[PATCH v4 17/19] x86: mm: Convert ptdump_walk_pgd_level_debugfs() to take an mm_struct

[Steven Price <steven.price@xxxxxxx>]

To enable x86 to use the generic walk_page_range() function, the
callers of ptdump_walk_pgd_level_debugfs() need to pass in the mm_struct.

This means that ptdump_walk_pgd_level_core() is now always passed a
valid pgd, so drop the support for pgd==NULL.

Signed-off-by: Steven Price <steven.price@xxxxxxx>
---
 arch/x86/include/asm/pgtable.h |  3 ++-
 arch/x86/mm/debug_pagetables.c |  8 ++++----
 arch/x86/mm/dump_pagetables.c  | 14 ++++++--------
 3 files changed, 12 insertions(+), 13 deletions(-)

diff --git a/arch/x86/include/asm/pgtable.h b/arch/x86/include/asm/pgtable.h
index 579959750f34..5abf693dc9b2 100644
--- a/arch/x86/include/asm/pgtable.h
+++ b/arch/x86/include/asm/pgtable.h
@@ -28,7 +28,8 @@ extern pgd_t early_top_pgt[PTRS_PER_PGD];
 int __init __early_make_pgtable(unsigned long address, pmdval_t pmd);
 
 void ptdump_walk_pgd_level(struct seq_file *m, struct mm_struct *mm);
-void ptdump_walk_pgd_level_debugfs(struct seq_file *m, pgd_t *pgd, bool user);
+void ptdump_walk_pgd_level_debugfs(struct seq_file *m, struct mm_struct *mm,
+				   bool user);
 void ptdump_walk_pgd_level_checkwx(void);
 void ptdump_walk_user_pgd_level_checkwx(void);
 
diff --git a/arch/x86/mm/debug_pagetables.c b/arch/x86/mm/debug_pagetables.c
index cd84f067e41d..824131052574 100644
--- a/arch/x86/mm/debug_pagetables.c
+++ b/arch/x86/mm/debug_pagetables.c
@@ -6,7 +6,7 @@
 
 static int ptdump_show(struct seq_file *m, void *v)
 {
-	ptdump_walk_pgd_level_debugfs(m, NULL, false);
+	ptdump_walk_pgd_level_debugfs(m, &init_mm, false);
 	return 0;
 }
 
@@ -16,7 +16,7 @@ static int ptdump_curknl_show(struct seq_file *m, void *v)
 {
 	if (current->mm->pgd) {
 		down_read(&current->mm->mmap_sem);
-		ptdump_walk_pgd_level_debugfs(m, current->mm->pgd, false);
+		ptdump_walk_pgd_level_debugfs(m, current->mm, false);
 		up_read(&current->mm->mmap_sem);
 	}
 	return 0;
@@ -31,7 +31,7 @@ static int ptdump_curusr_show(struct seq_file *m, void *v)
 {
 	if (current->mm->pgd) {
 		down_read(&current->mm->mmap_sem);
-		ptdump_walk_pgd_level_debugfs(m, current->mm->pgd, true);
+		ptdump_walk_pgd_level_debugfs(m, current->mm, true);
 		up_read(&current->mm->mmap_sem);
 	}
 	return 0;
@@ -46,7 +46,7 @@ static struct dentry *pe_efi;
 static int ptdump_efi_show(struct seq_file *m, void *v)
 {
 	if (efi_mm.pgd)
-		ptdump_walk_pgd_level_debugfs(m, efi_mm.pgd, false);
+		ptdump_walk_pgd_level_debugfs(m, &efi_mm, false);
 	return 0;
 }
 
diff --git a/arch/x86/mm/dump_pagetables.c b/arch/x86/mm/dump_pagetables.c
index f3663c5e8c6a..1c1b37c32787 100644
--- a/arch/x86/mm/dump_pagetables.c
+++ b/arch/x86/mm/dump_pagetables.c
@@ -527,16 +527,12 @@ static inline bool is_hypervisor_range(int idx)
 static void ptdump_walk_pgd_level_core(struct seq_file *m, pgd_t *pgd,
 				       bool checkwx, bool dmesg)
 {
-	pgd_t *start = INIT_PGD;
+	pgd_t *start = pgd;
 	pgprotval_t prot, eff;
 	int i;
 	struct pg_state st = {};
 
-	if (pgd) {
-		start = pgd;
-		st.to_dmesg = dmesg;
-	}
-
+	st.to_dmesg = dmesg;
 	st.check_wx = checkwx;
 	st.seq = m;
 	if (checkwx)
@@ -581,8 +577,10 @@ void ptdump_walk_pgd_level(struct seq_file *m, struct mm_struct *mm)
 	ptdump_walk_pgd_level_core(m, mm->pgd, false, true);
 }
 
-void ptdump_walk_pgd_level_debugfs(struct seq_file *m, pgd_t *pgd, bool user)
+void ptdump_walk_pgd_level_debugfs(struct seq_file *m, struct mm_struct *mm,
+				   bool user)
 {
+	pgd_t *pgd = mm->pgd;
 #ifdef CONFIG_PAGE_TABLE_ISOLATION
 	if (user && static_cpu_has(X86_FEATURE_PTI))
 		pgd = kernel_to_user_pgdp(pgd);
@@ -608,7 +606,7 @@ 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_pgd_level_core(NULL, INIT_PGD, true, false);
 }
 
 static int __init pt_dump_init(void)
-- 
2.20.1