[RFC PATCH 2/3] arm64: mm: Switch to using generic pt_dump

Steven Price
2019-04-17T14:34:41Z

Instead of providing our own callbacks for walking the page tables,
switch to using the generic version instead.

Signed-off-by: Steven Price <steven.price@arm.com>
---
arch/arm64/Kconfig | 1 +
arch/arm64/Kconfig.debug | 19 +-----
arch/arm64/include/asm/ptdump.h | 8 +--
arch/arm64/mm/Makefile | 4 +-
arch/arm64/mm/dump.c | 104 +++++++++-----------------------
arch/arm64/mm/ptdump_debugfs.c | 2 +-
6 files changed, 37 insertions(+), 101 deletions(-)

diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
index 117b2541ef3d..4ff55b3ce8dc 100644
--- a/arch/arm64/Kconfig
+++ b/arch/arm64/Kconfig
@@ -97,6 +97,7 @@ config ARM64
select GENERIC_IRQ_SHOW
select GENERIC_IRQ_SHOW_LEVEL
select GENERIC_PCI_IOMAP
+ select GENERIC_PTDUMP
select GENERIC_SCHED_CLOCK
select GENERIC_SMP_IDLE_THREAD
select GENERIC_STRNCPY_FROM_USER
diff --git a/arch/arm64/Kconfig.debug b/arch/arm64/Kconfig.debug
index 69c9170bdd24..570dba4d4a0e 100644
--- a/arch/arm64/Kconfig.debug
+++ b/arch/arm64/Kconfig.debug
@@ -1,21 +1,4 @@

-config ARM64_PTDUMP_CORE
- def_bool n
-
-config ARM64_PTDUMP_DEBUGFS
- bool "Export kernel pagetable layout to userspace via debugfs"
- depends on DEBUG_KERNEL
- select ARM64_PTDUMP_CORE
- select DEBUG_FS
- help
- Say Y here if you want to show the kernel pagetable layout in a
- debugfs file. This information is only useful for kernel developers
- who are working in architecture specific areas of the kernel.
- It is probably not a good idea to enable this feature in a production
- kernel.
-
- If in doubt, say N.
-
config PID_IN_CONTEXTIDR
bool "Write the current PID to the CONTEXTIDR register"
help
@@ -41,7 +24,7 @@ config ARM64_RANDOMIZE_TEXT_OFFSET

config DEBUG_WX
bool "Warn on W+X mappings at boot"
- select ARM64_PTDUMP_CORE
+ select PTDUMP_CORE
---help---
Generate a warning if any W+X mappings are found at boot.

diff --git a/arch/arm64/include/asm/ptdump.h b/arch/arm64/include/asm/ptdump.h
index 9e948a93d26c..f8fecda7b61d 100644
--- a/arch/arm64/include/asm/ptdump.h
+++ b/arch/arm64/include/asm/ptdump.h
@@ -16,7 +16,7 @@
#ifndef __ASM_PTDUMP_H
#define __ASM_PTDUMP_H

-#ifdef CONFIG_ARM64_PTDUMP_CORE
+#ifdef CONFIG_PTDUMP_CORE

#include <linux/mm_types.h>
#include <linux/seq_file.h>
@@ -32,15 +32,15 @@ struct ptdump_info {
unsigned long base_addr;
};

-void ptdump_walk_pgd(struct seq_file *s, struct ptdump_info *info);
-#ifdef CONFIG_ARM64_PTDUMP_DEBUGFS
+void ptdump_walk(struct seq_file *s, struct ptdump_info *info);
+#ifdef CONFIG_PTDUMP_DEBUGFS
void ptdump_debugfs_register(struct ptdump_info *info, const char *name);
#else
static inline void ptdump_debugfs_register(struct ptdump_info *info,
const char *name) { }
#endif
void ptdump_check_wx(void);
-#endif /* CONFIG_ARM64_PTDUMP_CORE */
+#endif /* CONFIG_PTDUMP_CORE */

#ifdef CONFIG_DEBUG_WX
#define debug_checkwx() ptdump_check_wx()
diff --git a/arch/arm64/mm/Makefile b/arch/arm64/mm/Makefile
index 849c1df3d214..d91030f0ffee 100644
--- a/arch/arm64/mm/Makefile
+++ b/arch/arm64/mm/Makefile
@@ -4,8 +4,8 @@ obj-y := dma-mapping.o extable.o fault.o init.o \
ioremap.o mmap.o pgd.o mmu.o \
context.o proc.o pageattr.o
obj-$(CONFIG_HUGETLB_PAGE) += hugetlbpage.o
-obj-$(CONFIG_ARM64_PTDUMP_CORE) += dump.o
-obj-$(CONFIG_ARM64_PTDUMP_DEBUGFS) += ptdump_debugfs.o
+obj-$(CONFIG_PTDUMP_CORE) += dump.o
+obj-$(CONFIG_PTDUMP_DEBUGFS) += ptdump_debugfs.o
obj-$(CONFIG_NUMA) += numa.o
obj-$(CONFIG_DEBUG_VIRTUAL) += physaddr.o
KASAN_SANITIZE_physaddr.o += n
diff --git a/arch/arm64/mm/dump.c b/arch/arm64/mm/dump.c
index ea20c1213498..e68df2ad8863 100644
--- a/arch/arm64/mm/dump.c
+++ b/arch/arm64/mm/dump.c
@@ -19,6 +19,7 @@
#include <linux/io.h>
#include <linux/init.h>
#include <linux/mm.h>
+#include <linux/ptdump.h>
#include <linux/sched.h>
#include <linux/seq_file.h>

