powerpc: Introduce entry_{32,64}.S, misc_{32,64}.S, systbl.S

The system call table has been consolidated into systbl.S.  We have
separate 32-bit and 64-bit versions of entry.S and misc.S since the
code is mostly sufficiently different to be not worth merging.
There are some common bits that will be extracted in future.

Signed-off-by: Paul Mackerras <paulus@samba.org>

1 files changed, 842 insertions, 0 deletions

diff --git a/arch/powerpc/kernel/entry_64.S b/arch/powerpc/kernel/entry_64.S
new file mode 100644
index 00000000000..22796e28881
--- /dev/null
+++ b/arch/powerpc/kernel/entry_64.S
@@ -0,0 +1,842 @@
+/*
+ *  arch/ppc64/kernel/entry.S
+ *
+ *  PowerPC version 
+ *    Copyright (C) 1995-1996 Gary Thomas (gdt@linuxppc.org)
+ *  Rewritten by Cort Dougan (cort@cs.nmt.edu) for PReP
+ *    Copyright (C) 1996 Cort Dougan <cort@cs.nmt.edu>
+ *  Adapted for Power Macintosh by Paul Mackerras.
+ *  Low-level exception handlers and MMU support
+ *  rewritten by Paul Mackerras.
+ *    Copyright (C) 1996 Paul Mackerras.
+ *  MPC8xx modifications Copyright (C) 1997 Dan Malek (dmalek@jlc.net).
+ *
+ *  This file contains the system call entry code, context switch
+ *  code, and exception/interrupt return code for PowerPC.
+ *
+ *  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 <linux/errno.h>
+#include <asm/unistd.h>
+#include <asm/processor.h>
+#include <asm/page.h>
+#include <asm/mmu.h>
+#include <asm/thread_info.h>
+#include <asm/ppc_asm.h>
+#include <asm/asm-offsets.h>
+#include <asm/cputable.h>
+
+#ifdef CONFIG_PPC_ISERIES
+#define DO_SOFT_DISABLE
+#endif
+
+/*
+ * System calls.
+ */
+	.section	".toc","aw"
+.SYS_CALL_TABLE:
+	.tc .sys_call_table[TC],.sys_call_table
+
+/* This value is used to mark exception frames on the stack. */
+exception_marker:
+	.tc	ID_72656773_68657265[TC],0x7265677368657265
+
+	.section	".text"
+	.align 7
+
+#undef SHOW_SYSCALLS
+
+	.globl system_call_common
+system_call_common:
+	andi.	r10,r12,MSR_PR
+	mr	r10,r1
+	addi	r1,r1,-INT_FRAME_SIZE
+	beq-	1f
+	ld	r1,PACAKSAVE(r13)
+1:	std	r10,0(r1)
+	std	r11,_NIP(r1)
+	std	r12,_MSR(r1)
+	std	r0,GPR0(r1)
+	std	r10,GPR1(r1)
+	std	r2,GPR2(r1)
+	std	r3,GPR3(r1)
+	std	r4,GPR4(r1)
+	std	r5,GPR5(r1)
+	std	r6,GPR6(r1)
+	std	r7,GPR7(r1)
+	std	r8,GPR8(r1)
+	li	r11,0
+	std	r11,GPR9(r1)
+	std	r11,GPR10(r1)
+	std	r11,GPR11(r1)
+	std	r11,GPR12(r1)
+	std	r9,GPR13(r1)
+	crclr	so
+	mfcr	r9
+	mflr	r10
+	li	r11,0xc01
+	std	r9,_CCR(r1)
+	std	r10,_LINK(r1)
+	std	r11,_TRAP(r1)
+	mfxer	r9
+	mfctr	r10
+	std	r9,_XER(r1)
+	std	r10,_CTR(r1)
+	std	r3,ORIG_GPR3(r1)
