[PATCH v2 0/6] KASAN support for 64-bit Book 3S powerpc

[PATCH v2 0/6] KASAN support for 64-bit Book 3S powerpc

[Paul Mackerras]

This patch series implements KASAN on 64-bit POWER with radix MMU,
such as POWER9 or POWER10.  Daniel Axtens posted previous versions of
these patches, but is no longer working on KASAN, and I have been
asked to get them ready for inclusion.

Because of various technical difficulties, mostly around the need to
allow for code that runs in real mode, we only support "outline" mode
(as opposed to "inline" mode), where the compiler adds a call to
a checking procedure before every store to memory.

This series has known deficiencies, specifically that the kernel will
crash on boot on a HPT system, and that out-of-bounds accesses to
module global data are not caught (which leads to one of the KASAN
tests failing).

v2: Split the large patch 3/3 of the previous series into three
patches and addressed review comments; put the generic documentation
changes in a separate patch at the end of the series; removed the RFC
tag.

Comments welcome.

Paul.

 Documentation/dev-tools/kasan.rst                  |   7 +-
 Documentation/powerpc/kasan.txt                    |  58 ++++++++++++
 arch/powerpc/Kconfig                               |   5 +-
 arch/powerpc/Kconfig.debug                         |   3 +-
 arch/powerpc/include/asm/book3s/64/hash.h          |   4 +
 arch/powerpc/include/asm/book3s/64/pgtable.h       |   3 +
 arch/powerpc/include/asm/book3s/64/radix.h         |  12 ++-
 arch/powerpc/include/asm/interrupt.h               |  52 ++++++++---
 arch/powerpc/include/asm/kasan.h                   |  22 +++++
 arch/powerpc/kernel/Makefile                       |  11 +++
 arch/powerpc/kernel/smp.c                          |  22 ++---
 arch/powerpc/kernel/traps.c                        |   6 +-
 arch/powerpc/kexec/Makefile                        |   2 +
 arch/powerpc/kvm/Makefile                          |   5 +
 arch/powerpc/lib/Makefile                          |   3 +
 arch/powerpc/mm/book3s64/Makefile                  |   9 ++
 arch/powerpc/mm/kasan/Makefile                     |   3 +-
 .../mm/kasan/{kasan_init_32.c => init_32.c}        |   0
 arch/powerpc/mm/kasan/init_book3s_64.c             | 103 +++++++++++++++++++++
 arch/powerpc/mm/ptdump/ptdump.c                    |   3 +-
 arch/powerpc/platforms/Kconfig.cputype             |   1 +
 arch/powerpc/platforms/powernv/Makefile            |   8 ++
 arch/powerpc/platforms/powernv/smp.c               |   2 +-
 arch/powerpc/platforms/pseries/Makefile            |   6 ++
 arch/powerpc/sysdev/xics/xics-common.c             |   4 +-
 arch/powerpc/sysdev/xive/common.c                  |   4 +-
 26 files changed, 320 insertions(+), 38 deletions(-)

[PATCH v2 1/6] kasan: Document support on 32-bit powerpc

[Paul Mackerras]

From: Daniel Axtens <dja@axtens.net>

KASAN is supported on 32-bit powerpc and the docs should reflect this.

Suggested-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Reviewed-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Daniel Axtens <dja@axtens.net>
Signed-off-by: Paul Mackerras <paulus@ozlabs.org>
---
 Documentation/powerpc/kasan.txt | 12 ++++++++++++
 1 file changed, 12 insertions(+)
 create mode 100644 Documentation/powerpc/kasan.txt

diff --git a/Documentation/powerpc/kasan.txt b/Documentation/powerpc/kasan.txt
new file mode 100644
index 000000000000..26bb0e8bb18c
--- /dev/null
+++ b/Documentation/powerpc/kasan.txt
@@ -0,0 +1,12 @@
+KASAN is supported on powerpc on 32-bit only.
+
+32 bit support
+==============
+
+KASAN is supported on both hash and nohash MMUs on 32-bit.
+
+The shadow area sits at the top of the kernel virtual memory space above the
+fixmap area and occupies one eighth of the total kernel virtual memory space.
+
+Instrumentation of the vmalloc area is optional, unless built with modules,
+in which case it is required.
-- 
2.35.3

[PATCH v2 2/6] powerpc/mm/kasan: rename kasan_init_32.c to init_32.c

[Paul Mackerras]

From: Daniel Axtens <dja@axtens.net>

kasan is already implied by the directory name, we don't need to
repeat it.

Suggested-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Daniel Axtens <dja@axtens.net>
Signed-off-by: Paul Mackerras <paulus@ozlabs.org>
---
 arch/powerpc/mm/kasan/Makefile                       | 2 +-
 arch/powerpc/mm/kasan/{kasan_init_32.c => init_32.c} | 0
 2 files changed, 1 insertion(+), 1 deletion(-)
 rename arch/powerpc/mm/kasan/{kasan_init_32.c => init_32.c} (100%)

diff --git a/arch/powerpc/mm/kasan/Makefile b/arch/powerpc/mm/kasan/Makefile
index bb1a5408b86b..bcbfd6f2eca3 100644
--- a/arch/powerpc/mm/kasan/Makefile
+++ b/arch/powerpc/mm/kasan/Makefile
@@ -2,6 +2,6 @@
 
 KASAN_SANITIZE := n
 
-obj-$(CONFIG_PPC32)           += kasan_init_32.o
+obj-$(CONFIG_PPC32)		+= init_32.o
 obj-$(CONFIG_PPC_8xx)		+= 8xx.o
 obj-$(CONFIG_PPC_BOOK3S_32)	+= book3s_32.o
diff --git a/arch/powerpc/mm/kasan/kasan_init_32.c b/arch/powerpc/mm/kasan/init_32.c
similarity index 100%
rename from arch/powerpc/mm/kasan/kasan_init_32.c
rename to arch/powerpc/mm/kasan/init_32.c
-- 
2.35.3

[PATCH v2 3/6] powerpc: Book3S 64-bit outline-only KASAN support

[Paul Mackerras]

From: Daniel Axtens <dja@axtens.net>

Implement a limited form of KASAN for Book3S 64-bit machines running under
the Radix MMU, supporting only outline mode.

 - Enable the compiler instrumentation to check addresses and maintain the
   shadow region. (This is the guts of KASAN which we can easily reuse.)

 - Require kasan-vmalloc support to handle modules and anything else in
   vmalloc space.

 - KASAN needs to be able to validate all pointer accesses, but we can't
   instrument all kernel addresses - only linear map and vmalloc. On boot,
   set up a single page of read-only shadow that marks all iomap and
   vmemmap accesses as valid.

 - Document KASAN in powerpc docs.

Background
----------

KASAN support on Book3S is a bit tricky to get right:

 - It would be good to support inline instrumentation so as to be able to
   catch stack issues that cannot be caught with outline mode.

 - Inline instrumentation requires a fixed offset.

 - Book3S runs code with translations off ("real mode") during boot,
   including a lot of generic device-tree parsing code which is used to
   determine MMU features.

    [ppc64 mm note: The kernel installs a linear mapping at effective
    address c000...-c008.... This is a one-to-one mapping with physical
    memory from 0000... onward. Because of how memory accesses work on
    powerpc 64-bit Book3S, a kernel pointer in the linear map accesses the
    same memory both with translations on (accessing as an 'effective
    address'), and with translations off (accessing as a 'real
    address'). This works in both guests and the hypervisor. For more
    details, see s5.7 of Book III of version 3 of the ISA, in particular
    the Storage Control Overview, s5.7.3, and s5.7.5 - noting that this
    KASAN implementation currently only supports Radix.]

