114cf11afSPaul Mackerras/* 214cf11afSPaul Mackerras * FPU support code, moved here from head.S so that it can be used 314cf11afSPaul Mackerras * by chips which use other head-whatever.S files. 414cf11afSPaul Mackerras * 514cf11afSPaul Mackerras * This program is free software; you can redistribute it and/or 614cf11afSPaul Mackerras * modify it under the terms of the GNU General Public License 714cf11afSPaul Mackerras * as published by the Free Software Foundation; either version 814cf11afSPaul Mackerras * 2 of the License, or (at your option) any later version. 914cf11afSPaul Mackerras * 1014cf11afSPaul Mackerras */ 1114cf11afSPaul Mackerras 1214cf11afSPaul Mackerras#include <linux/config.h> 13b3b8dc6cSPaul Mackerras#include <asm/reg.h> 1414cf11afSPaul Mackerras#include <asm/page.h> 1514cf11afSPaul Mackerras#include <asm/mmu.h> 1614cf11afSPaul Mackerras#include <asm/pgtable.h> 1714cf11afSPaul Mackerras#include <asm/cputable.h> 1814cf11afSPaul Mackerras#include <asm/cache.h> 1914cf11afSPaul Mackerras#include <asm/thread_info.h> 2014cf11afSPaul Mackerras#include <asm/ppc_asm.h> 2114cf11afSPaul Mackerras#include <asm/asm-offsets.h> 2214cf11afSPaul Mackerras 2314cf11afSPaul Mackerras/* 2414cf11afSPaul Mackerras * This task wants to use the FPU now. 2514cf11afSPaul Mackerras * On UP, disable FP for the task which had the FPU previously, 2614cf11afSPaul Mackerras * and save its floating-point registers in its thread_struct. 2714cf11afSPaul Mackerras * Load up this task's FP registers from its thread_struct, 2814cf11afSPaul Mackerras * enable the FPU for the current task and return to the task. 2914cf11afSPaul Mackerras */ 30b85a046aSPaul Mackerras_GLOBAL(load_up_fpu) 3114cf11afSPaul Mackerras mfmsr r5 3214cf11afSPaul Mackerras ori r5,r5,MSR_FP 3314cf11afSPaul Mackerras SYNC 3414cf11afSPaul Mackerras MTMSRD(r5) /* enable use of fpu now */ 3514cf11afSPaul Mackerras isync 3614cf11afSPaul Mackerras/* 3714cf11afSPaul Mackerras * For SMP, we don't do lazy FPU switching because it just gets too 3814cf11afSPaul Mackerras * horrendously complex, especially when a task switches from one CPU 3914cf11afSPaul Mackerras * to another. Instead we call giveup_fpu in switch_to. 4014cf11afSPaul Mackerras */ 4114cf11afSPaul Mackerras#ifndef CONFIG_SMP 42b85a046aSPaul Mackerras LOADBASE(r3, last_task_used_math) 43b85a046aSPaul Mackerras tophys(r3,r3) 44b85a046aSPaul Mackerras LDL r4,OFF(last_task_used_math)(r3) 45b85a046aSPaul Mackerras CMPI 0,r4,0 4614cf11afSPaul Mackerras beq 1f 47b85a046aSPaul Mackerras tophys(r4,r4) 4814cf11afSPaul Mackerras addi r4,r4,THREAD /* want last_task_used_math->thread */ 4914cf11afSPaul Mackerras SAVE_32FPRS(0, r4) 5014cf11afSPaul Mackerras mffs fr0 5114cf11afSPaul Mackerras stfd fr0,THREAD_FPSCR-4(r4) 52b85a046aSPaul Mackerras LDL r5,PT_REGS(r4) 53b85a046aSPaul Mackerras tophys(r5,r5) 54b85a046aSPaul Mackerras LDL r4,_MSR-STACK_FRAME_OVERHEAD(r5) 5514cf11afSPaul Mackerras li r10,MSR_FP|MSR_FE0|MSR_FE1 5614cf11afSPaul Mackerras andc r4,r4,r10 /* disable FP for previous task */ 57b85a046aSPaul Mackerras STL