Initial import

1 files changed, 393 insertions, 0 deletions

diff --git a/arch/sh/kernel/entry-common.S b/arch/sh/kernel/entry-common.S
new file mode 100644
index 000000000..13047a4fa
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+++ b/arch/sh/kernel/entry-common.S
@@ -0,0 +1,393 @@
+/* 
+ *  Copyright (C) 1999, 2000, 2002  Niibe Yutaka
+ *  Copyright (C) 2003 - 2008  Paul Mundt
+ *
+ * This file is subject to the terms and conditions of the GNU General Public
+ * License.  See the file "COPYING" in the main directory of this archive
+ * for more details.
+ *
+ */
+
+! NOTE:
+! GNU as (as of 2.9.1) changes bf/s into bt/s and bra, when the address
+! to be jumped is too far, but it causes illegal slot exception.
+
+/*	
+ * entry.S contains the system-call and fault low-level handling routines.
+ * This also contains the timer-interrupt handler, as well as all interrupts
+ * and faults that can result in a task-switch.
+ *
+ * NOTE: This code handles signal-recognition, which happens every time
+ * after a timer-interrupt and after each system call.
+ *
+ * NOTE: This code uses a convention that instructions in the delay slot
+ * of a transfer-control instruction are indented by an extra space, thus:
+ *
+ *    jmp	@k0	    ! control-transfer instruction
+ *     ldc	k1, ssr     ! delay slot
+ *
+ * Stack layout in 'ret_from_syscall':
+ * 	ptrace needs to have all regs on the stack.
+ *	if the order here is changed, it needs to be
+ *	updated in ptrace.c and ptrace.h
+ *
+ *	r0
+ *      ...
+ *	r15 = stack pointer
+ *	spc
+ *	pr
+ *	ssr
+ *	gbr
+ *	mach
+ *	macl
+ *	syscall #
+ *
+ */
+#include <asm/dwarf.h>
+
+#if defined(CONFIG_PREEMPT)
+#  define preempt_stop()	cli ; TRACE_IRQS_OFF
+#else
+#  define preempt_stop()
+#  define resume_kernel		__restore_all
+#endif
+
+
+	.align	2
+ENTRY(exception_error)
+	!
+	TRACE_IRQS_ON
+	sti
+	mov.l	1f, r0
+	jmp	@r0
+	 nop
+
+	.align	2
+1:	.long	do_exception_error
+
+	.align	2
+ret_from_exception:
+	CFI_STARTPROC simple
+	CFI_DEF_CFA r14, 0
+	CFI_REL_OFFSET 17, 64
+	CFI_REL_OFFSET 15, 60
+	CFI_REL_OFFSET 14, 56
+	CFI_REL_OFFSET 13, 52
+	CFI_REL_OFFSET 12, 48
+	CFI_REL_OFFSET 11, 44
+	CFI_REL_OFFSET 10, 40
+	CFI_REL_OFFSET 9, 36
+	CFI_REL_OFFSET 8, 32
+	preempt_stop()
+ENTRY(ret_from_irq)
+	!
+	mov	#OFF_SR, r0
+	mov.l	@(r0,r15), r0	! get status register
+	shll	r0
+	shll	r0		! kernel space?
+	get_current_thread_info r8, r0
+	bt	resume_kernel	! Yes, it's from kernel, go back soon
+
+#ifdef CONFIG_PREEMPT
+	bra	resume_userspace
+	 nop
+ENTRY(resume_kernel)
+	cli
+	TRACE_IRQS_OFF
+	mov.l	@(TI_PRE_COUNT,r8), r0	! current_thread_info->preempt_count
+	tst	r0, r0
+	bf	noresched
+need_resched:
+	mov.l	@(TI_FLAGS,r8), r0	! current_thread_info->flags
+	tst	#_TIF_NEED_RESCHED, r0	! need_resched set?
+	bt	noresched
+
+	mov	#OFF_SR, r0
+	mov.l	@(r0,r15), r0		! get status register
+	shlr	r0
+	and	#(0xf0>>1), r0		! interrupts off (exception path)?