 - Some code - most notably a lot of KVM code - also runs with translations
   off after boot.

 - Therefore any offset has to point to memory that is valid with
   translations on or off.

One approach is just to give up on inline instrumentation. This way
boot-time checks can be delayed until after the MMU is set is up, and we
can just not instrument any code that runs with translations off after
booting. Take this approach for now and require outline instrumentation.

Previous attempts allowed inline instrumentation. However, they came with
some unfortunate restrictions: only physically contiguous memory could be
used and it had to be specified at compile time. Maybe we can do better in
the future.

[paulus@ozlabs.org - Rebased onto 5.17.  Note that a kernel with
 CONFIG_KASAN=y will crash during boot on a machine using HPT
 translation because not all the entry points to the generic
 KASAN code are protected with a call to kasan_arch_is_ready().]

Originally-by: Balbir Singh <bsingharora@gmail.com> # ppc64 out-of-line radix version
Signed-off-by: Daniel Axtens <dja@axtens.net>
Signed-off-by: Paul Mackerras <paulus@ozlabs.org>
---
 Documentation/powerpc/kasan.txt              |  48 ++++++++-
 arch/powerpc/Kconfig                         |   5 +-
 arch/powerpc/Kconfig.debug                   |   3 +-
 arch/powerpc/include/asm/book3s/64/hash.h    |   4 +
 arch/powerpc/include/asm/book3s/64/pgtable.h |   3 +
 arch/powerpc/include/asm/book3s/64/radix.h   |  12 ++-
 arch/powerpc/include/asm/kasan.h             |  22 ++++
 arch/powerpc/kernel/Makefile                 |  11 ++
 arch/powerpc/kvm/Makefile                    |   5 +
 arch/powerpc/mm/book3s64/Makefile            |   9 ++
 arch/powerpc/mm/kasan/Makefile               |   1 +
 arch/powerpc/mm/kasan/init_book3s_64.c       | 103 +++++++++++++++++++
 arch/powerpc/mm/ptdump/ptdump.c              |   3 +-
 arch/powerpc/platforms/Kconfig.cputype       |   1 +
 arch/powerpc/platforms/powernv/Makefile      |   8 ++
 arch/powerpc/platforms/pseries/Makefile      |   3 +
 16 files changed, 234 insertions(+), 7 deletions(-)
 create mode 100644 arch/powerpc/mm/kasan/init_book3s_64.c

diff --git a/Documentation/powerpc/kasan.txt b/Documentation/powerpc/kasan.txt
index 26bb0e8bb18c..f032b4eaf205 100644
--- a/Documentation/powerpc/kasan.txt
+++ b/Documentation/powerpc/kasan.txt
@@ -1,4 +1,4 @@
-KASAN is supported on powerpc on 32-bit only.
+KASAN is supported on powerpc on 32-bit and Radix 64-bit only.
 
 32 bit support
 ==============
@@ -10,3 +10,49 @@ fixmap area and occupies one eighth of the total kernel virtual memory space.
 
 Instrumentation of the vmalloc area is optional, unless built with modules,
 in which case it is required.
+
+64 bit support
+==============
+
+Currently, only the radix MMU is supported. There have been versions for hash
+and Book3E processors floating around on the mailing list, but nothing has been
+merged.
+
+KASAN support on Book3S is a bit tricky to get right:
+
+ - It would be good to support inline instrumentation so as to be able to catch
+   stack issues that cannot be caught with outline mode.
+
+ - Inline instrumentation requires a fixed offset.
+
+ - Book3S runs code with translations off ("real mode") during boot, including a
+   lot of generic device-tree parsing code which is used to determine MMU
+   features.
+
+ - Some code - most notably a lot of KVM code - also runs with translations off
+   after boot.
+
+ - Therefore any offset has to point to memory that is valid with
+   translations on or off.
+
+One approach is just to give up on inline instrumentation. This way boot-time
+checks can be delayed until after the MMU is set is up, and we can just not
+instrument any code that runs with translations off after booting. This is the
+current approach.
+
+To avoid this limitiation, the KASAN shadow would have to be placed inside the
+linear mapping, using the same high-bits trick we use for the rest of the linear
+mapping. This is tricky:
+
+ - We'd like to place it near the start of physical memory. In theory we can do
+   this at run-time based on how much physical memory we have, but this requires
+   being able to arbitrarily relocate the kernel, which is basically the tricky
+   part of KASLR. Not being game to implement both tricky things at once, this
+   is hopefully something we can revisit once we get KASLR for Book3S.
+
+ - Alternatively, we can place the shadow at the _end_ of memory, but this
+   requires knowing how much contiguous physical memory a system has _at compile
+   time_. This is a big hammer, and has some unfortunate consequences: inablity
+   to handle discontiguous physical memory, total failure to boot on machines
+   with less memory than specified, and that machines with more memory than
+   specified can't use it. This was deemed unacceptable.
diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
index b779603978e1..0bf76e40c9c2 100644
--- a/arch/powerpc/Kconfig
+++ b/arch/powerpc/Kconfig
@@ -105,6 +105,7 @@ config PPC
 	# Please keep this list sorted alphabetically.
 	#
 	select ARCH_32BIT_OFF_T if PPC32
+	select ARCH_DISABLE_KASAN_INLINE	if PPC_RADIX_MMU
 	select ARCH_ENABLE_MEMORY_HOTPLUG
 	select ARCH_ENABLE_MEMORY_HOTREMOVE
 	select ARCH_HAS_COPY_MC			if PPC64
@@ -152,6 +153,7 @@ config PPC
 	select ARCH_WANT_IPC_PARSE_VERSION
 	select ARCH_WANT_IRQS_OFF_ACTIVATE_MM
 	select ARCH_WANT_LD_ORPHAN_WARN
+	select ARCH_WANTS_NO_INSTR
 	select ARCH_WEAK_RELEASE_ACQUIRE
 	select BINFMT_ELF
 	select BUILDTIME_TABLE_SORT
@@ -183,7 +185,8 @@ config PPC
 	select HAVE_ARCH_JUMP_LABEL
 	select HAVE_ARCH_JUMP_LABEL_RELATIVE
 	select HAVE_ARCH_KASAN			if PPC32 && PPC_PAGE_SHIFT <= 14
-	select HAVE_ARCH_KASAN_VMALLOC		if PPC32 && PPC_PAGE_SHIFT <= 14
+	select HAVE_ARCH_KASAN			if PPC_RADIX_MMU
+	select HAVE_ARCH_KASAN_VMALLOC		if HAVE_ARCH_KASAN
 	select HAVE_ARCH_KFENCE			if PPC_BOOK3S_32 || PPC_8xx || 40x
 	select HAVE_ARCH_KGDB
 	select HAVE_ARCH_MMAP_RND_BITS
diff --git a/arch/powerpc/Kconfig.debug b/arch/powerpc/Kconfig.debug
index 192f0ed0097f..9f363c143d86 100644
--- a/arch/powerpc/Kconfig.debug
+++ b/arch/powerpc/Kconfig.debug
@@ -374,4 +374,5 @@ config PPC_FAST_ENDIAN_SWITCH
 config KASAN_SHADOW_OFFSET
 	hex
 	depends on KASAN
-	default 0xe0000000
+	default 0xe0000000 if PPC32
+	default 0xa80e000000000000 if PPC64
diff --git a/arch/powerpc/include/asm/book3s/64/hash.h b/arch/powerpc/include/asm/book3s/64/hash.h
index a7a0572f3846..17e7a778c856 100644
--- a/arch/powerpc/include/asm/book3s/64/hash.h
+++ b/arch/powerpc/include/asm/book3s/64/hash.h
@@ -18,6 +18,10 @@
 #include <asm/book3s/64/hash-4k.h>
 #endif
 
