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x86/mm: Fix ELF_ET_DYN_BASE for 5-level paging

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On machines with 5-level paging we don't want to allocate mapping above
47-bit unless user explicitly asked for it. See b569bab78d ("x86/mm:
Prepare to expose larger address space to userspace") for details.

c715b72c1b ("mm: revert x86_64 and arm64 ELF_ET_DYN_BASE base
changes") broke the behaviour. After the commit elf binary and heap got
mapped above 47-bits.

Use DEFAULT_MAP_WINDOW instead of TASK_SIZE to determine ELF_ET_DYN_BASE so
it's forced to be below 47-bits unconditionally.

Fixes: c715b72c1b ("mm: revert x86_64 and arm64 ELF_ET_DYN_BASE base changes")
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: linux-mm@kvack.org
Cc: Andrew Morton <akpm@linux-foundation.org>
Link: https://lkml.kernel.org/r/20171107103804.47341-1-kirill.shutemov@linux.intel.com
This commit is contained in:
Kirill A. Shutemov 2017-11-07 13:38:04 +03:00 committed by Thomas Gleixner
parent d0cd64b02a
commit be739f4b5d
1 changed files with 1 additions and 1 deletions
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arch/x86/include/asm/elf.h
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@ -253,7 +253,7 @@ extern int force_personality32;
* space open for things that want to use the area for 32-bit pointers.
*/
#define ELF_ET_DYN_BASE (mmap_is_ia32() ? 0x000400000UL : \
(TASK_SIZE / 3 * 2))
(DEFAULT_MAP_WINDOW / 3 * 2))
/* This yields a mask that user programs can use to figure out what
instruction set this CPU supports. This could be done in user space,