[kernel-hardening][PATCH 1/3] arm: mm: dump: make page table dumping reusable
jinb.park
jinb.park7 at gmail.com
Fri Dec 1 02:39:41 PST 2017
This patch refactors the arm page table dumping code,
so multiple tables may be registered with the framework.
This patch refers below commits of arm64.
(4674fdb9f149 ("arm64: mm: dump: make page table dumping reusable"))
(4ddb9bf83349 ("arm64: dump: Make ptdump debugfs a separate option"))
Signed-off-by: Jinbum Park <jinb.park7 at gmail.com>
---
arch/arm/Kconfig.debug | 6 +++-
arch/arm/include/asm/ptdump.h | 48 ++++++++++++++++++++++++++++++++
arch/arm/mm/Makefile | 3 +-
arch/arm/mm/dump.c | 65 +++++++++++++++++++------------------------
arch/arm/mm/ptdump_debugfs.c | 34 ++++++++++++++++++++++
5 files changed, 117 insertions(+), 39 deletions(-)
create mode 100644 arch/arm/include/asm/ptdump.h
create mode 100644 arch/arm/mm/ptdump_debugfs.c
diff --git a/arch/arm/Kconfig.debug b/arch/arm/Kconfig.debug
index 17685e1..e7b94db 100644
--- a/arch/arm/Kconfig.debug
+++ b/arch/arm/Kconfig.debug
@@ -3,10 +3,14 @@ menu "Kernel hacking"
source "lib/Kconfig.debug"
-config ARM_PTDUMP
+config ARM_PTDUMP_CORE
+ def_bool n
+
+config ARM_PTDUMP_DEBUGFS
bool "Export kernel pagetable layout to userspace via debugfs"
depends on DEBUG_KERNEL
depends on MMU
+ select ARM_PTDUMP_CORE
select DEBUG_FS
---help---
Say Y here if you want to show the kernel pagetable layout in a
diff --git a/arch/arm/include/asm/ptdump.h b/arch/arm/include/asm/ptdump.h
new file mode 100644
index 0000000..3a6c0b7
--- /dev/null
+++ b/arch/arm/include/asm/ptdump.h
@@ -0,0 +1,48 @@
+/*
+ * 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_ARM_PTDUMP_CORE
+
+#include <linux/mm_types.h>
+#include <linux/seq_file.h>
+
+struct addr_marker {
+ unsigned long start_address;
+ char *name;
+};
+
+struct ptdump_info {
+ struct mm_struct *mm;
+ const struct addr_marker *markers;
+ unsigned long base_addr;
+};
+
+void ptdump_walk_pgd(struct seq_file *s, struct ptdump_info *info);
+#ifdef CONFIG_ARM_PTDUMP_DEBUGFS
+int ptdump_debugfs_register(struct ptdump_info *info, const char *name);
+#else
+static inline int ptdump_debugfs_register(struct ptdump_info *info,
+ const char *name)
+{
+ return 0;
+}
+#endif /* CONFIG_ARM_PTDUMP_DEBUGFS */
+
+#endif /* CONFIG_ARM_PTDUMP_CORE */
+
+#endif /* __ASM_PTDUMP_H */
diff --git a/arch/arm/mm/Makefile b/arch/arm/mm/Makefile
index 01bcc33..28be5f4 100644
--- a/arch/arm/mm/Makefile
+++ b/arch/arm/mm/Makefile
@@ -13,7 +13,8 @@ obj-y += nommu.o
obj-$(CONFIG_ARM_MPU) += pmsa-v7.o
endif
-obj-$(CONFIG_ARM_PTDUMP) += dump.o
+obj-$(CONFIG_ARM_PTDUMP_CORE) += dump.o
+obj-$(CONFIG_ARM_PTDUMP_DEBUGFS) += ptdump_debugfs.o
obj-$(CONFIG_MODULES) += proc-syms.o
obj-$(CONFIG_DEBUG_VIRTUAL) += physaddr.o
diff --git a/arch/arm/mm/dump.c b/arch/arm/mm/dump.c
index fc3b440..8dfe7c3 100644
--- a/arch/arm/mm/dump.c
+++ b/arch/arm/mm/dump.c
@@ -21,11 +21,7 @@
#include <asm/fixmap.h>
#include <asm/memory.h>
#include <asm/pgtable.h>
-
-struct addr_marker {
- unsigned long start_address;
- const char *name;
-};
+#include <asm/ptdump.h>
