From: Eric Dumazet <eric.dumazet@gmail.com>
To: Thomas Gleixner <tglx@linutronix.de>,
Linus Torvalds <torvalds@linux-foundation.org>
Cc: linux-kernel <linux-kernel@vger.kernel.org>,
Eric Dumazet <edumazet@google.com>,
Eric Dumazet <eric.dumazet@gmail.com>
Subject: [PATCH] x86/uaccess: small optimization in unsafe_copy_to_user()
Date: Fri, 16 Apr 2021 12:24:13 -0700 [thread overview]
Message-ID: <20210416192413.1514419-1-eric.dumazet@gmail.com> (raw)
From: Eric Dumazet <edumazet@google.com>
We have to loop only to copy u64 values.
After this first loop, we copy at most one u32, one u16 and one byte.
Signed-off-by: Eric Dumazet <edumazet@google.com>
---
arch/x86/include/asm/uaccess.h | 14 +++++++++++---
1 file changed, 11 insertions(+), 3 deletions(-)
diff --git a/arch/x86/include/asm/uaccess.h b/arch/x86/include/asm/uaccess.h
index c9fa7be3df82ddb9495961b3e2f22b1ac07edafa..ddb19bb8c86786d78407dcfb59623943ccbce8a8 100644
--- a/arch/x86/include/asm/uaccess.h
+++ b/arch/x86/include/asm/uaccess.h
@@ -517,15 +517,23 @@ do { \
len -= sizeof(type); \
}
+#define unsafe_copy_elem(dst, src, len, type, label) \
+ if (len >= sizeof(type)) { \
+ unsafe_put_user(*(type *)(src),(type __user *)(dst),label); \
+ dst += sizeof(type); \
+ src += sizeof(type); \
+ len -= sizeof(type); \
+ }
+
#define unsafe_copy_to_user(_dst,_src,_len,label) \
do { \
char __user *__ucu_dst = (_dst); \
const char *__ucu_src = (_src); \
size_t __ucu_len = (_len); \
unsafe_copy_loop(__ucu_dst, __ucu_src, __ucu_len, u64, label); \
- unsafe_copy_loop(__ucu_dst, __ucu_src, __ucu_len, u32, label); \
- unsafe_copy_loop(__ucu_dst, __ucu_src, __ucu_len, u16, label); \
- unsafe_copy_loop(__ucu_dst, __ucu_src, __ucu_len, u8, label); \
+ unsafe_copy_elem(__ucu_dst, __ucu_src, __ucu_len, u32, label); \
+ unsafe_copy_elem(__ucu_dst, __ucu_src, __ucu_len, u16, label); \
+ unsafe_copy_elem(__ucu_dst, __ucu_src, __ucu_len, u8, label); \
} while (0)
#define HAVE_GET_KERNEL_NOFAULT
--
2.31.1.368.gbe11c130af-goog
next reply other threads:[~2021-04-16 19:24 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-04-16 19:24 Eric Dumazet [this message]
2021-04-16 19:44 ` [PATCH] x86/uaccess: small optimization in unsafe_copy_to_user() Al Viro
2021-04-16 20:11 ` Eric Dumazet
2021-04-16 20:57 ` Eric Dumazet
2021-04-17 13:59 ` David Laight
2021-04-17 16:03 ` Linus Torvalds
2021-04-17 16:08 ` Linus Torvalds
2021-04-17 16:27 ` Linus Torvalds
2021-04-17 18:09 ` Al Viro
2021-04-17 20:30 ` Al Viro
2021-04-17 20:35 ` Al Viro
2021-04-17 22:11 ` Linus Torvalds
2021-04-18 0:50 ` Al Viro
2021-04-17 19:44 ` Eric Dumazet
2021-04-17 19:51 ` Linus Torvalds
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