[PATCH v3 0/5] all: s390: make compat wrappers the generic solution

From: Yury Norov
Date: Fri Feb 26 2016 - 09:35:37 EST

The problem that makes us use wrappers is that some compat
architectures allows user code to access top halves of registers.
This is not a problem for syscalls that are already handled by compat
code, or for that who has types of the same size in kernel and
userspace. In case of s390 and lp64/ilp32 the problem is in pointer
types, long, unsigned long.

S390 folks already have the solution for it. In this patchset,
it is turned to be general, as arm64/ilp32 needs it too.

This patchset is created as the part of the work of enabling arm64
with ILP32 user mode. See details here:

Acked-by: Heiko Carstens <heiko.carstens@xxxxxxxxxx>

This is the implementation of one of two possible approaches. First
one defines new syscall handler declaration macro, that creates both compat and
non-compat handlers, see [1]. This one declares all wrappers in separated file

- move 2 s390-related wrappers from kernel/compat_wrappers.h
to arch/s390/kernel/compat_linux.c
- comments extended
Build-tested on s390.

[1] http://www.spinics.net/lists/linux-s390/msg11593.html

Yury Norov (5):
all: syscall wrappers: add documentation
all: introduce COMPAT_WRAPPER option and enable it for s390
all: s390: move wrapper infrastructure to generic headers
all: s390: move compat_wrappers.c from arch/s390/kernel to kernel/
all: wrap needed syscalls in generic unistd

Documentation/adding-syscalls.txt | 32 +++++
arch/Kconfig | 4 +
arch/s390/Kconfig | 1 +
arch/s390/include/asm/compat.h | 17 ++-
arch/s390/kernel/Makefile | 2 +-
arch/s390/kernel/compat_wrapper.c | 180 ------------------------
include/linux/compat.h | 278 ++++++++++++++++++++++++++++++++++++++
include/linux/syscalls.h | 57 +-------
include/linux/syscalls_structs.h | 60 ++++++++
include/uapi/asm-generic/unistd.h | 231 +++++++++++++++----------------
kernel/Makefile | 1 +
kernel/compat_wrapper.c | 170 +++++++++++++++++++++++
12 files changed, 680 insertions(+), 353 deletions(-)
delete mode 100644 arch/s390/kernel/compat_wrapper.c
create mode 100644 include/linux/syscalls_structs.h
create mode 100644 kernel/compat_wrapper.c