+	ld	r2,PACATOC(r13)
+	addi	r9,r1,STACK_FRAME_OVERHEAD
+	ld	r11,exception_marker@toc(r2)
+	std	r11,-16(r9)		/* "regshere" marker */
+#ifdef CONFIG_PPC_ISERIES
+	/* Hack for handling interrupts when soft-enabling on iSeries */
+	cmpdi	cr1,r0,0x5555		/* syscall 0x5555 */
+	andi.	r10,r12,MSR_PR		/* from kernel */
+	crand	4*cr0+eq,4*cr1+eq,4*cr0+eq
+	beq	hardware_interrupt_entry
+	lbz	r10,PACAPROCENABLED(r13)
+	std	r10,SOFTE(r1)
+#endif
+	mfmsr	r11
+	ori	r11,r11,MSR_EE
+	mtmsrd	r11,1
+
+#ifdef SHOW_SYSCALLS
+	bl	.do_show_syscall
+	REST_GPR(0,r1)
+	REST_4GPRS(3,r1)
+	REST_2GPRS(7,r1)
+	addi	r9,r1,STACK_FRAME_OVERHEAD
+#endif
+	clrrdi	r11,r1,THREAD_SHIFT
+	li	r12,0
+	ld	r10,TI_FLAGS(r11)
+	stb	r12,TI_SC_NOERR(r11)
+	andi.	r11,r10,_TIF_SYSCALL_T_OR_A
+	bne-	syscall_dotrace
+syscall_dotrace_cont:
+	cmpldi	0,r0,NR_syscalls
+	bge-	syscall_enosys
+
+system_call:			/* label this so stack traces look sane */
+/*
+ * Need to vector to 32 Bit or default sys_call_table here,
+ * based on caller's run-mode / personality.
+ */
+	ld	r11,.SYS_CALL_TABLE@toc(2)
+	andi.	r10,r10,_TIF_32BIT
+	beq	15f
+	addi	r11,r11,8	/* use 32-bit syscall entries */
+	clrldi	r3,r3,32
+	clrldi	r4,r4,32
+	clrldi	r5,r5,32
+	clrldi	r6,r6,32
+	clrldi	r7,r7,32
+	clrldi	r8,r8,32
+15:
+	slwi	r0,r0,4
+	ldx	r10,r11,r0	/* Fetch system call handler [ptr] */
+	mtctr   r10
+	bctrl			/* Call handler */
+
+syscall_exit:
+#ifdef SHOW_SYSCALLS
+	std	r3,GPR3(r1)
+	bl	.do_show_syscall_exit
+	ld	r3,GPR3(r1)
+#endif
+	std	r3,RESULT(r1)
+	ld	r5,_CCR(r1)
+	li	r10,-_LAST_ERRNO
+	cmpld	r3,r10
+	clrrdi	r12,r1,THREAD_SHIFT
+	bge-	syscall_error
+syscall_error_cont:
+
+	/* check for syscall tracing or audit */
+	ld	r9,TI_FLAGS(r12)
+	andi.	r0,r9,(_TIF_SYSCALL_T_OR_A|_TIF_SINGLESTEP)
+	bne-	syscall_exit_trace
+syscall_exit_trace_cont:
+
+	/* disable interrupts so current_thread_info()->flags can't change,
+	   and so that we don't get interrupted after loading SRR0/1. */
+	ld	r8,_MSR(r1)
+	andi.	r10,r8,MSR_RI
+	beq-	unrecov_restore
+	mfmsr	r10
+	rldicl	r10,r10,48,1
+	rotldi	r10,r10,16
+	mtmsrd	r10,1
+	ld	r9,TI_FLAGS(r12)
+	andi.	r0,r9,(_TIF_SYSCALL_T_OR_A|_TIF_SIGPENDING|_TIF_NEED_RESCHED)
+	bne-	syscall_exit_work
+	ld	r7,_NIP(r1)
+	stdcx.	r0,0,r1			/* to clear the reservation */
+	andi.	r6,r8,MSR_PR
+	ld	r4,_LINK(r1)
+	beq-	1f			/* only restore r13 if */
+	ld	r13,GPR13(r1)		/* returning to usermode */
+1:	ld	r2,GPR2(r1)
+	li	r12,MSR_RI
+	andc	r10,r10,r12
+	mtmsrd	r10,1			/* clear MSR.RI */
+	ld	r1,GPR1(r1)
+	mtlr	r4
+	mtcr	r5
+	mtspr	SPRN_SRR0,r7
+	mtspr	SPRN_SRR1,r8
