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x86: get rid of user_atomic_cmpxchg_inatomic() 

Only one user left; the thing had been made polymorphic back in 2013
for the sake of MPX.  No point keeping it now that MPX is gone.
Convert futex_atomic_cmpxchg_inatomic() to user_access_{begin,end}()
while we are at it.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
This commit is contained in:
Al Viro 2020-03-19 22:23:48 -04:00
parent a251b2d513
commit f5544ba712
2 changed files with 19 additions and 94 deletions
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20
arch/x86/include/asm/futex.h
View File

@ -90,7 +90,25 @@ Efault:
static inline int futex_atomic_cmpxchg_inatomic(u32 *uval, u32 __user *uaddr,
u32 oldval, u32 newval)
{
return user_atomic_cmpxchg_inatomic(uval, uaddr, oldval, newval);
int ret = 0;
if (!user_access_begin(uaddr, sizeof(u32)))
return -EFAULT;
asm volatile("\n"
"1:\t" LOCK_PREFIX "cmpxchgl %4, %2\n"
"2:\n"
"\t.section .fixup, \"ax\"\n"
"3:\tmov %3, %0\n"
"\tjmp 2b\n"
"\t.previous\n"
_ASM_EXTABLE_UA(1b, 3b)
: "+r" (ret), "=a" (oldval), "+m" (*uaddr)
: "i" (-EFAULT), "r" (newval), "1" (oldval)
: "memory"
);
user_access_end();
*uval = oldval;
return ret;
}
#endif

93
arch/x86/include/asm/uaccess.h
View File

@ -584,99 +584,6 @@ extern __must_check long strnlen_user(const char __user *str, long n);
unsigned long __must_check clear_user(void __user *mem, unsigned long len);
unsigned long __must_check __clear_user(void __user *mem, unsigned long len);
extern void __cmpxchg_wrong_size(void)
__compiletime_error("Bad argument size for cmpxchg");
#define __user_atomic_cmpxchg_inatomic(uval, ptr, old, new, size) \
({ \
int __ret = 0; \
__typeof__(*(ptr)) __old = (old); \
__typeof__(*(ptr)) __new = (new); \
__uaccess_begin_nospec(); \
switch (size) { \
case 1: \
{ \
asm volatile("\n" \
"1:\t" LOCK_PREFIX "cmpxchgb %4, %2\n" \
"2:\n" \
"\t.section .fixup, \"ax\"\n" \
"3:\tmov %3, %0\n" \
"\tjmp 2b\n" \
"\t.previous\n" \
_ASM_EXTABLE_UA(1b, 3b) \
: "+r" (__ret), "=a" (__old), "+m" (*(ptr)) \
: "i" (-EFAULT), "q" (__new), "1" (__old) \
: "memory" \
); \
break; \
} \
case 2: \
{ \
asm volatile("\n" \
"1:\t" LOCK_PREFIX "cmpxchgw %4, %2\n" \
"2:\n" \
"\t.section .fixup, \"ax\"\n" \
"3:\tmov %3, %0\n" \
"\tjmp 2b\n" \
"\t.previous\n" \
_ASM_EXTABLE_UA(1b, 3b) \
: "+r" (__ret), "=a" (__old), "+m" (*(ptr)) \
: "i" (-EFAULT), "r" (__new), "1" (__old) \
: "memory" \
); \
break; \
} \
case 4: \
{ \
asm volatile("\n" \
"1:\t" LOCK_PREFIX "cmpxchgl %4, %2\n" \
"2:\n" \
"\t.section .fixup, \"ax\"\n" \
"3:\tmov %3, %0\n" \
"\tjmp 2b\n" \
"\t.previous\n" \
_ASM_EXTABLE_UA(1b, 3b) \
: "+r" (__ret), "=a" (__old), "+m" (*(ptr)) \
: "i" (-EFAULT), "r" (__new), "1" (__old) \
: "memory" \
); \
break; \
} \
case 8: \
{ \
if (!IS_ENABLED(CONFIG_X86_64)) \
__cmpxchg_wrong_size(); \
\
asm volatile("\n" \
"1:\t" LOCK_PREFIX "cmpxchgq %4, %2\n" \
"2:\n" \
"\t.section .fixup, \"ax\"\n" \
"3:\tmov %3, %0\n" \
"\tjmp 2b\n" \
"\t.previous\n" \
_ASM_EXTABLE_UA(1b, 3b) \
: "+r" (__ret), "=a" (__old), "+m" (*(ptr)) \
: "i" (-EFAULT), "r" (__new), "1" (__old) \
: "memory" \
); \
break; \
} \
default: \
__cmpxchg_wrong_size(); \
} \
__uaccess_end(); \
*(uval) = __old; \
__ret; \
})
#define user_atomic_cmpxchg_inatomic(uval, ptr, old, new) \
({ \
access_ok((ptr), sizeof(*(ptr))) ? \
__user_atomic_cmpxchg_inatomic((uval), (ptr), \
(old), (new), sizeof(*(ptr))) : \
-EFAULT; \
})
/*
* movsl can be slow when source and dest are not both 8-byte aligned
*/