Merge with master.kernel.org:/pub/scm/linux/kernel/git/torvalds/linux-2.6.git

1 files changed, 133 insertions, 0 deletions

diff --git a/arch/ppc/kernel/fpu.S b/arch/ppc/kernel/fpu.S
new file mode 100644
index 000000000000..6189b26f640f
--- /dev/null
+++ b/arch/ppc/kernel/fpu.S
@@ -0,0 +1,133 @@
+/*
+ *  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/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