+	rfid
+	b	.	/* prevent speculative execution */
+
+syscall_enosys:
+	li	r3,-ENOSYS
+	std	r3,RESULT(r1)
+	clrrdi	r12,r1,THREAD_SHIFT
+	ld	r5,_CCR(r1)
+
+syscall_error:
+	lbz	r11,TI_SC_NOERR(r12)
+	cmpwi	0,r11,0
+	bne-	syscall_error_cont
+	neg	r3,r3
+	oris	r5,r5,0x1000	/* Set SO bit in CR */
+	std	r5,_CCR(r1)
+	b	syscall_error_cont
+        
+/* Traced system call support */
+syscall_dotrace:
+	bl	.save_nvgprs
+	addi	r3,r1,STACK_FRAME_OVERHEAD
+	bl	.do_syscall_trace_enter
+	ld	r0,GPR0(r1)	/* Restore original registers */
+	ld	r3,GPR3(r1)
+	ld	r4,GPR4(r1)
+	ld	r5,GPR5(r1)
+	ld	r6,GPR6(r1)
+	ld	r7,GPR7(r1)
+	ld	r8,GPR8(r1)
+	addi	r9,r1,STACK_FRAME_OVERHEAD
+	clrrdi	r10,r1,THREAD_SHIFT
+	ld	r10,TI_FLAGS(r10)
+	b	syscall_dotrace_cont
+
+syscall_exit_trace:
+	std	r3,GPR3(r1)
+	bl	.save_nvgprs
+	addi	r3,r1,STACK_FRAME_OVERHEAD
+	bl	.do_syscall_trace_leave
+	REST_NVGPRS(r1)
+	ld	r3,GPR3(r1)
+	ld	r5,_CCR(r1)
+	clrrdi	r12,r1,THREAD_SHIFT
+	b	syscall_exit_trace_cont
+
+/* Stuff to do on exit from a system call. */
+syscall_exit_work:
+	std	r3,GPR3(r1)
+	std	r5,_CCR(r1)
+	b	.ret_from_except_lite
+
+/* Save non-volatile GPRs, if not already saved. */
+_GLOBAL(save_nvgprs)
+	ld	r11,_TRAP(r1)
+	andi.	r0,r11,1
+	beqlr-
+	SAVE_NVGPRS(r1)
+	clrrdi	r0,r11,1
+	std	r0,_TRAP(r1)
+	blr
+
+/*
+ * The sigsuspend and rt_sigsuspend system calls can call do_signal
+ * and thus put the process into the stopped state where we might
+ * want to examine its user state with ptrace.  Therefore we need
+ * to save all the nonvolatile registers (r14 - r31) before calling
+ * the C code.  Similarly, fork, vfork and clone need the full
+ * register state on the stack so that it can be copied to the child.
+ */
+_GLOBAL(ppc32_sigsuspend)
+	bl	.save_nvgprs
+	bl	.sys32_sigsuspend
+	b	70f
+
+_GLOBAL(ppc64_rt_sigsuspend)
+	bl	.save_nvgprs
+	bl	.sys_rt_sigsuspend
+	b	70f
+
+_GLOBAL(ppc32_rt_sigsuspend)
+	bl	.save_nvgprs
+	bl	.sys32_rt_sigsuspend
+70:	cmpdi	0,r3,0
+	/* If it returned an error, we need to return via syscall_exit to set
+	   the SO bit in cr0 and potentially stop for ptrace. */
+	bne	syscall_exit
+	/* If sigsuspend() returns zero, we are going into a signal handler. We
+	   may need to call audit_syscall_exit() to mark the exit from sigsuspend() */
+#ifdef CONFIG_AUDIT
+	ld	r3,PACACURRENT(r13)
+	ld	r4,AUDITCONTEXT(r3)
+	cmpdi	0,r4,0
+	beq	.ret_from_except	/* No audit_context: Leave immediately. */
+	li	r4, 2			/* AUDITSC_FAILURE */
+	li	r5,-4			/* It's always -EINTR */
+	bl	.audit_syscall_exit
+#endif
+	b	.ret_from_except
+
