Commit c4bc3980 authored Dec 16, 2017 by Thomas Gleixner Committed by Greg Kroah-Hartman Dec 29, 2017

x86/mm/dump_pagetables: Check PAGE_PRESENT for real



commit c05344947b37f7cda726e802457370bc6eac4d26 upstream.

The check for a present page in printk_prot():

       if (!pgprot_val(prot)) {
                /* Not present */

is bogus. If a PTE is set to PAGE_NONE then the pgprot_val is not zero and
the entry is decoded in bogus ways, e.g. as RX GLB. That is confusing when
analyzing mapping correctness. Check for the present bit to make an
informed decision.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Juergen Gross <jgross@suse.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

parent 662fd946

arch/x86/mm/dump_pagetables.c

+1 −1

Original line number	Diff line number	Diff line
		@@ -140,7 +140,7 @@ static void printk_prot(struct seq_file *m, pgprot_t prot, int level, bool dmsg)
		static const char * const level_name[] =
		{ "cr3", "pgd", "p4d", "pud", "pmd", "pte" };

		if (!pgprot_val(prot)) {
		if (!(pr & _PAGE_PRESENT)) {
		/* Not present */
		pt_dump_cont_printf(m, dmsg, " ");
		} else {