x86/mm: Fix ELF_ET_DYN_BASE for 5-level paging
On machines with 5-level paging we don't want to allocate mapping above
47-bit unless user explicitly asked for it. See b569bab78d8d ("x86/mm:
Prepare to expose larger address space to userspace") for details.
c715b72c1ba4 ("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: c715b72c1ba4 ("mm: revert x86_64 and arm64 ELF_ET_DYN_BASE base changes")
Signed-off-by: Kirill A. Shutemov <email@example.com>
Signed-off-by: Thomas Gleixner <firstname.lastname@example.org>
Acked-by: Michal Hocko <email@example.com>
Cc: Kees Cook <firstname.lastname@example.org>
Cc: Nicholas Piggin <email@example.com>
Cc: Andrew Morton <firstname.lastname@example.org>
diff --git a/arch/x86/include/asm/elf.h b/arch/x86/include/asm/elf.h
index c1a125e4..3a091ce 100644
@@ -253,7 +253,7 @@
* 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,