r4,_MSR-STACK_FRAME_OVERHEAD(r5) 5814cf11afSPaul Mackerras1: 5914cf11afSPaul Mackerras#endif /* CONFIG_SMP */ 6014cf11afSPaul Mackerras /* enable use of FP after return */ 61b85a046aSPaul Mackerras#ifdef CONFIG_PPC32 6214cf11afSPaul Mackerras mfspr r5,SPRN_SPRG3 /* current task's THREAD (phys) */ 6314cf11afSPaul Mackerras lwz r4,THREAD_FPEXC_MODE(r5) 6414cf11afSPaul Mackerras ori r9,r9,MSR_FP /* enable FP for current */ 6514cf11afSPaul Mackerras or r9,r9,r4 66b85a046aSPaul Mackerras#else 67b85a046aSPaul Mackerras ld r4,PACACURRENT(r13) 68b85a046aSPaul Mackerras addi r5,r4,THREAD /* Get THREAD */ 69b85a046aSPaul Mackerras ld r4,THREAD_FPEXC_MODE(r5) 70b85a046aSPaul Mackerras ori r12,r12,MSR_FP 71b85a046aSPaul Mackerras or r12,r12,r4 72b85a046aSPaul Mackerras std r12,_MSR(r1) 73b85a046aSPaul Mackerras#endif 7414cf11afSPaul Mackerras lfd fr0,THREAD_FPSCR-4(r5) 7514cf11afSPaul Mackerras mtfsf 0xff,fr0 7614cf11afSPaul Mackerras REST_32FPRS(0, r5) 7714cf11afSPaul Mackerras#ifndef CONFIG_SMP 7814cf11afSPaul Mackerras subi r4,r5,THREAD 79b85a046aSPaul Mackerras tovirt(r4,r4) 80b85a046aSPaul Mackerras STL r4,OFF(last_task_used_math)(r3) 8114cf11afSPaul Mackerras#endif /* CONFIG_SMP */ 8214cf11afSPaul Mackerras /* restore registers and return */ 8314cf11afSPaul Mackerras /* we haven't used ctr or xer or lr */ 8414cf11afSPaul Mackerras b fast_exception_return 8514cf11afSPaul Mackerras 8614cf11afSPaul Mackerras/* 8714cf11afSPaul Mackerras * giveup_fpu(tsk) 8814cf11afSPaul Mackerras * Disable FP for the task given as the argument, 8914cf11afSPaul Mackerras * and save the floating-point registers in its thread_struct. 9014cf11afSPaul Mackerras * Enables the FPU for use in the kernel on return. 9114cf11afSPaul Mackerras */ 92b85a046aSPaul Mackerras_GLOBAL(giveup_fpu) 9314cf11afSPaul Mackerras mfmsr r5 9414cf11afSPaul Mackerras ori r5,r5,MSR_FP 9514cf11afSPaul Mackerras SYNC_601 9614cf11afSPaul Mackerras ISYNC_601 9714cf11afSPaul Mackerras MTMSRD(r5) /* enable use of fpu now */ 9814cf11afSPaul Mackerras SYNC_601 9914cf11afSPaul Mackerras isync 100b85a046aSPaul Mackerras CMPI 0,r3,0 10114cf11afSPaul Mackerras beqlr- /* if no previous owner, done */ 10214cf11afSPaul Mackerras addi r3,r3,THREAD /* want THREAD of task */ 103b85a046aSPaul Mackerras LDL r5,PT_REGS(r3) 104b85a046aSPaul Mackerras CMPI 0,r5,0 10514cf11afSPaul Mackerras SAVE_32FPRS(0, r3) 10614cf11afSPaul Mackerras mffs fr0 10714cf11afSPaul Mackerras stfd fr0,THREAD_FPSCR-4(r3) 10814cf11afSPaul Mackerras beq 1f 109b85a046aSPaul Mackerras LDL r4,_MSR-STACK_FRAME_OVERHEAD(r5) 11014cf11afSPaul Mackerras li r3,MSR_FP|MSR_FE0|MSR_FE1 11114cf11afSPaul Mackerras andc r4,r4,r3 /* disable FP for previous task */ 112b85a046aSPaul Mackerras STL r4,_MSR-STACK_FRAME_OVERHEAD(r5) 11314cf11afSPaul Mackerras1: 11414cf11afSPaul Mackerras#ifndef CONFIG_SMP 11514cf11afSPaul Mackerras li r5,0 116b85a046aSPaul Mackerras LOADBASE(r4,last_task_used_math) 117b85a046aSPaul Mackerras STL r5,OFF(last_task_used_math)(r4) 11814cf11afSPaul Mackerras#endif /* CONFIG_SMP */ 11914cf11afSPaul Mackerras blr 120