/* * FPU support code, moved here from head.S so that it can be used * by chips which use other head-whatever.S files. * * This program is free software; you can redistribute it and/or * modify it under the terms of the GNU General Public License * as published by the Free Software Foundation; either version * 2 of the License, or (at your option) any later version. * */ #include <linux/config.h> #include <asm/reg.h> #include <asm/page.h> #include <asm/mmu.h> #include <asm/pgtable.h> #include <asm/cputable.h> #include <asm/cache.h> #include <asm/thread_info.h> #include <asm/ppc_asm.h> #include <asm/asm-offsets.h> /* * This task wants to use the FPU now. * On UP, disable FP for the task which had the FPU previously, * and save its floating-point registers in its thread_struct. * Load up this task's FP registers from its thread_struct, * enable the FPU for the current task and return to the task. */ _GLOBAL(load_up_fpu) mfmsr r5 ori r5,r5,MSR_FP SYNC MTMSRD(r5) /* enable use of fpu now */ isync /* * For SMP, we don't do lazy FPU switching because it just gets too * horrendously complex, especially when a task switches from one CPU * to another. Instead we call giveup_fpu in switch_to. */ #ifndef CONFIG_SMP LOADBASE(r3, last_task_used_math) toreal(r3) LDL r4,OFF(last_task_used_math)(r3) CMPI 0,r4,0 beq 1f toreal(r4) addi r4,r4,THREAD /* want last_task_used_math->thread */ SAVE_32FPRS(0, r4) mffs fr0 stfd fr0,THREAD_FPSCR(r4) LDL r5,PT_REGS(r4) toreal(r5) LDL r4,_MSR-STACK_FRAME_OVERHEAD(r5) li r10,MSR_FP|MSR_FE0|MSR_FE1 andc r4,r4,r10 /* disable FP for previous task */ STL r4,_MSR-STACK_FRAME_OVERHEAD(r5) 1: #endif /* CONFIG_SMP */ /* enable use of FP after return */ #ifdef CONFIG_PPC32 mfspr r5,SPRN_SPRG3 /* current task's THREAD (phys) */ lwz r4,THREAD_FPEXC_MODE(r5) ori r9,r9,MSR_FP /* enable FP for current */ or r9,r9,r4 #else ld r4,PACACURRENT(r13) addi r5,r4,THREAD /* Get THREAD */ ld r4,THREAD_FPEXC_MODE(r5) ori r12,r12,MSR_FP or r12,r12,r4 std r12,_MSR(r1) #endif lfd fr0,THREAD_FPSCR(r5) mtfsf 0xff,fr0 REST_32FPRS(0, r5) #ifndef CONFIG_SMP subi r4,r5,THREAD fromreal(r4) STL r4,OFF(last_task_used_math)(r3) #endif /* CONFIG_SMP */ /* restore registers and return */ /* we haven't used ctr or xer or lr */ b fast_exception_return /* * giveup_fpu(tsk) * Disable FP for the task given as the argument, * and save the floating-point registers in its thread_struct. * Enables the FPU for use in the kernel on return. */ _GLOBAL(giveup_fpu) mfmsr r5 ori r5,r5,MSR_FP SYNC_601 ISYNC_601 MTMSRD(r5) /* enable use of fpu now */ SYNC_601 isync CMPI 0,r3,0 beqlr- /* if no previous owner, done */ addi r3,r3,THREAD /* want THREAD of task */ LDL r5,PT_REGS(r3) CMPI 0,r5,0 SAVE_32FPRS(0, r3) mffs fr0 stfd fr0,THREAD_FPSCR(r3) beq 1f LDL r4,_MSR-STACK_FRAME_OVERHEAD(r5) li r3,MSR_FP|MSR_FE0|MSR_FE1 andc r4,r4,r3 /* disable FP for previous task */ STL r4,_MSR-STACK_FRAME_OVERHEAD(r5) 1: #ifndef CONFIG_SMP li r5,0 LOADBASE(r4,last_task_used_math) STL r5,OFF(last_task_used_math)(r4) #endif /* CONFIG_SMP */ blr /* * These are used in the alignment trap handler when emulating * single-precision loads and stores. * We restore and save the fpscr so the task gets the same result * and exceptions as if the cpu had performed the load or store. */ _GLOBAL(cvt_fd) lfd 0,THREAD_FPSCR(r5) /* load up fpscr value */ mtfsf 0xff,0 lfs 0,0(r3) stfd 0,0(r4) mffs 0 stfd 0,THREAD_FPSCR(r5) /* save new fpscr value */ blr _GLOBAL(cvt_df) lfd 0,THREAD_FPSCR(r5) /* load up fpscr value */ mtfsf 0xff,0 lfd 0,0(r3) stfs 0,0(r4) mffs 0 stfd 0,THREAD_FPSCR(r5) /* save new fpscr value */ blr