We, Linux/M32R project members, decided to change the kernel API/ABI.  This
modification is not small, but if we don't change it now, perhaps we have
no chance to change them hereafter.

* Why change the m32r kernel API/ABI?
- The m32r port has many old-style syscall interfaces,
  because we made m32r port refering to the other traditional archs.
  Some old syscalls are no longer used or can be safely removed
  by upgrading the GNU C library.
- To make the m32r kernel more secure, it is preferable to prevent
  stack region from being executed. (e.g. stack overflow)

* API/ABI changes
- include/asm-m32r/unistd.h: Upgrade to the new kernel API.
- arch/m32r/entry.S: Minimum update to the new ABI.
- Don't use UID16 syscalls.
- To make stack noexecutable:
  1) Don't use trampoline for signal handlers for kernel space (cf. sparc64):
    sys_signal: remove.
    sys_sigaction, sys_rt_sigaction: use glibc's restorer.
  2) Don't generate trampoline code by GCC in userspace:
    Support non-executable stack by the m32r gcc.
    --> done (for gcc-3.4.3/gcc-4.0)

* New userland
- This modification does *not* keep backward compatibility.
  So we have been prepared new userland, based on the new API/ABI.
  Already, more than 200 new Debian deb binary packages are available
  on the Linux/M32R site:
  http://debian.linux-m32r.org/dists/04_ordovician/ (for this new ABI)
Signed-off-by: NIIBE Yutaka <gniibe@fsij.org>
Signed-off-by: Hirokazu Takata <takata@linux-m32r.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>