Re: out-of-line x86 "put_user()" implementation

[Chuck Ebbert]

On Tue, 8 Feb 2005 at 18:27:08 -0800, Linus Torvalds wrote:

> +/*
> + * 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))
> +

  Should "cc" be on the clobber list since all the called functions alter EFLAGS?

  And in any case is it too much to ask for an 80-column limit? ;)

#define __put_user_1(x, ptr)                    \
__asm__ __volatile__(                           \
        "call __put_user_1"                     \
        : "=a" (__ret_pu)                       \
        : "0" ((typeof(*(ptr)))(x)), "c" (ptr)  \
        : "cc")
#define __put_user_2(x, ptr)                    \
__asm__ __volatile__(                           \
        "call __put_user_2"                     \
        : "=a" (__ret_pu)                       \
        : "0" ((typeof(*(ptr)))(x)), "c" (ptr)  \
        : "cc")
#define __put_user_4(x, ptr)                    \
__asm__ __volatile__(                           \
        "call __put_user_4"                     \
        : "=a" (__ret_pu)                       \
        : "0" ((typeof(*(ptr)))(x)), "c" (ptr)  \
        : "cc")
#define __put_user_8(x, ptr)                    \
__asm__ __volatile__(                           \
        "call __put_user_8"                     \
        : "=a" (__ret_pu)                       \
        : "A" ((typeof(*(ptr)))(x)), "c" (ptr)  \
        : "cc")
#define __put_user_X(x, ptr)                    \
__asm__ __volatile__(                           \
        "call __put_user_X"                     \
        : "=a" (__ret_pu)                       \
        : "c" (ptr)                             \
        : "cc")

--
Chuck
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