On architectures where the stack grows upwards (CONFIG_STACK_GROWSUP=y,
currently parisc and metag only) stack randomization sometimes leads to crashes
when the stack ulimit is set to lower values than STACK_RND_MASK (which is 8 MB
by default if not defined in arch-specific headers).

The problem is, that when the stack vm_area_struct is set up in fs/exec.c, the
additional space needed for the stack randomization (as defined by the value of
STACK_RND_MASK) was not taken into account yet and as such, when the stack
randomization code added a random offset to the stack start, the stack
effectively got smaller than what the user defined via rlimit_max(RLIMIT_STACK)
which then sometimes leads to out-of-stack situations and crashes.

This patch fixes it by adding the maximum possible amount of memory (based on
STACK_RND_MASK) which theoretically could be added by the stack randomization
code to the initial stack size. That way, the user-defined stack size is always
guaranteed to be at minimum what is defined via rlimit_max(RLIMIT_STACK).

This bug is currently not visible on the metag architecture, because on metag
STACK_RND_MASK is defined to 0 which effectively disables stack randomization.

The changes to fs/exec.c are inside an "#ifdef CONFIG_STACK_GROWSUP"
section, so it does not affect other platformws beside those where the
stack grows upwards (parisc and metag).

Signed-off-by: Helge Deller <deller@gmx.de>
Cc: linux-parisc@vger.kernel.org
Cc: James Hogan <james.hogan@imgtec.com>
Cc: linux-metag@vger.kernel.org
Cc: stable@vger.kernel.org # v3.16+

Add support for the flexible mmap memory layout (as described in
http://lwn.net/Articles/91829). This is especially very interesting on
parisc since we currently only support 32bit userspace (even with a
64bit Linux kernel).

Signed-off-by: Helge Deller <deller@gmx.de>

Process personality is stored together with other flags like UNAME26 in
an integer variable.  Overwriting this value with PER_LINUX drops all
other existing flags and as such broke tools like the uname26 tool.

Actually this was only broken on 32bit kernels, since for 32bit-ELF
binaries on 64-bit kernels the SET_PERSONALITY macro from
arch/parisc/kernel/binfmt_elf32.c is used which does not modifies the
personality value at all (which is wrong as long as we don't run HPUX
binaries or similiar).

Signed-off-by: Helge Deller <deller@gmx.de>

Currently all architectures but microblaze unconditionally define
USE_ELF_CORE_DUMP.  The microblaze omission seems like an error to me, so
let's kill this ifdef and make sure we are the same everywhere.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Acked-by: Hugh Dickins <hugh.dickins@tiscali.co.uk>
Cc: <linux-arch@vger.kernel.org>
Cc: Michal Simek <michal.simek@petalogix.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

elf.h probably won't be exported to userspace, but play it safe
and cram it in a #ifdef __KERNEL__ guard.

Signed-off-by: Kyle McMartin <kyle@mcmartin.ca>

* git://git.kernel.org/pub/scm/linux/kernel/git/kyle/parisc-2.6:
  parisc: convert to generic compat_sys_ptrace
  parisc: add rtc platform driver
  parisc: initialize unwinder much earlier
  parisc: add new syscalls
  parisc: hijack jump to start_kernel
  parisc: add pdc_coproc_cfg_unlocked and set_firmware_width_unlocked
  parisc: move include/asm-parisc to arch/parisc/include/asm
  parisc: move pdc_result to real2.S
  parisc: unify CCIO_COLLECT_STATS implementation
  parisc: add arch/parisc/kernel/.gitignore
  parisc: ropes.h - fix <asm-parisc/*> -> <asm/*>
  parisc: parisc-agp - fix <asm-parisc/*> -> <asm/*>

Resolve remove/rename conflict: include/asm-parisc/a.out.h is no longer
relevant.