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 #include <asm/export.h>
  28
  29 #ifdef CONFIG_VSX
  30 #define __REST_32FPVSRS(n,c,base)                                       \
  31 BEGIN_FTR_SECTION                                                       \
  32         b       2f;                                                     \
  33 END_FTR_SECTION_IFSET(CPU_FTR_VSX);                                     \
  34         REST_32FPRS(n,base);                                            \
  35         b       3f;                                                     \
  36 2:      REST_32VSRS(n,c,base);                                          \
  37 3:
  38
  39 #define __SAVE_32FPVSRS(n,c,base)                                       \
  40 BEGIN_FTR_SECTION                                                       \
  41         b       2f;                                                     \
  42 END_FTR_SECTION_IFSET(CPU_FTR_VSX);                                     \
  43         SAVE_32FPRS(n,base);                                            \
  44         b       3f;                                                     \
  45 2:      SAVE_32VSRS(n,c,base);                                          \
  46 3:
  47 #else
  48 #define __REST_32FPVSRS(n,b,base)       REST_32FPRS(n, base)
  49 #define __SAVE_32FPVSRS(n,b,base)       SAVE_32FPRS(n, base)
  50 #endif
  51 #define REST_32FPVSRS(n,c,base) __REST_32FPVSRS(n,__REG_##c,__REG_##base)
  52 #define SAVE_32FPVSRS(n,c,base) __SAVE_32FPVSRS(n,__REG_##c,__REG_##base)
  53
  54 /*
  55  * Load state from memory into FP registers including FPSCR.
  56  * Assumes the caller has enabled FP in the MSR.
  57  */
  58 _GLOBAL(load_fp_state)
  59         lfd     fr0,FPSTATE_FPSCR(r3)
  60         MTFSF_L(fr0)
  61         REST_32FPVSRS(0, R4, R3)
  62         blr
  63 EXPORT_SYMBOL(load_fp_state)
  64
  65 /*
  66  * Store FP state into memory, including FPSCR
  67  * Assumes the caller has enabled FP in the MSR.
  68  */
  69 _GLOBAL(store_fp_state)
  70         SAVE_32FPVSRS(0, R4, R3)
  71         mffs    fr0
  72         stfd    fr0,FPSTATE_FPSCR(r3)
  73         blr
  74 EXPORT_SYMBOL(store_fp_state)
  75
  76 /*
  77  * This task wants to use the FPU now.
  78  * On UP, disable FP for the task which had the FPU previously,
  79  * and save its floating-point registers in its thread_struct.
  80  * Load up this task's FP registers from its thread_struct,
  81  * enable the FPU for the current task and return to the task.
  82  * Note that on 32-bit this can only use registers that will be
  83  * restored by fast_exception_return, i.e. r3 - r6, r10 and r11.
  84  */
  85 _GLOBAL(load_up_fpu)
  86         mfmsr   r5
  87         ori     r5,r5,MSR_FP
  88 #ifdef CONFIG_VSX
  89 BEGIN_FTR_SECTION
  90         oris    r5,r5,MSR_VSX@h
  91 END_FTR_SECTION_IFSET(CPU_FTR_VSX)
  92 #endif
  93         SYNC
  94         MTMSRD(r5)                      /* enable use of fpu now */
  95         isync
  96         /* enable use of FP after return */
  97 #ifdef CONFIG_PPC32
  98         mfspr   r5,SPRN_SPRG_THREAD     /* current task's THREAD (phys) */
  99         lwz     r4,THREAD_FPEXC_MODE(r5)
 100         ori     r9,r9,MSR_FP            /* enable FP for current */
 101         or      r9,r9,r4
 102 #else
 103         ld      r4,PACACURRENT(r13)
 104         addi    r5,r4,THREAD            /* Get THREAD */
 105         lwz     r4,THREAD_FPEXC_MODE(r5)
 106         ori     r12,r12,MSR_FP
 107         or      r12,r12,r4
 108         std     r12,_MSR(r1)
 109 #endif
 110         /* Don't care if r4 overflows, this is desired behaviour */
 111         lbz     r4,THREAD_LOAD_FP(r5)
 112         addi    r4,r4,1
 113         stb     r4,THREAD_LOAD_FP(r5)
 114         addi    r10,r5,THREAD_FPSTATE
 115         lfd     fr0,FPSTATE_FPSCR(r10)
 116         MTFSF_L(fr0)
 117         REST_32FPVSRS(0, R4, R10)
 118         /* restore registers and return */
 119         /* we haven't used ctr or xer or lr */
 120         blr
 121
 122 /*
 123  * save_fpu(tsk)
 124  * Save the floating-point registers in its thread_struct.
 125  * Enables the FPU for use in the kernel on return.
 126  */
 127 _GLOBAL(save_fpu)
 128         addi    r3,r3,THREAD            /* want THREAD of task */
 129         PPC_LL  r6,THREAD_FPSAVEAREA(r3)
 130         PPC_LL  r5,PT_REGS(r3)
 131         PPC_LCMPI       0,r6,0
 132         bne     2f
 133         addi    r6,r3,THREAD_FPSTATE
 134 2:      SAVE_32FPVSRS(0, R4, R6)
 135         mffs    fr0
 136         stfd    fr0,FPSTATE_FPSCR(r6)
 137         blr
 138
 139 /*
 140  * These are used in the alignment trap handler when emulating
 141  * single-precision loads and stores.
 142  */
 143
 144 _GLOBAL(cvt_fd)
 145         lfs     0,0(r3)
 146         stfd    0,0(r4)
 147         blr
 148
 149 _GLOBAL(cvt_df)
 150         lfd     0,0(r3)
 151         stfs    0,0(r4)
 152         blr