x86/mm/pti: Move user W+X check into pti_finalize()

The user page-table gets the updated kernel mappings in pti_finalize(),
which runs after the RO+X permissions got applied to the kernel page-table
in mark_readonly().

But with CONFIG_DEBUG_WX enabled, the user page-table is already checked in
mark_readonly() for insecure mappings.  This causes false-positive
warnings, because the user page-table did not get the updated mappings yet.

Move the W+X check for the user page-table into pti_finalize() after it
updated all required mappings.

[ tglx: Folded !NX supported fix ]

Signed-off-by: Joerg Roedel <[email protected]>
Signed-off-by: Thomas Gleixner <[email protected]>
Cc: "H . Peter Anvin" <[email protected]>
Cc: [email protected]
Cc: Linus Torvalds <[email protected]>
Cc: Andy Lutomirski <[email protected]>
Cc: Dave Hansen <[email protected]>
Cc: Josh Poimboeuf <[email protected]>
Cc: Juergen Gross <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Borislav Petkov <[email protected]>
Cc: Jiri Kosina <[email protected]>
Cc: Boris Ostrovsky <[email protected]>
Cc: Brian Gerst <[email protected]>
Cc: David Laight <[email protected]>
Cc: Denys Vlasenko <[email protected]>
Cc: Eduardo Valentin <[email protected]>
Cc: Greg KH <[email protected]>
Cc: Will Deacon <[email protected]>
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: Andrea Arcangeli <[email protected]>
Cc: Waiman Long <[email protected]>
Cc: Pavel Machek <[email protected]>
Cc: "David H . Gutteridge" <[email protected]>
Cc: [email protected]
Link: https://lkml.kernel.org/r/[email protected]

3 files changed, 10 insertions, 5 deletions

diff --git a/arch/x86/include/asm/pgtable.h b/arch/x86/include/asm/pgtable.h
index e39088cb59ab..a1cb3339da8d 100644
--- a/arch/x86/include/asm/pgtable.h
+++ b/arch/x86/include/asm/pgtable.h
@@ -30,11 +30,14 @@ int __init __early_make_pgtable(unsigned long address, pmdval_t pmd);
 void ptdump_walk_pgd_level(struct seq_file *m, pgd_t *pgd);
 void ptdump_walk_pgd_level_debugfs(struct seq_file *m, pgd_t *pgd, bool user);
 void ptdump_walk_pgd_level_checkwx(void);
+void ptdump_walk_user_pgd_level_checkwx(void);
 
 #ifdef CONFIG_DEBUG_WX
-#define debug_checkwx() ptdump_walk_pgd_level_checkwx()
+#define debug_checkwx()		ptdump_walk_pgd_level_checkwx()
+#define debug_checkwx_user()	ptdump_walk_user_pgd_level_checkwx()
 #else
-#define debug_checkwx() do { } while (0)
+#define debug_checkwx()		do { } while (0)
+#define debug_checkwx_user()	do { } while (0)
 #endif
 
 /*
diff --git a/arch/x86/mm/dump_pagetables.c b/arch/x86/mm/dump_pagetables.c
index ccd92c4da57c..a12afff146d1 100644
--- a/arch/x86/mm/dump_pagetables.c
+++ b/arch/x86/mm/dump_pagetables.c
@@ -569,12 +569,13 @@ void ptdump_walk_pgd_level_debugfs(struct seq_file *m, pgd_t *pgd, bool user)
 }
 EXPORT_SYMBOL_GPL(ptdump_walk_pgd_level_debugfs);
 
-static void ptdump_walk_user_pgd_level_checkwx(void)
+void ptdump_walk_user_pgd_level_checkwx(void)
 {
 #ifdef CONFIG_PAGE_TABLE_ISOLATION
 	pgd_t *pgd = INIT_PGD;
 
-	if (!static_cpu_has(X86_FEATURE_PTI))
+	if (!(__supported_pte_mask & _PAGE_NX) ||
+	    !static_cpu_has(X86_FEATURE_PTI))
 		return;
 
 	pr_info("x86/mm: Checking user space page tables\n");
@@ -586,7 +587,6 @@ static void ptdump_walk_user_pgd_level_checkwx(void)
 void ptdump_walk_pgd_level_checkwx(void)
 {
 	ptdump_walk_pgd_level_core(NULL, NULL, true, false);
-	ptdump_walk_user_pgd_level_checkwx();
 }
 
 static int __init pt_dump_init(void)
diff --git a/arch/x86/mm/pti.c b/arch/x86/mm/pti.c
index 1dc5c683e7a5..d58b4aba9510 100644
--- a/arch/x86/mm/pti.c
+++ b/arch/x86/mm/pti.c
@@ -646,4 +646,6 @@ void pti_finalize(void)
 	 */
 	pti_clone_entry_text();
 	pti_clone_kernel_text();
+
+	debug_checkwx_user();
 }