linux-kernel - [RFC] breakage in 4223cc34365e4 (h8300: uaccess.h update)

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Date:	Sun, 2 Mar 2008 23:23:14 +0000
From:	Al Viro <viro@...IV.linux.org.uk>
To:	Yoshinori Sato <ysato@...rs.sourceforge.jp>
Cc:	linux-kernel@...r.kernel.org,
	Linus Torvalds <torvalds@...ux-foundation.org>
Subject: [RFC] breakage in 4223cc34365e4 (h8300: uaccess.h update)

	After that commit in asm-h8300/uaccess.h we have 

#define get_user(x, ptr)                                        \
({                                                              \
    int __gu_err = 0;                                           \
    uint32_t __gu_val = 0;                              \
    ^^^^^^^^^^^^^^^^^
    switch (sizeof(*(ptr))) {                                   \
    case 1:                                                     \
    case 2:                                                     \
    case 4:                                                     \
        __gu_val = *(ptr);                                      \
        break;                                                  \
    case 8:                                                     \
        memcpy(&__gu_val, ptr, sizeof (*(ptr)));                \
                               ^^^^^^^^^^^^^^^^

which, of course, is FUBAR whenever we actually hit that case - memcpy of
8 bytes into uint32_t is obviously wrong.  Why don't we simply do

#define get_user(x, ptr)                                        \
({                                                              \
    int __gu_err = 0;                                           \
    typeof(*(ptr)) __gu_val = *ptr;                             \
    switch (sizeof(*(ptr))) {                                   \
    case 1:                                                     \
    case 2:                                                     \
    case 4:                                                     \
    case 8:                                                     \
        break;                                                  \
    default:                                                    \
        __gu_err = __get_user_bad();                            \
        break;                                                  \
    }                                                           \
    (x) = __gu_val;                                             \
    __gu_err;                                                   \
})

and be done with that, anyway?
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