--- /dev/null
+/*
+ * 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/reg.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.
+ */
+_GLOBAL(load_up_fpu)
+ mfmsr r5
+ ori r5,r5,MSR_FP
+ 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
+ LOAD_REG_ADDRBASE(r3, last_task_used_math)
+ toreal(r3)
+ PPC_LL r4,ADDROFF(last_task_used_math)(r3)
+ PPC_LCMPI 0,r4,0
+ beq 1f
+ toreal(r4)
+ addi r4,r4,THREAD /* want last_task_used_math->thread */
+ SAVE_32FPRS(0, r4)
+ mffs fr0
+ stfd fr0,THREAD_FPSCR(r4)
+ PPC_LL r5,PT_REGS(r4)
+ toreal(r5)
+ PPC_LL r4,_MSR-STACK_FRAME_OVERHEAD(r5)
+ li r10,MSR_FP|MSR_FE0|MSR_FE1
+ andc r4,r4,r10 /* disable FP for previous task */
+ PPC_STL r4,_MSR-STACK_FRAME_OVERHEAD(r5)
+1:
+#endif /* CONFIG_SMP */
+ /* enable use of FP after return */
+#ifdef CONFIG_PPC32
+ 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
+#else
+ ld r4,PACACURRENT(r13)
+ addi r5,r4,THREAD /* Get THREAD */
+ lwz r4,THREAD_FPEXC_MODE(r5)
+ ori r12,r12,MSR_FP
+ or r12,r12,r4
+ std r12,_MSR(r1)
+#endif
+ lfd fr0,THREAD_FPSCR(r5)
+ mtfsf 0xff,fr0
+ REST_32FPRS(0, r5)
+#ifndef CONFIG_SMP
+ subi r4,r5,THREAD
+ fromreal(r4)
+ PPC_STL r4,ADDROFF(last_task_used_math)(r3)
+#endif /* CONFIG_SMP */
+ /* restore registers and return */
+ /* we haven't used ctr or xer or lr */
+ b fast_exception_return
+
+/*
+ * 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.
+ */
+_GLOBAL(giveup_fpu)
+ mfmsr r5
+ ori r5,r5,MSR_FP
+ SYNC_601
+ ISYNC_601
+ MTMSRD(r5) /* enable use of fpu now */
+ SYNC_601
+ isync
+ PPC_LCMPI 0,r3,0
+ beqlr- /* if no previous owner, done */
+ addi r3,r3,THREAD /* want THREAD of task */
+ PPC_LL r5,PT_REGS(r3)
+ PPC_LCMPI 0,r5,0
+ SAVE_32FPRS(0, r3)
+ mffs fr0
+ stfd fr0,THREAD_FPSCR(r3)
+ beq 1f
+ PPC_LL r4,_MSR-STACK_FRAME_OVERHEAD(r5)
+ li r3,MSR_FP|MSR_FE0|MSR_FE1
+ andc r4,r4,r3 /* disable FP for previous task */
+ PPC_STL r4,_MSR-STACK_FRAME_OVERHEAD(r5)
+1:
+#ifndef CONFIG_SMP
+ li r5,0
+ LOAD_REG_ADDRBASE(r4,last_task_used_math)
+ PPC_STL r5,ADDROFF(last_task_used_math)(r4)
+#endif /* CONFIG_SMP */
+ blr
+
+/*
+ * These are used in the alignment trap handler when emulating
+ * single-precision loads and stores.
+ * We restore and save the fpscr so the task gets the same result
+ * and exceptions as if the cpu had performed the load or store.
+ */
+
+_GLOBAL(cvt_fd)
+ lfd 0,THREAD_FPSCR(r5) /* load up fpscr value */
+ mtfsf 0xff,0
+ lfs 0,0(r3)
+ stfd 0,0(r4)
+ mffs 0
+ stfd 0,THREAD_FPSCR(r5) /* save new fpscr value */
+ blr
+
+_GLOBAL(cvt_df)
+ lfd 0,THREAD_FPSCR(r5) /* load up fpscr value */
+ mtfsf 0xff,0
+ lfd 0,0(r3)
+ stfs 0,0(r4)
+ mffs 0
+ stfd 0,THREAD_FPSCR(r5) /* save new fpscr value */
+ blr
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