path: root/arch/unicore32/kernel/entry.S

/*
 * linux/arch/unicore32/kernel/entry.S
 *
 * Code specific to PKUnity SoC and UniCore ISA
 *
 * Copyright (C) 2001-2010 GUAN Xue-tao
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 *
 *  Low-level vector interface routines
 */
#include <linux/init.h>
#include <linux/linkage.h>
#include <asm/assembler.h>
#include <asm/errno.h>
#include <asm/thread_info.h>
#include <asm/memory.h>
#include <asm/unistd.h>
#include <generated/asm-offsets.h>
#include "debug-macro.S"

@
@ Most of the stack format comes from struct pt_regs, but with
@ the addition of 8 bytes for storing syscall args 5 and 6.
@
#define S_OFF		8

/*
 * The SWI code relies on the fact that R0 is at the bottom of the stack
 * (due to slow/fast restore user regs).
 */
#if S_R0 != 0
#error "Please fix"
#endif

	.macro	zero_fp
#ifdef CONFIG_FRAME_POINTER
	mov	fp, #0
#endif
	.endm

	.macro	alignment_trap, rtemp
#ifdef CONFIG_ALIGNMENT_TRAP
	ldw	\rtemp, .LCcralign
	ldw	\rtemp, [\rtemp]
	movc	p0.c1, \rtemp, #0
#endif
	.endm

	.macro	load_user_sp_lr, rd, rtemp, offset = 0
	mov	\rtemp, asr
	xor	\rtemp, \rtemp, #(PRIV_MODE ^ SUSR_MODE)
	mov.a	asr, \rtemp			@ switch to the SUSR mode

	ldw	sp, [\rd+], #\offset		@ load sp_user
	ldw	lr, [\rd+], #\offset + 4	@ load lr_user

	xor	\rtemp, \rtemp, #(PRIV_MODE ^ SUSR_MODE)
	mov.a	asr, \rtemp			@ switch back to the PRIV mode
	.endm

	.macro	priv_exit, rpsr
	mov.a	bsr, \rpsr
	ldm.w	(r0 - r15), [sp]+
	ldm.b	(r16 - pc), [sp]+		@ load r0 - pc, asr
	.endm

	.macro	restore_user_regs, fast = 0, offset = 0
	ldw	r1, [sp+], #\offset + S_PSR	@ get calling asr
	ldw	lr, [sp+], #\offset + S_PC	@ get pc
	mov.a	bsr, r1				@ save in bsr_priv
	.if	\fast
	add	sp, sp, #\offset + S_R1		@ r0 is syscall return value
	ldm.w	(r1 - r15), [sp]+		@ get calling r1 - r15
	ldur	(r16 - lr), [sp]+		@ get calling r16 - lr
	.else
	ldm.w	(r0 - r15), [sp]+		@ get calling r0 - r15
	ldur	(r16 - lr), [sp]+		@ get calling r16 - lr
	.endif
	nop
	add	sp, sp, #S_FRAME_SIZE - S_R16
	mov.a	pc, lr				@ return
						@ and move bsr_priv into asr
	.endm

	.macro	get_thread_info, rd
	mov	\rd, sp >> #13
	mov	\rd, \rd << #13
	.endm

	.macro	get_irqnr_and_base, irqnr, irqstat, base, tmp
	ldw	\base, =(PKUNITY_INTC_BASE)
	ldw	\irqstat, [\base+], #0xC	@ INTC_ICIP
	ldw	\tmp,	  [\base+], #0x4	@ INTC_ICMR
	and.a	\irqstat, \irqstat, \tmp
	beq	1001f
	cntlz	\irqnr, \irqstat
	rsub	\irqnr, \irqnr, #31
1001:	/* EQ will be set if no irqs pending */
	.endm

