From c05344947b37f7cda726e802457370bc6eac4d26 Mon Sep 17 00:00:00 2001 From: Thomas Gleixner Date: Sat, 16 Dec 2017 01:14:39 +0100 Subject: [PATCH] x86/mm/dump_pagetables: Check PAGE_PRESENT for real 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 Cc: Andy Lutomirski Cc: Borislav Petkov Cc: Dave Hansen Cc: H. Peter Anvin Cc: Josh Poimboeuf Cc: Juergen Gross Cc: Linus Torvalds Cc: Peter Zijlstra Cc: linux-kernel@vger.kernel.org Signed-off-by: Ingo Molnar --- arch/x86/mm/dump_pagetables.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/arch/x86/mm/dump_pagetables.c b/arch/x86/mm/dump_pagetables.c index 5e3ac6fe6c9e3..1014cfb21c2c7 100644 --- a/arch/x86/mm/dump_pagetables.c +++ b/arch/x86/mm/dump_pagetables.c @@ -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 { -- 2.39.5