From: Thomas Gleixner <tglx@linutronix.de>
To: LKML <linux-kernel@vger.kernel.org>
Cc: x86@kernel.org, Peter Zijlstra <peterz@infradead.org>,
Dave Hansen <dave.hansen@linux.intel.com>,
keescook@google.com
Subject: [PATCH] x86/mm/dump_pagetables: Check PAGE_PRESENT for real
Date: Sat, 16 Dec 2017 01:59:17 +0100 (CET) [thread overview]
Message-ID: <alpine.DEB.2.20.1712160155420.2099@nanos> (raw)
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)) {
/* Not present */
pt_dump_cont_printf(m, dmsg, " ");
} else {
reply other threads:[~2017-12-16 0:59 UTC|newest]
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