+_GLOBAL(ppc_fork)
+	bl	.save_nvgprs
+	bl	.sys_fork
+	b	syscall_exit
+
+_GLOBAL(ppc_vfork)
+	bl	.save_nvgprs
+	bl	.sys_vfork
+	b	syscall_exit
+
+_GLOBAL(ppc_clone)
+	bl	.save_nvgprs
+	bl	.sys_clone
+	b	syscall_exit
+
+_GLOBAL(ppc32_swapcontext)
+	bl	.save_nvgprs
+	bl	.sys32_swapcontext
+	b	80f
+	
+_GLOBAL(ppc64_swapcontext)
+	bl	.save_nvgprs
+	bl	.sys_swapcontext
+	b	80f
+
+_GLOBAL(ppc32_sigreturn)
+	bl	.sys32_sigreturn
+	b	80f
+
+_GLOBAL(ppc32_rt_sigreturn)
+	bl	.sys32_rt_sigreturn
+	b	80f
+
+_GLOBAL(ppc64_rt_sigreturn)
+	bl	.sys_rt_sigreturn
+
+80:	cmpdi	0,r3,0
+	blt	syscall_exit
+	clrrdi	r4,r1,THREAD_SHIFT
+	ld	r4,TI_FLAGS(r4)
+	andi.	r4,r4,(_TIF_SYSCALL_T_OR_A|_TIF_SINGLESTEP)
+	beq+	81f
+	addi	r3,r1,STACK_FRAME_OVERHEAD
+	bl	.do_syscall_trace_leave
+81:	b	.ret_from_except
+
+_GLOBAL(ret_from_fork)
+	bl	.schedule_tail
+	REST_NVGPRS(r1)
+	li	r3,0
+	b	syscall_exit
+
+/*
+ * This routine switches between two different tasks.  The process
+ * state of one is saved on its kernel stack.  Then the state
+ * of the other is restored from its kernel stack.  The memory
+ * management hardware is updated to the second process's state.
+ * Finally, we can return to the second process, via ret_from_except.
+ * On entry, r3 points to the THREAD for the current task, r4
+ * points to the THREAD for the new task.
+ *
+ * Note: there are two ways to get to the "going out" portion
+ * of this code; either by coming in via the entry (_switch)
+ * or via "fork" which must set up an environment equivalent
+ * to the "_switch" path.  If you change this you'll have to change
+ * the fork code also.
+ *
+ * The code which creates the new task context is in 'copy_thread'
+ * in arch/ppc64/kernel/process.c
+ */
+	.align	7
+_GLOBAL(_switch)
+	mflr	r0
+	std	r0,16(r1)
+	stdu	r1,-SWITCH_FRAME_SIZE(r1)
+	/* r3-r13 are caller saved -- Cort */
+	SAVE_8GPRS(14, r1)
+	SAVE_10GPRS(22, r1)
+	mflr	r20		/* Return to switch caller */
+	mfmsr	r22
+	li	r0, MSR_FP
+#ifdef CONFIG_ALTIVEC
+BEGIN_FTR_SECTION
+	oris	r0,r0,MSR_VEC@h	/* Disable altivec */
+	mfspr	r24,SPRN_VRSAVE	/* save vrsave register value */
+	std	r24,THREAD_VRSAVE(r3)
+END_FTR_SECTION_IFSET(CPU_FTR_ALTIVEC)
+#endif /* CONFIG_ALTIVEC */
+	and.	r0,r0,r22
+	beq+	1f
+	andc	r22,r22,r0
+	mtmsrd	r22
+	isync
+1:	std	r20,_NIP(r1)
+	mfcr	r23
+	std	r23,_CCR(r1)
+	std	r1,KSP(r3)	/* Set old stack pointer */
+
+#ifdef CONFIG_SMP
+	/* We need a sync somewhere here to make sure that if the
+	 * previous task gets rescheduled on another CPU, it sees all
+	 * stores it has performed on this one.
