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 #ifdef CONFIG_PPC_TRANSACTIONAL_MEM
  54 /* void do_load_up_transact_fpu(struct thread_struct *thread)
  55  *
  56  * This is similar to load_up_fpu but for the transactional version of the FP
  57  * register set.  It doesn't mess with the task MSR or valid flags.
  58  * Furthermore, we don't do lazy FP with TM currently.
  59  */
  60 _GLOBAL(do_load_up_transact_fpu)
  61         mfmsr   r6
  62         ori     r5,r6,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)
  70
  71         addi    r7,r3,THREAD_TRANSACT_FPSTATE
  72         lfd     fr0,FPSTATE_FPSCR(r7)
  73         MTFSF_L(fr0)
  74         REST_32FPVSRS(0, R4, R7)
  75
  76         /* FP/VSX off again */
  77         MTMSRD(r6)
  78         SYNC
  79
  80         blr
  81 #endif /* CONFIG_PPC_TRANSACTIONAL_MEM */
  82
  83 /*
  84  * Enable use of the FPU, and VSX if possible, for the caller.
  85  */
  86 _GLOBAL(fp_enable)
  87         mfmsr   r3
  88         ori     r3,r3,MSR_FP
  89 #ifdef CONFIG_VSX
  90 BEGIN_FTR_SECTION
  91         oris    r3,r3,MSR_VSX@h
  92 END_FTR_SECTION_IFSET(CPU_FTR_VSX)
  93 #endif
  94         SYNC
  95         MTMSRD(r3)
  96         isync                   /* (not necessary for arch 2.02 and later) */
  97         blr
  98
  99 /*
 100  * Load state from memory into FP registers including FPSCR.
 101  * Assumes the caller has enabled FP in the MSR.
 102  */
 103 _GLOBAL(load_fp_state)
 104         lfd     fr0,FPSTATE_FPSCR(r3)
 105         MTFSF_L(fr0)
 106         REST_32FPVSRS(0, R4, R3)
 107         blr
 108
 109 /*
 110  * Store FP state into memory, including FPSCR
 111  * Assumes the caller has enabled FP in the MSR.
 112  */
 113 _GLOBAL(store_fp_state)
 114         SAVE_32FPVSRS(0, R4, R3)
 115         mffs    fr0
 116         stfd    fr0,FPSTATE_FPSCR(r3)
 117         blr
 118
 119 /*
 120  * This task wants to use the FPU now.
 121  * On UP, disable FP for the task which had the FPU previously,
 122  * and save its floating-point registers in its thread_struct.
 123  * Load up this task's FP registers from its thread_struct,
 124  * enable the FPU for the current task and return to the task.
 125  * Note that on 32-bit this can only use registers that will be
 126  * restored by fast_exception_return, i.e. r3 - r6, r10 and r11.
 127  */
 128 _GLOBAL(load_up_fpu)
 129         mfmsr   r5
 130         ori     r5,r5,MSR_FP
 131 #ifdef CONFIG_VSX
 132 BEGIN_FTR_SECTION
 133         oris    r5,r5,MSR_VSX@h
 134 END_FTR_SECTION_IFSET(CPU_FTR_VSX)
 135 #endif
 136         SYNC
 137         MTMSRD(r5)                      /* enable use of fpu now */
 138         isync
 139 /*
 140  * For SMP, we don't do lazy FPU switching because it just gets too
 141  * horrendously complex, especially when a task switches from one CPU
 142  * to another.  Instead we call giveup_fpu in switch_to.