+	cmp/eq	#(0xf0>>1), r0
+	bt	noresched
+	mov.l	1f, r0
+	jsr	@r0			! call preempt_schedule_irq
+	 nop
+	bra	need_resched
+	 nop
+
+noresched:
+	bra	__restore_all
+	 nop
+
+	.align 2
+1:	.long	preempt_schedule_irq
+#endif
+
+ENTRY(resume_userspace)
+	! r8: current_thread_info
+	cli
+	TRACE_IRQS_OFF
+	mov.l	@(TI_FLAGS,r8), r0		! current_thread_info->flags
+	tst	#(_TIF_WORK_MASK & 0xff), r0
+	bt/s	__restore_all
+	 tst	#_TIF_NEED_RESCHED, r0
+
+	.align	2
+work_pending:
+	! r0: current_thread_info->flags
+	! r8: current_thread_info
+	! t:  result of "tst	#_TIF_NEED_RESCHED, r0"
+	bf/s	work_resched
+	 tst	#(_TIF_SIGPENDING | _TIF_NOTIFY_RESUME), r0
+work_notifysig:
+	bt/s	__restore_all
+	 mov	r15, r4
+	mov	r12, r5		! set arg1(save_r0)
+	mov	r0, r6
+	sti
+	mov.l	2f, r1
+	mov.l	3f, r0
+	jmp	@r1
+	 lds	r0, pr
+work_resched:
+	mov.l	1f, r1
+	jsr	@r1				! schedule
+	 nop
+	cli
+	TRACE_IRQS_OFF
+	!
+	mov.l	@(TI_FLAGS,r8), r0		! current_thread_info->flags
+	tst	#(_TIF_WORK_MASK & 0xff), r0
+	bt	__restore_all
+	bra	work_pending
+	 tst	#_TIF_NEED_RESCHED, r0
+
+	.align	2
+1:	.long	schedule
+2:	.long	do_notify_resume
+3:	.long	resume_userspace
+
+	.align	2
+syscall_exit_work:
+	! r0: current_thread_info->flags
+	! r8: current_thread_info
+	tst	#(_TIF_WORK_SYSCALL_MASK & 0xff), r0
+	bt/s	work_pending
+	 tst	#_TIF_NEED_RESCHED, r0
+	TRACE_IRQS_ON
+	sti
+	mov	r15, r4
+	mov.l	8f, r0			! do_syscall_trace_leave
+	jsr	@r0
+	 nop
+	bra	resume_userspace
+	 nop
+
+	.align	2
+syscall_trace_entry:
+	!                     	Yes it is traced.
+	mov     r15, r4
+	mov.l	7f, r11		! Call do_syscall_trace_enter which notifies
+	jsr	@r11	    	! superior (will chomp R[0-7])
+	 nop
+	mov.l	r0, @(OFF_R0,r15)	! Save return value
+	!			Reload R0-R4 from kernel stack, where the
+	!   	    	    	parent may have modified them using
+	!   	    	    	ptrace(POKEUSR).  (Note that R0-R2 are
+	!   	    	    	reloaded from the kernel stack by syscall_call
+	!   	    	    	below, so don't need to be reloaded here.)
+	!   	    	    	This allows the parent to rewrite system calls
+	!   	    	    	and args on the fly.
+	mov.l	@(OFF_R4,r15), r4   ! arg0
+	mov.l	@(OFF_R5,r15), r5
+	mov.l	@(OFF_R6,r15), r6
+	mov.l	@(OFF_R7,r15), r7   ! arg3
+	mov.l	@(OFF_R3,r15), r3   ! syscall_nr
+	!
+	mov.l	2f, r10			! Number of syscalls
+	cmp/hs	r10, r3
+	bf	syscall_call
+	mov	#-ENOSYS, r0
+	bra	syscall_exit
+	 mov.l	r0, @(OFF_R0,r15)	! Return value
+
+__restore_all:
+	mov	#OFF_SR, r0
+	mov.l	@(r0,r15), r0	! get status register
+
+	shlr2	r0
+	and	#0x3c, r0
+	cmp/eq	#0x3c, r0
+	bt	1f
+	TRACE_IRQS_ON
+	bra	2f
+	 nop
+1:
+	TRACE_IRQS_OFF
+2:
+	mov.l	3f, r0
+	jmp	@r0
+	 nop
+
+	.align	2
+3:	.long	restore_all
+
+	.align	2
+syscall_badsys:			! Bad syscall number
+	get_current_thread_info r8, r0
+	mov	#-ENOSYS, r0
+	bra	resume_userspace
+	 mov.l	r0, @(OFF_R0,r15)	! Return value
+
+/*
+ * The main debug trap handler.
+ *
+ * r8=TRA (not the trap number!)
+ *
+ * Note: This assumes that the trapa value is left in its original
+ * form (without the shlr2 shift) so the calculation for the jump
+ * call table offset remains a simple in place mask.