static struct addr_marker address_markers[] = {
{ MODULES_VADDR, "Modules" },
@@ -335,50 +331,36 @@ static void walk_pud(struct pg_state *st, pgd_t *pgd, unsigned long start)
}
}
-static void walk_pgd(struct seq_file *m)
+static void walk_pgd(struct pg_state *st, struct mm_struct *mm,
+ unsigned long start)
{
- pgd_t *pgd = swapper_pg_dir;
- struct pg_state st;
- unsigned long addr;
+ pgd_t *pgd = pgd_offset(mm, 0UL);
unsigned i;
-
- memset(&st, 0, sizeof(st));
- st.seq = m;
- st.marker = address_markers;
+ unsigned long addr;
for (i = 0; i < PTRS_PER_PGD; i++, pgd++) {
- addr = i * PGDIR_SIZE;
+ addr = start + i * PGDIR_SIZE;
if (!pgd_none(*pgd)) {
- walk_pud(&st, pgd, addr);
+ walk_pud(st, pgd, addr);
} else {
- note_page(&st, addr, 1, pgd_val(*pgd), NULL);
+ note_page(st, addr, 1, pgd_val(*pgd), NULL);
}
}
-
- note_page(&st, 0, 0, 0, NULL);
}
-static int ptdump_show(struct seq_file *m, void *v)
+void ptdump_walk_pgd(struct seq_file *m, struct ptdump_info *info)
{
- walk_pgd(m);
- return 0;
-}
+ struct pg_state st = {
+ .seq = m,
+ .marker = info->markers,
+ };
-static int ptdump_open(struct inode *inode, struct file *file)
-{
- return single_open(file, ptdump_show, NULL);
+ walk_pgd(&st, info->mm, info->base_addr);
+ note_page(&st, 0, 0, 0, NULL);
}
-static const struct file_operations ptdump_fops = {
- .open = ptdump_open,
- .read = seq_read,
- .llseek = seq_lseek,
- .release = single_release,
-};
-
-static int ptdump_init(void)
+static void ptdump_initialize(void)
{
- struct dentry *pe;
unsigned i, j;
for (i = 0; i < ARRAY_SIZE(pg_level); i++)
@@ -387,9 +369,18 @@ static int ptdump_init(void)
pg_level[i].mask |= pg_level[i].bits[j].mask;
address_markers[2].start_address = VMALLOC_START;
+}
- pe = debugfs_create_file("kernel_page_tables", 0400, NULL, NULL,
- &ptdump_fops);
- return pe ? 0 : -ENOMEM;
+static struct ptdump_info kernel_ptdump_info = {
+ .mm = &init_mm,
+ .markers = address_markers,
+ .base_addr = 0,
+};
+
+static int ptdump_init(void)
+{
+ ptdump_initialize();
+ return ptdump_debugfs_register(&kernel_ptdump_info,
+ "kernel_page_tables");
}
__initcall(ptdump_init);
diff --git a/arch/arm/mm/ptdump_debugfs.c b/arch/arm/mm/ptdump_debugfs.c
new file mode 100644
index 0000000..be8d87b
--- /dev/null
+++ b/arch/arm/mm/ptdump_debugfs.c
@@ -0,0 +1,34 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <linux/debugfs.h>
+#include <linux/seq_file.h>
+
+#include <asm/ptdump.h>
+
+static int ptdump_show(struct seq_file *m, void *v)
+{
+ struct ptdump_info *info = m->private;
+
+ ptdump_walk_pgd(m, info);
+ return 0;
+}
+
+static int ptdump_open(struct inode *inode, struct file *file)
+{
+ return single_open(file, ptdump_show, inode->i_private);
+}
+
+static const struct file_operations ptdump_fops = {
+ .open = ptdump_open,
+ .read = seq_read,
+ .llseek = seq_lseek,
+ .release = single_release,
+};
+
+int ptdump_debugfs_register(struct ptdump_info *info, const char *name)
+{
+ struct dentry *pe;
+
+ pe = debugfs_create_file(name, 0400, NULL, info, &ptdump_fops);
+ return pe ? 0 : -ENOMEM;
+
+}
--
1.9.1
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