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Message-Id: <20210728190254.3921642-4-hca@linux.ibm.com>
Date: Wed, 28 Jul 2021 21:02:53 +0200
From: Heiko Carstens <hca@...ux.ibm.com>
To: Marco Elver <elver@...gle.com>,
Alexander Potapenko <glider@...gle.com>
Cc: Sven Schnelle <svens@...ux.ibm.com>,
Vasily Gorbik <gor@...ux.ibm.com>,
Christian Borntraeger <borntraeger@...ibm.com>,
kasan-dev@...glegroups.com, linux-mm@...ck.org,
linux-kernel@...r.kernel.org, linux-s390@...r.kernel.org
Subject: [PATCH 3/4] s390: add support for KFENCE
From: Sven Schnelle <svens@...ux.ibm.com>
Signed-off-by: Sven Schnelle <svens@...ux.ibm.com>
[hca@...ux.ibm.com: simplify/rework code]
Signed-off-by: Heiko Carstens <hca@...ux.ibm.com>
---
arch/s390/Kconfig | 1 +
arch/s390/include/asm/kfence.h | 42 ++++++++++++++++++++++++++++++++++
arch/s390/mm/fault.c | 9 ++++++--
arch/s390/mm/init.c | 3 ++-
arch/s390/mm/pageattr.c | 3 ++-
5 files changed, 54 insertions(+), 4 deletions(-)
create mode 100644 arch/s390/include/asm/kfence.h
diff --git a/arch/s390/Kconfig b/arch/s390/Kconfig
index a0e2130f0100..f20467af2ab2 100644
--- a/arch/s390/Kconfig
+++ b/arch/s390/Kconfig
@@ -138,6 +138,7 @@ config S390
select HAVE_ARCH_JUMP_LABEL_RELATIVE
select HAVE_ARCH_KASAN
select HAVE_ARCH_KASAN_VMALLOC
+ select HAVE_ARCH_KFENCE
select HAVE_ARCH_RANDOMIZE_KSTACK_OFFSET
select HAVE_ARCH_SECCOMP_FILTER
select HAVE_ARCH_SOFT_DIRTY
diff --git a/arch/s390/include/asm/kfence.h b/arch/s390/include/asm/kfence.h
new file mode 100644
index 000000000000..d55ba878378b
--- /dev/null
+++ b/arch/s390/include/asm/kfence.h
@@ -0,0 +1,42 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+
+#ifndef _ASM_S390_KFENCE_H
+#define _ASM_S390_KFENCE_H
+
+#include <linux/mm.h>
+#include <linux/kfence.h>
+#include <asm/set_memory.h>
+#include <asm/page.h>
+
+void __kernel_map_pages(struct page *page, int numpages, int enable);
+
+static __always_inline bool arch_kfence_init_pool(void)
+{
+ return true;
+}
+
+#define arch_kfence_test_address(addr) ((addr) & PAGE_MASK)
+
+/*
+ * Do not split kfence pool to 4k mapping with arch_kfence_init_pool(),
+ * but earlier where page table allocations still happen with memblock.
+ * Reason is that arch_kfence_init_pool() gets called when the system
+ * is still in a limbo state - disabling and enabling bottom halves is
+ * not yet allowed, but that is what our page_table_alloc() would do.
+ */
+static __always_inline void kfence_split_mapping(void)
+{
+#ifdef CONFIG_KFENCE
+ unsigned long pool_pages = KFENCE_POOL_SIZE >> PAGE_SHIFT;
+
+ set_memory_4k((unsigned long)__kfence_pool, pool_pages);
+#endif
+}
+
+static inline bool kfence_protect_page(unsigned long addr, bool protect)
+{
+ __kernel_map_pages(virt_to_page(addr), 1, !protect);
+ return true;
+}
+
+#endif /* _ASM_S390_KFENCE_H */
diff --git a/arch/s390/mm/fault.c b/arch/s390/mm/fault.c
index e33c43b38afe..52d82410486e 100644
--- a/arch/s390/mm/fault.c
+++ b/arch/s390/mm/fault.c
@@ -31,6 +31,7 @@
#include <linux/kprobes.h>
#include <linux/uaccess.h>
#include <linux/hugetlb.h>
+#include <linux/kfence.h>
#include <asm/asm-offsets.h>
#include <asm/diag.h>
#include <asm/gmap.h>
@@ -356,6 +357,7 @@ static inline vm_fault_t do_exception(struct pt_regs *regs, int access)
unsigned long address;
unsigned int flags;
vm_fault_t fault;
+ bool is_write;
tsk = current;
/*
@@ -369,6 +371,8 @@ static inline vm_fault_t do_exception(struct pt_regs *regs, int access)
mm = tsk->mm;
trans_exc_code = regs->int_parm_long;
+ address = trans_exc_code & __FAIL_ADDR_MASK;
+ is_write = (trans_exc_code & store_indication) == 0x400;
/*
* Verify that the fault happened in user space, that
@@ -379,6 +383,8 @@ static inline vm_fault_t do_exception(struct pt_regs *regs, int access)
type = get_fault_type(regs);
switch (type) {
case KERNEL_FAULT:
+ if (kfence_handle_page_fault(address, is_write, regs))
+ return 0;
goto out;
case USER_FAULT:
case GMAP_FAULT:
@@ -387,12 +393,11 @@ static inline vm_fault_t do_exception(struct pt_regs *regs, int access)
break;
}
- address = trans_exc_code & __FAIL_ADDR_MASK;
perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, regs, address);
flags = FAULT_FLAG_DEFAULT;
if (user_mode(regs))
flags |= FAULT_FLAG_USER;
- if (access == VM_WRITE || (trans_exc_code & store_indication) == 0x400)
+ if (access == VM_WRITE || is_write)
flags |= FAULT_FLAG_WRITE;
mmap_read_lock(mm);
diff --git a/arch/s390/mm/init.c b/arch/s390/mm/init.c
index 8ac710de1ab1..f3db3caa8447 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/kfence.h>
#include <asm/ptdump.h>
#include <asm/dma.h>
#include <asm/lowcore.h>
@@ -200,7 +201,7 @@ void __init mem_init(void)
high_memory = (void *) __va(max_low_pfn * PAGE_SIZE);
pv_init();
-
+ kfence_split_mapping();
/* Setup guest page hinting */
cmma_init();
diff --git a/arch/s390/mm/pageattr.c b/arch/s390/mm/pageattr.c
index b09fd5c7f85f..550048843fd6 100644
--- a/arch/s390/mm/pageattr.c
+++ b/arch/s390/mm/pageattr.c
@@ -4,6 +4,7 @@
* Author(s): Jan Glauber <jang@...ux.vnet.ibm.com>
*/
#include <linux/hugetlb.h>
+#include <linux/kfence.h>
#include <linux/mm.h>
#include <asm/cacheflush.h>
#include <asm/facility.h>
@@ -324,7 +325,7 @@ int __set_memory(unsigned long addr, int numpages, unsigned long flags)
return change_page_attr(addr, addr + numpages * PAGE_SIZE, flags);
}
-#ifdef CONFIG_DEBUG_PAGEALLOC
+#if defined(CONFIG_DEBUG_PAGEALLOC) || defined(CONFIG_KFENCE)
static void ipte_range(pte_t *pte, unsigned long address, int nr)
{
--
2.25.1
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