mm: add generic ptdump

[linux-block.git] / mm / ptdump.c

diff --git a/mm/ptdump.c b/mm/ptdump.c
new file mode 100644 (file)
index 0000000..868638b
--- /dev/null
+++ b/mm/ptdump.c
@@ -0,0 +1,139 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#include <linux/pagewalk.h>
+#include <linux/ptdump.h>
+#include <linux/kasan.h>
+
+#ifdef CONFIG_KASAN
+/*
+ * This is an optimization for KASAN=y case. Since all kasan page tables
+ * eventually point to the kasan_early_shadow_page we could call note_page()
+ * right away without walking through lower level page tables. This saves
+ * us dozens of seconds (minutes for 5-level config) while checking for
+ * W+X mapping or reading kernel_page_tables debugfs file.
+ */
+static inline int note_kasan_page_table(struct mm_walk *walk,
+                                       unsigned long addr)
+{
+       struct ptdump_state *st = walk->private;
+
+       st->note_page(st, addr, 5, pte_val(kasan_early_shadow_pte[0]));
+
+       walk->action = ACTION_CONTINUE;
+
+       return 0;
+}
+#endif
+
+static int ptdump_pgd_entry(pgd_t *pgd, unsigned long addr,
+                           unsigned long next, struct mm_walk *walk)
+{
+       struct ptdump_state *st = walk->private;
+       pgd_t val = READ_ONCE(*pgd);
+
+#if CONFIG_PGTABLE_LEVELS > 4 && defined(CONFIG_KASAN)
+       if (pgd_page(val) == virt_to_page(lm_alias(kasan_early_shadow_p4d)))
+               return note_kasan_page_table(walk, addr);
+#endif
+
+       if (pgd_leaf(val))
+               st->note_page(st, addr, 1, pgd_val(val));
+
+       return 0;
+}
+
+static int ptdump_p4d_entry(p4d_t *p4d, unsigned long addr,
+                           unsigned long next, struct mm_walk *walk)
+{
+       struct ptdump_state *st = walk->private;
+       p4d_t val = READ_ONCE(*p4d);
+
+#if CONFIG_PGTABLE_LEVELS > 3 && defined(CONFIG_KASAN)
+       if (p4d_page(val) == virt_to_page(lm_alias(kasan_early_shadow_pud)))
+               return note_kasan_page_table(walk, addr);
+#endif
+
+       if (p4d_leaf(val))
+               st->note_page(st, addr, 2, p4d_val(val));
+
+       return 0;
+}
+
+static int ptdump_pud_entry(pud_t *pud, unsigned long addr,
+                           unsigned long next, struct mm_walk *walk)
+{
+       struct ptdump_state *st = walk->private;
+       pud_t val = READ_ONCE(*pud);
+
+#if CONFIG_PGTABLE_LEVELS > 2 && defined(CONFIG_KASAN)
+       if (pud_page(val) == virt_to_page(lm_alias(kasan_early_shadow_pmd)))
+               return note_kasan_page_table(walk, addr);
+#endif
+
+       if (pud_leaf(val))
+               st->note_page(st, addr, 3, pud_val(val));
+
+       return 0;
+}
+
+static int ptdump_pmd_entry(pmd_t *pmd, unsigned long addr,
+                           unsigned long next, struct mm_walk *walk)
+{
+       struct ptdump_state *st = walk->private;
+       pmd_t val = READ_ONCE(*pmd);
+
+#if defined(CONFIG_KASAN)
+       if (pmd_page(val) == virt_to_page(lm_alias(kasan_early_shadow_pte)))
+               return note_kasan_page_table(walk, addr);
+#endif
+
+       if (pmd_leaf(val))
+               st->note_page(st, addr, 4, pmd_val(val));
+
+       return 0;
+}
+
+static int ptdump_pte_entry(pte_t *pte, unsigned long addr,
+                           unsigned long next, struct mm_walk *walk)
+{
+       struct ptdump_state *st = walk->private;
+
+       st->note_page(st, addr, 5, pte_val(READ_ONCE(*pte)));
+
+       return 0;
+}
+
+static int ptdump_hole(unsigned long addr, unsigned long next,
+                      int depth, struct mm_walk *walk)
+{
+       struct ptdump_state *st = walk->private;
+
+       st->note_page(st, addr, depth + 1, 0);
+
+       return 0;
+}
+
+static const struct mm_walk_ops ptdump_ops = {
+       .pgd_entry      = ptdump_pgd_entry,
+       .p4d_entry      = ptdump_p4d_entry,
+       .pud_entry      = ptdump_pud_entry,
+       .pmd_entry      = ptdump_pmd_entry,
+       .pte_entry      = ptdump_pte_entry,
+       .pte_hole       = ptdump_hole,
+};
+
+void ptdump_walk_pgd(struct ptdump_state *st, struct mm_struct *mm)
+{
+       const struct ptdump_range *range = st->range;
+
+       down_read(&mm->mmap_sem);
+       while (range->start != range->end) {
+               walk_page_range_novma(mm, range->start, range->end,
+                                     &ptdump_ops, st);
+               range++;
+       }
+       up_read(&mm->mmap_sem);
+
+       /* Flush out the last page */
+       st->note_page(st, 0, 0, 0);
+}