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-rw-r--r--mm/ptdump.c165
1 files changed, 165 insertions, 0 deletions
diff --git a/mm/ptdump.c b/mm/ptdump.c
new file mode 100644
index 000000000..8adab455a
--- /dev/null
+++ b/mm/ptdump.c
@@ -0,0 +1,165 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#include <linux/pagewalk.h>
+#include <linux/ptdump.h>
+#include <linux/kasan.h>
+
+#if defined(CONFIG_KASAN_GENERIC) || defined(CONFIG_KASAN_SW_TAGS)
+/*
+ * 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, 4, 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_GENERIC) || defined(CONFIG_KASAN_SW_TAGS))
+ if (pgd_page(val) == virt_to_page(lm_alias(kasan_early_shadow_p4d)))
+ return note_kasan_page_table(walk, addr);
+#endif
+
+ if (st->effective_prot)
+ st->effective_prot(st, 0, pgd_val(val));
+
+ if (pgd_leaf(val)) {
+ st->note_page(st, addr, 0, pgd_val(val));
+ walk->action = ACTION_CONTINUE;
+ }
+
+ 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_GENERIC) || defined(CONFIG_KASAN_SW_TAGS))
+ if (p4d_page(val) == virt_to_page(lm_alias(kasan_early_shadow_pud)))
+ return note_kasan_page_table(walk, addr);
+#endif
+
+ if (st->effective_prot)
+ st->effective_prot(st, 1, p4d_val(val));
+
+ if (p4d_leaf(val)) {
+ st->note_page(st, addr, 1, p4d_val(val));
+ walk->action = ACTION_CONTINUE;
+ }
+
+ 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_GENERIC) || defined(CONFIG_KASAN_SW_TAGS))
+ if (pud_page(val) == virt_to_page(lm_alias(kasan_early_shadow_pmd)))
+ return note_kasan_page_table(walk, addr);
+#endif
+
+ if (st->effective_prot)
+ st->effective_prot(st, 2, pud_val(val));
+
+ if (pud_leaf(val)) {
+ st->note_page(st, addr, 2, pud_val(val));
+ walk->action = ACTION_CONTINUE;
+ }
+
+ 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_GENERIC) || defined(CONFIG_KASAN_SW_TAGS)
+ if (pmd_page(val) == virt_to_page(lm_alias(kasan_early_shadow_pte)))
+ return note_kasan_page_table(walk, addr);
+#endif
+
+ if (st->effective_prot)
+ st->effective_prot(st, 3, pmd_val(val));
+ if (pmd_leaf(val)) {
+ st->note_page(st, addr, 3, pmd_val(val));
+ walk->action = ACTION_CONTINUE;
+ }
+
+ 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;
+ pte_t val = ptep_get(pte);
+
+ if (st->effective_prot)
+ st->effective_prot(st, 4, pte_val(val));
+
+ st->note_page(st, addr, 4, pte_val(val));
+
+ 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, 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, pgd_t *pgd)
+{
+ const struct ptdump_range *range = st->range;
+
+ mmap_write_lock(mm);
+ while (range->start != range->end) {
+ walk_page_range_novma(mm, range->start, range->end,
+ &ptdump_ops, pgd, st);
+ range++;
+ }
+ mmap_write_unlock(mm);
+
+ /* Flush out the last page */
+ st->note_page(st, 0, -1, 0);
+}