[PATCH v2 4/6] arm64: mm: dump: make page table dumping reusable

Ard Biesheuvel
2016-04-22T16:48:06Z

From: Mark Rutland <mark.rutland@arm.com>

For debugging purposes, it would be nice if we could export page tables
other than the swapper_pg_dir to userspace. To enable this, this patch
refactors the arm64 page table dumping code such that multiple tables
may be registered with the framework, and exported under debugfs.

Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
---
arch/arm64/include/asm/ptdump.h | 44 ++++++++++++++++++++
arch/arm64/mm/dump.c | 32 ++++++++------
2 files changed, 64 insertions(+), 12 deletions(-)

diff --git a/arch/arm64/include/asm/ptdump.h b/arch/arm64/include/asm/ptdump.h
new file mode 100644
index 000000000000..fe82d693638a
--- /dev/null
+++ b/arch/arm64/include/asm/ptdump.h
@@ -0,0 +1,44 @@
+/*
+ * Copyright (C) 2014 ARM Ltd.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program. If not, see <http://www.gnu.org/licenses/>.
+ */
+#ifndef __ASM_PTDUMP_H
+#define __ASM_PTDUMP_H
+
+#ifdef CONFIG_ARM64_PTDUMP
+
+#include <linux/mm_types.h>
+
+struct addr_marker {
+ unsigned long start_address;
+ char name[32];
+};
+
+struct ptdump_info {
+ struct mm_struct *mm;
+ const struct addr_marker *markers;
+ unsigned long base_addr;
+ unsigned long max_addr;
+};
+
+int ptdump_register(struct ptdump_info *info, const char *name);
+
+#else
+static inline int ptdump_register(struct ptdump_info *info, const char *name)
+{
+ return 0;
+}
+#endif /* CONFIG_ARM64_PTDUMP */
+
+#endif /* __ASM_PTDUMP_H */
diff --git a/arch/arm64/mm/dump.c b/arch/arm64/mm/dump.c
index 024f803e2fb4..73d7227d1403 100644
--- a/arch/arm64/mm/dump.c
+++ b/arch/arm64/mm/dump.c
@@ -27,11 +27,7 @@
#include <asm/memory.h>
#include <asm/pgtable.h>
#include <asm/pgtable-hwdef.h>
-
-struct addr_marker {
- unsigned long start_address;
- char name[32];
-};
+#include <asm/ptdump.h>

static const struct addr_marker address_markers[] = {
#ifdef CONFIG_KASAN
@@ -284,7 +280,8 @@ static void walk_pud(struct pg_state *st, pgd_t *pgd, unsigned long start)
}
}

-static void walk_pgd(struct pg_state *st, struct mm_struct *mm, unsigned long start)
+static void walk_pgd(struct pg_state *st, struct mm_struct *mm,
+ unsigned long start)
{
pgd_t *pgd = pgd_offset(mm, 0UL);
unsigned i;
@@ -303,12 +300,13 @@ static void walk_pgd(struct pg_state *st, struct mm_struct *mm, unsigned long st

static int ptdump_show(struct seq_file *m, void *v)
{
+ struct ptdump_info *info = m->private;
struct pg_state st = {
.seq = m,
- .marker = address_markers,
+ .marker = info->markers,
};

- walk_pgd(&st, &init_mm, VA_START);
+ walk_pgd(&st, info->mm, info->base_addr);

note_page(&st, 0, 0, 0);
return 0;
@@ -316,7 +314,7 @@ static int ptdump_show(struct seq_file *m, void *v)

static int ptdump_open(struct inode *inode, struct file *file)
{
- return single_open(file, ptdump_show, NULL);
+ return single_open(file, ptdump_show, inode->i_private);
}

static const struct file_operations ptdump_fops = {
@@ -326,7 +324,7 @@ static const struct file_operations ptdump_fops = {
.release = single_release,
};

-static int ptdump_init(void)
+int ptdump_register(struct ptdump_info *info, const char *name)
{
struct dentry *pe;
unsigned i, j;
@@ -336,8 +334,18 @@ static int ptdump_init(void)
for (j = 0; j < pg_level[i].num; j++)
pg_level[i].mask |= pg_level[i].bits[j].mask;

- pe = debugfs_create_file("kernel_page_tables", 0400, NULL, NULL,
- &ptdump_fops);
+ pe = debugfs_create_file(name, 0400, NULL, info, &ptdump_fops);
return pe ? 0 : -ENOMEM;
}
+
+static struct ptdump_info kernel_ptdump_info = {
+ .mm = &init_mm,
+ .markers = address_markers,
+ .base_addr = VA_START,
+};
+
+static int ptdump_init(void)
+{
+ return ptdump_register(&kernel_ptdump_info, "kernel_page_tables");
+}
device_initcall(ptdump_init);
--
2.7.4