The patch titled
Subject: arm64, kfence: enable KFENCE for ARM64
has been added to the -mm tree. Its filename is
arm64-kfence-enable-kfence-for-arm64.patch
This patch should soon appear at
https://ozlabs.org/~akpm/mmots/broken-out/arm64-kfence-enable-kfence-for-arm64.patch
and later at
https://ozlabs.org/~akpm/mmotm/broken-out/arm64-kfence-enable-kfence-for-arm64.patch
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------------------------------------------------------
From: Marco Elver <elver@xxxxxxxxxx>
Subject: arm64, kfence: enable KFENCE for ARM64
Add architecture specific implementation details for KFENCE and enable
KFENCE for the arm64 architecture. In particular, this implements the
required interface in <asm/kfence.h>.
KFENCE requires that attributes for pages from its memory pool can
individually be set. Therefore, force the entire linear map to be mapped
at page granularity. Doing so may result in extra memory allocated for
page tables in case rodata=full is not set; however, currently
CONFIG_RODATA_FULL_DEFAULT_ENABLED=y is the default, and the common case
is therefore not affected by this change.
Link: https://lkml.kernel.org/r/20201103175841.3495947-4-elver@xxxxxxxxxx
Signed-off-by: Alexander Potapenko <glider@xxxxxxxxxx>
Signed-off-by: Marco Elver <elver@xxxxxxxxxx>
Reviewed-by: Dmitry Vyukov <dvyukov@xxxxxxxxxx>
Co-developed-by: Alexander Potapenko <glider@xxxxxxxxxx>
Reviewed-by: Jann Horn <jannh@xxxxxxxxxx>
Cc: Andrey Konovalov <andreyknvl@xxxxxxxxxx>
Cc: Andrey Ryabinin <aryabinin@xxxxxxxxxxxxx>
Cc: Andy Lutomirski <luto@xxxxxxxxxx>
Cc: Borislav Petkov <bp@xxxxxxxxx>
Cc: Catalin Marinas <catalin.marinas@xxxxxxx>
Cc: Christopher Lameter <cl@xxxxxxxxx>
Cc: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx>
Cc: David Rientjes <rientjes@xxxxxxxxxx>
Cc: Eric Dumazet <edumazet@xxxxxxxxxx>
Cc: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
Cc: Hillf Danton <hdanton@xxxxxxxx>
Cc: "H. Peter Anvin" <hpa@xxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxxxxx>
Cc: Joern Engel <joern@xxxxxxxxxxxxxxx>
Cc: Jonathan Corbet <corbet@xxxxxxx>
Cc: Joonsoo Kim <iamjoonsoo.kim@xxxxxxx>
Cc: Kees Cook <keescook@xxxxxxxxxxxx>
Cc: Mark Rutland <mark.rutland@xxxxxxx>
Cc: Paul E. McKenney <paulmck@xxxxxxxxxx>
Cc: Pekka Enberg <penberg@xxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: SeongJae Park <sjpark@xxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: Vlastimil Babka <vbabka@xxxxxxx>
Cc: Will Deacon <will@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
arch/arm64/Kconfig | 1 +
arch/arm64/include/asm/kfence.h | 19 +++++++++++++++++++
arch/arm64/mm/fault.c | 4 ++++
arch/arm64/mm/mmu.c | 7 ++++++-
4 files changed, 30 insertions(+), 1 deletion(-)
--- /dev/null
+++ a/arch/arm64/include/asm/kfence.h
@@ -0,0 +1,19 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+
+#ifndef __ASM_KFENCE_H
+#define __ASM_KFENCE_H
+
+#include <asm/cacheflush.h>
+
+#define KFENCE_SKIP_ARCH_FAULT_HANDLER "el1_sync"
+
+static inline bool arch_kfence_init_pool(void) { return true; }
+
+static inline bool kfence_protect_page(unsigned long addr, bool protect)
+{
+ set_memory_valid(addr, 1, !protect);
+
+ return true;
+}
+
+#endif /* __ASM_KFENCE_H */
--- a/arch/arm64/Kconfig~arm64-kfence-enable-kfence-for-arm64
+++ a/arch/arm64/Kconfig
@@ -137,6 +137,7 @@ config ARM64
select HAVE_ARCH_JUMP_LABEL_RELATIVE
select HAVE_ARCH_KASAN if !(ARM64_16K_PAGES && ARM64_VA_BITS_48)
select HAVE_ARCH_KASAN_SW_TAGS if HAVE_ARCH_KASAN
+ select HAVE_ARCH_KFENCE
select HAVE_ARCH_KGDB
select HAVE_ARCH_MMAP_RND_BITS
select HAVE_ARCH_MMAP_RND_COMPAT_BITS if COMPAT
--- a/arch/arm64/mm/fault.c~arm64-kfence-enable-kfence-for-arm64
+++ a/arch/arm64/mm/fault.c
@@ -10,6 +10,7 @@
#include <linux/acpi.h>
#include <linux/bitfield.h>
#include <linux/extable.h>
+#include <linux/kfence.h>
#include <linux/signal.h>
#include <linux/mm.h>
#include <linux/hardirq.h>
@@ -322,6 +323,9 @@ static void __do_kernel_fault(unsigned l
} else if (addr < PAGE_SIZE) {
msg = "NULL pointer dereference";
} else {
+ if (kfence_handle_page_fault(addr))
+ return;
+
msg = "paging request";
}
--- a/arch/arm64/mm/mmu.c~arm64-kfence-enable-kfence-for-arm64
+++ a/arch/arm64/mm/mmu.c
@@ -1449,7 +1449,12 @@ int arch_add_memory(int nid, u64 start,
{
int ret, flags = 0;
- if (rodata_full || debug_pagealloc_enabled())
+ /*
+ * KFENCE requires linear map to be mapped at page granularity, so that
+ * it is possible to protect/unprotect single pages in the KFENCE pool.
+ */
+ if (rodata_full || debug_pagealloc_enabled() ||
+ IS_ENABLED(CONFIG_KFENCE))
flags = NO_BLOCK_MAPPINGS | NO_CONT_MAPPINGS;
__create_pgd_mapping(swapper_pg_dir, start, __phys_to_virt(start),
_
Patches currently in -mm which might be from elver@xxxxxxxxxx are
arm64-kfence-enable-kfence-for-arm64.patch
kfence-documentation-add-kfence-documentation.patch
kfence-add-test-suite.patch
maintainers-add-entry-for-kfence.patch
