cregit-Linux how code gets into the kernel

Release 4.14 arch/nios2/include/asm/uaccess.h

/*
 * User space memory access functions for Nios II
 *
 * Copyright (C) 2010-2011, Tobias Klauser <tklauser@distanz.ch>
 * Copyright (C) 2009, Wind River Systems Inc
 *   Implemented by fredrik.markstrom@gmail.com and ivarholmqvist@gmail.com
 *
 * 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.
 */

#ifndef _ASM_NIOS2_UACCESS_H

#define _ASM_NIOS2_UACCESS_H

#include <linux/string.h>

#include <asm/page.h>

#include <asm/extable.h>

/*
 * Segment stuff
 */

#define MAKE_MM_SEG(s)		((mm_segment_t) { (s) })

#define USER_DS			MAKE_MM_SEG(0x80000000UL)

#define KERNEL_DS		MAKE_MM_SEG(0)


#define get_ds()		(KERNEL_DS)


#define get_fs()		(current_thread_info()->addr_limit)

#define set_fs(seg)		(current_thread_info()->addr_limit = (seg))


#define segment_eq(a, b)	((a).seg == (b).seg)


#define __access_ok(addr, len)			\
	(((signed long)(((long)get_fs().seg) &  \
                ((long)(addr) | (((long)(addr)) + (len)) | (len)))) == 0)


#define access_ok(type, addr, len)		\
	likely(__access_ok((unsigned long)(addr), (unsigned long)(len)))


# define __EX_TABLE_SECTION	".section __ex_table,\"a\"\n"


#define user_addr_max() (uaccess_kernel() ? ~0UL : TASK_SIZE)

/*
 * Zero Userspace
 */


static inline unsigned long __must_check __clear_user(void __user *to, unsigned long n) { __asm__ __volatile__ ( "1: stb zero, 0(%1)\n" " addi %0, %0, -1\n" " addi %1, %1, 1\n" " bne %0, zero, 1b\n" "2:\n" __EX_TABLE_SECTION ".word 1b, 2b\n" ".previous\n" : "=r" (n), "=r" (to) : "0" (n), "1" (to) ); return n; }

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static inline unsigned long __must_check clear_user(void __user *to, unsigned long n) { if (!access_ok(VERIFY_WRITE, to, n)) return n; return __clear_user(to, n); }

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extern unsigned long raw_copy_from_user(void *to, const void __user *from, unsigned long n); extern unsigned long raw_copy_to_user(void __user *to, const void *from, unsigned long n); #define INLINE_COPY_FROM_USER #define INLINE_COPY_TO_USER extern long strncpy_from_user(char *__to, const char __user *__from, long __len); extern __must_check long strlen_user(const char __user *str); extern __must_check long strnlen_user(const char __user *s, long n); /* Optimized macros */ #define __get_user_asm(val, insn, addr, err) \ { \ __asm__ __volatile__( \ " movi %0, %3\n" \ "1: " insn " %1, 0(%2)\n" \ " movi %0, 0\n" \ "2:\n" \ " .section __ex_table,\"a\"\n" \ " .word 1b, 2b\n" \ " .previous" \ : "=&r" (err), "=r" (val) \ : "r" (addr), "i" (-EFAULT)); \ } #define __get_user_unknown(val, size, ptr, err) do { \ err = 0; \ if (__copy_from_user(&(val), ptr, size)) { \ err = -EFAULT; \ } \ } while (0) #define __get_user_common(val, size, ptr, err) \ do { \ switch (size) { \ case 1: \ __get_user_asm(val, "ldbu", ptr, err); \ break; \ case 2: \ __get_user_asm(val, "ldhu", ptr, err); \ break; \ case 4: \ __get_user_asm(val, "ldw", ptr, err); \ break; \ default: \ __get_user_unknown(val, size, ptr, err); \ break; \ } \ } while (0) #define __get_user(x, ptr) \ ({ \ long __gu_err = -EFAULT; \ const __typeof__(*(ptr)) __user *__gu_ptr = (ptr); \ unsigned long __gu_val = 0; \ __get_user_common(__gu_val, sizeof(*(ptr)), __gu_ptr, __gu_err);\ (x) = (__force __typeof__(x))__gu_val; \ __gu_err; \ }) #define get_user(x, ptr) \ ({ \ long __gu_err = -EFAULT; \ const __typeof__(*(ptr)) __user *__gu_ptr = (ptr); \ unsigned long __gu_val = 0; \ if (access_ok(VERIFY_READ, __gu_ptr, sizeof(*__gu_ptr))) \ __get_user_common(__gu_val, sizeof(*__gu_ptr), \ __gu_ptr, __gu_err); \ (x) = (__force __typeof__(x))__gu_val; \ __gu_err; \ }) #define __put_user_asm(val, insn, ptr, err) \ { \ __asm__ __volatile__( \ " movi %0, %3\n" \ "1: " insn " %1, 0(%2)\n" \ " movi %0, 0\n" \ "2:\n" \ " .section __ex_table,\"a\"\n" \ " .word 1b, 2b\n" \ " .previous\n" \ : "=&r" (err) \ : "r" (val), "r" (ptr), "i" (-EFAULT)); \ } #define put_user(x, ptr) \ ({ \ long __pu_err = -EFAULT; \ __typeof__(*(ptr)) __user *__pu_ptr = (ptr); \ __typeof__(*(ptr)) __pu_val = (__typeof(*ptr))(x); \ if (access_ok(VERIFY_WRITE, __pu_ptr, sizeof(*__pu_ptr))) { \ switch (sizeof(*__pu_ptr)) { \ case 1: \ __put_user_asm(__pu_val, "stb", __pu_ptr, __pu_err); \ break; \ case 2: \ __put_user_asm(__pu_val, "sth", __pu_ptr, __pu_err); \ break; \ case 4: \ __put_user_asm(__pu_val, "stw", __pu_ptr, __pu_err); \ break; \ default: \ /* XXX: This looks wrong... */ \ __pu_err = 0; \ if (copy_to_user(__pu_ptr, &(__pu_val), \ sizeof(*__pu_ptr))) \ __pu_err = -EFAULT; \ break; \ } \ } \ __pu_err; \ }) #define __put_user(x, ptr) put_user(x, ptr) #endif /* _ASM_NIOS2_UACCESS_H */

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