#ifdef CONFIG_DEBUG_LL
	.macro	printreg, reg, temp
		adr	\temp, 901f
		stm	(r0-r3), [\temp]+
		stw	lr, [\temp+], #0x10
		mov	r0, \reg
		b.l	printhex8
		mov	r0, #':'
		b.l	printch
		mov	r0, pc
		b.l	printhex8
		adr	r0, 902f
		b.l	printascii
		adr	\temp, 901f
		ldm	(r0-r3), [\temp]+
		ldw	lr, [\temp+], #0x10
		b	903f
901:	.word	0, 0, 0, 0, 0	@ r0-r3, lr
902:	.asciz	": epip4d\n"
	.align
903:
	.endm
#endif

/*
 * These are the registers used in the syscall handler, and allow us to
 * have in theory up to 7 arguments to a function - r0 to r6.
 *
 * Note that tbl == why is intentional.
 *
 * We must set at least "tsk" and "why" when calling ret_with_reschedule.
 */
scno	.req	r21		@ syscall number
tbl	.req	r22		@ syscall table pointer
why	.req	r22		@ Linux syscall (!= 0)
tsk	.req	r23		@ current thread_info

/*
 * Interrupt handling.  Preserves r17, r18, r19
 */
	.macro	intr_handler
1:	get_irqnr_and_base r0, r6, r5, lr
	beq	2f
	mov	r1, sp
	@
	@ routine called with r0 = irq number, r1 = struct pt_regs *
	@
	adr	lr, 1b
	b	asm_do_IRQ
2:
	.endm

/*
 * PRIV mode handlers
 */
	.macro	priv_entry
	sub	sp, sp, #(S_FRAME_SIZE - 4)
	stm	(r1 - r15), [sp]+
	add	r5, sp, #S_R15
	stm	(r16 - r28), [r5]+

	ldm	(r1 - r3), [r0]+
	add	r5, sp, #S_SP - 4	@ here for interlock avoidance
	mov	r4, #-1			@  ""  ""      ""       ""
	add	r0, sp, #(S_FRAME_SIZE - 4)
	stw.w	r1, [sp+], #-4		@ save the "real" r0 copied
					@ from the exception stack

	mov	r1, lr

	@
	@ We are now ready to fill in the remaining blanks on the stack:
	@
	@  r0 - sp_priv
	@  r1 - lr_priv
	@  r2 - lr_<exception>, already fixed up for correct return/restart
	@  r3 - bsr_<exception>
	@  r4 - orig_r0 (see pt_regs definition in ptrace.h)
	@
	stm	(r0 - r4), [r5]+
	.endm

/*
 * User mode handlers
 *
 */
	.macro	user_entry
	sub	sp, sp, #S_FRAME_SIZE
	stm	(r1 - r15), [sp+]
	add	r4, sp, #S_R16
	stm	(r16 - r28), [r4]+

	ldm	(r1 - r3), [r0]+
	add	r0, sp, #S_PC		@ here for interlock avoidance
	mov	r4, #-1			@  ""  ""     ""        ""

	stw	r1, [sp]		@ save the "real" r0 copied
					@ from the exception stack

	@
	@ We are now ready to fill in the remaining blanks on the stack:
	@
	@  r2 - lr_<exception>, already fixed up for correct return/restart
	@  r3 - bsr_<exception>
	@  r4 - orig_r0 (see pt_regs definition in ptrace.h)
	@
	@ Also, separately save sp_user and lr_user
	@
	stm	(r2 - r4), [r0]+
	stur	(sp, lr), [r0-]

	@
	@ Enable the alignment trap while in kernel mode
	@
	alignment_trap r0

	@
	@ Clear FP to mark the first stack frame
	@
	zero_fp
	.endm

	.text

@
@ __invalid - generic code for failed exception
@			(re-entrant version of handlers)
@
__invalid:
	sub	sp, sp, #S_FRAME_SIZE
	stm	(r1 - r15), [sp+]
	add	r1, sp, #S_R16
	stm	(r16 - r28, sp, lr