root/arch/powerpc/kernel/fpu.S

   1 /* SPDX-License-Identifier: GPL-2.0-or-later */
   2 /*
   3  *  FPU support code, moved here from head.S so that it can be used
   4  *  by chips which use other head-whatever.S files.
   5  *
   6  *    Copyright (C) 1995-1996 Gary Thomas (gdt@linuxppc.org)
   7  *    Copyright (C) 1996 Cort Dougan <cort@cs.nmt.edu>
   8  *    Copyright (C) 1996 Paul Mackerras.
   9  *    Copyright (C) 1997 Dan Malek (dmalek@jlc.net).
  10  */
  11 
  12 #include <asm/reg.h>
  13 #include <asm/page.h>
  14 #include <asm/mmu.h>
  15 #include <asm/pgtable.h>
  16 #include <asm/cputable.h>
  17 #include <asm/cache.h>
  18 #include <asm/thread_info.h>
  19 #include <asm/ppc_asm.h>
  20 #include <asm/asm-offsets.h>
  21 #include <asm/ptrace.h>
  22 #include <asm/export.h>
  23 #include <asm/asm-compat.h>
  24 #include <asm/feature-fixups.h>
  25 
  26 #ifdef CONFIG_VSX
  27 #define __REST_32FPVSRS(n,c,base)                                       \
  28 BEGIN_FTR_SECTION                                                       \
  29         b       2f;                                                     \
  30 END_FTR_SECTION_IFSET(CPU_FTR_VSX);                                     \
  31         REST_32FPRS(n,base);                                            \
  32         b       3f;                                                     \
  33 2:      REST_32VSRS(n,c,base);                                          \
  34 3:
  35 
  36 #define __SAVE_32FPVSRS(n,c,base)                                       \
  37 BEGIN_FTR_SECTION                                                       \
  38         b       2f;                                                     \
  39 END_FTR_SECTION_IFSET(CPU_FTR_VSX);                                     \
  40         SAVE_32FPRS(n,base);                                            \
  41         b       3f;                                                     \
  42 2:      SAVE_32VSRS(n,c,base);                                          \
  43 3:
  44 #else
  45 #define __REST_32FPVSRS(n,b,base)       REST_32FPRS(n, base)
  46 #define __SAVE_32FPVSRS(n,b,base)       SAVE_32FPRS(n, base)
  47 #endif
  48 #define REST_32FPVSRS(n,c,base) __REST_32FPVSRS(n,__REG_##c,__REG_##base)
  49 #define SAVE_32FPVSRS(n,c,base) __SAVE_32FPVSRS(n,__REG_##c,__REG_##base)
  50 
  51 /*
  52  * Load state from memory into FP registers including FPSCR.
  53  * Assumes the caller has enabled FP in the MSR.
  54  */
  55 _GLOBAL(load_fp_state)
  56         lfd     fr0,FPSTATE_FPSCR(r3)
  57         MTFSF_L(fr0)
  58         REST_32FPVSRS(0, R4, R3)
  59         blr
  60 EXPORT_SYMBOL(load_fp_state)
  61 _ASM_NOKPROBE_SYMBOL(load_fp_state); /* used by restore_math */
  62 
  63 /*
  64  * Store FP state into memory, including FPSCR
  65  * Assumes the caller has enabled FP in the MSR.
  66  */
  67 _GLOBAL(store_fp_state)
  68         SAVE_32FPVSRS(0, R4, R3)
  69         mffs    fr0
  70         stfd    fr0,FPSTATE_FPSCR(r3)
  71         blr
  72 EXPORT_SYMBOL(store_fp_state)
  73 
  74 /*
  75  * This task wants to use the FPU now.
  76  * On UP, disable FP for the task which had the FPU previously,
  77  * and save its floating-point registers in its thread_struct.
  78  * Load up this task's FP registers from its thread_struct,
  79  * enable the FPU for the current task and return to the task.
  80  * Note that on 32-bit this can only use registers that will be
  81  * restored by fast_exception_return, i.e. r3 - r6, r10 and r11.
  82  */
  83 _GLOBAL(load_up_fpu)
  84         mfmsr   r5
  85         ori     r5,r5,MSR_FP
  86 #ifdef CONFIG_VSX
  87 BEGIN_FTR_SECTION
  88         oris    r5,r5,MSR_VSX@h
  89 END_FTR_SECTION_IFSET(CPU_FTR_VSX)
  90 #endif
  91         SYNC
  92         MTMSRD(r5)                      /* enable use of fpu now */
  93         isync
  94         /* enable use of FP after return */
  95 #ifdef CONFIG_PPC32
  96         mfspr   r5,SPRN_SPRG_THREAD     /* current task's THREAD (phys) */
  97         lwz     r4,THREAD_FPEXC_MODE(r5)
  98         ori     r9,r9,MSR_FP            /* enable FP for current */
  99         or      r9,r9,r4
 100 #else
 101         ld      r4,PACACURRENT(r13)
 102         addi    r5,r4,THREAD            /* Get THREAD */
 103         lwz     r4,THREAD_FPEXC_MODE(r5)
 104         ori     r12,r12,MSR_FP
 105         or      r12,r12,r4
 106         std     r12,_MSR(r1)
 107 #endif
 108         /* Don't care if r4 overflows, this is desired behaviour */
 109         lbz     r4,THREAD_LOAD_FP(r5)
 110         addi    r4,r4,1
 111         stb     r4,THREAD_LOAD_FP(r5)
 112         addi    r10,r5,THREAD_FPSTATE
 113         lfd     fr0,FPSTATE_FPSCR(r10)
 114         MTFSF_L(fr0)
 115         REST_32FPVSRS(0, R4, R10)
 116         /* restore registers and return */
 117         /* we haven't used ctr or xer or lr */
 118         blr
 119 
 120 /*
 121  * save_fpu(tsk)
 122  * Save the floating-point registers in its thread_struct.
 123  * Enables the FPU for use in the kernel on return.
 124  */
 125 _GLOBAL(save_fpu)
 126         addi    r3,r3,THREAD            /* want THREAD of task */
 127         PPC_LL  r6,THREAD_FPSAVEAREA(r3)
 128         PPC_LL  r5,PT_REGS(r3)
 129         PPC_LCMPI       0,r6,0
 130         bne     2f
 131         addi    r6,r3,THREAD_FPSTATE
 132 2:      SAVE_32FPVSRS(0, R4, R6)
 133         mffs    fr0
 134         stfd    fr0,FPSTATE_FPSCR(r6)
 135         blr
 136 
 137 /*
 138  * These are used in the alignment trap handler when emulating
 139  * single-precision loads and stores.
 140  */
 141 
 142 _GLOBAL(cvt_fd)
 143         lfs     0,0(r3)
 144         stfd    0,0(r4)
 145         blr
 146 
 147 _GLOBAL(cvt_df)
 148         lfd     0,0(r3)
 149         stfs    0,0(r4)
 150         blr