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Commit f4e342c8 authored by Boris Ostrovsky's avatar Boris Ostrovsky Committed by Thomas Gleixner
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x86/mm: Skip the hypervisor range when walking PGD 



The range between 0xffff800000000000 and 0xffff87ffffffffff is reserved
for hypervisor and therefore we should not try to follow PGD's indexes
corresponding to those addresses.

While this has always been a problem, with the new W+X warning
mechanism ptdump_walk_pgd_level_core() can now be called during boot,
causing a PV Xen guest to crash.

[ tglx: Replaced the macro with a readable inline ]

Fixes: e1a58320 "x86/mm: Warn on W^X mappings"
Reported-by: default avatarSander Eikelenboom <linux@eikelenboom.it>
Signed-off-by: default avatarBoris Ostrovsky <boris.ostrovsky@oracle.com>
Cc: xen-devel@lists.xen.org
Link: http://lkml.kernel.org/r/1446749795-27764-1-git-send-email-boris.ostrovsky@oracle.com


Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
parent 3849e91f

arch/x86/mm/dump_pagetables.c

+16 −1
Original line number Diff line number Diff line
@@ -358,6 +358,21 @@ static void walk_pud_level(struct seq_file *m, struct pg_state *st, pgd_t addr, 
#define pgd_none(a)  pud_none(__pud(pgd_val(a)))

#endif



#ifdef CONFIG_X86_64

static inline bool is_hypervisor_range(int idx)

{

	/*

	 * ffff800000000000 - ffff87ffffffffff is reserved for

	 * the hypervisor.

	 */

	return paravirt_enabled() &&

		(idx >= pgd_index(__PAGE_OFFSET) - 16) &&

		(idx < pgd_index(__PAGE_OFFSET));

}

#else

static inline bool is_hypervisor_range(int idx) { return false; }

#endif



static void ptdump_walk_pgd_level_core(struct seq_file *m, pgd_t *pgd,

				       bool checkwx)

{
@@ -381,7 +396,7 @@ static void ptdump_walk_pgd_level_core(struct seq_file *m, pgd_t *pgd, 


	for (i = 0; i < PTRS_PER_PGD; i++) {

		st.current_address = normalize_addr(i * PGD_LEVEL_MULT);

		if (!pgd_none(*start)) {

		if (!pgd_none(*start) && !is_hypervisor_range(i)) {

			if (pgd_large(*start) || !pgd_present(*start)) {

				prot = pgd_flags(*start);

				note_page(m, &st, __pgprot(prot), 1);