1/* 2 * This file is subject to the terms and conditions of the GNU General Public 3 * License. See the file "COPYING" in the main directory of this archive 4 * for more details. 5 * 6 * Copyright (C) 1994, 95, 96, 97, 98, 99, 2003, 06 by Ralf Baechle 7 * Copyright (C) 1996 by Paul M. Antoine 8 * Copyright (C) 1999 Silicon Graphics 9 * Kevin D. Kissell, kevink@mips.org and Carsten Langgaard, carstenl@mips.com 10 * Copyright (C) 2000 MIPS Technologies, Inc. 11 */ 12#ifndef _ASM_SWITCH_TO_H 13#define _ASM_SWITCH_TO_H 14 15#include <asm/cpu-features.h> 16#include <asm/watch.h> 17#include <asm/dsp.h> 18#include <asm/cop2.h> 19#include <asm/fpu.h> 20 21struct task_struct; 22 23/** 24 * resume - resume execution of a task 25 * @prev: The task previously executed. 26 * @next: The task to begin executing. 27 * @next_ti: task_thread_info(next). 28 * 29 * This function is used whilst scheduling to save the context of prev & load 30 * the context of next. Returns prev. 31 */ 32extern asmlinkage struct task_struct *resume(struct task_struct *prev, 33 struct task_struct *next, struct thread_info *next_ti); 34 35extern unsigned int ll_bit; 36extern struct task_struct *ll_task; 37 38#ifdef CONFIG_MIPS_MT_FPAFF 39 40/* 41 * Handle the scheduler resume end of FPU affinity management. We do this 42 * inline to try to keep the overhead down. If we have been forced to run on 43 * a "CPU" with an FPU because of a previous high level of FP computation, 44 * but did not actually use the FPU during the most recent time-slice (CU1 45 * isn't set), we undo the restriction on cpus_allowed. 46 * 47 * We're not calling set_cpus_allowed() here, because we have no need to 48 * force prompt migration - we're already switching the current CPU to a 49 * different thread. 50 */ 51 52#define __mips_mt_fpaff_switch_to(prev) \ 53do { \ 54 struct thread_info *__prev_ti = task_thread_info(prev); \ 55 \ 56 if (cpu_has_fpu && \ 57 test_ti_thread_flag(__prev_ti, TIF_FPUBOUND) && \ 58 (!(KSTK_STATUS(prev) & ST0_CU1))) { \ 59 clear_ti_thread_flag(__prev_ti, TIF_FPUBOUND); \ 60 prev->cpus_allowed = prev->thread.user_cpus_allowed; \ 61 } \ 62 next->thread.emulated_fp = 0; \ 63} while(0) 64 65#else 66#define __mips_mt_fpaff_switch_to(prev) do { (void) (prev); } while (0) 67#endif 68 69#define __clear_software_ll_bit() \ 70do { if (cpu_has_rw_llb) { \ 71 write_c0_lladdr(0); \ 72 } else { \ 73 if (!__builtin_constant_p(cpu_has_llsc) || !cpu_has_llsc)\ 74 ll_bit = 0; \ 75 } \ 76} while (0) 77 78/* 79 * For newly created kernel threads switch_to() will return to 80 * ret_from_kernel_thread, newly created user threads to ret_from_fork. 81 * That is, everything following resume() will be skipped for new threads. 82 * So everything that matters to new threads should be placed before resume(). 83 */ 84#define switch_to(prev, next, last) \ 85do { \ 86 __mips_mt_fpaff_switch_to(prev); \ 87 lose_fpu_inatomic(1, prev); \ 88 if (cpu_has_dsp) { \ 89 __save_dsp(prev); \ 90 __restore_dsp(next); \ 91 } \ 92 if (cop2_present) { \ 93 set_c0_status(ST0_CU2); \ 94 if ((KSTK_STATUS(prev) & ST0_CU2)) { \ 95 if (cop2_lazy_restore) \ 96 KSTK_STATUS(prev) &= ~ST0_CU2; \ 97 cop2_save(prev); \ 98 } \ 99 if (KSTK_STATUS(next) & ST0_CU2 && \ 100 !cop2_lazy_restore) { \ 101 cop2_restore(next); \ 102 } \ 103 clear_c0_status(ST0_CU2); \ 104 } \ 105 __clear_software_ll_bit(); \ 106 if (cpu_has_userlocal) \ 107 write_c0_userlocal(task_thread_info(next)->tp_value); \ 108 __restore_watch(); \ 109 (last) = resume(prev, next, task_thread_info(next)); \ 110} while (0) 111 112#endif /* _ASM_SWITCH_TO_H */ 113