aa0d6e70d3
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.de Signed-off-by: Arnd Bergmann <arnd@arndb.de> Reviewed-by: Heiko Carstens <heiko.carstens@de.ibm.com> [heiko.carstens@de.ibm.com: compile fix for !CONFIG_COMPAT] Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com> Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.