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x86/mm: Make __VIRTUAL_MASK_SHIFT dynamic

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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>
This commit is contained in:
Kirill A. Shutemov
2018-02-14 14:16:55 +03:00
committed by Ingo Molnar
parent 162434e7f5
commit 09e61a779e
4 changed files with 26 additions and 4 deletions
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12
arch/x86/entry/entry_64.S
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@@ -274,8 +274,20 @@ GLOBAL(entry_SYSCALL_64_after_hwframe)
* Change top bits to match most significant bit (47th or 56th bit
* depending on paging mode) in the address.
*/
#ifdef CONFIG_X86_5LEVEL
testl $1, pgtable_l5_enabled(%rip)
jz 1f
shl $(64 - 57), %rcx
sar $(64 - 57), %rcx
jmp 2f
1:
shl $(64 - 48), %rcx
sar $(64 - 48), %rcx
2:
#else
shl $(64 - (__VIRTUAL_MASK_SHIFT+1)), %rcx
sar $(64 - (__VIRTUAL_MASK_SHIFT+1)), %rcx
#endif
/* If this changed %rcx, it was not canonical */
cmpq %rcx, %r11