2 * r2300_switch.S: R2300 specific task switching code.
4 * Copyright (C) 1994, 1995, 1996, 1999 by Ralf Baechle
5 * Copyright (C) 1994, 1995, 1996 by Andreas Busse
7 * Multi-cpu abstraction and macros for easier reading:
8 * Copyright (C) 1996 David S. Miller (davem@davemloft.net)
10 * Further modifications to make this work:
11 * Copyright (c) 1998-2000 Harald Koerfgen
14 #include <asm/cachectl.h>
15 #include <asm/export.h>
16 #include <asm/fpregdef.h>
17 #include <asm/mipsregs.h>
18 #include <asm/asm-offsets.h>
19 #include <asm/regdef.h>
20 #include <asm/stackframe.h>
21 #include <asm/thread_info.h>
23 #include <asm/asmmacro.h>
29 * Offset to the current process status flags, the first 32 bytes of the
32 #define ST_OFF (_THREAD_SIZE - 32 - PT_SIZE + PT_STATUS)
35 * task_struct *resume(task_struct *prev, task_struct *next,
36 * struct thread_info *next_ti)
40 sw t1, THREAD_STATUS(a0)
41 cpu_save_nonscratch a0
42 sw ra, THREAD_REG31(a0)
44 #if defined(CONFIG_CC_STACKPROTECTOR) && !defined(CONFIG_SMP)
45 PTR_LA t8, __stack_chk_guard
46 LONG_L t9, TASK_STACK_CANARY(a1)
51 * The order of restoring the registers takes care of the race
52 * updating $28, $29 and kernelsp without disabling ints.
55 cpu_restore_nonscratch a1
57 addiu t1, $28, _THREAD_SIZE - 32
60 mfc0 t1, CP0_STATUS /* Do we really need this? */
63 lw a2, THREAD_STATUS(a1)
73 * Save a thread's fp context.
76 EXPORT_SYMBOL(_save_fp)
77 fpu_save_single a0, t1 # clobbers t1
82 * Restore a thread's fp context.
85 fpu_restore_single a0, t1 # clobbers t1
90 * Load the FPU with signalling NANS. This bit pattern we're using has
91 * the property that no matter whether considered as single or as double
92 * precision represents signaling NANS.
94 * The value to initialize fcr31 to comes in $a0.