+	 */
+	sync
+#endif /* CONFIG_SMP */
+
+	addi	r6,r4,-THREAD	/* Convert THREAD to 'current' */
+	std	r6,PACACURRENT(r13)	/* Set new 'current' */
+
+	ld	r8,KSP(r4)	/* new stack pointer */
+BEGIN_FTR_SECTION
+	clrrdi	r6,r8,28	/* get its ESID */
+	clrrdi	r9,r1,28	/* get current sp ESID */
+	clrldi.	r0,r6,2		/* is new ESID c00000000? */
+	cmpd	cr1,r6,r9	/* or is new ESID the same as current ESID? */
+	cror	eq,4*cr1+eq,eq
+	beq	2f		/* if yes, don't slbie it */
+
+	/* Bolt in the new stack SLB entry */
+	ld	r7,KSP_VSID(r4)	/* Get new stack's VSID */
+	oris	r0,r6,(SLB_ESID_V)@h
+	ori	r0,r0,(SLB_NUM_BOLTED-1)@l
+	slbie	r6
+	slbie	r6		/* Workaround POWER5 < DD2.1 issue */
+	slbmte	r7,r0
+	isync
+
+2:
+END_FTR_SECTION_IFSET(CPU_FTR_SLB)
+	clrrdi	r7,r8,THREAD_SHIFT	/* base of new stack */
+	/* Note: this uses SWITCH_FRAME_SIZE rather than INT_FRAME_SIZE
+	   because we don't need to leave the 288-byte ABI gap at the
+	   top of the kernel stack. */
+	addi	r7,r7,THREAD_SIZE-SWITCH_FRAME_SIZE
+
+	mr	r1,r8		/* start using new stack pointer */
+	std	r7,PACAKSAVE(r13)
+
+	ld	r6,_CCR(r1)
+	mtcrf	0xFF,r6
+
+#ifdef CONFIG_ALTIVEC
+BEGIN_FTR_SECTION
+	ld	r0,THREAD_VRSAVE(r4)
+	mtspr	SPRN_VRSAVE,r0		/* if G4, restore VRSAVE reg */
+END_FTR_SECTION_IFSET(CPU_FTR_ALTIVEC)
+#endif /* CONFIG_ALTIVEC */
+
+	/* r3-r13 are destroyed -- Cort */
+	REST_8GPRS(14, r1)
+	REST_10GPRS(22, r1)
+
+	/* convert old thread to its task_struct for return value */
+	addi	r3,r3,-THREAD
+	ld	r7,_NIP(r1)	/* Return to _switch caller in new task */
+	mtlr	r7
+	addi	r1,r1,SWITCH_FRAME_SIZE
+	blr
+
+	.align	7
+_GLOBAL(ret_from_except)
+	ld	r11,_TRAP(r1)
+	andi.	r0,r11,1
+	bne	.ret_from_except_lite
+	REST_NVGPRS(r1)
+
+_GLOBAL(ret_from_except_lite)
+	/*
+	 * Disable interrupts so that current_thread_info()->flags
+	 * can't change between when we test it and when we return
+	 * from the interrupt.
+	 */
+	mfmsr	r10		/* Get current interrupt state */
+	rldicl	r9,r10,48,1	/* clear MSR_EE */
+	rotldi	r9,r9,16
+	mtmsrd	r9,1		/* Update machine state */
+
+#ifdef CONFIG_PREEMPT
+	clrrdi	r9,r1,THREAD_SHIFT	/* current_thread_info() */
+	li	r0,_TIF_NEED_RESCHED	/* bits to check */
+	ld	r3,_MSR(r1)
+	ld	r4,TI_FLAGS(r9)
+	/* Move MSR_PR bit in r3 to _TIF_SIGPENDING position in r0 */
+	rlwimi	r0,r3,32+TIF_SIGPENDING-MSR_PR_LG,_TIF_SIGPENDING
+	and.	r0,r4,r0	/* check NEED_RESCHED and maybe SIGPENDING */
+	bne	do_work
+
+#else /* !CONFIG_PREEMPT */
+	ld	r3,_MSR(r1)	/* Returning to user mode? */
+	andi.	r3,r3,MSR_PR
+	beq	restore		/* if not, just restore regs and return */
+
+	/* Check current_thread_info()->flags */
+	clrrdi	r9,r1,THREAD_SHIFT
+	ld	r4,TI_FLAGS(r9)
