On Mon, 7 Feb 2005, Ingo Molnar wrote:
>
> boots fine and shrinks the image size quite noticeably:
>
> [Nr] Name Type Addr Off Size
> [ 1] .text PROGBITS c0100000 001000 2771a9 [vmlinux-orig]
> [ 1] .text PROGBITS c0100000 001000 2742dd [vmlinux-patched]
>
> that's 11980 bytes off a 2585001 bytes .text, a 0.5% size reduction.
> This patch we want ...
Goodie. Here's a slightly more recent version, where I cleaned up the
assembly code (no need to save %ecx if we just update %ebx instead, which
makes the code a bit more readable too - and doing it this way should
hopefully make it easier for an out-of-order CPU to start the memops
earlier too. Who knows..)
I'm not going to put this into 2.6.11, since I worry about compiler
interactions, but the more people who test it anyway, the better.
Linus
-----
# This is a BitKeeper generated diff -Nru style patch.
#
# ChangeSet
# 2005/02/07 08:14:28-08:00 [EMAIL PROTECTED]
# x86: make "put_user()" be out-of-line
#
# It's really too big to be inlined.
#
# Ingo tests and reports: this shrinks his kernel text size by
# about 12kB (roughly 0.5%)
#
# arch/i386/lib/putuser.S
# 2005/02/07 08:14:17-08:00 [EMAIL PROTECTED] +86 -0
#
# include/asm-i386/uaccess.h
# 2005/02/07 08:14:17-08:00 [EMAIL PROTECTED] +27 -3
# x86: make "put_user()" be out-of-line
#
# arch/i386/lib/putuser.S
# 2005/02/07 08:14:17-08:00 [EMAIL PROTECTED] +0 -0
# BitKeeper file /home/torvalds/v2.6/linux/arch/i386/lib/putuser.S
#
# arch/i386/lib/Makefile
# 2005/02/07 08:14:17-08:00 [EMAIL PROTECTED] +1 -1
# x86: make "put_user()" be out-of-line
#
# arch/i386/kernel/i386_ksyms.c
# 2005/02/07 08:14:17-08:00 [EMAIL PROTECTED] +5 -0
# x86: make "put_user()" be out-of-line
#
diff -Nru a/arch/i386/kernel/i386_ksyms.c b/arch/i386/kernel/i386_ksyms.c
--- a/arch/i386/kernel/i386_ksyms.c 2005-02-07 17:16:32 -08:00
+++ b/arch/i386/kernel/i386_ksyms.c 2005-02-07 17:16:32 -08:00
@@ -97,6 +97,11 @@
EXPORT_SYMBOL(__get_user_2);
EXPORT_SYMBOL(__get_user_4);
+EXPORT_SYMBOL(__put_user_1);
+EXPORT_SYMBOL(__put_user_2);
+EXPORT_SYMBOL(__put_user_4);
+EXPORT_SYMBOL(__put_user_8);
+
EXPORT_SYMBOL(strpbrk);
EXPORT_SYMBOL(strstr);
diff -Nru a/arch/i386/lib/Makefile b/arch/i386/lib/Makefile
--- a/arch/i386/lib/Makefile 2005-02-07 17:16:32 -08:00
+++ b/arch/i386/lib/Makefile 2005-02-07 17:16:32 -08:00
@@ -3,7 +3,7 @@
#
-lib-y = checksum.o delay.o usercopy.o getuser.o memcpy.o strstr.o \
+lib-y = checksum.o delay.o usercopy.o getuser.o putuser.o memcpy.o strstr.o \
bitops.o
lib-$(CONFIG_X86_USE_3DNOW) += mmx.o
diff -Nru a/arch/i386/lib/putuser.S b/arch/i386/lib/putuser.S
--- /dev/null Wed Dec 31 16:00:00 196900
+++ b/arch/i386/lib/putuser.S 2005-02-07 17:16:32 -08:00
@@ -0,0 +1,86 @@
+/*
+ * __put_user functions.
+ *
+ * (C) Copyright 2005 Linus Torvalds
+ *
+ * These functions have a non-standard call interface
+ * to make them more efficient, especially as they
+ * return an error value in addition to the "real"
+ * return value.
+ */
+#include <asm/thread_info.h>
+
+
+/*
+ * __put_user_X
+ *
+ * Inputs: %eax[:%edx] contains the data
+ * %ecx contains the address
+ *
+ * Outputs: %eax is error code (0 or -EFAULT)
+ *
+ * These functions should not modify any other registers,
+ * as they get called from within inline assembly.
