[PATCH v3 29/34] arm64: mm: Convert mm/dump.c to use walk_page_range()

[Steven Price]

Now walk_page_range() can walk kernel page tables, we can switch the
arm64 ptdump code over to using it, simplifying the code.

Signed-off-by: Steven Price <steven.price@xxxxxxx>
---
 arch/arm64/mm/dump.c | 108 +++++++++++++++++++++----------------------
 1 file changed, 53 insertions(+), 55 deletions(-)

diff --git a/arch/arm64/mm/dump.c b/arch/arm64/mm/dump.c
index 99bb8facb5cb..ee0bc1441dd0 100644
--- a/arch/arm64/mm/dump.c
+++ b/arch/arm64/mm/dump.c
@@ -286,73 +286,71 @@ static void note_page(struct pg_state *st, unsigned long addr, unsigned level,
 
 }
 
-static void walk_pte(struct pg_state *st, pmd_t *pmdp, unsigned long start,
-		     unsigned long end)
+static int pud_entry(pud_t *pud, unsigned long addr,
+		unsigned long next, struct mm_walk *walk)
 {
-	unsigned long addr = start;
-	pte_t *ptep = pte_offset_kernel(pmdp, start);
+	struct pg_state *st = walk->private;
+	pud_t val = READ_ONCE(*pud);
 
-	do {
-		note_page(st, addr, 4, READ_ONCE(pte_val(*ptep)));
-	} while (ptep++, addr += PAGE_SIZE, addr != end);
+	if (pud_table(val))
+		return 0;
+
+	note_page(st, addr, 2, pud_val(val));
+
+	return 0;
 }
 
-static void walk_pmd(struct pg_state *st, pud_t *pudp, unsigned long start,
-		     unsigned long end)
+static int pmd_entry(pmd_t *pmd, unsigned long addr,
+		unsigned long next, struct mm_walk *walk)
 {
-	unsigned long next, addr = start;
-	pmd_t *pmdp = pmd_offset(pudp, start);
-
-	do {
-		pmd_t pmd = READ_ONCE(*pmdp);
-		next = pmd_addr_end(addr, end);
-
-		if (pmd_none(pmd) || pmd_sect(pmd)) {
-			note_page(st, addr, 3, pmd_val(pmd));
-		} else {
-			BUG_ON(pmd_bad(pmd));
-			walk_pte(st, pmdp, addr, next);
-		}
-	} while (pmdp++, addr = next, addr != end);
+	struct pg_state *st = walk->private;
+	pmd_t val = READ_ONCE(*pmd);
+
+	if (pmd_table(val))
+		return 0;
+
+	note_page(st, addr, 3, pmd_val(val));
+
+	return 0;
 }
 
-static void walk_pud(struct pg_state *st, pgd_t *pgdp, unsigned long start,
-		     unsigned long end)
+static int pte_entry(pte_t *pte, unsigned long addr,
+		unsigned long next, struct mm_walk *walk)
 {
-	unsigned long next, addr = start;
-	pud_t *pudp = pud_offset(pgdp, start);
-
-	do {
-		pud_t pud = READ_ONCE(*pudp);
-		next = pud_addr_end(addr, end);
-
-		if (pud_none(pud) || pud_sect(pud)) {
-			note_page(st, addr, 2, pud_val(pud));
-		} else {
-			BUG_ON(pud_bad(pud));
-			walk_pmd(st, pudp, addr, next);
-		}
-	} while (pudp++, addr = next, addr != end);
+	struct pg_state *st = walk->private;
+	pte_t val = READ_ONCE(*pte);
+
+	note_page(st, addr, 4, pte_val(val));
+
+	return 0;
+}
+
+static int pte_hole(unsigned long addr, unsigned long next, int depth,
+		struct mm_walk *walk)
+{
+	struct pg_state *st = walk->private;
+
+	note_page(st, addr, depth+1, 0);
+
+	return 0;
 }
 
 static void walk_pgd(struct pg_state *st, struct mm_struct *mm,
-		     unsigned long start)
+		unsigned long start)
 {
-	unsigned long end = (start < TASK_SIZE_64) ? TASK_SIZE_64 : 0;
-	unsigned long next, addr = start;
-	pgd_t *pgdp = pgd_offset(mm, start);
-
-	do {
-		pgd_t pgd = READ_ONCE(*pgdp);
-		next = pgd_addr_end(addr, end);
-
-		if (pgd_none(pgd)) {
-			note_page(st, addr, 1, pgd_val(pgd));
-		} else {
-			BUG_ON(pgd_bad(pgd));
-			walk_pud(st, pgdp, addr, next);
-		}
-	} while (pgdp++, addr = next, addr != end);
+	struct mm_walk walk = {
+		.mm = mm,
+		.private = st,
+		.pud_entry = pud_entry,
+		.pmd_entry = pmd_entry,
+		.pte_entry = pte_entry,
+		.pte_hole = pte_hole
+	};
+	down_read(&mm->mmap_sem);
+	walk_page_range(start, start | (((unsigned long)PTRS_PER_PGD <<
+					 PGDIR_SHIFT) - 1),
+			&walk);
+	up_read(&mm->mmap_sem);
 }
 
 void ptdump_walk_pgd(struct seq_file *m, struct ptdump_info *info)
-- 
2.20.1