+#define H_PTRS_PER_PTE		(1 << H_PTE_INDEX_SIZE)
+#define H_PTRS_PER_PMD		(1 << H_PMD_INDEX_SIZE)
+#define H_PTRS_PER_PUD		(1 << H_PUD_INDEX_SIZE)
+
 /* Bits to set in a PMD/PUD/PGD entry valid bit*/
 #define HASH_PMD_VAL_BITS		(0x8000000000000000UL)
 #define HASH_PUD_VAL_BITS		(0x8000000000000000UL)
diff --git a/arch/powerpc/include/asm/book3s/64/pgtable.h b/arch/powerpc/include/asm/book3s/64/pgtable.h
index 875730d5af40..010eb373fcb3 100644
--- a/arch/powerpc/include/asm/book3s/64/pgtable.h
+++ b/arch/powerpc/include/asm/book3s/64/pgtable.h
@@ -232,6 +232,9 @@ extern unsigned long __pmd_frag_size_shift;
 #define PTRS_PER_PUD	(1 << PUD_INDEX_SIZE)
 #define PTRS_PER_PGD	(1 << PGD_INDEX_SIZE)
 
+#define MAX_PTRS_PER_PTE ((H_PTRS_PER_PTE > R_PTRS_PER_PTE) ? H_PTRS_PER_PTE : R_PTRS_PER_PTE)
+#define MAX_PTRS_PER_PMD ((H_PTRS_PER_PMD > R_PTRS_PER_PMD) ? H_PTRS_PER_PMD : R_PTRS_PER_PMD)
+#define MAX_PTRS_PER_PUD ((H_PTRS_PER_PUD > R_PTRS_PER_PUD) ? H_PTRS_PER_PUD : R_PTRS_PER_PUD)
 #define MAX_PTRS_PER_PGD	(1 << (H_PGD_INDEX_SIZE > RADIX_PGD_INDEX_SIZE ? \
 				       H_PGD_INDEX_SIZE : RADIX_PGD_INDEX_SIZE))
 
diff --git a/arch/powerpc/include/asm/book3s/64/radix.h b/arch/powerpc/include/asm/book3s/64/radix.h
index d090d9612348..686001eda936 100644
--- a/arch/powerpc/include/asm/book3s/64/radix.h
+++ b/arch/powerpc/include/asm/book3s/64/radix.h
@@ -35,6 +35,11 @@
 #define RADIX_PMD_SHIFT		(PAGE_SHIFT + RADIX_PTE_INDEX_SIZE)
 #define RADIX_PUD_SHIFT		(RADIX_PMD_SHIFT + RADIX_PMD_INDEX_SIZE)
 #define RADIX_PGD_SHIFT		(RADIX_PUD_SHIFT + RADIX_PUD_INDEX_SIZE)
+
+#define R_PTRS_PER_PTE		(1 << RADIX_PTE_INDEX_SIZE)
+#define R_PTRS_PER_PMD		(1 << RADIX_PMD_INDEX_SIZE)
+#define R_PTRS_PER_PUD		(1 << RADIX_PUD_INDEX_SIZE)
+
 /*
  * Size of EA range mapped by our pagetables.
  */
@@ -68,11 +73,11 @@
  *
  *
  * 3rd quadrant expanded:
- * +------------------------------+
- * |                              |
+ * +------------------------------+  Highest address (0xc010000000000000)
+ * +------------------------------+  KASAN shadow end (0xc00fc00000000000)
  * |                              |
  * |                              |
- * +------------------------------+  Kernel vmemmap end (0xc010000000000000)
+ * +------------------------------+  Kernel vmemmap end/shadow start (0xc00e000000000000)
  * |                              |
  * |           512TB		  |
  * |                              |
@@ -91,6 +96,7 @@
  * +------------------------------+  Kernel linear (0xc.....)
  */
 
+/* For the sizes of the shadow area, see kasan.h */
 
 /*
  * If we store section details in page->flags we can't increase the MAX_PHYSMEM_BITS
diff --git a/arch/powerpc/include/asm/kasan.h b/arch/powerpc/include/asm/kasan.h
index 3c478e5ef24c..a6be4025cba2 100644
--- a/arch/powerpc/include/asm/kasan.h
+++ b/arch/powerpc/include/asm/kasan.h
@@ -30,9 +30,31 @@
 
 #define KASAN_SHADOW_OFFSET	ASM_CONST(CONFIG_KASAN_SHADOW_OFFSET)
 
+#ifdef CONFIG_PPC32
 #define KASAN_SHADOW_END	(-(-KASAN_SHADOW_START >> KASAN_SHADOW_SCALE_SHIFT))
+#elif defined(CONFIG_PPC_BOOK3S_64)
+/*
+ * The shadow ends before the highest accessible address
+ * because we don't need a shadow for the shadow. Instead:
+ * c00e000000000000 << 3 + a80e000000000000 = c00fc00000000000
+ */
+#define KASAN_SHADOW_END 0xc00fc00000000000UL
+#endif
 
 #ifdef CONFIG_KASAN
+#ifdef CONFIG_PPC_BOOK3S_64
+DECLARE_STATIC_KEY_FALSE(powerpc_kasan_enabled_key);
+
+static __always_inline bool kasan_arch_is_ready(void)
+{
+	if (static_branch_likely(&powerpc_kasan_enabled_key))
+		return true;
+	return false;
+}
+
+#define kasan_arch_is_ready kasan_arch_is_ready
+#endif
+
 void kasan_early_init(void);
 void kasan_mmu_init(void);
 void kasan_init(void);
diff --git a/arch/powerpc/kernel/Makefile b/arch/powerpc/kernel/Makefile
index 4d7829399570..e46335da7f72 100644
--- a/arch/powerpc/kernel/Makefile
+++ b/arch/powerpc/kernel/Makefile
@@ -33,6 +33,17 @@ KASAN_SANITIZE_early_32.o := n
 KASAN_SANITIZE_cputable.o := n
 KASAN_SANITIZE_prom_init.o := n
 KASAN_SANITIZE_btext.o := n
+KASAN_SANITIZE_paca.o := n
+KASAN_SANITIZE_setup_64.o := n
+KASAN_SANITIZE_mce.o := n
+KASAN_SANITIZE_mce_power.o := n
+
+# we have to be particularly careful in ppc64 to exclude code that
+# runs with translations off, as we cannot access the shadow with
+# translations off. However, ppc32 can sanitize this.
+ifdef CONFIG_PPC64
+KASAN_SANITIZE_traps.o := n
+endif
 
 ifdef CONFIG_KASAN
 CFLAGS_early_32.o += -DDISABLE_BRANCH_PROFILING
diff --git a/arch/powerpc/kvm/Makefile b/arch/powerpc/kvm/Makefile
index 9bdfc8b50899..ed0569b2a3d4 100644
--- a/arch/powerpc/kvm/Makefile
+++ b/arch/powerpc/kvm/Makefile
@@ -134,3 +134,8 @@ obj-$(CONFIG_KVM_BOOK3S_64_PR) += kvm-pr.o
 obj-$(CONFIG_KVM_BOOK3S_64_HV) += kvm-hv.o
 
 obj-y += $(kvm-book3s_64-builtin-objs-y)
+
+# KVM does a lot in real-mode, and 64-bit Book3S KASAN doesn't support that
+ifdef CONFIG_PPC_BOOK3S_64
+KASAN_SANITIZE := n
+endif
diff --git a/arch/powerpc/mm/book3s64/Makefile b/arch/powerpc/mm/book3s64/Makefile
index 2d50cac499c5..3150159e5121 100644
--- a/arch/powerpc/mm/book3s64/Makefile
+++ b/arch/powerpc/mm/book3s64/Makefile
@@ -24,3 +24,12 @@ obj-$(CONFIG_PPC_PKEY)	+= pkeys.o
 
