diff --git a/arch/s390/Kconfig b/arch/s390/Kconfig
index 85bf121211d10cc8603872fbb0175afce96ba016..2052b39b845971ab30293d4fb445aee76c0c2946 100644
--- a/arch/s390/Kconfig
+++ b/arch/s390/Kconfig
@@ -60,6 +60,7 @@ config S390
def_bool y
select ARCH_BINFMT_ELF_STATE
select ARCH_HAS_DEBUG_VM_PGTABLE
+ select ARCH_HAS_DEBUG_WX
select ARCH_HAS_DEVMEM_IS_ALLOWED
select ARCH_HAS_ELF_RANDOMIZE
select ARCH_HAS_FORTIFY_SOURCE
diff --git a/arch/s390/configs/debug_defconfig b/arch/s390/configs/debug_defconfig
index f79eafb597cb3252b42bf7554730a78df1008f16..901723e4ed6311a9093ac64fa999695c0a258b27 100644
--- a/arch/s390/configs/debug_defconfig
+++ b/arch/s390/configs/debug_defconfig
@@ -774,6 +774,7 @@ CONFIG_MAGIC_SYSRQ=y
CONFIG_DEBUG_PAGEALLOC=y
CONFIG_PAGE_OWNER=y
CONFIG_DEBUG_RODATA_TEST=y
+CONFIG_DEBUG_WX=y
CONFIG_PTDUMP_DEBUGFS=y
CONFIG_DEBUG_OBJECTS=y
CONFIG_DEBUG_OBJECTS_SELFTEST=y
diff --git a/arch/s390/configs/defconfig b/arch/s390/configs/defconfig
index 9593cc8a9efd6a5df97e4844b2fdb574afe6b61f..87da48c8513054e06712a2563dc870135ba4bfc3 100644
--- a/arch/s390/configs/defconfig
+++ b/arch/s390/configs/defconfig
@@ -758,6 +758,7 @@ CONFIG_GDB_SCRIPTS=y
CONFIG_FRAME_WARN=1024
CONFIG_DEBUG_SECTION_MISMATCH=y
CONFIG_MAGIC_SYSRQ=y
+CONFIG_DEBUG_WX=y
CONFIG_PTDUMP_DEBUGFS=y
CONFIG_DEBUG_MEMORY_INIT=y
CONFIG_PANIC_ON_OOPS=y
diff --git a/arch/s390/include/asm/ptdump.h b/arch/s390/include/asm/ptdump.h
new file mode 100644
index 0000000000000000000000000000000000000000..f960b2896606a141bf2906cf3c9fc81481c7c322
--- /dev/null
+++ b/arch/s390/include/asm/ptdump.h
@@ -0,0 +1,14 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+
+#ifndef _ASM_S390_PTDUMP_H
+#define _ASM_S390_PTDUMP_H
+
+void ptdump_check_wx(void);
+
+static inline void debug_checkwx(void)
+{
+ if (IS_ENABLED(CONFIG_DEBUG_WX))
+ ptdump_check_wx();
+}
+
+#endif /* _ASM_S390_PTDUMP_H */
diff --git a/arch/s390/mm/Makefile b/arch/s390/mm/Makefile
index 8ab9daeeace3802e83f79b1eb7301f6051a4b786..cd67e94c16aa2a82a42bd77eaaefe6539de2c228 100644
--- a/arch/s390/mm/Makefile
+++ b/arch/s390/mm/Makefile
@@ -8,7 +8,7 @@ obj-y += page-states.o pageattr.o pgtable.o pgalloc.o
obj-$(CONFIG_CMM) += cmm.o
obj-$(CONFIG_HUGETLB_PAGE) += hugetlbpage.o
-obj-$(CONFIG_PTDUMP_DEBUGFS) += dump_pagetables.o
+obj-$(CONFIG_PTDUMP_CORE) += dump_pagetables.o
obj-$(CONFIG_PGSTE) += gmap.o
KASAN_SANITIZE_kasan_init.o := n
diff --git a/arch/s390/mm/dump_pagetables.c b/arch/s390/mm/dump_pagetables.c
index b7401a2f93f32db3a353a2e02ff161926ad7dd3a..4b27c1a533de84840231edcf9748b46583477630 100644
--- a/arch/s390/mm/dump_pagetables.c
+++ b/arch/s390/mm/dump_pagetables.c
@@ -5,6 +5,7 @@
#include <linux/debugfs.h>
#include <linux/mm.h>
#include <linux/kasan.h>
+#include <asm/ptdump.h>
#include <asm/kasan.h>
#include <asm/sections.h>
@@ -47,6 +48,8 @@ struct pg_state {
struct seq_file *seq;
int level;
unsigned int current_prot;
+ bool check_wx;
+ unsigned long wx_pages;
unsigned long start_address;
const struct addr_marker *marker;
};
@@ -81,6 +84,26 @@ static void print_prot(struct seq_file *m, unsigned int pr, int level)
pt_dump_seq_puts(m, (pr & _PAGE_NOEXEC) ? "NX\n" : "X\n");
}
+static void note_prot_wx(struct pg_state *st, unsigned long addr)
+{
+#ifdef CONFIG_DEBUG_WX
+ if (!st->check_wx)
+ return;
+ if (st->current_prot & _PAGE_INVALID)
+ return;
