[PATCH v2 1/4] powerpc: Enable KFENCE for PPC32
From: Christophe Leroy
Date: Thu Mar 04 2021 - 09:36:42 EST
Add architecture specific implementation details for KFENCE and enable
KFENCE for the ppc32 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 Read/Write linear map to be
mapped at page granularity.
Signed-off-by: Christophe Leroy <christophe.leroy@xxxxxxxxxx>
Acked-by: Marco Elver <elver@xxxxxxxxxx>
---
v2: Added debug_pagealloc_enabled_or_kfence()
---
arch/powerpc/Kconfig | 13 ++++++------
arch/powerpc/include/asm/kfence.h | 33 +++++++++++++++++++++++++++++++
arch/powerpc/mm/book3s32/mmu.c | 2 +-
arch/powerpc/mm/fault.c | 7 ++++++-
arch/powerpc/mm/init_32.c | 3 +++
arch/powerpc/mm/mmu_decl.h | 5 +++++
arch/powerpc/mm/nohash/8xx.c | 4 ++--
7 files changed, 57 insertions(+), 10 deletions(-)
create mode 100644 arch/powerpc/include/asm/kfence.h
diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
index 386ae12d8523..d46db0bfb998 100644
--- a/arch/powerpc/Kconfig
+++ b/arch/powerpc/Kconfig
@@ -185,6 +185,7 @@ config PPC
select HAVE_ARCH_KASAN if PPC32 && PPC_PAGE_SHIFT <= 14
select HAVE_ARCH_KASAN_VMALLOC if PPC32 && PPC_PAGE_SHIFT <= 14
select HAVE_ARCH_KGDB
+ select HAVE_ARCH_KFENCE if PPC32
select HAVE_ARCH_MMAP_RND_BITS
select HAVE_ARCH_MMAP_RND_COMPAT_BITS if COMPAT
select HAVE_ARCH_NVRAM_OPS
@@ -786,7 +787,7 @@ config THREAD_SHIFT
config DATA_SHIFT_BOOL
bool "Set custom data alignment"
depends on ADVANCED_OPTIONS
- depends on STRICT_KERNEL_RWX || DEBUG_PAGEALLOC
+ depends on STRICT_KERNEL_RWX || DEBUG_PAGEALLOC || KFENCE
depends on PPC_BOOK3S_32 || (PPC_8xx && !PIN_TLB_DATA && !STRICT_KERNEL_RWX)
help
This option allows you to set the kernel data alignment. When
@@ -798,13 +799,13 @@ config DATA_SHIFT_BOOL
config DATA_SHIFT
int "Data shift" if DATA_SHIFT_BOOL
default 24 if STRICT_KERNEL_RWX && PPC64
- range 17 28 if (STRICT_KERNEL_RWX || DEBUG_PAGEALLOC) && PPC_BOOK3S_32
- range 19 23 if (STRICT_KERNEL_RWX || DEBUG_PAGEALLOC) && PPC_8xx
+ range 17 28 if (STRICT_KERNEL_RWX || DEBUG_PAGEALLOC || KFENCE) && PPC_BOOK3S_32
+ range 19 23 if (STRICT_KERNEL_RWX || DEBUG_PAGEALLOC || KFENCE) && PPC_8xx
default 22 if STRICT_KERNEL_RWX && PPC_BOOK3S_32
- default 18 if DEBUG_PAGEALLOC && PPC_BOOK3S_32
+ default 18 if (DEBUG_PAGEALLOC || KFENCE) && PPC_BOOK3S_32
default 23 if STRICT_KERNEL_RWX && PPC_8xx
- default 23 if DEBUG_PAGEALLOC && PPC_8xx && PIN_TLB_DATA
- default 19 if DEBUG_PAGEALLOC && PPC_8xx
+ default 23 if (DEBUG_PAGEALLOC || KFENCE) && PPC_8xx && PIN_TLB_DATA
+ default 19 if (DEBUG_PAGEALLOC || KFENCE) && PPC_8xx
default PPC_PAGE_SHIFT
help
On Book3S 32 (603+), DBATs are used to map kernel text and rodata RO.
diff --git a/arch/powerpc/include/asm/kfence.h b/arch/powerpc/include/asm/kfence.h
new file mode 100644
index 000000000000..a9846b68c6b9
--- /dev/null
+++ b/arch/powerpc/include/asm/kfence.h
@@ -0,0 +1,33 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * powerpc KFENCE support.
