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s390: use generic strncpy/strnlen from_user

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The s390 variant of strncpy_from_user() is slightly faster than the
generic variant, however convert to the generic variant now to follow
most if not all other architectures.

Converting to the generic variant was already considered a couple of
years ago. See commit f5c8b96010 ("s390/uaccess: use sane length for
__strncpy_from_user()").

Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
This commit is contained in:
Heiko Carstens 2021-07-22 22:07:30 +02:00 committed by Arnd Bergmann
parent b26b181651
commit e93a1cb8d2
3 changed files with 4 additions and 68 deletions
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2
arch/s390/Kconfig
View File

@ -130,6 +130,8 @@ config S390
select GENERIC_GETTIMEOFDAY
select GENERIC_PTDUMP
select GENERIC_SMP_IDLE_THREAD
select GENERIC_STRNCPY_FROM_USER
select GENERIC_STRNLEN_USER
select GENERIC_TIME_VSYSCALL
select GENERIC_VDSO_TIME_NS
select HAVE_ALIGNED_STRUCT_PAGE if SLUB

18
arch/s390/include/asm/uaccess.h
View File

@ -233,23 +233,9 @@ raw_copy_in_user(void __user *to, const void __user *from, unsigned long n);
/*
* Copy a null terminated string from userspace.
*/
long __must_check strncpy_from_user(char *dst, const char __user *src, long count);
long __strncpy_from_user(char *dst, const char __user *src, long count);
static inline long __must_check
strncpy_from_user(char *dst, const char __user *src, long count)
{
might_fault();
return __strncpy_from_user(dst, src, count);
}
unsigned long __must_check __strnlen_user(const char __user *src, unsigned long count);
static inline unsigned long strnlen_user(const char __user *src, unsigned long n)
{
might_fault();
return __strnlen_user(src, n);
}
long __must_check strnlen_user(const char __user *src, long count);
/*
* Zero Userspace

52
arch/s390/lib/uaccess.c
View File

@ -338,55 +338,3 @@ unsigned long __clear_user(void __user *to, unsigned long size)
return clear_user_xc(to, size);
}
EXPORT_SYMBOL(__clear_user);
static inline unsigned long strnlen_user_srst(const char __user *src,
unsigned long size)
{
unsigned long tmp1, tmp2;
asm volatile(
" lghi 0,0\n"
" la %2,0(%1)\n"
" la %3,0(%0,%1)\n"
" slgr %0,%0\n"
" sacf 256\n"
"0: srst %3,%2\n"
" jo 0b\n"
" la %0,1(%3)\n" /* strnlen_user results includes \0 */
" slgr %0,%1\n"
"1: sacf 768\n"
EX_TABLE(0b,1b)
: "+a" (size), "+a" (src), "=a" (tmp1), "=a" (tmp2)
:
: "cc", "memory", "0");
return size;
}
unsigned long __strnlen_user(const char __user *src, unsigned long size)
{
if (unlikely(!size))
return 0;
return strnlen_user_srst(src, size);
}
EXPORT_SYMBOL(__strnlen_user);
long __strncpy_from_user(char *dst, const char __user *src, long size)
{
size_t done, len, offset, len_str;
if (unlikely(size <= 0))
return 0;
done = 0;
do {
offset = (size_t)src & (L1_CACHE_BYTES - 1);
len = min(size - done, L1_CACHE_BYTES - offset);
if (copy_from_user(dst, src, len))
return -EFAULT;
len_str = strnlen(dst, len);
done += len_str;
src += len_str;
dst += len_str;
} while ((len_str == len) && (done < size));
return done;
}
EXPORT_SYMBOL(__strncpy_from_user);