+	andi.	r0,r4,_TIF_USER_WORK_MASK
+	bne	do_work
+#endif
+
+restore:
+#ifdef CONFIG_PPC_ISERIES
+	ld	r5,SOFTE(r1)
+	cmpdi	0,r5,0
+	beq	4f
+	/* Check for pending interrupts (iSeries) */
+	ld	r3,PACALPPACA+LPPACAANYINT(r13)
+	cmpdi	r3,0
+	beq+	4f			/* skip do_IRQ if no interrupts */
+
+	li	r3,0
+	stb	r3,PACAPROCENABLED(r13)	/* ensure we are soft-disabled */
+	ori	r10,r10,MSR_EE
+	mtmsrd	r10			/* hard-enable again */
+	addi	r3,r1,STACK_FRAME_OVERHEAD
+	bl	.do_IRQ
+	b	.ret_from_except_lite		/* loop back and handle more */
+
+4:	stb	r5,PACAPROCENABLED(r13)
+#endif
+
+	ld	r3,_MSR(r1)
+	andi.	r0,r3,MSR_RI
+	beq-	unrecov_restore
+
+	andi.	r0,r3,MSR_PR
+
+	/*
+	 * r13 is our per cpu area, only restore it if we are returning to
+	 * userspace
+	 */
+	beq	1f
+	REST_GPR(13, r1)
+1:
+	ld	r3,_CTR(r1)
+	ld	r0,_LINK(r1)
+	mtctr	r3
+	mtlr	r0
+	ld	r3,_XER(r1)
+	mtspr	SPRN_XER,r3
+
+	REST_8GPRS(5, r1)
+
+	stdcx.	r0,0,r1		/* to clear the reservation */
+
+	mfmsr	r0
+	li	r2, MSR_RI
+	andc	r0,r0,r2
+	mtmsrd	r0,1
+
+	ld	r0,_MSR(r1)
+	mtspr	SPRN_SRR1,r0
+
+	ld	r2,_CCR(r1)
+	mtcrf	0xFF,r2
+	ld	r2,_NIP(r1)
+	mtspr	SPRN_SRR0,r2
+
+	ld	r0,GPR0(r1)
+	ld	r2,GPR2(r1)
+	ld	r3,GPR3(r1)
+	ld	r4,GPR4(r1)
+	ld	r1,GPR1(r1)
+
+	rfid
+	b	.	/* prevent speculative execution */
+
+/* Note: this must change if we start using the TIF_NOTIFY_RESUME bit */
+do_work:
+#ifdef CONFIG_PREEMPT
+	andi.	r0,r3,MSR_PR	/* Returning to user mode? */
+	bne	user_work
+	/* Check that preempt_count() == 0 and interrupts are enabled */
+	lwz	r8,TI_PREEMPT(r9)
+	cmpwi	cr1,r8,0
+#ifdef CONFIG_PPC_ISERIES
+	ld	r0,SOFTE(r1)
+	cmpdi	r0,0
+#else
+	andi.	r0,r3,MSR_EE
+#endif
+	crandc	eq,cr1*4+eq,eq
+	bne	restore
+	/* here we are preempting the current task */
+1:
+#ifdef CONFIG_PPC_ISERIES
+	li	r0,1
+	stb	r0,PACAPROCENABLED(r13)
+#endif
+	ori	r10,r10,MSR_EE
+	mtmsrd	r10,1		/* reenable interrupts */
+	bl	.preempt_schedule
+	mfmsr	r10
+	clrrdi	r9,r1,THREAD_SHIFT
+	rldicl	r10,r10,48,1	/* disable interrupts again */
+	rotldi	r10,r10,16
+	mtmsrd	r10,1
+	ld	r4,TI_FLAGS(r9)
+	andi.	r0,r4,_TIF_NEED_RESCHED
+	bne	1b
+	b	restore
+
+user_work:
+#endif
+	/* Enable interrupts */
+	ori	r10,r10,MSR_EE
+	mtmsrd	r10,1
+
+	andi.	r0,r4,_TIF_NEED_RESCHED
+	beq	1f
+	bl	.schedule
+	b	.ret_from_except_lite
+
+1:	bl	.save_nvgprs
+	li	r3,0
+	addi	r4,r1,STACK_FRAME_OVERHEAD
+	bl	.do_signal
+	b	.ret_from_except
+
+unrecov_restore:
+	addi	r3,r1,STACK_FRAME_OVERHEAD
+	bl	.unrecoverable_exception
+	b	unrecov_restore
+
+#ifdef CONFIG_PPC_RTAS
+/*
+ * On CHRP, the Run-Time Abstraction Services (RTAS) have to be
+ * called with the MMU off.
+ *
+ * In addition, we need to be in 32b mode, at least for now.
