTR_SECTION_IFSET(CPU_FTR_VSX);                                     \
  33         REST_32FPRS(n,base);                                            \
  34         b       3f;                                                     \
  35 2:      REST_32VSRS(n,c,base);                                          \
  36 3:
  37
  38 #define __SAVE_32FPVSRS(n,c,base)                                       \
  39 BEGIN_FTR_SECTION                                                       \
  40         b       2f;                                                     \
  41 END_FTR_SECTION_IFSET(CPU_FTR_VSX);                                     \
  42         SAVE_32FPRS(n,base);                                            \
  43         b       3f;                                                     \
  44 2:      SAVE_32VSRS(n,c,base);                                          \
  45 3:
  46 #else
  47 #define __REST_32FPVSRS(n,b,base)       REST_32FPRS(n, base)
  48 #define __SAVE_32FPVSRS(n,b,base)       SAVE_32FPRS(n, base)
  49 #endif
  50 #define REST_32FPVSRS(n,c,base) __REST_32FPVSRS(n,__REG_##c,__REG_##base)
  51 #define SAVE_32FPVSRS(n,c,base) __SAVE_32FPVSRS(n,__REG_##c,__REG_##base)
  52
  53 /*
  54  * This task wants to use the FPU now.
  55  * On UP, disable FP for the task which had the FPU previously,
  56  * and save its floating-point registers in its thread_struct.
  57  * Load up this task's FP registers from its thread_struct,
  58  * enable the FPU for the current task and return to the task.
  59  */
  60 _GLOBAL(load_up_fpu)
  61         mfmsr   r5
  62         ori     r5,r5,MSR_FP
  63 #ifdef CONFIG_VSX
  64 BEGIN_FTR_SECTION
  65         oris    r5,r5,MSR_VSX@h
  66 END_FTR_SECTION_IFSET(CPU_FTR_VSX)
  67 #endif
  68         SYNC
  69         MTMSRD(r5)                      /* enable use of fpu now */
  70         isync
  71 /*
  72  * For SMP, we don't do lazy FPU switching because it just gets too
  73  * horrendously complex, especially when a task switches from one CPU
  74  * to another.  Instead we call giveup_fpu in switch_to.
  75  */
  76 #ifndef CONFIG_SMP
  77         LOAD_REG_ADDRBASE(r3, last_task_used_math)
  78         toreal(r3)
  79         PPC_LL  r4,ADDROFF(last_task_used_math)(r3)
  80         PPC_LCMPI       0,r4,0
  81         beq     1f
  82         toreal(r4)
  83         addi    r4,r4,THREAD            /* want last_task_used_math->thread */
  84         SAVE_32FPVSRS(0, R5, R4)
  85         mffs    fr0
  86         stfd    fr0,THREAD_FPSCR(r4)
  87         PPC_LL  r5,PT_REGS(r4)
  88         toreal(r5)
  89         PPC_LL  r4,_MSR-STACK_FRAME_OVERHEAD(r5)
  90         li      r10,MSR_FP|MSR_FE0|MSR_FE1
  91         andc    r4,r4,r10               /* disable FP for previous task */
  92         PPC_STL r4,_MSR-STACK_FRAME_OVERHEAD(r5)
  93 1:
  94 #endif /* CONFIG_SMP */
  95         /* enable use of FP after return */
  96 #ifdef CONFIG_PPC32
  97         mfspr   r5,SPRN_SPRG_THREAD             /* current task's THREAD (phys) */
  98         lwz     r4,THREAD_FPEXC_MODE(r5)
  99         ori     r9,r9,MSR_FP            /* enable FP for current */
 100         or      r9,r9,r4
 101 #else
 102         ld      r4,PACACURRENT(r13)
 103         addi    r5,r4,THREAD            /* Get THREAD */
 104         lwz     r4,THREAD_FPEXC_MODE(r5)
 105         ori     r12,r12,MSR_FP
 106         or      r12,r12,r4
 107         std     r12,_MSR(r1)
 108 #endif
 109         lfd     fr0,THREAD_FPSCR(r5)
 110         MTFSF_L(fr0)
 111         REST_32FPVSRS(0, R4, R5)
 112 #ifndef CONFIG_SMP
 113         subi    r4,r5,THREAD
 114         fromreal(r4)
 115         PPC_STL r4,ADDROFF(last_task_used_math)(r3)
 116 #endif /* CONFIG_SMP */
 117         /* restore registers and return */
 118         /* we haven't used ctr or xer or lr */
 119         blr
 120
 121 /*
 122  * giveup_fpu(tsk)
 123  * Disable FP for the task given as the argument,
 124  * and save the floating-point registers in its thread_struct.
 125  * Enables the FPU for use in the kernel on return.
 126  */
 127 _GLOBAL(giveup_fpu)
 128         mfmsr   r5
 129         ori     r5,r5,MSR_FP
 130 #ifdef CONFIG_VSX
 131 BEGIN_FTR_SECTION
 132         oris    r5,r5,MSR_VSX@h
 133 END_FTR_SECTION_IFSET(CPU_FTR_VSX)
 134 #endif
 135         SYNC_601
 136         ISYNC_601
 137         MTMSRD(r5)                      /* enable use of fpu now */
 138         SYNC_601
 139         isync
 140         PPC_LCMPI       0,r3,0
 141         beqlr-                          /* if no previous owner, done */
 142         addi    r3,r3,THREAD            /* want THREAD of task */
 143         PPC_LL  r5,PT_REGS(r3)
 144         PPC_LCMPI       0,r5,0
 145         SAVE_32FPVSRS(0, R4 ,R3)
 146         mffs    fr0
 147         stfd    fr0,THREAD_FPSCR(r3)
 148         beq     1f
 149         PPC_LL  r4,_MSR-STACK_FRAME_OVERHEAD(r5)
 150         li      r3,MSR_FP|MSR_FE0|MSR_FE1
 151 #ifdef CONFIG_VSX
 152 BEGIN_FTR_SECTION
 153         oris    r3,r3,MSR_VSX@h
 154 END_FTR_SECTION_IFSET(CPU_FTR_VSX)
 155 #endif
 156         andc    r4,r4,r3                /* disable FP for previous task */
 157         PPC_STL r4,_MSR-STACK_FRAME_OVERHEAD(r5)
 158 1:
 159 #ifndef CONFIG_SMP
 160         li      r5,0
 161         LOAD_REG_ADDRBASE(r4,last_task_used_math)
 162         PPC_STL r5,ADDROFF(last_task_used_math)(r4)
 163 #endif /* CONFIG_SMP */
 164         blr
 165
 166 /*
 167  * These are used in the alignment trap handler when emulating
 168  * single-precision loads and stores.
 169  */
 170
 171 _GLOBAL(cvt_fd)
 172         lfs     0,0(r3)
 173         stfd    0,0(r4)
 174         blr
 175
 176 _GLOBAL(cvt_df)
 177         lfd     0,0(r3)
 178         stfs    0,0(r4)
 179         blr