powerpc: Merge enough to start building in arch/powerpc.
This creates the directory structure under arch/powerpc and a bunch
of Kconfig files. It does a first-cut merge of arch/powerpc/mm,
arch/powerpc/lib and arch/powerpc/platforms/powermac. This is enough
to build a 32-bit powermac kernel with ARCH=powerpc.
For now we are getting some unmerged files from arch/ppc/kernel and
arch/ppc/syslib, or arch/ppc64/kernel. This makes some minor changes
to files in those directories and files outside arch/powerpc.
The boot directory is still not merged. That's going to be interesting.
Signed-off-by: Paul Mackerras <paulus@samba.org>
diff --git a/arch/powerpc/kernel/fpu.S b/arch/powerpc/kernel/fpu.S
new file mode 100644
index 0000000..665d7d3
--- /dev/null
+++ b/arch/powerpc/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/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