+ * 
+ * Note: r3 is an input parameter to rtas, so don't trash it...
+ */
+_GLOBAL(enter_rtas)
+	mflr	r0
+	std	r0,16(r1)
+        stdu	r1,-RTAS_FRAME_SIZE(r1)	/* Save SP and create stack space. */
+
+	/* Because RTAS is running in 32b mode, it clobbers the high order half
+	 * of all registers that it saves.  We therefore save those registers
+	 * RTAS might touch to the stack.  (r0, r3-r13 are caller saved)
+   	 */
+	SAVE_GPR(2, r1)			/* Save the TOC */
+	SAVE_GPR(13, r1)		/* Save paca */
+	SAVE_8GPRS(14, r1)		/* Save the non-volatiles */
+	SAVE_10GPRS(22, r1)		/* ditto */
+
+	mfcr	r4
+	std	r4,_CCR(r1)
+	mfctr	r5
+	std	r5,_CTR(r1)
+	mfspr	r6,SPRN_XER
+	std	r6,_XER(r1)
+	mfdar	r7
+	std	r7,_DAR(r1)
+	mfdsisr	r8
+	std	r8,_DSISR(r1)
+	mfsrr0	r9
+	std	r9,_SRR0(r1)
+	mfsrr1	r10
+	std	r10,_SRR1(r1)
+
+	/* There is no way it is acceptable to get here with interrupts enabled,
+	 * check it with the asm equivalent of WARN_ON
+	 */
+	mfmsr	r6
+	andi.	r0,r6,MSR_EE
+1:	tdnei	r0,0
+.section __bug_table,"a"
+	.llong	1b,__LINE__ + 0x1000000, 1f, 2f
+.previous
+.section .rodata,"a"
+1:	.asciz	__FILE__
+2:	.asciz "enter_rtas"
+.previous
+	
+	/* Unfortunately, the stack pointer and the MSR are also clobbered,
+	 * so they are saved in the PACA which allows us to restore
+	 * our original state after RTAS returns.
+         */
+	std	r1,PACAR1(r13)
+        std	r6,PACASAVEDMSR(r13)
+
+	/* Setup our real return addr */	
+	SET_REG_TO_LABEL(r4,.rtas_return_loc)
+	SET_REG_TO_CONST(r9,KERNELBASE)
+	sub	r4,r4,r9
+       	mtlr	r4
+
+	li	r0,0
+	ori	r0,r0,MSR_EE|MSR_SE|MSR_BE|MSR_RI
+	andc	r0,r6,r0
+	
+        li      r9,1
+        rldicr  r9,r9,MSR_SF_LG,(63-MSR_SF_LG)
+	ori	r9,r9,MSR_IR|MSR_DR|MSR_FE0|MSR_FE1|MSR_FP
+	andc	r6,r0,r9
+	ori	r6,r6,MSR_RI
+	sync				/* disable interrupts so SRR0/1 */
+	mtmsrd	r0			/* don't get trashed */
+
+	SET_REG_TO_LABEL(r4,rtas)
+	ld	r5,RTASENTRY(r4)	/* get the rtas->entry value */
+	ld	r4,RTASBASE(r4)		/* get the rtas->base value */
+	
+	mtspr	SPRN_SRR0,r5
+	mtspr	SPRN_SRR1,r6
+	rfid
+	b	.	/* prevent speculative execution */
+
+_STATIC(rtas_return_loc)
+	/* relocation is off at this point */
+	mfspr	r4,SPRN_SPRG3	        /* Get PACA */
+	SET_REG_TO_CONST(r5, KERNELBASE)
+        sub     r4,r4,r5                /* RELOC the PACA base pointer */
+
+	mfmsr   r6
+	li	r0,MSR_RI
+	andc	r6,r6,r0
+	sync	
+	mtmsrd  r6
+        
+        ld	r1,PACAR1(r4)           /* Restore our SP */
+	LOADADDR(r3,.rtas_restore_regs)
+        ld	r4,PACASAVEDMSR(r4)     /* Restore our MSR */
+
+	mtspr	SPRN_SRR0,r3