 143  */
 144 #ifndef CONFIG_SMP
 145         LOAD_REG_ADDRBASE(r3, last_task_used_math)
 146         toreal(r3)
 147         PPC_LL  r4,ADDROFF(last_task_used_math)(r3)
 148         PPC_LCMPI       0,r4,0
 149         beq     1f
 150         toreal(r4)
 151         addi    r4,r4,THREAD            /* want last_task_used_math->thread */
 152         addi    r10,r4,THREAD_FPSTATE
 153         SAVE_32FPVSRS(0, R5, R10)
 154         mffs    fr0
 155         stfd    fr0,FPSTATE_FPSCR(r10)
 156         PPC_LL  r5,PT_REGS(r4)
 157         toreal(r5)
 158         PPC_LL  r4,_MSR-STACK_FRAME_OVERHEAD(r5)
 159         li      r10,MSR_FP|MSR_FE0|MSR_FE1
 160         andc    r4,r4,r10               /* disable FP for previous task */
 161         PPC_STL r4,_MSR-STACK_FRAME_OVERHEAD(r5)
 162 1:
 163 #endif /* CONFIG_SMP */
 164         /* enable use of FP after return */
 165 #ifdef CONFIG_PPC32
 166         mfspr   r5,SPRN_SPRG_THREAD     /* current task's THREAD (phys) */
 167         lwz     r4,THREAD_FPEXC_MODE(r5)
 168         ori     r9,r9,MSR_FP            /* enable FP for current */
 169         or      r9,r9,r4
 170 #else
 171         ld      r4,PACACURRENT(r13)
 172         addi    r5,r4,THREAD            /* Get THREAD */
 173         lwz     r4,THREAD_FPEXC_MODE(r5)
 174         ori     r12,r12,MSR_FP
 175         or      r12,r12,r4
 176         std     r12,_MSR(r1)
 177 #endif
 178         addi    r10,r5,THREAD_FPSTATE
 179         lfd     fr0,FPSTATE_FPSCR(r10)
 180         MTFSF_L(fr0)
 181         REST_32FPVSRS(0, R4, R10)
 182 #ifndef CONFIG_SMP
 183         subi    r4,r5,THREAD
 184         fromreal(r4)
 185         PPC_STL r4,ADDROFF(last_task_used_math)(r3)
 186 #endif /* CONFIG_SMP */
 187         /* restore registers and return */
 188         /* we haven't used ctr or xer or lr */
 189         blr
 190
 191 /*
 192  * giveup_fpu(tsk)
 193  * Disable FP for the task given as the argument,
 194  * and save the floating-point registers in its thread_struct.
 195  * Enables the FPU for use in the kernel on return.
 196  */
 197 _GLOBAL(giveup_fpu)
 198         mfmsr   r5
 199         ori     r5,r5,MSR_FP
 200 #ifdef CONFIG_VSX
 201 BEGIN_FTR_SECTION
 202         oris    r5,r5,MSR_VSX@h
 203 END_FTR_SECTION_IFSET(CPU_FTR_VSX)
 204 #endif
 205         SYNC_601
 206         ISYNC_601
 207         MTMSRD(r5)                      /* enable use of fpu now */
 208         SYNC_601
 209         isync
 210         PPC_LCMPI       0,r3,0
 211         beqlr-                          /* if no previous owner, done */
 212         addi    r3,r3,THREAD            /* want THREAD of task */
 213         PPC_LL  r6,THREAD_FPSAVEAREA(r3)
 214         PPC_LL  r5,PT_REGS(r3)
 215         PPC_LCMPI       0,r6,0
 216         bne     2f
 217         addi    r6,r3,THREAD_FPSTATE
 218 2:      PPC_LCMPI       0,r5,0
 219         SAVE_32FPVSRS(0, R4, R6)
 220         mffs    fr0
 221         stfd    fr0,FPSTATE_FPSCR(r6)
 222         beq     1f
 223         PPC_LL  r4,_MSR-STACK_FRAME_OVERHEAD(r5)
 224         li      r3,MSR_FP|MSR_FE0|MSR_FE1
 225 #ifdef CONFIG_VSX
 226 BEGIN_FTR_SECTION
 227         oris    r3,r3,MSR_VSX@h
 228 END_FTR_SECTION_IFSET(CPU_FTR_VSX)
 229 #endif
 230         andc    r4,r4,r3                /* disable FP for previous task */
 231         PPC_STL r4,_MSR-STACK_FRAME_OVERHEAD(r5)
 232 1:
 233 #ifndef CONFIG_SMP
 234         li      r5,0
 235         LOAD_REG_ADDRBASE(r4,last_task_used_math)
 236         PPC_STL r5,ADDROFF(last_task_used_math)(r4)
 237 #endif /* CONFIG_SMP */
 238         blr
 239
 240 /*
 241  * These are used in the alignment trap handler when emulating
 242  * single-precision loads and stores.
 243  */
 244
 245 _GLOBAL(cvt_fd)
 246         lfs     0,0(r3)
 247         stfd    0,0(r4)
 248         blr
 249
 250 _GLOBAL(cvt_df)
 251         lfd     0,0(r3)
 252         stfs    0,0(r4)
 253         blr