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authorDaniel Axtens <dja@axtens.net>2021-06-28 19:40:39 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2021-06-29 10:53:53 -0700
commit158f25522ca8cc87f512a03ed5e2a5923bd37eb3 (patch)
tree8704e29df9aabbe21841c2178446f49809c38dc5 /lib
parent3ff16d30f593d80a958104ee06a94562a12c5879 (diff)
kasan: allow an architecture to disable inline instrumentation
Patch series "KASAN core changes for ppc64 radix KASAN", v16. Building on the work of Christophe, Aneesh and Balbir, I've ported KASAN to 64-bit Book3S kernels running on the Radix MMU. I've been trying this for a while, but we keep having collisions between the kasan code in the mm tree and the code I want to put in to the ppc tree. This series just contains the kasan core changes that we need. There should be no noticeable changes to other platforms. This patch (of 4): 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. * on ppc64 atm, the shadow lives in virtual memory and isn't accessible in real mode. However, before we turn on virtual memory, we parse the device tree to determine which platform and MMU we're running under. That calls generic DT code, which is instrumented. Inline instrumentation in DT would unconditionally attempt to touch the shadow region, which we won't have set up yet, and would crash. We can make outline mode wait for the arch to be ready, but we can't change what the compiler inserts for inline mode. Link: https://lkml.kernel.org/r/20210624034050.511391-1-dja@axtens.net Link: https://lkml.kernel.org/r/20210624034050.511391-2-dja@axtens.net Signed-off-by: Daniel Axtens <dja@axtens.net> Reviewed-by: Marco Elver <elver@google.com> Reviewed-by: Andrey Konovalov <andreyknvl@gmail.com> Cc: Christophe Leroy <christophe.leroy@csgroup.eu> Cc: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com> Cc: Balbir Singh <bsingharora@gmail.com> Cc: Alexander Potapenko <glider@google.com> Cc: Andrey Ryabinin <ryabinin.a.a@gmail.com> Cc: Dmitry Vyukov <dvyukov@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'lib')
-rw-r--r--lib/Kconfig.kasan12
1 files changed, 12 insertions, 0 deletions
diff --git a/lib/Kconfig.kasan b/lib/Kconfig.kasan
index cffc2ebbf185..c3b228828a80 100644
--- a/lib/Kconfig.kasan
+++ b/lib/Kconfig.kasan
@@ -12,6 +12,13 @@ config HAVE_ARCH_KASAN_HW_TAGS
config HAVE_ARCH_KASAN_VMALLOC
bool
+config ARCH_DISABLE_KASAN_INLINE
+ bool
+ help
+ An architecture might not support inline instrumentation.
+ When this option is selected, inline and stack instrumentation are
+ disabled.
+
config CC_HAS_KASAN_GENERIC
def_bool $(cc-option, -fsanitize=kernel-address)
@@ -130,6 +137,7 @@ 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 +149,7 @@ 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 +163,9 @@ 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, stack
+ instrumentation is also disabled as it adds inline-style
+ instrumentation that is run unconditionally.
config KASAN_SW_TAGS_IDENTIFY
bool "Enable memory corruption identification"