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 27#ifdef CONFIG_VSX 28#define REST_32FPVSRS(n,c,base) \ 29BEGIN_FTR_SECTION \ 30 b 2f; \ 31END_FTR_SECTION_IFSET(CPU_FTR_VSX); \ 32 REST_32FPRS(n,base); \ 33 b 3f; \ 342: REST_32VSRS(n,c,base); \ 353: 36 37#define SAVE_32FPVSRS(n,c,base) \ 38BEGIN_FTR_SECTION \ 39 b 2f; \ 40END_FTR_SECTION_IFSET(CPU_FTR_VSX); \ 41 SAVE_32FPRS(n,base); \ 42 b 3f; \ 432: SAVE_32VSRS(n,c,base); \ 443: 45#else 46#define REST_32FPVSRS(n,b,base) REST_32FPRS(n, base) 47#define SAVE_32FPVSRS(n,b,base) SAVE_32FPRS(n, base) 48#endif 49 50/* 51 * This task wants to use the FPU now. 52 * On UP, disable FP for the task which had the FPU previously, 53 * and save its floating-point registers in its thread_struct. 54 * Load up this task's FP registers from its thread_struct, 55 * enable the FPU for the current task and return to the task. 56 */ 57_GLOBAL(load_up_fpu) 58 mfmsr r5 59 ori r5,r5,MSR_FP 60#ifdef CONFIG_VSX 61BEGIN_FTR_SECTION 62 oris r5,r5,MSR_VSX@h 63END_FTR_SECTION_IFSET(CPU_FTR_VSX) 64#endif 65 SYNC 66 MTMSRD(r5) /* enable use of fpu now */ 67 isync 68/* 69 * For SMP, we don't do lazy FPU switching because it just gets too 70 * horrendously complex, especially when a task switches from one CPU 71 * to another. Instead we call giveup_fpu in switch_to. 72 */ 73#ifndef CONFIG_SMP 74 LOAD_REG_ADDRBASE(r3, last_task_used_math) 75 toreal(r3) 76 PPC_LL r4,ADDROFF(last_task_used_math)(r3) 77 PPC_LCMPI 0,r4,0 78 beq 1f 79 toreal(r4) 80 addi r4,r4,THREAD /* want last_task_used_math->thread */ 81 SAVE_32FPVSRS(0, r5, r4) 82 mffs fr0 83 stfd fr0,THREAD_FPSCR(r4) 84 PPC_LL r5,PT_REGS(r4) 85 toreal(r5) 86 PPC_LL r4,_MSR-STACK_FRAME_OVERHEAD(r5) 87 li r10,MSR_FP|MSR_FE0|MSR_FE1 88 andc r4,r4,r10 /* disable FP for previous task */ 89 PPC_STL r4,_MSR-STACK_FRAME_OVERHEAD(r5) 901: 91#endif /* CONFIG_SMP */ 92 /* enable use of FP after return */ 93#ifdef CONFIG_PPC32 94 mfspr r5,SPRN_SPRG3 /* current task's THREAD (phys) */ 95 lwz r4,THREAD_FPEXC_MODE(r5) 96 ori r9,r9,MSR_FP /* enable FP for current */ 97 or r9,r9,r4 98#else 99 ld r4,PACACURRENT(r13) 100 addi r5,r4,THREAD /* Get THREAD */ 101 lwz r4,THREAD_FPEXC_MODE(r5) 102 ori r12,r12,MSR_FP 103 or r12,r12,r4 104 std r12,_MSR(r1) 105#endif 106 lfd fr0,THREAD_FPSCR(r5) 107 MTFSF_L(fr0) 108 REST_32FPVSRS(0, r4, r5) 109#ifndef CONFIG_SMP 110 subi r4,r5,THREAD 111 fromreal(r4) 112 PPC_STL r4,ADDROFF(last_task_used_math)(r3) 113#endif /* CONFIG_SMP */ 114 /* restore registers and return */ 115 /* we haven't used ctr or xer or lr */ 116 blr 117 118/* 119 * giveup_fpu(tsk) 120 * Disable FP for the task given as the argument, 121 * and save the floating-point registers in its thread_struct. 122 * Enables the FPU for use in the kernel on return. 123 */ 124_GLOBAL(giveup_fpu) 125 mfmsr r5 126 ori r5,r5,MSR_FP 127#ifdef CONFIG_VSX 128BEGIN_FTR_SECTION 129 oris r5,r5,MSR_VSX@h 130END_FTR_SECTION_IFSET(CPU_FTR_VSX) 131#endif 132 SYNC_601 133 ISYNC_601 134 MTMSRD(r5) /* enable use of fpu now */ 135 SYNC_601 136 isync 137 PPC_LCMPI 0,r3,0 138 beqlr- /* if no previous owner, done */ 139 addi r3,r3,THREAD /* want THREAD of task */ 140 PPC_LL r5,PT_REGS(r3) 141 PPC_LCMPI 0,r5,0 142 SAVE_32FPVSRS(0, r4 ,r3) 143 mffs fr0 144 stfd fr0,THREAD_FPSCR(r3) 145 beq 1f 146 PPC_LL r4,_MSR-STACK_FRAME_OVERHEAD(r5) 147 li r3,MSR_FP|MSR_FE0|MSR_FE1 148 andc r4,r4,r3 /* disable FP for previous task */ 149 PPC_STL r4,_MSR-STACK_FRAME_OVERHEAD(r5) 1501: 151#ifndef CONFIG_SMP 152 li r5,0 153 LOAD_REG_ADDRBASE(r4,last_task_used_math) 154 PPC_STL r5,ADDROFF(last_task_used_math)(r4) 155#endif /* CONFIG_SMP */ 156 blr 157 158/* 159 * These are used in the alignment trap handler when emulating 160 * single-precision loads and stores. 161 * We restore and save the fpscr so the task gets the same result 162 * and exceptions as if the cpu had performed the load or store. 163 */ 164 165_GLOBAL(cvt_fd) 166 lfd 0,THREAD_FPSCR(r5) /* load up fpscr value */ 167 MTFSF_L(0) 168 lfs 0,0(r3) 169 stfd 0,0(r4) 170 mffs 0 171 stfd 0,THREAD_FPSCR(r5) /* save new fpscr value */ 172 blr 173 174_GLOBAL(cvt_df) 175 lfd 0,THREAD_FPSCR(r5) /* load up fpscr value */ 176 MTFSF_L(0) 177 lfd 0,0(r3) 178 stfs 0,0(r4) 179 mffs 0 180 stfd 0,THREAD_FPSCR(r5) /* save new fpscr value */ 181 blr 182