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Commit 51fc41a9 authored by Max Filippov's avatar Max Filippov Committed by Chris Zankel
Browse files

xtensa: fix fast_store_prohibited _PAGE_WRITABLE_BIT test 



Before _PAGE_WRITABLE_BIT test fast_store_prohibited must make sure that
PTE is present. Otherwise 'writable' bit is undefined and may be reused
in the 'file offset' or 'swap type' PTE fields.

Signed-off-by: default avatarMax Filippov <jcmvbkbc@gmail.com>
Signed-off-by: default avatarChris Zankel <chris@zankel.net>
parent 7711ece9

arch/xtensa/kernel/entry.S

+6 −1
Original line number Diff line number Diff line
@@ -1792,10 +1792,15 @@ ENTRY(fast_store_prohibited) 
	l32i	a0, a0, 0

	beqz	a0, 2f



	/* Note that we assume _PAGE_WRITABLE_BIT is only set if pte is valid.*/

	/*

	 * Note that we test _PAGE_WRITABLE_BIT only if PTE is present

	 * and is not PAGE_NONE. See pgtable.h for possible PTE layouts.

	 */



	_PTE_OFFSET(a0, a1, a4)

	l32i	a4, a0, 0		# read pteval

	movi	a1, _PAGE_CA_INVALID

	ball	a4, a1, 2f

	bbci.l	a4, _PAGE_WRITABLE_BIT, 2f



	movi	a1, _PAGE_ACCESSED | _PAGE_DIRTY | _PAGE_HW_WRITE