 # Instrumenting the SLB fault path can lead to duplicate SLB entries
 KCOV_INSTRUMENT_slb.o := n
+
+# Parts of these can run in real mode and therefore are
+# not safe with the current outline KASAN implementation
+KASAN_SANITIZE_mmu_context.o := n
+KASAN_SANITIZE_pgtable.o := n
+KASAN_SANITIZE_radix_pgtable.o := n
+KASAN_SANITIZE_radix_tlb.o := n
+KASAN_SANITIZE_slb.o := n
+KASAN_SANITIZE_pkeys.o := n
diff --git a/arch/powerpc/mm/kasan/Makefile b/arch/powerpc/mm/kasan/Makefile
index bcbfd6f2eca3..4999aadb1867 100644
--- a/arch/powerpc/mm/kasan/Makefile
+++ b/arch/powerpc/mm/kasan/Makefile
@@ -5,3 +5,4 @@ KASAN_SANITIZE := n
 obj-$(CONFIG_PPC32)		+= init_32.o
 obj-$(CONFIG_PPC_8xx)		+= 8xx.o
 obj-$(CONFIG_PPC_BOOK3S_32)	+= book3s_32.o
+obj-$(CONFIG_PPC_BOOK3S_64)	+= init_book3s_64.o
diff --git a/arch/powerpc/mm/kasan/init_book3s_64.c b/arch/powerpc/mm/kasan/init_book3s_64.c
new file mode 100644
index 000000000000..afe551b03db9
--- /dev/null
+++ b/arch/powerpc/mm/kasan/init_book3s_64.c
@@ -0,0 +1,103 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * KASAN for 64-bit Book3S powerpc
+ *
+ * Copyright (C) 2019-2020 IBM Corporation
+ * Author: Daniel Axtens <dja@axtens.net>
+ */
+
+/*
+# ppc64 turns on virtual memory late in boot, after calling into generic code
+# like the device-tree parser, so it uses this in conjunction with a hook in
+# outline mode to avoid invalid access early in boot.
+*/
+
+#define DISABLE_BRANCH_PROFILING
+
+#include <linux/kasan.h>
+#include <linux/printk.h>
+#include <linux/sched/task.h>
+#include <linux/memblock.h>
+#include <asm/pgalloc.h>
+
+DEFINE_STATIC_KEY_FALSE(powerpc_kasan_enabled_key);
+
+static void __init kasan_init_phys_region(void *start, void *end)
+{
+	unsigned long k_start, k_end, k_cur;
+	void *va;
+
+	if (start >= end)
+		return;
+
+	k_start = ALIGN_DOWN((unsigned long)kasan_mem_to_shadow(start), PAGE_SIZE);
+	k_end = ALIGN((unsigned long)kasan_mem_to_shadow(end), PAGE_SIZE);
+
+	va = memblock_alloc(k_end - k_start, PAGE_SIZE);
+	for (k_cur = k_start; k_cur < k_end; k_cur += PAGE_SIZE, va += PAGE_SIZE)
+		map_kernel_page(k_cur, __pa(va), PAGE_KERNEL);
+}
+
+void __init kasan_init(void)
+{
+	/*
+	 * We want to do the following things:
+	 *  1) Map real memory into the shadow for all physical memblocks
+	 *     This takes us from c000... to c008...
+	 *  2) Leave a hole over the shadow of vmalloc space. KASAN_VMALLOC
+	 *     will manage this for us.
+	 *     This takes us from c008... to c00a...
+	 *  3) Map the 'early shadow'/zero page over iomap and vmemmap space.
+	 *     This takes us up to where we start at c00e...
+	 */
+
+	void *k_start = kasan_mem_to_shadow((void *)RADIX_VMALLOC_END);
+	void *k_end = kasan_mem_to_shadow((void *)RADIX_VMEMMAP_END);
+	phys_addr_t start, end;
+	u64 i;
+	pte_t zero_pte = pfn_pte(virt_to_pfn(kasan_early_shadow_page), PAGE_KERNEL);
+
+	if (!early_radix_enabled()) {
+		pr_warn("KASAN not enabled as it requires radix!");
+		return;
+	}
+
+	for_each_mem_range(i, &start, &end)
+		kasan_init_phys_region((void *)start, (void *)end);
+
+	for (i = 0; i < PTRS_PER_PTE; i++)
+		__set_pte_at(&init_mm, (unsigned long)kasan_early_shadow_page,
+			     &kasan_early_shadow_pte[i], zero_pte, 0);
+
+	for (i = 0; i < PTRS_PER_PMD; i++)
+		pmd_populate_kernel(&init_mm, &kasan_early_shadow_pmd[i],
+				    kasan_early_shadow_pte);
+
+	for (i = 0; i < PTRS_PER_PUD; i++)
+		pud_populate(&init_mm, &kasan_early_shadow_pud[i],
+			     kasan_early_shadow_pmd);
+
+	/* map the early shadow over the iomap and vmemmap space */
+	kasan_populate_early_shadow(k_start, k_end);
+
+	/* mark early shadow region as RO and wipe it */
+	zero_pte = pfn_pte(virt_to_pfn(kasan_early_shadow_page), PAGE_KERNEL_RO);
+	for (i = 0; i < PTRS_PER_PTE; i++)
+		__set_pte_at(&init_mm, (unsigned long)kasan_early_shadow_page,
+			     &kasan_early_shadow_pte[i], zero_pte, 0);
+
+	/*
+	 * clear_page relies on some cache info that hasn't been set up yet.
+	 * It ends up looping ~forever and blows up other data.
+	 * Use memset instead.
+	 */
+	memset(kasan_early_shadow_page, 0, PAGE_SIZE);
+
+	static_branch_inc(&powerpc_kasan_enabled_key);
+
+	/* Enable error messages */
+	init_task.kasan_depth = 0;
+	pr_info("KASAN init done\n");
+}
+
+void __init kasan_late_init(void) { }
diff --git a/arch/powerpc/mm/ptdump/ptdump.c b/arch/powerpc/mm/ptdump/ptdump.c
index 8c846982766f..2313053fe679 100644
--- a/arch/powerpc/mm/ptdump/ptdump.c
+++ b/arch/powerpc/mm/ptdump/ptdump.c
@@ -21,6 +21,7 @@
 #include <linux/seq_file.h>
 #include <asm/fixmap.h>
 #include <linux/const.h>
+#include <linux/kasan.h>
 #include <asm/page.h>
 #include <asm/hugetlb.h>
 
