powerpc,mmap: properly account for stack randomization in mmap_base

When RLIMIT_STACK is, for example, 256MB, the current code results in a
gap between the top of the task and mmap_base of 256MB, failing to take
into account the amount by which the stack address was randomized.  In
other words, the stack gets less than RLIMIT_STACK space.

Ensure that the gap between the stack and mmap_base always takes stack
randomization and the stack guard gap into account.

Inspired by Daniel Micay's linux-hardened tree.

Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Rik van Riel <[email protected]>
Reported-by: Florian Weimer <[email protected]>
Cc: Ingo Molnar <[email protected]>
Cc: Will Deacon <[email protected]>
Cc: Daniel Micay <[email protected]>
Cc: Benjamin Herrenschmidt <[email protected]>
Cc: Hugh Dickins <[email protected]>
Cc: Catalin Marinas <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

0 files changed, 0 insertions, 0 deletions