Messages in this thread Patch in this message | | | Date | Mon, 18 Dec 2017 15:07:23 +0100 | From | Borislav Petkov <> | Subject | Re: [patch V163 01/51] x86/mm/dump_pagetables: Check PAGE_PRESENT for real |
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On Mon, Dec 18, 2017 at 12:42:16PM +0100, Thomas Gleixner wrote: > From: Thomas Gleixner <tglx@linutronix.de> > > 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> > --- > arch/x86/mm/dump_pagetables.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > --- 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 > static const char * const level_name[] = > { "cr3", "pgd", "p4d", "pud", "pmd", "pte" }; > > - if (!pgprot_val(prot)) { > + if (!(pgprot_val(prot) & _PAGE_PRESENT)) {
Just a minor thing: there's a local pr variable a couple of lines up which is pgprot_val(prot). So you could do additionally:
diff --git a/arch/x86/mm/dump_pagetables.c b/arch/x86/mm/dump_pagetables.c index dd8820e5da28..1014cfb21c2c 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) & _PAGE_PRESENT)) { + if (!(pr & _PAGE_PRESENT)) { /* Not present */ pt_dump_cont_printf(m, dmsg, " "); } else { -- Regardless,
Reviewed-by: Borislav Petkov <bp@suse.de>
-- Regards/Gruss, Boris.
SUSE Linux GmbH, GF: Felix Imendörffer, Jane Smithard, Graham Norton, HRB 21284 (AG Nürnberg) --
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