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 21 struct 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 */ 32 extern asmlinkage struct task_struct *resume(struct task_struct *prev, 33 struct task_struct *next, struct thread_info *next_ti); 34 35 extern unsigned int ll_bit; 36 extern 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) \ 53 do { \ 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() \ 70 do { 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 * Check FCSR for any unmasked exceptions pending set with `ptrace', 80 * clear them and send a signal. 81 */ 82 #define __sanitize_fcr31(next) \ 83 do { \ 84 unsigned long fcr31 = mask_fcr31_x(next->thread.fpu.fcr31); \ 85 void __user *pc; \ 86 \ 87 if (unlikely(fcr31)) { \ 88 pc = (void __user *)task_pt_regs(next)->cp0_epc; \ 89 next->thread.fpu.fcr31 &= ~fcr31; \ 90 force_fcr31_sig(fcr31, pc, next); \ 91 } \ 92 } while (0) 93 94 /* 95 * For newly created kernel threads switch_to() will return to 96 * ret_from_kernel_thread, newly created user threads to ret_from_fork. 97 * That is, everything following resume() will be skipped for new threads. 98 * So everything that matters to new threads should be placed before resume(). 99 */ 100 #define switch_to(prev, next, last) \ 101 do { \ 102 __mips_mt_fpaff_switch_to(prev); \ 103 lose_fpu_inatomic(1, prev); \ 104 if (tsk_used_math(next)) \ 105 __sanitize_fcr31(next); \ 106 if (cpu_has_dsp) { \ 107 __save_dsp(prev); \ 108 __restore_dsp(next); \ 109 } \ 110 if (cop2_present) { \ 111 set_c0_status(ST0_CU2); \ 112 if ((KSTK_STATUS(prev) & ST0_CU2)) { \ 113 if (cop2_lazy_restore) \ 114 KSTK_STATUS(prev) &= ~ST0_CU2; \ 115 cop2_save(prev); \ 116 } \ 117 if (KSTK_STATUS(next) & ST0_CU2 && \ 118 !cop2_lazy_restore) { \ 119 cop2_restore(next); \ 120 } \ 121 clear_c0_status(ST0_CU2); \ 122 } \ 123 __clear_software_ll_bit(); \ 124 if (cpu_has_userlocal) \ 125 write_c0_userlocal(task_thread_info(next)->tp_value); \ 126 __restore_watch(next); \ 127 (last) = resume(prev, next, task_thread_info(next)); \ 128 } while (0) 129 130 #endif /* _ASM_SWITCH_TO_H */ 131