path: root/arch/arm26/kernel/entry.S

/* arch/arm26/kernel/entry.S
 * 
 * Assembled from chunks of code in arch/arm
 *
 * Copyright (C) 2003 Ian Molton
 * Based on the work of RMK.
 *
 */

#include <linux/linkage.h>

#include <asm/assembler.h>
#include <asm/asm_offsets.h>
#include <asm/errno.h>
#include <asm/hardware.h>
#include <asm/sysirq.h>
#include <asm/thread_info.h>
#include <asm/page.h>
#include <asm/ptrace.h>

	.macro	zero_fp
#ifndef CONFIG_NO_FRAME_POINTER
	mov	fp, #0
#endif
	.endm

	.text

@ Bad Abort numbers
@ -----------------
@
#define BAD_PREFETCH	0
#define BAD_DATA	1
#define BAD_ADDREXCPTN	2
#define BAD_IRQ		3
#define BAD_UNDEFINSTR	4

@ OS version number used in SWIs
@  RISC OS is 0
@  RISC iX is 8
@
#define OS_NUMBER	9
#define ARMSWI_OFFSET	0x000f0000

@
@ Stack format (ensured by USER_* and SVC_*)
@ PSR and PC are comined on arm26
@

#define S_OFF		8

#define S_OLD_R0	64
#define S_PC		60
#define S_LR		56
#define S_SP		52
#define S_IP		48
#define S_FP		44
#define S_R10		40
#define S_R9		36
#define S_R8		32
#define S_R7		28
#define S_R6		24
#define S_R5		20
#define S_R4		16
#define S_R3		12
#define S_R2		8
#define S_R1		4
#define S_R0		0

	.macro	save_user_regs
	str	r0, [sp, #-4]!   @ Store SVC r0
	str	lr, [sp, #-4]!   @ Store user mode PC
	sub	sp, sp, #15*4
	stmia	sp, {r0 - lr}^   @ Store the other user-mode regs
	mov	r0, r0
	.endm

	.macro	slow_restore_user_regs
	ldmia	sp, {r0 - lr}^   @ restore the user regs not including PC
	mov	r0, r0
	ldr	lr, [sp, #15*4]  @ get user PC
	add	sp, sp, #15*4+8  @ free stack
	movs	pc, lr           @ return
	.endm

	.macro	fast_restore_user_regs
	add	sp, sp, #S_OFF
	ldmib	sp, {r1 - lr}^
	mov	r0, r0
	ldr	lr, [sp, #15*4]
	add	sp, sp, #15*4+8
	movs	pc, lr
	.endm

	.macro	save_svc_regs
	str     sp, [sp, #-16]!
	str     lr, [sp, #8]
	str     lr, [sp, #4]
	stmfd   sp!, {r0 - r12}
	mov     r0, #-1
	str     r0, [sp, #S_OLD_R0]
	zero_fp
	.endm

	.macro	save_svc_regs_irq
	str     sp, [sp, #-16]!
	str     lr, [sp, #4]
	ldr     lr, .LCirq
	ldr     lr, [lr]
	str     lr, [sp, #8]
	stmfd   sp!, {r0 - r12}
	mov     r0, #-1
	str     r0, [sp, #S_OLD_R0]
	zero_fp
	.endm

	.macro	restore_svc_regs
                ldmfd   sp, {r0 - pc}^
	.endm

	.macro	mask_pc, rd, rm
	bic	\rd, \rm, #PCMASK
	.endm

	.macro  disable_irqs, temp
	mov     \temp, pc
	orr     \temp, \temp, #PSR_I_BIT
	teqp    \temp, #0
	.endm

	.macro	enable_irqs, temp
	mov     \temp, pc
	and     \temp, \temp, #~PSR_I_BIT
	teqp	\temp, #0
	.endm

	.macro	initialise_traps_extra
	.endm

	.macro	get_thread_info, rd
	mov	\rd, sp, lsr #13
	mov	\rd, \rd, lsl #13
	.endm

/*
 * 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	r7		@ syscall number
tbl	.req	r8		@ syscall table pointer
why	.req	r8		@ Linux syscall (!= 0)
tsk	.req	r9		@ current thread_info

/*
 * Get the system call number.
 */
	.macro	get_scno
	mask_pc	lr, lr
	ldr	scno, [lr, #-4]		@ get SWI instruction
	.endm
/*
 *  -----------------------------------------------------------------------
 */

/* 
 * We rely 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

/*
 * This is the fast syscall return path.  We do as little as
 * possible here, and this includes saving r0 back into the SVC
 * stack.
 */
ret_fast_syscall:
	disable_irqs r1				@ disable interrupts
	ldr	r1, [tsk, #TI_FLAGS]
	tst	r1, #_TIF_WORK_MASK
	bne	fast_work_pending
	fast_restore_user_regs

/*
 * Ok, we need to do extra processing, enter the slow path.
 */
fast_work_pending:
	str