[Xen-ia64-devel] Need cmpxchg_user for ia64

["Magenheimer, Dan (HP Labs Fort Collins)" <dan.magenheimer@xxxxxx>]

Anybody want to write a fancy macro?  I need a cmpxchg_user() macro
that corresponds to the following x86 code used in grant_table.c
and defined in include/asm-x86/system.h, but (of course) works
for ia64.  It must also conform to the ia64 __ex_table convention.

Please include a Signed-off-by as this will be new code for Xen.

Thanks!
Dan

/*
 * This function causes value _o to be changed to _n at location _p.
 * If this access causes a fault then we return 1, otherwise we return
0.
 * If no fault occurs then _o is updated to the value we saw at _p. If
this
 * is the same as the initial value of _o then _n is written to location
_p.
 */
#define __cmpxchg_user(_p,_o,_n,_isuff,_oppre,_regtype)
\
    __asm__ __volatile__ (
\
        "1: " LOCK_PREFIX "cmpxchg"_isuff" %"_oppre"2,%3\n"
\
        "2:\n"
\
        ".section .fixup,\"ax\"\n"
\
        "3:     movl $1,%1\n"
\
        "       jmp 2b\n"
\
        ".previous\n"
\
        ".section __ex_table,\"a\"\n"
\
        "       .align 4\n"
\
        "       .long 1b,3b\n"
\
        ".previous"
\
        : "=a" (_o), "=r" (_rc)
\
        : _regtype (_n), "m" (*__xg((volatile void *)_p)), "0" (_o), "1"
(0) \
        : "memory");
#define cmpxchg_user(_p,_o,_n)
\
({
\
    int _rc;
\
    switch ( sizeof(*(_p)) ) {
\
    case 1:
\
        __cmpxchg_user(_p,_o,_n,"b","b","q");
\
        break;
\
    case 2:
\
        __cmpxchg_user(_p,_o,_n,"w","w","r");
\
        break;
\
    case 4:
\
        __cmpxchg_user(_p,_o,_n,"l","","r");
\
        break;
\
    case 8:
\
        __asm__ __volatile__ (
\
            "1: " LOCK_PREFIX "cmpxchg8b %4\n"
\
            "2:\n"
\
            ".section .fixup,\"ax\"\n"
\
            "3:     movl $1,%1\n"
\
            "       jmp 2b\n"
\
            ".previous\n"
\
            ".section __ex_table,\"a\"\n"
\
            "       .align 4\n"
\
            "       .long 1b,3b\n"
\
            ".previous"
\
            : "=A" (_o), "=r" (_rc)
\
            : "c" ((u32)((u64)(_n)>>32)), "b" ((u32)(_n)),
\
              "m" (*__xg((volatile void *)(_p))), "0" (_o), "1" (0)
\
            : "memory");
\
        break;
\
    }
\
    _rc;
\
})

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