• Arnd Bergmann's avatar
    s390: autogenerate compat syscall wrappers · aa0d6e70
    Arnd Bergmann authored
    Any system call that takes a pointer argument on s390 requires
    a wrapper function to do a 31-to-64 zero-extension, these are
    currently generated in arch/s390/kernel/compat_wrapper.c.
    
    On arm64 and x86, we already generate similar wrappers for all
    system calls in the place of their definition, just for a different
    purpose (they load the arguments from pt_regs).
    
    We can do the same thing here, by adding an asm/syscall_wrapper.h
    file with a copy of all the relevant macros to override the generic
    version. Besides the addition of the compat entry point, these also
    rename the entry points with a __s390_ or __s390x_ prefix, similar
    to what we do on arm64 and x86. This in turn requires renaming
    a few things, and adding a proper ni_syscall() entry point.
    
    In order to still compile system call definitions that pass an
    loff_t argument, the __SC_COMPAT_CAST() macro checks for that
    and forces an -ENOSYS error, which was the best I could come up
    with. Those functions must obviously not get called from user
    space, but instead require hand-written compat_sys_*() handlers,
    which fortunately already exist.
    
    Link: https://lore.kernel.org/lkml/20190116131527.2071570-5-arnd@arndb.deSigned-off-by: default avatarArnd Bergmann <arnd@arndb.de>
    Reviewed-by: default avatarHeiko Carstens <heiko.carstens@de.ibm.com>
    [heiko.carstens@de.ibm.com: compile fix for !CONFIG_COMPAT]
    Signed-off-by: default avatarHeiko Carstens <heiko.carstens@de.ibm.com>
    Signed-off-by: default avatarMartin Schwidefsky <schwidefsky@de.ibm.com>
    aa0d6e70
entry.S 40.5 KB