* [tip: locking/core] x86: get rid of user_atomic_cmpxchg_inatomic()
@ 2020-03-28 11:06 tip-bot2 for Al Viro
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From: tip-bot2 for Al Viro @ 2020-03-28 11:06 UTC (permalink / raw)
To: linux-tip-commits; +Cc: Al Viro, x86, LKML
The following commit has been merged into the locking/core branch of tip:
Commit-ID: f5544ba712afd1b01dd856c7eecfb5d30beaf920
Gitweb: https://git.kernel.org/tip/f5544ba712afd1b01dd856c7eecfb5d30beaf920
Author: Al Viro <viro@zeniv.linux.org.uk>
AuthorDate: Thu, 19 Mar 2020 22:23:48 -04:00
Committer: Al Viro <viro@zeniv.linux.org.uk>
CommitterDate: Fri, 27 Mar 2020 23:58:55 -04:00
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>
---
arch/x86/include/asm/futex.h | 20 ++++++-
arch/x86/include/asm/uaccess.h | 93 +---------------------------------
2 files changed, 19 insertions(+), 94 deletions(-)
diff --git a/arch/x86/include/asm/futex.h b/arch/x86/include/asm/futex.h
index 5ff7626..f9c0011 100644
--- a/arch/x86/include/asm/futex.h
+++ b/arch/x86/include/asm/futex.h
@@ -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
diff --git a/arch/x86/include/asm/uaccess.h b/arch/x86/include/asm/uaccess.h
index 61d93f0..ea6fc64 100644
--- a/arch/x86/include/asm/uaccess.h
+++ b/arch/x86/include/asm/uaccess.h
@@ -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
*/
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