[PATCH v4 1/5] mm: add ARCH_SUPPORTS_NON_LEAF_PTDUMP

[Maxwell Bland <mbland@xxxxxxxxxxxx>]

Provide a Kconfig option indicating if note_page can be called for
intermediate page directories during ptdump.

Signed-off-by: Maxwell Bland <mbland@xxxxxxxxxxxx>
---
 mm/Kconfig.debug |  9 +++++++++
 mm/ptdump.c      | 21 +++++++++++++--------
 2 files changed, 22 insertions(+), 8 deletions(-)

diff --git a/mm/Kconfig.debug b/mm/Kconfig.debug
index afc72fde0f03..6af5ecfdef93 100644
--- a/mm/Kconfig.debug
+++ b/mm/Kconfig.debug
@@ -201,6 +201,15 @@ config PTDUMP_DEBUGFS
 
 	  If in doubt, say N.
 
+config ARCH_SUPPORTS_NON_LEAF_PTDUMP
+	bool "Include intermediate directory entries in pagetable dumps"
+	default n
+	help
+	  Enable the inclusion of intermediate page directory entries in calls
+	  to the ptdump API. Once an architecture defines correct ptdump
+	  behavior for PGD, PUD, P4D, and PMD entries, this config can be
+	  selected.
+
 config HAVE_DEBUG_KMEMLEAK
 	bool
 
diff --git a/mm/ptdump.c b/mm/ptdump.c
index 106e1d66e9f9..6180708669fe 100644
--- a/mm/ptdump.c
+++ b/mm/ptdump.c
@@ -41,10 +41,11 @@ static int ptdump_pgd_entry(pgd_t *pgd, unsigned long addr,
 	if (st->effective_prot)
 		st->effective_prot(st, 0, pgd_val(val));
 
-	if (pgd_leaf(val)) {
+	if (IS_ENABLED(CONFIG_ARCH_SUPPORTS_NON_LEAF_PTDUMP) || pgd_leaf(val))
 		st->note_page(st, addr, 0, pgd_val(val));
+
+	if (pgd_leaf(val))
 		walk->action = ACTION_CONTINUE;
-	}
 
 	return 0;
 }
@@ -64,10 +65,11 @@ static int ptdump_p4d_entry(p4d_t *p4d, unsigned long addr,
 	if (st->effective_prot)
 		st->effective_prot(st, 1, p4d_val(val));
 
-	if (p4d_leaf(val)) {
+	if (IS_ENABLED(CONFIG_ARCH_SUPPORTS_NON_LEAF_PTDUMP) || pgd_leaf(val))
 		st->note_page(st, addr, 1, p4d_val(val));
+
+	if (p4d_leaf(val))
 		walk->action = ACTION_CONTINUE;
-	}
 
 	return 0;
 }
@@ -87,10 +89,11 @@ static int ptdump_pud_entry(pud_t *pud, unsigned long addr,
 	if (st->effective_prot)
 		st->effective_prot(st, 2, pud_val(val));
 
-	if (pud_leaf(val)) {
+	if (IS_ENABLED(CONFIG_ARCH_SUPPORTS_NON_LEAF_PTDUMP) || pgd_leaf(val))
 		st->note_page(st, addr, 2, pud_val(val));
+
+	if (pud_leaf(val))
 		walk->action = ACTION_CONTINUE;
-	}
 
 	return 0;
 }
@@ -108,10 +111,12 @@ static int ptdump_pmd_entry(pmd_t *pmd, unsigned long addr,
 
 	if (st->effective_prot)
 		st->effective_prot(st, 3, pmd_val(val));
-	if (pmd_leaf(val)) {
+
+	if (IS_ENABLED(CONFIG_ARCH_SUPPORTS_NON_LEAF_PTDUMP) || pgd_leaf(val))
 		st->note_page(st, addr, 3, pmd_val(val));
+
+	if (pmd_leaf(val))
 		walk->action = ACTION_CONTINUE;
-	}
 
 	return 0;
 }
-- 
2.39.2