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