/*
* FPU support code, moved here from head.S so that it can be used
* by chips which use other head-whatever.S files.
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version
* 2 of the License, or (at your option) any later version.
*
*/
#include <linux/config.h>
#include <asm/processor.h>
#include <asm/page.h>
#include <asm/mmu.h>
#include <asm/pgtable.h>
#include <asm/cputable.h>
#include <asm/cache.h>
#include <asm/thread_info.h>
#include <asm/ppc_asm.h>
#include <asm/asm-offsets.h>
/*
* This task wants to use the FPU now.
* On UP, disable FP for the task which had the FPU previously,
* and save its floating-point registers in its thread_struct.
* Load up this task's FP registers from its thread_struct,
* enable the FPU for the current task and return to the task.
*/
.globl load_up_fpu
load_up_fpu:
mfmsr r5
ori r5,r5,MSR_FP
#ifdef CONFIG_PPC64BRIDGE
clrldi r5,r5,1 /* turn off 64-bit mode */
#endif /* CONFIG_PPC64BRIDGE */
SYNC
MTMSRD(r5) /* enable use of fpu now */
isync
/*
* For SMP, we don't do lazy FPU switching because it just gets too
* horrendously complex, especially when a task switches from one CPU
* to another. Instead we call giveup_fpu in switch_to.
*/
#ifndef CONFIG_SMP
tophys(r6,0) /* get __pa constant */
addis r3,r6,last_task_used_math@ha
lwz r4,last_task_used_math@l(r3)
cmpwi 0,r4,0
beq 1f
add r4,r4,r6
addi r4,r4,THREAD /* want last_task_used_math->thread */
SAVE_32FPRS(0, r4)
mffs fr0
stfd fr0,THREAD_FPSCR-4(r4)
lwz r5,PT_REGS(r4)
add r5,r5,r6
lwz r4,_MSR-STACK_FRAME_OVERHEAD(r5)
li r10,MSR_FP|MSR_FE0|MSR_FE1
andc r4,r4,r10 /* disable FP for previous task */
stw r4,_MSR-STACK_FRAME_OVERHEAD(r5)
1:
#endif /* CONFIG_SMP */
/* enable use of FP after return */
mfspr r5,SPRN_SPRG3 /* current task's THREAD (phys) */
lwz r4,THREAD_FPEXC_MODE(r5)
ori r9,r9,MSR_FP /* enable FP for current */
or r9,r9,r4
lfd fr0,THREAD_FPSCR-4(r5)
mtfsf 0xff,fr0
REST_32FPRS(0, r5)
#ifndef CONFIG_SMP
subi r4,r5,THREAD
sub r4,r4,r6
stw r4,last_task_used_math@l(r3)
#endif /* CONFIG_SMP */
/* restore registers and return */
/* we haven't used ctr or xer or lr */
b fast_exception_return
/*
* FP unavailable trap from kernel - print a message, but let
* the task use FP in the kernel until it returns to user mode.
*/
.globl KernelFP
KernelFP:
lwz r3,_MSR(r1)
ori r3,r3,MSR_FP
stw r3,_MSR(r1) /* enable use of FP after return */
lis r3,86f@h
ori r3,r3,86f@l
mr r4,r2 /* current */
lwz r5,_NIP(r1)
bl printk
b ret_from_except
86: .string "floating point used in kernel (task=%p, pc=%x)\n"
.align 4,0
/*
* giveup_fpu(tsk)
* Disable FP for the task given as the argument,
* and save the floating-point registers in its thread_struct.
* Enables the FPU for use in the kernel on return.
*/
.globl giveup_fpu
giveup_fpu:
mfmsr r5
ori r5,r5,MSR_FP
SYNC_601
ISYNC_601
MTMSRD(r5) /* enable use of fpu now */
SYNC_601
isync
cmpwi 0,r3,0
beqlr- /* if no previous owner, done */
addi r3,r3,THREAD /* want THREAD of task */
lwz r5,PT_REGS(r3)
cmpwi 0,r5,0
SAVE_32FPRS(0, r3)
mffs fr0
stfd fr0,THREAD_FPSCR-4(r3)
beq 1f
lwz r4,_MSR-STACK_FRAME_OVERHEAD(r5)
li r3,MSR_FP|MSR_FE0|MSR_FE1
andc r4,r4,r3 /* disable FP for previous task */
stw r4,_MSR-STACK_FRAME_OVERHEAD(r5)
1:
#ifndef CONFIG_SMP
li r5,0
lis r4,last_task_used_math@ha
stw r5,last_task_used_math@l(r4)
#endif /* CONFIG_SMP */
blr