+ */
+
+#define ENTER pushl %ebx ; GET_THREAD_INFO(%ebx)
+#define EXIT popl %ebx ; ret
+
+.text
+.align 4
+.globl __put_user_1
+__put_user_1:
+ ENTER
+ cmpl TI_addr_limit(%ebx),%ecx
+ jae bad_put_user
+1: movb %al,(%ecx)
+ xorl %eax,%eax
+ EXIT
+
+.align 4
+.globl __put_user_2
+__put_user_2:
+ ENTER
+ movl TI_addr_limit(%ebx),%ebx
+ subl $1,%ebx
+ cmpl %ebx,%ecx
+ jae bad_put_user
+2: movw %ax,(%ecx)
+ xorl %eax,%eax
+ EXIT
+
+.align 4
+.globl __put_user_4
+__put_user_4:
+ ENTER
+ movl TI_addr_limit(%ebx),%ebx
+ subl $3,%ebx
+ cmpl %ebx,%ecx
+ jae bad_put_user
+3: movl %eax,(%ecx)
+ xorl %eax,%eax
+ EXIT
+
+.align 4
+.globl __put_user_8
+__put_user_8:
+ ENTER
+ movl TI_addr_limit(%ebx),%ebx
+ subl $7,%ebx
+ cmpl %ebx,%ecx
+ jae bad_put_user
+3: movl %eax,(%ecx)
+4: movl %edx,4(%ecx)
+ xorl %eax,%eax
+ EXIT
+
+bad_put_user:
+ movl $-14,%eax
+ EXIT
+
+.section __ex_table,"a"
+ .long 1b,bad_put_user
+ .long 2b,bad_put_user
+ .long 3b,bad_put_user
+ .long 4b,bad_put_user
+.previous
diff -Nru a/include/asm-i386/uaccess.h b/include/asm-i386/uaccess.h
--- a/include/asm-i386/uaccess.h 2005-02-07 17:16:32 -08:00
+++ b/include/asm-i386/uaccess.h 2005-02-07 17:16:32 -08:00
@@ -185,6 +185,21 @@
extern void __put_user_bad(void);
+/*
+ * Strange magic calling convention: pointer in %ecx,
+ * value in %eax(:%edx), return value in %eax, no clobbers.
+ */
+extern void __put_user_1(void);
+extern void __put_user_2(void);
+extern void __put_user_4(void);
+extern void __put_user_8(void);
+
+#define __put_user_1(x, ptr) __asm__ __volatile__("call __put_user_1":"=a"
(__ret_pu):"0" ((typeof(*(ptr)))(x)), "c" (ptr))
+#define __put_user_2(x, ptr) __asm__ __volatile__("call __put_user_2":"=a"
(__ret_pu):"0" ((typeof(*(ptr)))(x)), "c" (ptr))
+#define __put_user_4(x, ptr) __asm__ __volatile__("call __put_user_4":"=a"
(__ret_pu):"0" ((typeof(*(ptr)))(x)), "c" (ptr))
+#define __put_user_8(x, ptr) __asm__ __volatile__("call __put_user_8":"=A"
(__ret_pu):"0" ((typeof(*(ptr)))(x)), "c" (ptr))
+#define __put_user_X(x, ptr) __asm__ __volatile__("call __put_user_X":"=a"
(__ret_pu):"c" (ptr))
+
/**
* put_user: - Write a simple value into user space.
* @x: Value to copy to user space.
@@ -201,9 +216,18 @@
*
* Returns zero on success, or -EFAULT on error.
*/
-#define put_user(x,ptr)
\
- __put_user_check((__typeof__(*(ptr)))(x),(ptr),sizeof(*(ptr)))
-
+#define put_user(x,ptr) \
+({ int __ret_pu; \
+ __chk_user_ptr(ptr); \
+ switch(sizeof(*(ptr))) { \
+ case 1: __put_user_1(x, ptr); break; \
+ case 2: __put_user_2(x, ptr); break; \
+ case 4: __put_user_4(x, ptr); break; \
+ case 8: __put_user_8(x, ptr); break; \
+ default:__put_user_X(x, ptr); break; \
+ } \
+ __ret_pu; \
+})
/**
* __get_user: - Get a simple variable from user space, with less checking.
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to [EMAIL PROTECTED]
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
