linux-kernel - [PATCH 1/3] powerpc: get rid of small constant size cases in raw_copy_{to,from}

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Date:   Mon, 11 Jan 2021 12:45:58 +0000 (UTC)
From:   Christophe Leroy <christophe.leroy@...roup.eu>
To:     Benjamin Herrenschmidt <benh@...nel.crashing.org>,
        Paul Mackerras <paulus@...ba.org>,
        Michael Ellerman <mpe@...erman.id.au>, cmr@...efail.de
Cc:     linux-kernel@...r.kernel.org, linuxppc-dev@...ts.ozlabs.org
Subject: [PATCH 1/3] powerpc: get rid of small constant size cases in
 raw_copy_{to,from}_user()

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@...roup.eu>
---
 arch/powerpc/include/asm/uaccess.h | 45 ------------------------------
 1 file changed, 45 deletions(-)

diff --git a/arch/powerpc/include/asm/uaccess.h b/arch/powerpc/include/asm/uaccess.h
index 501c9a79038c..6e97616e03e8 100644
--- a/arch/powerpc/include/asm/uaccess.h
+++ b/arch/powerpc/include/asm/uaccess.h
@@ -407,30 +407,6 @@ 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:
-			barrier_nospec();
-			__get_user_size(*(u8 *)to, from, 1, ret);
-			break;
-		case 2:
-			barrier_nospec();
-			__get_user_size(*(u16 *)to, from, 2, ret);
-			break;
-		case 4:
-			barrier_nospec();
-			__get_user_size(*(u32 *)to, from, 4, ret);
-			break;
-		case 8:
-			barrier_nospec();
-			__get_user_size(*(u64 *)to, from, 8, ret);
-			break;
-		}
-		if (ret == 0)
-			return 0;
-	}
 
 	barrier_nospec();
 	allow_read_from_user(from, n);
@@ -442,27 +418,6 @@ 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