@@ -289,11 +290,11 @@ static void populate_markers(void)
 #endif
 	address_markers[i++].start_address = FIXADDR_START;
 	address_markers[i++].start_address = FIXADDR_TOP;
+#endif /* CONFIG_PPC64 */
 #ifdef CONFIG_KASAN
 	address_markers[i++].start_address = KASAN_SHADOW_START;
 	address_markers[i++].start_address = KASAN_SHADOW_END;
 #endif
-#endif /* CONFIG_PPC64 */
 }
 
 static int ptdump_show(struct seq_file *m, void *v)
diff --git a/arch/powerpc/platforms/Kconfig.cputype b/arch/powerpc/platforms/Kconfig.cputype
index 87bc1929ee5a..b6562d39b9c4 100644
--- a/arch/powerpc/platforms/Kconfig.cputype
+++ b/arch/powerpc/platforms/Kconfig.cputype
@@ -104,6 +104,7 @@ config PPC_BOOK3S_64
 	select HAVE_MOVE_PUD
 	select IRQ_WORK
 	select PPC_64S_HASH_MMU if !PPC_RADIX_MMU
+	select KASAN_VMALLOC if KASAN
 
 config PPC_BOOK3E_64
 	bool "Embedded processors"
diff --git a/arch/powerpc/platforms/powernv/Makefile b/arch/powerpc/platforms/powernv/Makefile
index dc7b37c23b60..6488b3842199 100644
--- a/arch/powerpc/platforms/powernv/Makefile
+++ b/arch/powerpc/platforms/powernv/Makefile
@@ -1,4 +1,12 @@
 # SPDX-License-Identifier: GPL-2.0
+
+# nothing that deals with real mode is safe to KASAN
+# in particular, idle code runs a bunch of things in real mode
+KASAN_SANITIZE_idle.o := n
+KASAN_SANITIZE_pci-ioda.o := n
+# pnv_machine_check_early
+KASAN_SANITIZE_setup.o := n
+
 obj-y			+= setup.o opal-call.o opal-wrappers.o opal.o opal-async.o
 obj-y			+= idle.o opal-rtc.o opal-nvram.o opal-lpc.o opal-flash.o
 obj-y			+= rng.o opal-elog.o opal-dump.o opal-sysparam.o opal-sensor.o
diff --git a/arch/powerpc/platforms/pseries/Makefile b/arch/powerpc/platforms/pseries/Makefile
index ee60b59024b4..b407fdeb6e78 100644
--- a/arch/powerpc/platforms/pseries/Makefile
+++ b/arch/powerpc/platforms/pseries/Makefile
@@ -32,3 +32,6 @@ obj-$(CONFIG_SUSPEND)		+= suspend.o
 obj-$(CONFIG_PPC_VAS)		+= vas.o
 
 obj-$(CONFIG_ARCH_HAS_CC_PLATFORM)	+= cc_platform.o
+
+# nothing that operates in real mode is safe for KASAN
+KASAN_SANITIZE_ras.o := n
-- 
2.35.3

[PATCH v2 4/6] powerpc/kasan: Don't instrument non-maskable or raw interrupts

[Paul Mackerras]

From: Daniel Axtens <dja@axtens.net>

Disable address sanitization for raw and non-maskable interrupt
handlers, because they can run in real mode, where we cannot access
the shadow memory.  (Note that kasan_arch_is_ready() doesn't test for
real mode, since it is a static branch for speed, and in any case not
all the entry points to the generic KASAN code are protected by
kasan_arch_is_ready guards.)

The changes to interrupt_nmi_enter/exit_prepare() look larger than
they actually are.  The changes are equivalent to adding
!IS_ENABLED(CONFIG_KASAN) to the conditions for calling nmi_enter() or
nmi_exit() in real mode.  That is, the code is equivalent to using the
following condition for calling nmi_enter/exit:

	if (((!IS_ENABLED(CONFIG_PPC_BOOK3S_64) ||
			!firmware_has_feature(FW_FEATURE_LPAR) ||
			radix_enabled()) &&
		    !IS_ENABLED(CONFIG_KASAN) ||
		(mfmsr() & MSR_DR))

That unwieldy condition has been split into several statements with
comments, for easier reading.

The nmi_ipi_lock functions that call atomic functions (i.e.,
nmi_ipi_lock_start(), nmi_ipi_lock() and nmi_ipi_unlock()), besides
being marked noinstr, now call arch_atomic_* functions instead of
atomic_* functions because with KASAN enabled, the atomic_* functions
are wrappers which explicitly do address sanitization on their
arguments.  Since we are trying to avoid address sanitization, we have
to use the lower-level arch_atomic_* versions.

In hv_nmi_check_nonrecoverable(), the regs_set_unrecoverable() call
has been open-coded so as to avoid having to either trust the inlining
or mark regs_set_unrecoverable() as noinstr.

[paulus@ozlabs.org: combined a few work-in-progress commits of
 Daniel's and wrote the commit message.]

Signed-off-by: Daniel Axtens <dja@axtens.net>
Signed-off-by: Paul Mackerras <paulus@ozlabs.org>
---
 arch/powerpc/include/asm/interrupt.h | 52 +++++++++++++++++++++-------
 arch/powerpc/kernel/smp.c            | 22 ++++++------
 arch/powerpc/kernel/traps.c          |  6 ++--
 arch/powerpc/lib/Makefile            |  3 ++
 arch/powerpc/platforms/powernv/smp.c |  2 +-
 5 files changed, 59 insertions(+), 26 deletions(-)

diff --git a/arch/powerpc/include/asm/interrupt.h b/arch/powerpc/include/asm/interrupt.h
index fc28f46d2f9d..fb244b6ca7f0 100644
--- a/arch/powerpc/include/asm/interrupt.h
+++ b/arch/powerpc/include/asm/interrupt.h
@@ -327,22 +327,46 @@ static inline void interrupt_nmi_enter_prepare(struct pt_regs *regs, struct inte
 	}
 #endif
 
+	/* If data relocations are enabled, it's safe to use nmi_enter() */
+	if (mfmsr() & MSR_DR) {
+		nmi_enter();
+		return;
+	}
+
 	/*
-	 * Do not use nmi_enter() for pseries hash guest taking a real-mode
+	 * But do not use nmi_enter() for pseries hash guest taking a real-mode
 	 * NMI because not everything it touches is within the RMA limit.
 	 */
-	if (!IS_ENABLED(CONFIG_PPC_BOOK3S_64) ||
-			!firmware_has_feature(FW_FEATURE_LPAR) ||
-			radix_enabled() || (mfmsr() & MSR_DR))
-		nmi_enter();
+	if (IS_ENABLED(CONFIG_PPC_BOOK3S_64) &&
+	    firmware_has_feature(FW_FEATURE_LPAR) &&
+	    !radix_enabled())
+		return;
+
+	/*
+	 * Likewise, don't use it if we have some form of instrumentation (like
+	 * KASAN shadow) that is not safe to access in real mode (even on radix)
+	 */
+	if (IS_ENABLED(CONFIG_KASAN))
+		return;
+
+	/* Otherwise, it should be safe to call it */
+	nmi_enter();
 }
 
 static inline void interrupt_nmi_exit_prepare(struct pt_regs *regs, struct interrupt_nmi_state *state)
 {
-	if (!IS_ENABLED(CONFIG_PPC_BOOK3S_64) ||
-			!firmware_has_feature(FW_FEATURE_LPAR) ||
-			radix_enabled() || (mfmsr() & MSR_DR))
+	if (mfmsr() & MSR_DR) {
+		// nmi_exit if relocations are on
 		nmi_exit();
+	} else if (IS_ENABLED(CONFIG_PPC_BOOK3S_64) &&
+		   firmware_has_feature(FW_FEATURE_LPAR) &&
+		   !radix_enabled()) {
+		// no nmi_exit for a pseries hash guest taking a real mode exception
+	} else if (IS_ENABLED(CONFIG_KASAN)) {
+		// no nmi_exit for KASAN in real mode
+	} else {
+		nmi_exit();
+	}
 
