From: Daniel Axtens <dja@axtens.net>
To: linux-kernel@vger.kernel.org, linux-mm@kvack.org,
linuxppc-dev@lists.ozlabs.org, kasan-dev@googlegroups.com,
christophe.leroy@csgroup.eu, aneesh.kumar@linux.ibm.com,
bsingharora@gmail.com
Cc: elver@google.com, Daniel Axtens <dja@axtens.net>
Subject: [PATCH v12 1/6] kasan: allow an architecture to disable inline instrumentation
Date: Tue, 15 Jun 2021 11:47:00 +1000 [thread overview]
Message-ID: <20210615014705.2234866-2-dja@axtens.net> (raw)
In-Reply-To: <20210615014705.2234866-1-dja@axtens.net>
For annoying architectural reasons, it's very difficult to support inline
instrumentation on powerpc64.
Add a Kconfig flag to allow an arch to disable inline. (It's a bit
annoying to be 'backwards', but I'm not aware of any way to have
an arch force a symbol to be 'n', rather than 'y'.)
We also disable stack instrumentation in this case as it does things that
are functionally equivalent to inline instrumentation, namely adding
code that touches the shadow directly without going through a C helper.
Signed-off-by: Daniel Axtens <dja@axtens.net>
---
lib/Kconfig.kasan | 14 ++++++++++++++
1 file changed, 14 insertions(+)
diff --git a/lib/Kconfig.kasan b/lib/Kconfig.kasan
index cffc2ebbf185..935814f332a7 100644
--- a/lib/Kconfig.kasan
+++ b/lib/Kconfig.kasan
@@ -12,6 +12,15 @@ config HAVE_ARCH_KASAN_HW_TAGS
config HAVE_ARCH_KASAN_VMALLOC
bool
+# Sometimes an architecture might not be able to support inline instrumentation
+# but might be able to support outline instrumentation. This option allows an
+# arch to prevent inline and stack instrumentation from being enabled.
+# ppc64 turns on virtual memory late in boot, after calling into generic code
+# like the device-tree parser, so it uses this in conjuntion with a hook in
+# outline mode to avoid invalid access early in boot.
+config ARCH_DISABLE_KASAN_INLINE
+ bool
+
config CC_HAS_KASAN_GENERIC
def_bool $(cc-option, -fsanitize=kernel-address)
@@ -130,6 +139,7 @@ config KASAN_OUTLINE
config KASAN_INLINE
bool "Inline instrumentation"
+ depends on !ARCH_DISABLE_KASAN_INLINE
help
Compiler directly inserts code checking shadow memory before
memory accesses. This is faster than outline (in some workloads
@@ -141,6 +151,7 @@ endchoice
config KASAN_STACK
bool "Enable stack instrumentation (unsafe)" if CC_IS_CLANG && !COMPILE_TEST
depends on KASAN_GENERIC || KASAN_SW_TAGS
+ depends on !ARCH_DISABLE_KASAN_INLINE
default y if CC_IS_GCC
help
The LLVM stack address sanitizer has a know problem that
@@ -154,6 +165,9 @@ config KASAN_STACK
but clang users can still enable it for builds without
CONFIG_COMPILE_TEST. On gcc it is assumed to always be safe
to use and enabled by default.
+ If the architecture disables inline instrumentation, this is
+ also disabled as it adds inline-style instrumentation that
+ is run unconditionally.
config KASAN_SW_TAGS_IDENTIFY
bool "Enable memory corruption identification"
--
2.27.0
next prev parent reply other threads:[~2021-06-15 2:46 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-06-15 1:46 [PATCH v12 0/6] KASAN core changes for ppc64 radix KASAN Daniel Axtens
2021-06-15 1:47 ` Daniel Axtens [this message]
2021-06-15 7:46 ` [PATCH v12 1/6] kasan: allow an architecture to disable inline instrumentation Marco Elver
2021-06-15 7:46 ` Marco Elver
2021-06-15 7:46 ` Marco Elver
2021-06-16 4:39 ` Daniel Axtens
2021-06-16 4:39 ` Daniel Axtens
2021-06-15 1:47 ` [PATCH v12 2/6] kasan: allow architectures to provide an outline readiness check Daniel Axtens
2021-06-15 1:47 ` Daniel Axtens
2021-06-15 10:08 ` Marco Elver
2021-06-15 10:08 ` Marco Elver
2021-06-15 10:08 ` Marco Elver
2021-06-16 4:41 ` Daniel Axtens
2021-06-16 4:41 ` Daniel Axtens
2021-06-15 1:47 ` [PATCH v12 3/6] kasan: define and use MAX_PTRS_PER_* for early shadow tables Daniel Axtens
2021-06-15 1:47 ` [PATCH v12 4/6] kasan: Document support on 32-bit powerpc Daniel Axtens
2021-06-15 1:47 ` [PATCH v12 5/6] powerpc/mm/kasan: rename kasan_init_32.c to init_32.c Daniel Axtens
2021-06-15 1:47 ` [PATCH v12 6/6] [RFC] powerpc: Book3S 64-bit outline-only KASAN support Daniel Axtens
2021-06-15 10:31 ` [PATCH v12 0/6] KASAN core changes for ppc64 radix KASAN Marco Elver
2021-06-15 10:31 ` Marco Elver
2021-06-15 10:31 ` Marco Elver
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