+ if (st->current_prot & _PAGE_PROTECT)
+ return;
+ if (st->current_prot & _PAGE_NOEXEC)
+ return;
+ /* The first lowcore page is currently still W+X. */
+ if (addr == PAGE_SIZE)
+ return;
+ WARN_ONCE(1, "s390/mm: Found insecure W+X mapping at address %pS\n",
+ (void *)st->start_address);
+ st->wx_pages += (addr - st->start_address) / PAGE_SIZE;
+#endif /* CONFIG_DEBUG_WX */
+}
+
static void note_page(struct ptdump_state *pt_st, unsigned long addr, int level, u64 val)
{
int width = sizeof(unsigned long) * 2;
@@ -109,6 +132,7 @@ static void note_page(struct ptdump_state *pt_st, unsigned long addr, int level,
st->level = level;
} else if (prot != st->current_prot || level != st->level ||
addr >= st->marker[1].start_address) {
+ note_prot_wx(st, addr);
pt_dump_seq_printf(m, "0x%0*lx-0x%0*lx ",
width, st->start_address,
width, addr);
@@ -129,6 +153,40 @@ static void note_page(struct ptdump_state *pt_st, unsigned long addr, int level,
}
}
+#ifdef CONFIG_DEBUG_WX
+void ptdump_check_wx(void)
+{
+ struct pg_state st = {
+ .ptdump = {
+ .note_page = note_page,
+ .range = (struct ptdump_range[]) {
+ {.start = 0, .end = max_addr},
+ {.start = 0, .end = 0},
+ }
+ },
+ .seq = NULL,
+ .level = -1,
+ .current_prot = 0,
+ .check_wx = true,
+ .wx_pages = 0,
+ .start_address = 0,
+ .marker = (struct addr_marker[]) {
+ { .start_address = 0, .name = NULL},
+ { .start_address = -1, .name = NULL},
+ },
+ };
+
+ if (!MACHINE_HAS_NX)
+ return;
+ ptdump_walk_pgd(&st.ptdump, &init_mm, NULL);
+ if (st.wx_pages)
+ pr_warn("Checked W+X mappings: FAILED, %lu W+X pages found\n", st.wx_pages);
+ else
+ pr_info("Checked W+X mappings: passed, no unexpected W+X pages found\n");
+}
+#endif /* CONFIG_DEBUG_WX */
+
+#ifdef CONFIG_PTDUMP_DEBUGFS
static int ptdump_show(struct seq_file *m, void *v)
{
struct pg_state st = {
@@ -142,6 +200,8 @@ static int ptdump_show(struct seq_file *m, void *v)
.seq = m,
.level = -1,
.current_prot = 0,
+ .check_wx = false,
+ .wx_pages = 0,
.start_address = 0,
.marker = address_markers,
};
@@ -154,6 +214,7 @@ static int ptdump_show(struct seq_file *m, void *v)
return 0;
}
DEFINE_SHOW_ATTRIBUTE(ptdump);
+#endif /* CONFIG_PTDUMP_DEBUGFS */
static int pt_dump_init(void)
{
@@ -167,7 +228,8 @@ static int pt_dump_init(void)
address_markers[MODULES_NR].start_address = MODULES_VADDR;
address_markers[VMEMMAP_NR].start_address = (unsigned long) vmemmap;
address_markers[VMALLOC_NR].start_address = VMALLOC_START;
- debugfs_create_file("kernel_page_tables", 0400, NULL, NULL, &ptdump_fops);
+ if (IS_ENABLED(CONFIG_PTDUMP_DEBUGFS))
+ debugfs_create_file("kernel_page_tables", 0400, NULL, NULL, &ptdump_fops);
return 0;
}
device_initcall(pt_dump_init);
diff --git a/arch/s390/mm/init.c b/arch/s390/mm/init.c
index 0d282081dc1f8b1c59579200a58c802d921adda7..d3ddb436136117b279a3dd0a29814f45b8f4a51f 100644
--- a/arch/s390/mm/init.c
+++ b/arch/s390/mm/init.c
@@ -34,6 +34,7 @@
#include <asm/processor.h>
#include <linux/uaccess.h>
#include <asm/pgalloc.h>
+#include <asm/ptdump.h>
#include <asm/dma.h>
#include <asm/lowcore.h>
#include <asm/tlb.h>
@@ -129,6 +130,7 @@ void mark_rodata_ro(void)
set_memory_ro((unsigned long)__start_ro_after_init, size >> PAGE_SHIFT);
pr_info("Write protected read-only-after-init data: %luk\n", size >> 10);
+ debug_checkwx();
}
int set_memory_encrypted(unsigned long addr, int numpages)