 	/*
 	 * nmi does not call nap_adjust_return because nmi should not create
@@ -410,7 +434,8 @@ static inline void interrupt_nmi_exit_prepare(struct pt_regs *regs, struct inter
  * Specific handlers may have additional restrictions.
  */
 #define DEFINE_INTERRUPT_HANDLER_RAW(func)				\
-static __always_inline long ____##func(struct pt_regs *regs);		\
+static __always_inline __no_sanitize_address __no_kcsan long		\
+____##func(struct pt_regs *regs);					\
 									\
 interrupt_handler long func(struct pt_regs *regs)			\
 {									\
@@ -424,7 +449,8 @@ interrupt_handler long func(struct pt_regs *regs)			\
 }									\
 NOKPROBE_SYMBOL(func);							\
 									\
-static __always_inline long ____##func(struct pt_regs *regs)
+static __always_inline __no_sanitize_address __no_kcsan long		\
+____##func(struct pt_regs *regs)
 
 /**
  * DECLARE_INTERRUPT_HANDLER - Declare synchronous interrupt handler function
@@ -549,7 +575,8 @@ static __always_inline void ____##func(struct pt_regs *regs)
  * body with a pair of curly brackets.
  */
 #define DEFINE_INTERRUPT_HANDLER_NMI(func)				\
-static __always_inline long ____##func(struct pt_regs *regs);		\
+static __always_inline __no_sanitize_address __no_kcsan long		\
+____##func(struct pt_regs *regs);					\
 									\
 interrupt_handler long func(struct pt_regs *regs)			\
 {									\
@@ -566,7 +593,8 @@ interrupt_handler long func(struct pt_regs *regs)			\
 }									\
 NOKPROBE_SYMBOL(func);							\
 									\
-static __always_inline long ____##func(struct pt_regs *regs)
+static __always_inline  __no_sanitize_address __no_kcsan long		\
+____##func(struct pt_regs *regs)
 
 
 /* Interrupt handlers */
diff --git a/arch/powerpc/kernel/smp.c b/arch/powerpc/kernel/smp.c
index b7fd6a72aa76..5fedadc27952 100644
--- a/arch/powerpc/kernel/smp.c
+++ b/arch/powerpc/kernel/smp.c
@@ -413,32 +413,32 @@ static struct cpumask nmi_ipi_pending_mask;
 static bool nmi_ipi_busy = false;
 static void (*nmi_ipi_function)(struct pt_regs *) = NULL;
 
-static void nmi_ipi_lock_start(unsigned long *flags)
+noinstr static void nmi_ipi_lock_start(unsigned long *flags)
 {
 	raw_local_irq_save(*flags);
 	hard_irq_disable();
-	while (atomic_cmpxchg(&__nmi_ipi_lock, 0, 1) == 1) {
+	while (arch_atomic_cmpxchg(&__nmi_ipi_lock, 0, 1) == 1) {
 		raw_local_irq_restore(*flags);
-		spin_until_cond(atomic_read(&__nmi_ipi_lock) == 0);
+		spin_until_cond(arch_atomic_read(&__nmi_ipi_lock) == 0);
 		raw_local_irq_save(*flags);
 		hard_irq_disable();
 	}
 }
 
-static void nmi_ipi_lock(void)
+noinstr static void nmi_ipi_lock(void)
 {
-	while (atomic_cmpxchg(&__nmi_ipi_lock, 0, 1) == 1)
-		spin_until_cond(atomic_read(&__nmi_ipi_lock) == 0);
+	while (arch_atomic_cmpxchg(&__nmi_ipi_lock, 0, 1) == 1)
+		spin_until_cond(arch_atomic_read(&__nmi_ipi_lock) == 0);
 }
 
-static void nmi_ipi_unlock(void)
+noinstr static void nmi_ipi_unlock(void)
 {
 	smp_mb();
-	WARN_ON(atomic_read(&__nmi_ipi_lock) != 1);
-	atomic_set(&__nmi_ipi_lock, 0);
+	WARN_ON(arch_atomic_read(&__nmi_ipi_lock) != 1);
+	arch_atomic_set(&__nmi_ipi_lock, 0);
 }
 
-static void nmi_ipi_unlock_end(unsigned long *flags)
+noinstr static void nmi_ipi_unlock_end(unsigned long *flags)
 {
 	nmi_ipi_unlock();
 	raw_local_irq_restore(*flags);
@@ -447,7 +447,7 @@ static void nmi_ipi_unlock_end(unsigned long *flags)
 /*
  * Platform NMI handler calls this to ack
  */
-int smp_handle_nmi_ipi(struct pt_regs *regs)
+noinstr int smp_handle_nmi_ipi(struct pt_regs *regs)
 {
 	void (*fn)(struct pt_regs *) = NULL;
 	unsigned long flags;
diff --git a/arch/powerpc/kernel/traps.c b/arch/powerpc/kernel/traps.c
index a08bb7cefdc5..3aaa50e5c72f 100644
--- a/arch/powerpc/kernel/traps.c
+++ b/arch/powerpc/kernel/traps.c
@@ -393,7 +393,7 @@ void _exception(int signr, struct pt_regs *regs, int code, unsigned long addr)
  * Builds that do not support KVM could take this second option to increase
  * the recoverability of NMIs.
  */
-void hv_nmi_check_nonrecoverable(struct pt_regs *regs)
+noinstr void hv_nmi_check_nonrecoverable(struct pt_regs *regs)
 {
 #ifdef CONFIG_PPC_POWERNV
 	unsigned long kbase = (unsigned long)_stext;
@@ -433,7 +433,9 @@ void hv_nmi_check_nonrecoverable(struct pt_regs *regs)
 	return;
 
 nonrecoverable:
-	regs_set_unrecoverable(regs);
+	regs->msr &= ~MSR_RI;
+	local_paca->hsrr_valid = 0;
+	local_paca->srr_valid = 0;
 #endif
 }
 DEFINE_INTERRUPT_HANDLER_NMI(system_reset_exception)
diff --git a/arch/powerpc/lib/Makefile b/arch/powerpc/lib/Makefile
index 5d1881d2e39a..8560c912186d 100644
--- a/arch/powerpc/lib/Makefile
+++ b/arch/powerpc/lib/Makefile
@@ -13,6 +13,9 @@ CFLAGS_REMOVE_feature-fixups.o = $(CC_FLAGS_FTRACE)
 
 KASAN_SANITIZE_code-patching.o := n
 KASAN_SANITIZE_feature-fixups.o := n
+# restart_table.o contains functions called in the NMI interrupt path
+# which can be in real mode. Disable KASAN.
+KASAN_SANITIZE_restart_table.o := n
 
 ifdef CONFIG_KASAN
 CFLAGS_code-patching.o += -DDISABLE_BRANCH_PROFILING
diff --git a/arch/powerpc/platforms/powernv/smp.c b/arch/powerpc/platforms/powernv/smp.c
index cbb67813cd5d..9e1a25398f98 100644
--- a/arch/powerpc/platforms/powernv/smp.c
+++ b/arch/powerpc/platforms/powernv/smp.c
@@ -345,7 +345,7 @@ static void __init pnv_smp_probe(void)
 	}
 }
 
-static int pnv_system_reset_exception(struct pt_regs *regs)
+noinstr static int pnv_system_reset_exception(struct pt_regs *regs)
 {
 	if (smp_handle_nmi_ipi(regs))
 		return 1;
-- 
2.35.3

[PATCH v2 5/6] powerpc/kasan: Disable address sanitization in kexec paths

[Paul Mackerras]

From: Daniel Axtens <dja@axtens.net>

The kexec code paths involve code that necessarily run in real mode,
as CPUs are disabled and control is transferred to the new kernel.
Disable address sanitization for the kexec code and the functions
called in real mode on CPUs being disabled.

[paulus@ozlabs.org: combined a few work-in-progress commits of
 Daniel's and wrote the commit message.]

