Commit 98b861a3 authored by Arnd Bergmann's avatar Arnd Bergmann
Browse files

asm-generic: uaccess: remove inline strncpy_from_user/strnlen_user 



The inline version is used on three NOMMU architectures and is
particularly inefficient when it scans the string one byte at a time
twice. It also lacks a check for user_addr_max(), but this is
probably ok on NOMMU targets.

Consolidate the asm-generic implementation with the library version
that is used everywhere else.  This version is generalized enough to
work efficiently on both MMU and NOMMU targets, and using the
same code everywhere reduces the potential for subtle bugs.

Mark the prototypes as __must_check in the process.

Reviewed-by: default avatarGeert Uytterhoeven <geert@linux-m68k.org>
Acked-by: default avatarGeert Uytterhoeven <geert@linux-m68k.org>
Reviewed-by: default avatarChristoph Hellwig <hch@lst.de>
Signed-off-by: default avatarArnd Bergmann <arnd@arndb.de>
parent e93a1cb8

arch/h8300/Kconfig

+2 −0
Original line number Diff line number Diff line
@@ -11,6 +11,8 @@ config H8300 
	select GENERIC_IRQ_SHOW

	select FRAME_POINTER

	select GENERIC_CPU_DEVICES

	select GENERIC_STRNCPY_FROM_USER

	select GENERIC_STRNLEN_USER

	select MODULES_USE_ELF_RELA

	select COMMON_CLK

	select ARCH_WANT_FRAME_POINTERS

arch/m68k/Kconfig

+2 −2
Original line number Diff line number Diff line
@@ -16,8 +16,8 @@ config M68K 
	select GENERIC_CPU_DEVICES

	select GENERIC_IOMAP

	select GENERIC_IRQ_SHOW

	select GENERIC_STRNCPY_FROM_USER if MMU

	select GENERIC_STRNLEN_USER if MMU

	select GENERIC_STRNCPY_FROM_USER

	select GENERIC_STRNLEN_USER

	select HAVE_AOUT if MMU

	select HAVE_ASM_MODVERSIONS

	select HAVE_DEBUG_BUGVERBOSE

arch/riscv/Kconfig

+2 −2
Original line number Diff line number Diff line
@@ -56,8 +56,8 @@ config RISCV 
	select GENERIC_PTDUMP if MMU

	select GENERIC_SCHED_CLOCK

	select GENERIC_SMP_IDLE_THREAD

	select GENERIC_STRNCPY_FROM_USER if MMU

	select GENERIC_STRNLEN_USER if MMU

	select GENERIC_STRNCPY_FROM_USER

	select GENERIC_STRNLEN_USER

	select GENERIC_TIME_VSYSCALL if MMU && 64BIT

	select HANDLE_DOMAIN_IRQ

	select HAVE_ARCH_AUDITSYSCALL

include/asm-generic/uaccess.h

+9 −38
Original line number Diff line number Diff line
@@ -119,6 +119,11 @@ static inline void set_fs(mm_segment_t fs) 
#ifndef uaccess_kernel

#define uaccess_kernel() (get_fs().seg == KERNEL_DS.seg)

#endif



#ifndef user_addr_max

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

#endif



#endif /* CONFIG_SET_FS */



#define access_ok(addr, size) __access_ok((unsigned long)(addr),(size))
@@ -243,44 +248,6 @@ static inline int __get_user_fn(size_t size, const void __user *ptr, void *x) 


extern int __get_user_bad(void) __attribute__((noreturn));



/*

 * Copy a null terminated string from userspace.

 */

#ifndef strncpy_from_user

static inline long

strncpy_from_user(char *dst, const char __user *src, long count)

{

	char *tmp;



	if (!access_ok(src, 1))

		return -EFAULT;



	strncpy(dst, (const char __force *)src, count);

	for (tmp = dst; *tmp && count > 0; tmp++, count--)

		;

	return (tmp - dst);

}

#endif



#ifndef strnlen_user

/*

 * Return the size of a string (including the ending 0)

 *

 * Return 0 on exception, a value greater than N if too long

 *

 * Unlike strnlen, strnlen_user includes the nul terminator in

 * its returned count. Callers should check for a returned value

 * greater than N as an indication the string is too long.

 */

static inline long strnlen_user(const char __user *src, long n)

{

	if (!access_ok(src, 1))

		return 0;



	return strnlen(src, n) + 1;

}

#endif



/*

 * Zero Userspace

 */
@@ -305,4 +272,8 @@ clear_user(void __user *to, unsigned long n) 


#include <asm/extable.h>



__must_check long strncpy_from_user(char *dst, const char __user *src,

				    long count);

__must_check long strnlen_user(const char __user *src, long n);



#endif /* __ASM_GENERIC_UACCESS_H */