• Andrew Morton's avatar
    [PATCH] s390: add support for 6 system call arguments (FUTEX_CMP_REQUEUE) · f1b2f7ff
    Andrew Morton authored
    From: Martin Schwidefsky <schwidefsky@de.ibm.com>
    
    This patch adds support for 6 system call arguments on s390.  The first
    exploiter of this will be the sys_futex system call for the
    FUTEX_CMP_REQUEUE operation.  The idea is simple: use register %r7 for the
    6th argument.  This can be extended to 7/8/9/...  arguments if there ever
    will be the need for it.  To call the system call function in the kernel
    the additional arguments needs to get stored on the stack.  8 bytes are
    added to the head of struct pt_regs.  %r7 is stored to the additional field
    for all system calls.  The store is hidden in a
    address-generation-interlock slot, it doesn't slow down the system call
    path.
    Signed-off-by: default avatarMartin Schwidefsky <schwidefsky@de.ibm.com>
    Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
    Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
    f1b2f7ff
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