On Tue, 8 Feb 2005, Linus Torvalds wrote:
>
> Hmm.. I always thought "A" was the _pairing_ of %eax/%edx, not "eax or
> edx"?
Ahh. Some testing shows that gcc really seems to think of it as "eax or
edx", ie you can do
asm("uglee %0 %1": :"a" (1), "A" (2));
and it will output
movl $1, %eax
movl $2, %edx
uglee %eax %edx
without complaining.
Live and learn.
That brings up another issue: if I don't care which registers a 64-bit
value goes into, can I get the "low reg" and "high reg" names some way? In
this case I'm constrained, and do want eactly %eax:%edx, but in some other
cases I might not care, and wouldn't mind having a
asm("addl %2,%L0 ; adcl $0,%H0"
:"=r" (ll_result)
:"r" (increment), "0" (ll_input));
to add a 32-bit number to a 64-bit one (this is totally made up, since gcc
can probably generate this sequence itself, but you get the idea -
allowing the asm to treat the low/high parts of the 64-bit entity
separately, without forcing them into one specific pair).
v4 with your asm constrain fix appended.
Linus
-----
# This is a BitKeeper generated diff -Nru style patch.
#
# ChangeSet
# 2005/02/08 18:18:46-08:00 [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%).
#
# Updated on input from Richard Henderson on how the "A" constraint
# works on x86.
#
# arch/i386/lib/putuser.S
# 2005/02/08 18:18:35-08:00 [EMAIL PROTECTED] +87 -0
#
# include/asm-i386/uaccess.h
# 2005/02/08 18:18:35-08:00 [EMAIL PROTECTED] +27 -13
# x86: make "put_user()" be out-of-line
#
# arch/i386/lib/putuser.S
# 2005/02/08 18:18:35-08:00 [EMAIL PROTECTED] +0 -0
# BitKeeper file /home/torvalds/v2.6/linux/arch/i386/lib/putuser.S
#
# arch/i386/lib/Makefile
# 2005/02/08 18:18:34-08:00 [EMAIL PROTECTED] +1 -1
# x86: make "put_user()" be out-of-line
#
# arch/i386/kernel/i386_ksyms.c
# 2005/02/08 18:18:34-08:00 [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 2005-02-08 18:25:22 -08:00
+++ b/arch/i386/kernel/i386_ksyms.c 2005-02-08 18:25:22 -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 2005-02-08 18:25:22 -08:00
+++ b/arch/i386/lib/Makefile 2005-02-08 18:25:22 -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 2005-02-08 18:25:22 -08:00
@@ -0,0 +1,87 @@
+/*
+ * __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
+4: movl %eax,(%ecx)
+5: 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
+ .long 5b,bad_put_user
+.previous
diff -Nru a/include/asm-i386/uaccess.h b/include/asm-i386/uaccess.h
--- a/include/asm-i386/uaccess.h 2005-02-08 18:25:22 -08:00
+++ b/include/asm-i386/uaccess.h 2005-02-08 18:25:22 -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):"A" ((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.
@@ -258,16 +282,6 @@
__pu_err; \
})
-
-#define __put_user_check(x,ptr,size) \
-({ \
- long __pu_err = -EFAULT; \
- __typeof__(*(ptr)) __user *__pu_addr = (ptr); \
- might_sleep(); \
- if (access_ok(VERIFY_WRITE,__pu_addr,size)) \
- __put_user_size((x),__pu_addr,(size),__pu_err,-EFAULT); \
- __pu_err; \
-})
#define __put_user_u64(x, addr, err) \
__asm__ __volatile__( \
-
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