@@ -69,6 +70,7 @@ static const struct addr_marker address_markers[] = {
* dumps out a description of the range.
*/
struct pg_state {
+ struct ptdump_state ptdump;
struct seq_file *seq;
const struct addr_marker *marker;
unsigned long start_address;
@@ -172,6 +174,10 @@ static struct pg_level pg_level[] = {
.name = "PGD",
.bits = pte_bits,
.num = ARRAY_SIZE(pte_bits),
+ }, { /* p4d */
+ .name = "P4D",
+ .bits = pte_bits,
+ .num = ARRAY_SIZE(pte_bits),
}, { /* pud */
.name = (CONFIG_PGTABLE_LEVELS > 3) ? "PUD" : "PGD",
.bits = pte_bits,
@@ -234,9 +240,10 @@ static void note_prot_wx(struct pg_state *st, unsigned long addr)
st->wx_pages += (addr - st->start_address) / PAGE_SIZE;
}

-static void note_page(struct pg_state *st, unsigned long addr, int level,
- u64 val)
+static void note_page(struct ptdump_state *pt_st, unsigned long addr, int level,
+ unsigned long val)
{
+ struct pg_state *st = container_of(pt_st, struct pg_state, ptdump);
static const char units[] = "KMGTPE";
u64 prot = 0;

@@ -289,83 +296,21 @@ static void note_page(struct pg_state *st, unsigned long addr, int level,

}

-static int pud_entry(pud_t *pud, unsigned long addr,
- unsigned long next, struct mm_walk *walk)
-{
- struct pg_state *st = walk->private;
- pud_t val = READ_ONCE(*pud);
-
- if (pud_table(val))
- return 0;
-
- note_page(st, addr, 2, pud_val(val));
-
- return 0;
-}
-
-static int pmd_entry(pmd_t *pmd, unsigned long addr,
- unsigned long next, struct mm_walk *walk)
-{
- 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 int pte_entry(pte_t *pte, unsigned long addr,
- unsigned long next, struct mm_walk *walk)
-{
- 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,
- struct mm_walk *walk)
-{
- struct pg_state *st = walk->private;
-
- note_page(st, addr, -1, 0);
-
- return 0;
-}
-
-static void walk_pgd(struct pg_state *st, struct mm_struct *mm,
- unsigned long start)
-{
- 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)
+void ptdump_walk(struct seq_file *s, struct ptdump_info *info)
{
struct pg_state st = {
- .seq = m,
+ .seq = s,
.marker = info->markers,
+ .ptdump = {
+ .note_page = note_page,
+ .range = (struct ptdump_range[]){
+ {info->base_addr, ~0UL},
+ {0, 0}
+ }
+ }
};

- walk_pgd(&st, info->mm, info->base_addr);
-
- note_page(&st, 0, 0, 0);
+ ptdump_walk_pgd(&st.ptdump, info->mm);
}

static void ptdump_initialize(void)
@@ -393,10 +338,17 @@ void ptdump_check_wx(void)
{ -1, NULL},
},
.check_wx = true,
+ .ptdump = {
+ .note_page = note_page,
+ .range = (struct ptdump_range[]) {
+ {VA_START, ~0UL},
+ {0, 0}
+ }
+ }
};

- walk_pgd(&st, &init_mm, VA_START);
- note_page(&st, 0, 0, 0);
+ ptdump_walk_pgd(&st.ptdump, &init_mm);
+
if (st.wx_pages || st.uxn_pages)
pr_warn("Checked W+X mappings: FAILED, %lu W+X pages found, %lu non-UXN pages found\n",
st.wx_pages, st.uxn_pages);
diff --git a/arch/arm64/mm/ptdump_debugfs.c b/arch/arm64/mm/ptdump_debugfs.c
index 064163f25592..1f2eae3e988b 100644
--- a/arch/arm64/mm/ptdump_debugfs.c
+++ b/arch/arm64/mm/ptdump_debugfs.c
@@ -7,7 +7,7 @@
static int ptdump_show(struct seq_file *m, void *v)
{
struct ptdump_info *info = m->private;
- ptdump_walk_pgd(m, info);
+ ptdump_walk(m, info);
return 0;
}
DEFINE_SHOW_ATTRIBUTE(ptdump);
--
2.20.1