/* * This file is subject to the terms and conditions of the GNU General Public * License. See the file "COPYING" in the main directory of this archive * for more details. * * Copyright (C) 1994, 1995, 1996, 1998, 1999, 2002, 2003 Ralf Baechle * Copyright (C) 1996 David S. Miller (dm@engr.sgi.com) * Copyright (C) 1994, 1995, 1996, by Andreas Busse * Copyright (C) 1999 Silicon Graphics, Inc. * Copyright (C) 2000 MIPS Technologies, Inc. * written by Carsten Langgaard, carstenl@mips.com */ #include #include #include #include #include #include #include #include #include #include #include #include /* * Offset to the current process status flags, the first 32 bytes of the * stack are not used. */ #define ST_OFF (_THREAD_SIZE - 32 - PT_SIZE + PT_STATUS) /* * FPU context is saved iff the process has used it's FPU in the current * time slice as indicated by _TIF_USEDFPU. In any case, the CU1 bit for user * space STATUS register should be 0, so that a process *always* starts its * userland with FPU disabled after each context switch. * * FPU will be enabled as soon as the process accesses FPU again, through * do_cpu() trap. */ /* * task_struct *resume(task_struct *prev, task_struct *next, * struct thread_info *next_ti) */ .align 5 LEAF(resume) #ifndef CONFIG_CPU_HAS_LLSC sw zero, ll_bit #endif mfc0 t1, CP0_STATUS LONG_S t1, THREAD_STATUS(a0) cpu_save_nonscratch a0 LONG_S ra, THREAD_REG31(a0) /* * check if we need to save FPU registers */ PTR_L t3, TASK_THREAD_INFO(a0) LONG_L t0, TI_FLAGS(t3) li t1, _TIF_USEDFPU and t2, t0, t1 beqz t2, 1f nor t1, zero, t1 and t0, t0, t1 LONG_S t0, TI_FLAGS(t3) /* * clear saved user stack CU1 bit */ LONG_L t0, ST_OFF(t3) li t1, ~ST0_CU1 and t0, t0, t1 LONG_S t0, ST_OFF(t3) fpu_save_double a0 t1 t0 t2 # c0_status passed in t1 # clobbers t0 and t2 1: /* * The order of restoring the registers takes care of the race * updating $28, $29 and kernelsp without disabling ints. */ move $28, a2 cpu_restore_nonscratch a1 PTR_ADDIU t0, $28, _THREAD_SIZE - 32 set_saved_sp t0, t1, t2 mfc0 t1, CP0_STATUS /* Do we really need this? */ li a3, 0xff01 and t1, a3 LONG_L a2, THREAD_STATUS(a1) nor a3, $0, a3 and a2, a3 or a2, t1 mtc0 a2, CP0_STATUS move v0, a0 jr ra END(resume) /* * Save a thread's fp context. */ LEAF(_save_fp) #ifdef CONFIG_64BIT mfc0 t1, CP0_STATUS #endif fpu_save_double a0 t1 t0 t2 # clobbers t1 jr ra END(_save_fp) /* * Restore a thread's fp context. */ LEAF(_restore_fp) fpu_restore_double a0, t1 # clobbers t1 jr ra END(_restore_fp) /* * Load the FPU with signalling NANS. This bit pattern we're using has * the property that no matter whether considered as single or as double * precision represents signaling NANS. * * We initialize fcr31 to rounding to nearest, no exceptions. */ #define FPU_DEFAULT 0x00000000 LEAF(_init_fpu) mfc0 t0, CP0_STATUS li t1, ST0_CU1 or t0, t1 mtc0 t0, CP0_STATUS fpu_enable_hazard li t1, FPU_DEFAULT ctc1 t1, fcr31 li t1, -1 # SNaN #ifdef CONFIG_64BIT sll t0, t0, 5 bgez t0, 1f # 16 / 32 register mode? dmtc1 t1, $f1 dmtc1 t1, $f3 dmtc1 t1, $f5 dmtc1 t1, $f7 dmtc1 t1, $f9 dmtc1 t1, $f11 dmtc1 t1, $f13 dmtc1 t1, $f15 dmtc1 t1, $f17 dmtc1 t1, $f19 dmtc1 t1, $f21 dmtc1 t1, $f23 dmtc1 t1, $f25 dmtc1 t1, $f27 dmtc1 t1, $f29 dmtc1 t1, $f31 1: #endif #ifdef CONFIG_CPU_MIPS32 mtc1 t1, $f0 mtc1 t1, $f1 mtc1 t1, $f2 mtc1 t1, $f3 mtc1 t1, $f4 mtc1 t1, $f5 mtc1 t1, $f6 mtc1 t1, $f7 mtc1 t1, $f8 mtc1 t1, $f9 mtc1 t1, $f10 mtc1 t1, $f11 mtc1 t1, $f12 mtc1 t1, $f13 mtc1 t1, $f14 mtc1 t1, $f15 mtc1 t1, $f16 mtc1 t1, $f17 mtc1 t1, $f18 mtc1 t1, $f19 mtc1 t1, $f20 mtc1 t1, $f21 mtc1 t1, $f22 mtc1 t1, $f23 mtc1 t1, $f24 mtc1 t1, $f25 mtc1 t1, $f26 mtc1 t1, $f27 mtc1 t1, $f28 mtc1 t1, $f29 mtc1 t1, $f30 mtc1 t1, $f31 #else .set mips3 dmtc1 t1, $f0 dmtc1 t1, $f2 dmtc1 t1, $f4 dmtc1 t1, $f6 dmtc1 t1, $f8 dmtc1 t1, $f10 dmtc1 t1, $f12 dmtc1 t1, $f14 dmtc1 t1, $f16 dmtc1 t1, $f18 dmtc1 t1, $f20 dmtc1 t1, $f22 dmtc1 t1, $f24 dmtc1 t1, $f26 dmtc1 t1, $f28 dmtc1 t1, $f30 #endif jr ra END(_init_fpu)