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author | Heiko Carstens <heiko.carstens@de.ibm.com> | 2016-06-20 10:35:20 +0200 |
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committer | Martin Schwidefsky <schwidefsky@de.ibm.com> | 2016-06-28 09:32:27 +0200 |
commit | dc4aace160165bd15400a79f9f5ab97405278f48 (patch) | |
tree | b9bda648dbb6be08deea6af9fd4e6061e16a1797 /arch | |
parent | 109ab954713bd07c96f65ceddab4886069a110ab (diff) | |
download | linux-stable-dc4aace160165bd15400a79f9f5ab97405278f48.tar.gz linux-stable-dc4aace160165bd15400a79f9f5ab97405278f48.tar.bz2 linux-stable-dc4aace160165bd15400a79f9f5ab97405278f48.zip |
s390/uaccess: fix __put_get_user_asm define
The __put_get_user_asm defines an inline assmembly which makes use of
the asm register construct. The parameters passed to that define may
also contain function calls.
It is a gcc restriction that between register asm statements and the
use of any such annotated variables function calls may clobber the
register / variable contents. Or in other words: gcc would generate
broken code.
This can be achieved e.g. with the following code:
get_user(x, func() ? a : b);
where the call of func would clobber register zero which is used by
the __put_get_user_asm define.
To avoid this add two static inline functions which don't have these
side effects.
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Diffstat (limited to 'arch')
-rw-r--r-- | arch/s390/include/asm/uaccess.h | 61 |
1 files changed, 59 insertions, 2 deletions
diff --git a/arch/s390/include/asm/uaccess.h b/arch/s390/include/asm/uaccess.h index 2ea7f3208cd2..9b49cf1daa8f 100644 --- a/arch/s390/include/asm/uaccess.h +++ b/arch/s390/include/asm/uaccess.h @@ -151,8 +151,65 @@ unsigned long __must_check __copy_to_user(void __user *to, const void *from, __rc; \ }) -#define __put_user_fn(x, ptr, size) __put_get_user_asm(ptr, x, size, 0x810000UL) -#define __get_user_fn(x, ptr, size) __put_get_user_asm(x, ptr, size, 0x81UL) +static inline int __put_user_fn(void *x, void __user *ptr, unsigned long size) +{ + unsigned long spec = 0x810000UL; + int rc; + + switch (size) { + case 1: + rc = __put_get_user_asm((unsigned char __user *)ptr, + (unsigned char *)x, + size, spec); + break; + case 2: + rc = __put_get_user_asm((unsigned short __user *)ptr, + (unsigned short *)x, + size, spec); + break; + case 4: + rc = __put_get_user_asm((unsigned int __user *)ptr, + (unsigned int *)x, + size, spec); + break; + case 8: + rc = __put_get_user_asm((unsigned long __user *)ptr, + (unsigned long *)x, + size, spec); + break; + }; + return rc; +} + +static inline int __get_user_fn(void *x, const void __user *ptr, unsigned long size) +{ + unsigned long spec = 0x81UL; + int rc; + + switch (size) { + case 1: + rc = __put_get_user_asm((unsigned char *)x, + (unsigned char __user *)ptr, + size, spec); + break; + case 2: + rc = __put_get_user_asm((unsigned short *)x, + (unsigned short __user *)ptr, + size, spec); + break; + case 4: + rc = __put_get_user_asm((unsigned int *)x, + (unsigned int __user *)ptr, + size, spec); + break; + case 8: + rc = __put_get_user_asm((unsigned long *)x, + (unsigned long __user *)ptr, + size, spec); + break; + }; + return rc; +} #else /* CONFIG_HAVE_MARCH_Z10_FEATURES */ |