Signed-off-by: Daniel Axtens <dja@axtens.net>
Signed-off-by: Paul Mackerras <paulus@ozlabs.org>
---
 arch/powerpc/kexec/Makefile             | 2 ++
 arch/powerpc/platforms/pseries/Makefile | 3 +++
 arch/powerpc/sysdev/xics/xics-common.c  | 4 ++--
 arch/powerpc/sysdev/xive/common.c       | 4 ++--
 4 files changed, 9 insertions(+), 4 deletions(-)

diff --git a/arch/powerpc/kexec/Makefile b/arch/powerpc/kexec/Makefile
index b6c52608cb49..0c2abe7f9908 100644
--- a/arch/powerpc/kexec/Makefile
+++ b/arch/powerpc/kexec/Makefile
@@ -13,3 +13,5 @@ obj-$(CONFIG_KEXEC_FILE)	+= file_load.o ranges.o file_load_$(BITS).o elf_$(BITS)
 GCOV_PROFILE_core_$(BITS).o := n
 KCOV_INSTRUMENT_core_$(BITS).o := n
 UBSAN_SANITIZE_core_$(BITS).o := n
+KASAN_SANITIZE_core.o := n
+KASAN_SANITIZE_core_$(BITS) := n
diff --git a/arch/powerpc/platforms/pseries/Makefile b/arch/powerpc/platforms/pseries/Makefile
index b407fdeb6e78..98e878c32a21 100644
--- a/arch/powerpc/platforms/pseries/Makefile
+++ b/arch/powerpc/platforms/pseries/Makefile
@@ -35,3 +35,6 @@ obj-$(CONFIG_ARCH_HAS_CC_PLATFORM)	+= cc_platform.o
 
 # nothing that operates in real mode is safe for KASAN
 KASAN_SANITIZE_ras.o := n
+KASAN_SANITIZE_kexec.o := n
+#machine_kexec
+KASAN_SANITIZE_setup.o := n
diff --git a/arch/powerpc/sysdev/xics/xics-common.c b/arch/powerpc/sysdev/xics/xics-common.c
index f3fb2a12124c..322b2b8bd467 100644
--- a/arch/powerpc/sysdev/xics/xics-common.c
+++ b/arch/powerpc/sysdev/xics/xics-common.c
@@ -146,7 +146,7 @@ void __init xics_smp_probe(void)
 
 #endif /* CONFIG_SMP */
 
-void xics_teardown_cpu(void)
+noinstr void xics_teardown_cpu(void)
 {
 	struct xics_cppr *os_cppr = this_cpu_ptr(&xics_cppr);
 
@@ -159,7 +159,7 @@ void xics_teardown_cpu(void)
 	icp_ops->teardown_cpu();
 }
 
-void xics_kexec_teardown_cpu(int secondary)
+noinstr void xics_kexec_teardown_cpu(int secondary)
 {
 	xics_teardown_cpu();
 
diff --git a/arch/powerpc/sysdev/xive/common.c b/arch/powerpc/sysdev/xive/common.c
index 1ca5564bda9d..87b825b7401d 100644
--- a/arch/powerpc/sysdev/xive/common.c
+++ b/arch/powerpc/sysdev/xive/common.c
@@ -1241,7 +1241,7 @@ static int xive_setup_cpu_ipi(unsigned int cpu)
 	return 0;
 }
 
-static void xive_cleanup_cpu_ipi(unsigned int cpu, struct xive_cpu *xc)
+noinstr static void xive_cleanup_cpu_ipi(unsigned int cpu, struct xive_cpu *xc)
 {
 	unsigned int xive_ipi_irq = xive_ipi_cpu_to_irq(cpu);
 
@@ -1634,7 +1634,7 @@ void xive_flush_interrupt(void)
 
 #endif /* CONFIG_SMP */
 
-void xive_teardown_cpu(void)
+noinstr void xive_teardown_cpu(void)
 {
 	struct xive_cpu *xc = __this_cpu_read(xive_cpu);
 	unsigned int cpu = smp_processor_id();
-- 
2.35.3

[PATCH v2 6/6] Documentation/kasan: Update details of KASAN on powerpc

[Paul Mackerras]

From: Daniel Axtens <dja@axtens.net>

Signed-off-by: Paul Mackerras <paulus@ozlabs.org>
---
 Documentation/dev-tools/kasan.rst | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/Documentation/dev-tools/kasan.rst b/Documentation/dev-tools/kasan.rst
index 8089c559d339..448995c11bee 100644
--- a/Documentation/dev-tools/kasan.rst
+++ b/Documentation/dev-tools/kasan.rst
@@ -36,7 +36,9 @@ Both software KASAN modes work with SLUB and SLAB memory allocators,
 while the hardware tag-based KASAN currently only supports SLUB.
 
 Currently, generic KASAN is supported for the x86_64, arm, arm64, xtensa, s390,
-and riscv architectures, and tag-based KASAN modes are supported only for arm64.
+and riscv architectures. It is also supported on powerpc for 32-bit kernels and
+for 64-bit kernels running under the Radix MMU. Tag-based KASAN modes are
+supported only for arm64.
 
 Usage
 -----
@@ -351,6 +353,9 @@ With ``CONFIG_KASAN_VMALLOC``, KASAN can cover vmalloc space at the
 cost of greater memory usage. Currently, this is supported on x86,
 riscv, s390, and powerpc.
 
+It is optional, except on 64-bit powerpc kernels, and on 32-bit
+powerpc kernels with module support, where it is required.
+
 This works by hooking into vmalloc and vmap and dynamically
 allocating real shadow memory to back the mappings.
 
-- 
2.35.3

Re: [PATCH v2 0/6] KASAN support for 64-bit Book 3S powerpc

[Christophe Leroy]

Le 18/05/2022 à 12:03, Paul Mackerras a écrit :
> This patch series implements KASAN on 64-bit POWER with radix MMU,
> such as POWER9 or POWER10.  Daniel Axtens posted previous versions of
> these patches, but is no longer working on KASAN, and I have been
> asked to get them ready for inclusion.
> 
> Because of various technical difficulties, mostly around the need to
> allow for code that runs in real mode, we only support "outline" mode
> (as opposed to "inline" mode), where the compiler adds a call to
> a checking procedure before every store to memory.
> 
> This series has known deficiencies, specifically that the kernel will
> crash on boot on a HPT system, and that out-of-bounds accesses to
> module global data are not caught (which leads to one of the KASAN
> tests failing).
> 
> v2: Split the large patch 3/3 of the previous series into three
> patches and addressed review comments; put the generic documentation
> changes in a separate patch at the end of the series; removed the RFC
> tag.
> 
> Comments welcome.

The series looks good to me.

Maybe patch 3 should go after patches 4 and 5 which are preparation patches.

