[PATCH v2 1/3] powerpc/uaccess: get rid of small constant size cases in raw_copy_{to,from}_user()

[PATCH v2 1/3] powerpc/uaccess: get rid of small constant size cases in raw_copy_{to,from}_user()

[Christophe Leroy]

Copied from commit 4b842e4e25b1 ("x86: get rid of small
constant size cases in raw_copy_{to,from}_user()")

Very few call sites where that would be triggered remain, and none
of those is anywhere near hot enough to bother.

Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
---
 arch/powerpc/include/asm/uaccess.h | 41 ------------------------------
 1 file changed, 41 deletions(-)

diff --git a/arch/powerpc/include/asm/uaccess.h b/arch/powerpc/include/asm/uaccess.h
index 93d33f7e8b53..a4d2569173ac 100644
--- a/arch/powerpc/include/asm/uaccess.h
+++ b/arch/powerpc/include/asm/uaccess.h
@@ -398,26 +398,6 @@ static inline unsigned long raw_copy_from_user(void *to,
 		const void __user *from, unsigned long n)
 {
 	unsigned long ret;
-	if (__builtin_constant_p(n) && (n <= 8)) {
-		ret = 1;
-
-		switch (n) {
-		case 1:
-			__get_user_size(*(u8 *)to, from, 1, ret);
-			break;
-		case 2:
-			__get_user_size(*(u16 *)to, from, 2, ret);
-			break;
-		case 4:
-			__get_user_size(*(u32 *)to, from, 4, ret);
-			break;
-		case 8:
-			__get_user_size(*(u64 *)to, from, 8, ret);
-			break;
-		}
-		if (ret == 0)
-			return 0;
-	}
 
 	allow_read_from_user(from, n);
 	ret = __copy_tofrom_user((__force void __user *)to, from, n);
@@ -428,27 +408,6 @@ static inline unsigned long raw_copy_from_user(void *to,
 static inline unsigned long
 raw_copy_to_user_allowed(void __user *to, const void *from, unsigned long n)
 {
-	if (__builtin_constant_p(n) && (n <= 8)) {
-		unsigned long ret = 1;
-
-		switch (n) {
-		case 1:
-			__put_user_size_allowed(*(u8 *)from, (u8 __user *)to, 1, ret);
-			break;
-		case 2:
-			__put_user_size_allowed(*(u16 *)from, (u16 __user *)to, 2, ret);
-			break;
-		case 4:
-			__put_user_size_allowed(*(u32 *)from, (u32 __user *)to, 4, ret);
-			break;
-		case 8:
-			__put_user_size_allowed(*(u64 *)from, (u64 __user *)to, 8, ret);
-			break;
-		}
-		if (ret == 0)
-			return 0;
-	}
-
 	return __copy_tofrom_user(to, (__force const void __user *)from, n);
 }
 
-- 
2.25.0

[PATCH v2 2/3] powerpc/uaccess: Merge __put_user_size_allowed() into __put_user_size()

[Christophe Leroy]

__put_user_size_allowed() is only called from __put_user_size() now.

Merge them together.

Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
---
 arch/powerpc/include/asm/uaccess.h | 10 +++-------
 1 file changed, 3 insertions(+), 7 deletions(-)

diff --git a/arch/powerpc/include/asm/uaccess.h b/arch/powerpc/include/asm/uaccess.h
index a4d2569173ac..2fb1d95f10d3 100644
--- a/arch/powerpc/include/asm/uaccess.h
+++ b/arch/powerpc/include/asm/uaccess.h
@@ -108,22 +108,18 @@ static inline bool __access_ok(unsigned long addr, unsigned long size)
 
 extern long __put_user_bad(void);
 
-#define __put_user_size_allowed(x, ptr, size, retval)		\
+#define __put_user_size(x, ptr, size, retval)			\
 do {								\
 	__label__ __pu_failed;					\
 								\
 	retval = 0;						\
+	allow_write_to_user(ptr, size);				\
 	__put_user_size_goto(x, ptr, size, __pu_failed);	\
+	prevent_write_to_user(ptr, size);			\
 	break;							\
 								\
 __pu_failed:							\
 	retval = -EFAULT;					\
-} while (0)
-
-#define __put_user_size(x, ptr, size, retval)			\
-do {								\
-	allow_write_to_user(ptr, size);				\
-	__put_user_size_allowed(x, ptr, size, retval);		\
 	prevent_write_to_user(ptr, size);			\
 } while (0)
 
-- 
2.25.0

[PATCH v2 3/3] powerpc/uaccess: Merge raw_copy_to_user_allowed() into raw_copy_to_user()

[Christophe Leroy]

Since commit 17bc43367fc2 ("powerpc/uaccess: Implement
unsafe_copy_to_user() as a simple loop"), raw_copy_to_user_allowed()
is only used by raw_copy_to_user().

Merge raw_copy_to_user_allowed() into raw_copy_to_user().

Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
---
 arch/powerpc/include/asm/uaccess.h | 8 +-------
 1 file changed, 1 insertion(+), 7 deletions(-)

diff --git a/arch/powerpc/include/asm/uaccess.h b/arch/powerpc/include/asm/uaccess.h
index 2fb1d95f10d3..33b2de642120 100644
--- a/arch/powerpc/include/asm/uaccess.h
+++ b/arch/powerpc/include/asm/uaccess.h
@@ -401,19 +401,13 @@ static inline unsigned long raw_copy_from_user(void *to,
 	return ret;
 }
 
-static inline unsigned long
-raw_copy_to_user_allowed(void __user *to, const void *from, unsigned long n)
-{
-	return __copy_tofrom_user(to, (__force const void __user *)from, n);
-}
-
 static inline unsigned long
 raw_copy_to_user(void __user *to, const void *from, unsigned long n)
 {
 	unsigned long ret;
 
 	allow_write_to_user(to, n);
-	ret = raw_copy_to_user_allowed(to, from, n);
+	ret = __copy_tofrom_user(to, (__force const void __user *)from, n);
 	prevent_write_to_user(to, n);
 	return ret;
 }
-- 
2.25.0

Re: [PATCH v2 1/3] powerpc/uaccess: get rid of small constant size cases in raw_copy_{to,from}_user()

[Michael Ellerman]

On Tue, 9 Feb 2021 14:02:12 +0000 (UTC), Christophe Leroy wrote:
> Copied from commit 4b842e4e25b1 ("x86: get rid of small
> constant size cases in raw_copy_{to,from}_user()")
> 
> Very few call sites where that would be triggered remain, and none
> of those is anywhere near hot enough to bother.

Applied to powerpc/next.

[1/3] powerpc/uaccess: get rid of small constant size cases in raw_copy_{to,from}_user()
      https://git.kernel.org/powerpc/c/6b385d1d7c0a346758e35b128815afa25d4709ee
[2/3] powerpc/uaccess: Merge __put_user_size_allowed() into __put_user_size()
      https://git.kernel.org/powerpc/c/95d019e0f9225954e33b6efcad315be9d548a4d7
[3/3] powerpc/uaccess: Merge raw_copy_to_user_allowed() into raw_copy_to_user()
      https://git.kernel.org/powerpc/c/052f9d206f6c4b5b512b8c201d375f2dd194be35

cheers