+ */
+debug_trap:
+	mov	r8, r0
+	and	#(0xf << 2), r0
+	mov.l	1f, r8
+	add	r0, r8
+	mov.l	@r8, r8
+	jsr	@r8
+	 nop
+	bra	__restore_all
+	 nop
+	CFI_ENDPROC
+
+	.align	2
+1:	.long	debug_trap_table
+
+/*
+ * Syscall interface:
+ *
+ *	Syscall #: R3
+ *	Arguments #0 to #3: R4--R7
+ *	Arguments #4 to #6: R0, R1, R2
+ *	TRA: (number of arguments + ABI revision) x 4
+ *
+ * This code also handles delegating other traps to the BIOS/gdb stub
+ * according to:
+ *
+ * Trap number
+ * (TRA>>2)	Purpose
+ * --------	-------
+ * 0x00-0x0f	original SH-3/4 syscall ABI (not in general use).
+ * 0x10-0x1f	general SH-3/4 syscall ABI.
+ * 0x20-0x2f	syscall ABI for SH-2 parts.
+ * 0x30-0x3f	debug traps used by the kernel.
+ * 0x40-0xff	Not supported by all parts, so left unhandled.
+ *
+ * Note: When we're first called, the TRA value must be shifted
+ * right 2 bits in order to get the value that was used as the "trapa"
+ * argument.
+ */
+
+	.align	2
+	.globl	ret_from_fork
+ret_from_fork:
+	mov.l	1f, r8
+	jsr	@r8
+	 mov	r0, r4
+	bra	syscall_exit
+	 nop
+
+	.align	2
+	.globl	ret_from_kernel_thread
+ret_from_kernel_thread:
+	mov.l	1f, r8
+	jsr	@r8
+	 mov	r0, r4
+	mov.l	@(OFF_R5,r15), r5   ! fn
+	jsr	@r5
+	 mov.l	@(OFF_R4,r15), r4   ! arg
+	bra	syscall_exit
+	 nop
+
+	.align	2
+1:	.long	schedule_tail
+
+/*
+ * The poorly named main trapa decode and dispatch routine, for
+ * system calls and debug traps through their respective jump tables.
+ */
+ENTRY(system_call)
+	setup_frame_reg
+#if !defined(CONFIG_CPU_SH2)
+	mov.l	1f, r9
+	mov.l	@r9, r8		! Read from TRA (Trap Address) Register
+#endif
+
+	mov	#OFF_TRA, r10
+	add	r15, r10
+	mov.l	r8, @r10		! set TRA value to tra
+
+	/*
+	 * Check the trap type
+	 */
+	mov	#((0x20 << 2) - 1), r9
+	cmp/hi	r9, r8
+	bt/s	debug_trap		! it's a debug trap..
+	 nop
+
+	TRACE_IRQS_ON
+	sti
+
+	!
+	get_current_thread_info r8, r10
+	mov.l	@(TI_FLAGS,r8), r8
+	mov	#(_TIF_WORK_SYSCALL_MASK & 0xff), r10
+	mov	#(_TIF_WORK_SYSCALL_MASK >> 8), r9
+	tst	r10, r8
+	shll8	r9
+	bf	syscall_trace_entry
+	tst	r9, r8
+	bf	syscall_trace_entry
+	!
+	mov.l	2f, r8			! Number of syscalls
+	cmp/hs	r8, r3
+	bt	syscall_badsys
+	!
+syscall_call:
+	shll2	r3		! x4
+	mov.l	3f, r8		! Load the address of sys_call_table
+	add	r8, r3
+	mov.l	@r3, r8
+	mov.l	@(OFF_R2,r15), r2
+	mov.l	@(OFF_R1,r15), r1
+	mov.l	@(OFF_R0,r15), r0
+	mov.l	r2, @-r15
+	mov.l	r1, @-r15
+	mov.l	r0, @-r15
+	jsr	@r8	    	! jump to specific syscall handler
+	 nop
+	add	#12, r15
+	mov.l	@(OFF_R0,r15), r12		! save r0
+	mov.l	r0, @(OFF_R0,r15)		! save the return value
+	!
+syscall_exit:
+	cli
+	TRACE_IRQS_OFF
+	!
+	get_current_thread_info r8, r0
+	mov.l	@(TI_FLAGS,r8), r0		! current_thread_info->flags
+	tst	#(_TIF_ALLWORK_MASK & 0xff), r0
+	mov	#(_TIF_ALLWORK_MASK >> 8), r1
+	bf	syscall_exit_work
+	shlr8	r0
+	tst	r0, r1
+	bf	syscall_exit_work
+	bra	__restore_all
+	 nop
+	.align	2
+#if !defined(CONFIG_CPU_SH2)
+1:	.long	TRA
+#endif
+2:	.long	NR_syscalls
+3:	.long	sys_call_table
+7:	.long	do_syscall_trace_enter
+8:	.long	do_syscall_trace_leave