+ *
+ * Copyright (C) 2020 CS GROUP France
+ */
+
+#ifndef __ASM_POWERPC_KFENCE_H
+#define __ASM_POWERPC_KFENCE_H
+
+#include <linux/mm.h>
+#include <asm/pgtable.h>
+
+static inline bool arch_kfence_init_pool(void)
+{
+ return true;
+}
+
+static inline bool kfence_protect_page(unsigned long addr, bool protect)
+{
+ pte_t *kpte = virt_to_kpte(addr);
+
+ if (protect) {
+ pte_update(&init_mm, addr, kpte, _PAGE_PRESENT, 0, 0);
+ flush_tlb_kernel_range(addr, addr + PAGE_SIZE);
+ } else {
+ pte_update(&init_mm, addr, kpte, 0, _PAGE_PRESENT, 0);
+ }
+
+ return true;
+}
+
+#endif /* __ASM_POWERPC_KFENCE_H */
diff --git a/arch/powerpc/mm/book3s32/mmu.c b/arch/powerpc/mm/book3s32/mmu.c
index d7eb266a3f7a..a0db398b5c26 100644
--- a/arch/powerpc/mm/book3s32/mmu.c
+++ b/arch/powerpc/mm/book3s32/mmu.c
@@ -162,7 +162,7 @@ unsigned long __init mmu_mapin_ram(unsigned long base, unsigned long top)
unsigned long border = (unsigned long)__init_begin - PAGE_OFFSET;
- if (debug_pagealloc_enabled() || __map_without_bats) {
+ if (debug_pagealloc_enabled_or_kfence() || __map_without_bats) {
pr_debug_once("Read-Write memory mapped without BATs\n");
if (base >= border)
return base;
diff --git a/arch/powerpc/mm/fault.c b/arch/powerpc/mm/fault.c
index bb368257b55c..bea13682c909 100644
--- a/arch/powerpc/mm/fault.c
+++ b/arch/powerpc/mm/fault.c
@@ -32,6 +32,7 @@
#include <linux/context_tracking.h>
#include <linux/hugetlb.h>
#include <linux/uaccess.h>
+#include <linux/kfence.h>
#include <asm/firmware.h>
#include <asm/interrupt.h>
@@ -418,8 +419,12 @@ static int ___do_page_fault(struct pt_regs *regs, unsigned long address,
* take a page fault to a kernel address or a page fault to a user
* address outside of dedicated places
*/
- if (unlikely(!is_user && bad_kernel_fault(regs, error_code, address, is_write)))
+ if (unlikely(!is_user && bad_kernel_fault(regs, error_code, address, is_write))) {
+ if (kfence_handle_page_fault(address, is_write, regs))
+ return 0;
+
return SIGSEGV;
+ }
/*
* If we're in an interrupt, have no user context or are running
diff --git a/arch/powerpc/mm/init_32.c b/arch/powerpc/mm/init_32.c
index 02c7db4087cb..3d690be48e84 100644
--- a/arch/powerpc/mm/init_32.c
+++ b/arch/powerpc/mm/init_32.c
@@ -97,6 +97,9 @@ static void __init MMU_setup(void)
if (IS_ENABLED(CONFIG_PPC_8xx))
return;
+ if (IS_ENABLED(CONFIG_KFENCE))
+ __map_without_ltlbs = 1;
+
if (debug_pagealloc_enabled())
__map_without_ltlbs = 1;
diff --git a/arch/powerpc/mm/mmu_decl.h b/arch/powerpc/mm/mmu_decl.h
index 998810e68562..7dac910c0b21 100644
--- a/arch/powerpc/mm/mmu_decl.h
+++ b/arch/powerpc/mm/mmu_decl.h
@@ -185,3 +185,8 @@ void ptdump_check_wx(void);
#else
static inline void ptdump_check_wx(void) { }
#endif
+
+static inline bool debug_pagealloc_enabled_or_kfence(void)
+{
+ return IS_ENABLED(CONFIG_KFENCE) || debug_pagealloc_enabled();
+}
diff --git a/arch/powerpc/mm/nohash/8xx.c b/arch/powerpc/mm/nohash/8xx.c
index 19a3eec1d8c5..71bfdbedacee 100644
--- a/arch/powerpc/mm/nohash/8xx.c
+++ b/arch/powerpc/mm/nohash/8xx.c
@@ -149,7 +149,7 @@ unsigned long __init mmu_mapin_ram(unsigned long base, unsigned long top)
{
unsigned long etext8 = ALIGN(__pa(_etext), SZ_8M);
unsigned long sinittext = __pa(_sinittext);
- bool strict_boundary = strict_kernel_rwx_enabled() || debug_pagealloc_enabled();
+ bool strict_boundary = strict_kernel_rwx_enabled() || debug_pagealloc_enabled_or_kfence();
unsigned long boundary = strict_boundary ? sinittext : etext8;
unsigned long einittext8 = ALIGN(__pa(_einittext), SZ_8M);
@@ -161,7 +161,7 @@ unsigned long __init mmu_mapin_ram(unsigned long base, unsigned long top)
return 0;
mmu_mapin_ram_chunk(0, boundary, PAGE_KERNEL_TEXT, true);
- if (debug_pagealloc_enabled()) {
+ if (debug_pagealloc_enabled_or_kfence()) {
top = boundary;
} else {
mmu_mapin_ram_chunk(boundary, einittext8, PAGE_KERNEL_TEXT, true);
--
2.25.0