[PATCH v11 1/6] kasan: allow an architecture to disable inline instrumentation
From: Daniel Axtens <hidden>
Date: 2021-03-19 14:41:51
Also in:
linux-mm, lkml
Subsystem:
kasan, library code, the rest · Maintainers:
Andrey Ryabinin, Andrew Morton, Linus Torvalds
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 <redacted> --- lib/Kconfig.kasan | 8 ++++++++ 1 file changed, 8 insertions(+)
diff --git a/lib/Kconfig.kasan b/lib/Kconfig.kasan
index cffc2ebbf185..7e237dbb6df3 100644
--- a/lib/Kconfig.kasan
+++ b/lib/Kconfig.kasan@@ -12,6 +12,9 @@ config HAVE_ARCH_KASAN_HW_TAGS config HAVE_ARCH_KASAN_VMALLOC bool +config ARCH_DISABLE_KASAN_INLINE + def_bool n + config CC_HAS_KASAN_GENERIC def_bool $(cc-option, -fsanitize=kernel-address)
@@ -130,6 +133,7 @@ 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
@@ -142,6 +146,7 @@ config KASAN_STACK bool "Enable stack instrumentation (unsafe)" if CC_IS_CLANG && !COMPILE_TEST depends on KASAN_GENERIC || KASAN_SW_TAGS default y if CC_IS_GCC + depends on !ARCH_DISABLE_KASAN_INLINE help The LLVM stack address sanitizer has a know problem that causes excessive stack usage in a lot of functions, see
@@ -154,6 +159,9 @@ 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"
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2.27.0