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

[Joerg Roedel]

From: Joerg Roedel <jroe...@suse.de>

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.

Signed-off-by: Joerg Roedel <jroe...@suse.de>
---
 arch/x86/include/asm/pgtable.h | 7 +++++--
 arch/x86/mm/dump_pagetables.c  | 3 +--
 arch/x86/mm/pti.c              | 2 ++
 3 files changed, 8 insertions(+), 4 deletions(-)

diff --git a/arch/x86/include/asm/pgtable.h b/arch/x86/include/asm/pgtable.h
index e39088cb..a1cb333 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 ccd92c4..b8ab901 100644
--- a/arch/x86/mm/dump_pagetables.c
+++ b/arch/x86/mm/dump_pagetables.c
@@ -569,7 +569,7 @@ 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;
@@ -586,7 +586,6 @@ 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 69a9d60..026a89a 100644
--- a/arch/x86/mm/pti.c
+++ b/arch/x86/mm/pti.c
@@ -628,4 +628,6 @@ void pti_finalize(void)
         */
        pti_clone_entry_text();
        pti_clone_kernel_text();
+
+       debug_checkwx_user();
 }
-- 
2.7.4