/* * linux/arch/arm/lib/getuser.S * * Copyright (C) 2001 Russell King * * 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. * * Idea from x86 version, (C) Copyright 1998 Linus Torvalds * * These functions have a non-standard call interface to make them more * efficient, especially as they return an error value in addition to * the "real" return value. * * __get_user_X * * Inputs: r0 contains the address * Outputs: r0 is the error code * r2, r3 contains the zero-extended value * lr corrupted * * No other registers must be altered. (see <asm/uaccess.h> * for specific ASM register usage). * * Note that ADDR_LIMIT is either 0 or 0xc0000000. * Note also that it is intended that __get_user_bad is not global. */ #include <linux/linkage.h> #include <asm/errno.h> ENTRY(__get_user_1) 1: ldrbt r2, [r0] mov r0, #0 mov pc, lr ENDPROC(__get_user_1) ENTRY(__get_user_2) 2: ldrbt r2, [r0], #1 3: ldrbt r3, [r0] #ifndef __ARMEB__ orr r2, r2, r3, lsl #8 #else orr r2, r3, r2, lsl #8 #endif mov r0, #0 mov pc, lr ENDPROC(__get_user_2) ENTRY(__get_user_4) 4: ldrt r2, [r0] mov r0, #0 mov pc, lr ENDPROC(__get_user_4) __get_user_bad: mov r2, #0 mov r0, #-EFAULT mov pc, lr ENDPROC(__get_user_bad) .section __ex_table, "a" .long 1b, __get_user_bad .long 2b, __get_user_bad .long 3b, __get_user_bad .long 4b, __get_user_bad .previous