Christophe

> 
> Paul.
> 
>   Documentation/dev-tools/kasan.rst                  |   7 +-
>   Documentation/powerpc/kasan.txt                    |  58 ++++++++++++
>   arch/powerpc/Kconfig                               |   5 +-
>   arch/powerpc/Kconfig.debug                         |   3 +-
>   arch/powerpc/include/asm/book3s/64/hash.h          |   4 +
>   arch/powerpc/include/asm/book3s/64/pgtable.h       |   3 +
>   arch/powerpc/include/asm/book3s/64/radix.h         |  12 ++-
>   arch/powerpc/include/asm/interrupt.h               |  52 ++++++++---
>   arch/powerpc/include/asm/kasan.h                   |  22 +++++
>   arch/powerpc/kernel/Makefile                       |  11 +++
>   arch/powerpc/kernel/smp.c                          |  22 ++---
>   arch/powerpc/kernel/traps.c                        |   6 +-
>   arch/powerpc/kexec/Makefile                        |   2 +
>   arch/powerpc/kvm/Makefile                          |   5 +
>   arch/powerpc/lib/Makefile                          |   3 +
>   arch/powerpc/mm/book3s64/Makefile                  |   9 ++
>   arch/powerpc/mm/kasan/Makefile                     |   3 +-
>   .../mm/kasan/{kasan_init_32.c => init_32.c}        |   0
>   arch/powerpc/mm/kasan/init_book3s_64.c             | 103 +++++++++++++++++++++
>   arch/powerpc/mm/ptdump/ptdump.c                    |   3 +-
>   arch/powerpc/platforms/Kconfig.cputype             |   1 +
>   arch/powerpc/platforms/powernv/Makefile            |   8 ++
>   arch/powerpc/platforms/powernv/smp.c               |   2 +-
>   arch/powerpc/platforms/pseries/Makefile            |   6 ++
>   arch/powerpc/sysdev/xics/xics-common.c             |   4 +-
>   arch/powerpc/sysdev/xive/common.c                  |   4 +-
>   26 files changed, 320 insertions(+), 38 deletions(-)

Re: [PATCH v2 0/6] KASAN support for 64-bit Book 3S powerpc

[Michael Ellerman]

On Wed, 18 May 2022 20:03:27 +1000, Paul Mackerras wrote:
> This patch series implements KASAN on 64-bit POWER with radix MMU,
> such as POWER9 or POWER10.  Daniel Axtens posted previous versions of
> these patches, but is no longer working on KASAN, and I have been
> asked to get them ready for inclusion.
> 
> Because of various technical difficulties, mostly around the need to
> allow for code that runs in real mode, we only support "outline" mode
> (as opposed to "inline" mode), where the compiler adds a call to
> a checking procedure before every store to memory.
> 
> [...]

Patches 1-5 applied to powerpc/next.

[1/6] kasan: Document support on 32-bit powerpc
      https://git.kernel.org/powerpc/c/60e832def18de7a0753393034c6ae459b3bee70a
[2/6] powerpc/mm/kasan: rename kasan_init_32.c to init_32.c
      https://git.kernel.org/powerpc/c/f08aed52412c860f68e30da148da58ad8e40a43b
[3/6] powerpc: Book3S 64-bit outline-only KASAN support
      https://git.kernel.org/powerpc/c/41b7a347bf1491e7300563bb224432608b41f62a
[4/6] powerpc/kasan: Don't instrument non-maskable or raw interrupts
      https://git.kernel.org/powerpc/c/5352090a999570c6e8a701bcb755fd91e8c5a2cd
[5/6] powerpc/kasan: Disable address sanitization in kexec paths
      https://git.kernel.org/powerpc/c/2ab2d5794f14c08676690bf0859f16cc768bb3a4

cheers

Re: [PATCH v2 3/6] powerpc: Book3S 64-bit outline-only KASAN support

[Guenter Roeck]

Hi,

On Wed, May 18, 2022 at 08:05:31PM +1000, Paul Mackerras wrote:
> From: Daniel Axtens <dja@axtens.net>
> 
> Implement a limited form of KASAN for Book3S 64-bit machines running under
> the Radix MMU, supporting only outline mode.
> 
>  - Enable the compiler instrumentation to check addresses and maintain the
>    shadow region. (This is the guts of KASAN which we can easily reuse.)
> 
>  - Require kasan-vmalloc support to handle modules and anything else in
>    vmalloc space.
> 
>  - KASAN needs to be able to validate all pointer accesses, but we can't
>    instrument all kernel addresses - only linear map and vmalloc. On boot,
>    set up a single page of read-only shadow that marks all iomap and
>    vmemmap accesses as valid.
> 
>  - Document KASAN in powerpc docs.
> 

With this patch applied, powerpc:allmodconfig builds fail as follows.

Building powerpc:allmodconfig ... failed
--------------
Error log:
Error: External symbol 'memset' referenced from prom_init.c
make[3]: [arch/powerpc/kernel/Makefile:202: arch/powerpc/kernel/prom_init_check] Error 1 (ignored)
powerpc64-linux-ld: drivers/gpu/drm/amd/amdgpu/../display/dc/dml/display_mode_lib.o uses hard float, drivers/gpu/drm/amd/amdgpu/../display/dc/dcn31/dcn31_resource.o uses soft float
powerpc64-linux-ld: failed to merge target specific data of file drivers/gpu/drm/amd/amdgpu/../display/dc/dcn31/dcn31_resource.o
powerpc64-linux-ld: drivers/gpu/drm/amd/amdgpu/../display/dc/dml/display_mode_lib.o uses hard float, drivers/gpu/drm/amd/amdgpu/../display/dc/dcn315/dcn315_resource.o uses soft float
powerpc64-linux-ld: failed to merge target specific data of file drivers/gpu/drm/amd/amdgpu/../display/dc/dcn315/dcn315_resource.o
powerpc64-linux-ld: drivers/gpu/drm/amd/amdgpu/../display/dc/dml/display_mode_lib.o uses hard float, drivers/gpu/drm/amd/amdgpu/../display/dc/dcn316/dcn316_resource.o uses soft float
powerpc64-linux-ld: failed to merge target specific data of file drivers/gpu/drm/amd/amdgpu/../display/dc/dcn316/dcn316_resource.o
make[5]: [scripts/Makefile.build:435: drivers/gpu/drm/amd/amdgpu/amdgpu.o] Error 1 (ignored)
make[2]: *** No rule to make target 'drivers/gpu/drm/amd/amdgpu/amdgpu.o', needed by 'modules-only.symvers'.  Stop.
make[1]: [Makefile:1753: modules] Error 2 (ignored)

This is with gcc 11.3 and binutils 2.38. I also tried with gcc 11.2 and
binutils 2.36.1, with the same results.

Reverting this patch fixes the problem.

Guenter

Re: [PATCH v2 6/6] Documentation/kasan: Update details of KASAN on powerpc

[Christophe Leroy]

Le 18/05/2022 à 12:07, Paul Mackerras a écrit :
> From: Daniel Axtens <dja@axtens.net>
> 
> Signed-off-by: Paul Mackerras <paulus@ozlabs.org>

This change doesn't apply, can you rebase ?

Thanks
Christophe

> ---
>   Documentation/dev-tools/kasan.rst | 7 ++++++-
>   1 file changed, 6 insertions(+), 1 deletion(-)
> 
> diff --git a/Documentation/dev-tools/kasan.rst b/Documentation/dev-tools/kasan.rst
> index 8089c559d339..448995c11bee 100644
> --- a/Documentation/dev-tools/kasan.rst
> +++ b/Documentation/dev-tools/kasan.rst
> @@ -36,7 +36,9 @@ Both software KASAN modes work with SLUB and SLAB memory allocators,
>   while the hardware tag-based KASAN currently only supports SLUB.
>   
>   Currently, generic KASAN is supported for the x86_64, arm, arm64, xtensa, s390,
> -and riscv architectures, and tag-based KASAN modes are supported only for arm64.
> +and riscv architectures. It is also supported on powerpc for 32-bit kernels and
> +for 64-bit kernels running under the Radix MMU. Tag-based KASAN modes are
> +supported only for arm64.
>   
>   Usage
>   -----
> @@ -351,6 +353,9 @@ With ``CONFIG_KASAN_VMALLOC``, KASAN can cover vmalloc space at the
>   cost of greater memory usage. Currently, this is supported on x86,
>   riscv, s390, and powerpc.
>   
> +It is optional, except on 64-bit powerpc kernels, and on 32-bit
> +powerpc kernels with module support, where it is required.
> +
>   This works by hooking into vmalloc and vmap and dynamically
>   allocating real shadow memory to back the mappings.
>