+	mtspr	SPRN_SRR1,r4
+	rfid
+	b	.	/* prevent speculative execution */
+
+_STATIC(rtas_restore_regs)
+	/* relocation is on at this point */
+	REST_GPR(2, r1)			/* Restore the TOC */
+	REST_GPR(13, r1)		/* Restore paca */
+	REST_8GPRS(14, r1)		/* Restore the non-volatiles */
+	REST_10GPRS(22, r1)		/* ditto */
+
+	mfspr	r13,SPRN_SPRG3
+
+	ld	r4,_CCR(r1)
+	mtcr	r4
+	ld	r5,_CTR(r1)
+	mtctr	r5
+	ld	r6,_XER(r1)
+	mtspr	SPRN_XER,r6
+	ld	r7,_DAR(r1)
+	mtdar	r7
+	ld	r8,_DSISR(r1)
+	mtdsisr	r8
+	ld	r9,_SRR0(r1)
+	mtsrr0	r9
+	ld	r10,_SRR1(r1)
+	mtsrr1	r10
+
+        addi	r1,r1,RTAS_FRAME_SIZE	/* Unstack our frame */
+	ld	r0,16(r1)		/* get return address */
+
+	mtlr    r0
+        blr				/* return to caller */
+
+#endif /* CONFIG_PPC_RTAS */
+
+#ifdef CONFIG_PPC_MULTIPLATFORM
+
+_GLOBAL(enter_prom)
+	mflr	r0
+	std	r0,16(r1)
+        stdu	r1,-PROM_FRAME_SIZE(r1)	/* Save SP and create stack space */
+
+	/* Because PROM is running in 32b mode, it clobbers the high order half
+	 * of all registers that it saves.  We therefore save those registers
+	 * PROM might touch to the stack.  (r0, r3-r13 are caller saved)
+   	 */
+	SAVE_8GPRS(2, r1)
+	SAVE_GPR(13, r1)
+	SAVE_8GPRS(14, r1)
+	SAVE_10GPRS(22, r1)
+	mfcr	r4
+	std	r4,_CCR(r1)
+	mfctr	r5
+	std	r5,_CTR(r1)
+	mfspr	r6,SPRN_XER
+	std	r6,_XER(r1)
+	mfdar	r7
+	std	r7,_DAR(r1)
+	mfdsisr	r8
+	std	r8,_DSISR(r1)
+	mfsrr0	r9
+	std	r9,_SRR0(r1)
+	mfsrr1	r10
+	std	r10,_SRR1(r1)
+	mfmsr	r11
+	std	r11,_MSR(r1)
+
+	/* Get the PROM entrypoint */
+	ld	r0,GPR4(r1)
+	mtlr	r0
+
+	/* Switch MSR to 32 bits mode
+	 */
+        mfmsr   r11
+        li      r12,1
+        rldicr  r12,r12,MSR_SF_LG,(63-MSR_SF_LG)
+        andc    r11,r11,r12
+        li      r12,1
+        rldicr  r12,r12,MSR_ISF_LG,(63-MSR_ISF_LG)
+        andc    r11,r11,r12
+        mtmsrd  r11
+        isync
+
+	/* Restore arguments & enter PROM here... */
+	ld	r3,GPR3(r1)
+	blrl
+
+	/* Just make sure that r1 top 32 bits didn't get
+	 * corrupt by OF
+	 */
+	rldicl	r1,r1,0,32
+
+	/* Restore the MSR (back to 64 bits) */
+	ld	r0,_MSR(r1)
+	mtmsrd	r0
+        isync
+
+	/* Restore other registers */
+	REST_GPR(2, r1)
+	REST_GPR(13, r1)
+	REST_8GPRS(14, r1)
+	REST_10GPRS(22, r1)
+	ld	r4,_CCR(r1)
+	mtcr	r4
+	ld	r5,_CTR(r1)
+	mtctr	r5
+	ld	r6,_XER(r1)
+	mtspr	SPRN_XER,r6
+	ld	r7,_DAR(r1)
+	mtdar	r7
+	ld	r8,_DSISR(r1)
+	mtdsisr	r8
+	ld	r9,_SRR0(r1)
+	mtsrr0	r9
+	ld	r10,_SRR1(r1)
+	mtsrr1	r10
+	
+        addi	r1,r1,PROM_FRAME_SIZE
+	ld	r0,16(r1)
+	mtlr    r0
+        blr
+	
+#endif	/* CONFIG_PPC_MULTIPLATFORM */