x86/mm: Make __VIRTUAL_MASK_SHIFT dynamic
For boot-time switching between paging modes, we need to be able to
adjust virtual mask shifts.
The change doesn't affect the kernel image size much:
text data bss dec hex filename
8628892 4734340 1368064 14731296 e0c820 vmlinux.before
8628966 4734340 1368064 14731370 e0c86a vmlinux.after
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@suse.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-mm@kvack.org
Link: http://lkml.kernel.org/r/20180214111656.88514-9-kirill.shutemov@linux.intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
diff --git a/arch/x86/mm/kaslr.c b/arch/x86/mm/kaslr.c
index 515b98a..d079878 100644
--- a/arch/x86/mm/kaslr.c
+++ b/arch/x86/mm/kaslr.c
@@ -52,7 +52,7 @@ static __initdata struct kaslr_memory_region {
unsigned long *base;
unsigned long size_tb;
} kaslr_regions[] = {
- { &page_offset_base, 1 << (__PHYSICAL_MASK_SHIFT - TB_SHIFT) /* Maximum */ },
+ { &page_offset_base, 0 },
{ &vmalloc_base, VMALLOC_SIZE_TB },
{ &vmemmap_base, 1 },
};
@@ -93,6 +93,8 @@ void __init kernel_randomize_memory(void)
if (!kaslr_memory_enabled())
return;
+ kaslr_regions[0].size_tb = 1 << (__PHYSICAL_MASK_SHIFT - TB_SHIFT);
+
/*
* Update Physical memory mapping to available and
* add padding if needed (especially for memory hotplug support).