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Commit 5a654ba7 authored by Jeremy Fitzhardinge's avatar Jeremy Fitzhardinge Committed by Ingo Molnar
Browse files

x86/cpa: use an undefined PTE bit for testing CPA 



Rather than using _PAGE_GLOBAL - which not all CPUs support - to test
CPA, use one of the reserved-for-software-use PTE flags instead.  This
allows CPA testing to work on CPUs which don't support PGD.

Signed-off-by: default avatarJeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Cc: Stephen Tweedie <sct@redhat.com>
Cc: Eduardo Habkost <ehabkost@redhat.com>
Cc: Mark McLoughlin <markmc@redhat.com>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
parent ef5e94af

arch/x86/mm/pageattr-test.c

+13 −8
Original line number Diff line number Diff line 
/*

 * self test for change_page_attr.

 *

 * Clears the global bit on random pages in the direct mapping, then reverts

 * and compares page tables forwards and afterwards.

 * Clears the a test pte bit on random pages in the direct mapping,

 * then reverts and compares page tables forwards and afterwards.

 */

#include <linux/bootmem.h>

#include <linux/kthread.h>
@@ -32,6 +32,13 @@ enum { 
	GPS			= (1<<30)

};



#define PAGE_TESTBIT	__pgprot(_PAGE_UNUSED1)



static int pte_testbit(pte_t pte)

{

	return pte_flags(pte) & _PAGE_UNUSED1;

}



struct split_state {

	long lpg, gpg, spg, exec;

	long min_exec, max_exec;
@@ -165,15 +172,14 @@ static int pageattr_test(void) 
			continue;

		}



		err = change_page_attr_clear(addr[i], len[i],

					       __pgprot(_PAGE_GLOBAL));

		err = change_page_attr_set(addr[i], len[i], PAGE_TESTBIT);

		if (err < 0) {

			printk(KERN_ERR "CPA %d failed %d\n", i, err);

			failed++;

		}



		pte = lookup_address(addr[i], &level);

		if (!pte || pte_global(*pte) || pte_huge(*pte)) {

		if (!pte || !pte_testbit(*pte) || pte_huge(*pte)) {

			printk(KERN_ERR "CPA %lx: bad pte %Lx\n", addr[i],

				pte ? (u64)pte_val(*pte) : 0ULL);

			failed++;
@@ -198,14 +204,13 @@ static int pageattr_test(void) 
			failed++;

			continue;

		}

		err = change_page_attr_set(addr[i], len[i],

					     __pgprot(_PAGE_GLOBAL));

		err = change_page_attr_clear(addr[i], len[i], PAGE_TESTBIT);

		if (err < 0) {

			printk(KERN_ERR "CPA reverting failed: %d\n", err);

			failed++;

		}

		pte = lookup_address(addr[i], &level);

		if (!pte || !pte_global(*pte)) {

		if (!pte || pte_testbit(*pte)) {

			printk(KERN_ERR "CPA %lx: bad pte after revert %Lx\n",

				addr[i], pte ? (u64)pte_val(*pte) : 0ULL);

			failed++;