Merge branch 'nocache-cleanup'

This series cleans up some of the special user copy functions naming and
semantics.  In particular, get rid of the (very traditional) double
underscore names and behavior: the whole "optimize away the range check"
model has been largely excised from the other user accessors because
it's so subtle and can be unsafe, but also because it's just not a
relevant optimization any more.

To do that, a couple of drivers that misused the "user" copies as kernel
copies in order to get non-temporal stores had to be fixed up, but that
kind of code should never have been allowed anyway.

The x86-only "nocache" version was also renamed to more accurately
reflect what it actually does.

This was all done because I looked at this code due to a report by Jann
Horn, and I just couldn't stand the inconsistent naming, the horrible
semantics, and the random misuse of these functions.  This code should
probably be cleaned up further, but it's at least slightly closer to
normal semantics.

I had a more intrusive series that went even further in trying to
normalize the semantics, but that ended up hitting so many other
inconsistencies between different architectures in this area (eg
'size_t' vs 'unsigned long' vs 'int' as size arguments, and various
iovec check differences that Vasily Gorbik pointed out) that I ended up
with this more limited version that fixed the worst of the issues.

Reported-by: Jann Horn <jannh@google.com>
Tested-by: Will Deacon <will@kernel.org>
Link: https://lore.kernel.org/all/CAHk-=wgg1QVWNWG-UCFo1hx0zqrPnB3qhPzUTrWNft+MtXQXig@mail.gmail.com/

* nocache-cleanup:
  x86-64/arm64/powerpc: clean up and rename __copy_from_user_flushcache
  x86: rename and clean up __copy_from_user_inatomic_nocache()
  x86-64: rename misleadingly named '__copy_user_nocache()' function

3 files changed, 11 insertions, 15 deletions

diff --git a/arch/x86/include/asm/uaccess.h b/arch/x86/include/asm/uaccess.h
index 367297b188c3..3a0dd3c2b233 100644
--- a/arch/x86/include/asm/uaccess.h
+++ b/arch/x86/include/asm/uaccess.h
@@ -507,7 +507,7 @@ extern struct movsl_mask {
 } ____cacheline_aligned_in_smp movsl_mask;
 #endif
 
-#define ARCH_HAS_NOCACHE_UACCESS 1
+#define ARCH_HAS_NONTEMPORAL_UACCESS 1
 
 /*
  * The "unsafe" user accesses aren't really "unsafe", but the naming
diff --git a/arch/x86/include/asm/uaccess_32.h b/arch/x86/include/asm/uaccess_32.h
index 40379a1adbb8..fff19e73ccb3 100644
--- a/arch/x86/include/asm/uaccess_32.h
+++ b/arch/x86/include/asm/uaccess_32.h
@@ -26,13 +26,7 @@ raw_copy_from_user(void *to, const void __user *from, unsigned long n)
 	return __copy_user_ll(to, (__force const void *)from, n);
 }
 
-static __always_inline unsigned long
-__copy_from_user_inatomic_nocache(void *to, const void __user *from,
-				  unsigned long n)
-{
-       return __copy_from_user_ll_nocache_nozero(to, from, n);
-}
-
+unsigned long __must_check copy_from_user_inatomic_nontemporal(void *, const void __user *, unsigned 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);
 
diff --git a/arch/x86/include/asm/uaccess_64.h b/arch/x86/include/asm/uaccess_64.h
index 915124011c27..20de34cc9aa6 100644
--- a/arch/x86/include/asm/uaccess_64.h
+++ b/arch/x86/include/asm/uaccess_64.h
@@ -147,26 +147,28 @@ raw_copy_to_user(void __user *dst, const void *src, unsigned long size)
 	return copy_user_generic((__force void *)dst, src, size);
 }
 
-extern long __copy_user_nocache(void *dst, const void __user *src, unsigned size);
-extern long __copy_user_flushcache(void *dst, const void __user *src, unsigned size);
+#define copy_to_nontemporal copy_to_nontemporal
+extern size_t copy_to_nontemporal(void *dst, const void *src, size_t size);
+extern size_t copy_user_flushcache(void *dst, const void __user *src, size_t size);
 
 static inline int
-__copy_from_user_inatomic_nocache(void *dst, const void __user *src,
+copy_from_user_inatomic_nontemporal(void *dst, const void __user *src,
 				  unsigned size)
 {
 	long ret;
 	kasan_check_write(dst, size);
+	src = mask_user_address(src);
 	stac();
-	ret = __copy_user_nocache(dst, src, size);
+	ret = copy_to_nontemporal(dst, (__force const void *)src, size);
 	clac();
 	return ret;
 }
 
-static inline int
-__copy_from_user_flushcache(void *dst, const void __user *src, unsigned size)
+static inline size_t
+copy_from_user_flushcache(void *dst, const void __user *src, size_t size)
 {
 	kasan_check_write(dst, size);
-	return __copy_user_flushcache(dst, src, size);
+	return copy_user_flushcache(dst, src, size);
 }
 
 /*