2 * FPU support code, moved here from head.S so that it can be used
3 * by chips which use other head-whatever.S files.
5 * Copyright (C) 1995-1996 Gary Thomas (gdt@linuxppc.org)
6 * Copyright (C) 1996 Cort Dougan <cort@cs.nmt.edu>
7 * Copyright (C) 1996 Paul Mackerras.
8 * Copyright (C) 1997 Dan Malek (dmalek@jlc.net).
10 * This program is free software; you can redistribute it and/or
11 * modify it under the terms of the GNU General Public License
12 * as published by the Free Software Foundation; either version
13 * 2 of the License, or (at your option) any later version.
20 #include <asm/pgtable.h>
21 #include <asm/cputable.h>
22 #include <asm/cache.h>
23 #include <asm/thread_info.h>
24 #include <asm/ppc_asm.h>
25 #include <asm/asm-offsets.h>
28 #define REST_32FPVSRS(n,c,base) \
31 END_FTR_SECTION_IFSET(CPU_FTR_VSX); \
32 REST_32FPRS(n,base); \
34 2: REST_32VSRS(n,c,base); \
37 #define SAVE_32FPVSRS(n,c,base) \
40 END_FTR_SECTION_IFSET(CPU_FTR_VSX); \
41 SAVE_32FPRS(n,base); \
43 2: SAVE_32VSRS(n,c,base); \
46 #define REST_32FPVSRS(n,b,base) REST_32FPRS(n, base)
47 #define SAVE_32FPVSRS(n,b,base) SAVE_32FPRS(n, base)
51 * This task wants to use the FPU now.
52 * On UP, disable FP for the task which had the FPU previously,
53 * and save its floating-point registers in its thread_struct.
54 * Load up this task's FP registers from its thread_struct,
55 * enable the FPU for the current task and return to the task.
63 END_FTR_SECTION_IFSET(CPU_FTR_VSX)
66 MTMSRD(r5) /* enable use of fpu now */
69 * For SMP, we don't do lazy FPU switching because it just gets too
70 * horrendously complex, especially when a task switches from one CPU
71 * to another. Instead we call giveup_fpu in switch_to.
74 LOAD_REG_ADDRBASE(r3, last_task_used_math)
76 PPC_LL r4,ADDROFF(last_task_used_math)(r3)
80 addi r4,r4,THREAD /* want last_task_used_math->thread */
81 SAVE_32FPVSRS(0, r5, r4)
83 stfd fr0,THREAD_FPSCR(r4)
86 PPC_LL r4,_MSR-STACK_FRAME_OVERHEAD(r5)
87 li r10,MSR_FP|MSR_FE0|MSR_FE1
88 andc r4,r4,r10 /* disable FP for previous task */
89 PPC_STL r4,_MSR-STACK_FRAME_OVERHEAD(r5)
91 #endif /* CONFIG_SMP */
92 /* enable use of FP after return */
94 mfspr r5,SPRN_SPRG_THREAD /* current task's THREAD (phys) */
95 lwz r4,THREAD_FPEXC_MODE(r5)
96 ori r9,r9,MSR_FP /* enable FP for current */
99 ld r4,PACACURRENT(r13)
100 addi r5,r4,THREAD /* Get THREAD */
101 lwz r4,THREAD_FPEXC_MODE(r5)
106 lfd fr0,THREAD_FPSCR(r5)
108 REST_32FPVSRS(0, r4, r5)
112 PPC_STL r4,ADDROFF(last_task_used_math)(r3)
113 #endif /* CONFIG_SMP */
114 /* restore registers and return */
115 /* we haven't used ctr or xer or lr */
120 * Disable FP for the task given as the argument,
121 * and save the floating-point registers in its thread_struct.
122 * Enables the FPU for use in the kernel on return.
130 END_FTR_SECTION_IFSET(CPU_FTR_VSX)
134 MTMSRD(r5) /* enable use of fpu now */
138 beqlr- /* if no previous owner, done */
139 addi r3,r3,THREAD /* want THREAD of task */
140 PPC_LL r5,PT_REGS(r3)
142 SAVE_32FPVSRS(0, r4 ,r3)
144 stfd fr0,THREAD_FPSCR(r3)
146 PPC_LL r4,_MSR-STACK_FRAME_OVERHEAD(r5)
147 li r3,MSR_FP|MSR_FE0|MSR_FE1
151 END_FTR_SECTION_IFSET(CPU_FTR_VSX)
153 andc r4,r4,r3 /* disable FP for previous task */
154 PPC_STL r4,_MSR-STACK_FRAME_OVERHEAD(r5)
158 LOAD_REG_ADDRBASE(r4,last_task_used_math)
159 PPC_STL r5,ADDROFF(last_task_used_math)(r4)
160 #endif /* CONFIG_SMP */
164 * These are used in the alignment trap handler when emulating
165 * single-precision loads and stores.