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authorAnders Roxell <anders.roxell@linaro.org>2019-03-07 16:30:16 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2019-03-07 18:32:02 -0800
commit1a6a1dbeb72fce7517665b365085ea405490c2d5 (patch)
treee485878f879abac0c03ab366352bfee1cfc2aa61
parent663cb6340c6e84fe29aa6d0fa63d85ea6bd6cd19 (diff)
download96b-common-1a6a1dbeb72fce7517665b365085ea405490c2d5.tar.gz
lib/ubsan: default UBSAN_ALIGNMENT to not set
When booting an allmodconfig kernel, there are a lot of false-positives. With a message like this 'UBSAN: Undefined behaviour in...' with a call trace that follows. UBSAN warnings are a result of enabling noisy CONFIG_UBSAN_ALIGNMENT which is disabled by default if HAVE_EFFICIENT_UNALIGNED_ACCESS=y. It's noisy even if don't have efficient unaligned access, e.g. people often add __cacheline_aligned_in_smp in structs, but forget to align allocations of such struct (kmalloc() give 8-byte alignment in worst case). Rework so that when building a allmodconfig kernel that turns everything into '=m' or '=y' will turn off UBSAN_ALIGNMENT. [aryabinin@virtuozzo.com: changelog addition] Link: http://lkml.kernel.org/r/20181217150326.30933-1-anders.roxell@linaro.org Signed-off-by: Anders Roxell <anders.roxell@linaro.org> Suggested-by: Arnd Bergmann <arnd@arndb.de> Acked-by: Andrey Ryabinin <aryabinin@virtuozzo.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
-rw-r--r--lib/Kconfig.ubsan14
1 files changed, 9 insertions, 5 deletions
diff --git a/lib/Kconfig.ubsan b/lib/Kconfig.ubsan
index 98fa559ebd80..a2ae4a8e4fa6 100644
--- a/lib/Kconfig.ubsan
+++ b/lib/Kconfig.ubsan
@@ -27,15 +27,19 @@ config UBSAN_SANITIZE_ALL
Enabling this option will get kernel image size increased
significantly.
-config UBSAN_ALIGNMENT
- bool "Enable checking of pointers alignment"
+config UBSAN_NO_ALIGNMENT
+ bool "Disable checking of pointers alignment"
depends on UBSAN
- default y if !HAVE_EFFICIENT_UNALIGNED_ACCESS
+ default y if HAVE_EFFICIENT_UNALIGNED_ACCESS
help
- This option enables detection of unaligned memory accesses.
- Enabling this option on architectures that support unaligned
+ This option disables the check of unaligned memory accesses.
+ This option should be used when building allmodconfig.
+ Disabling this option on architectures that support unaligned
accesses may produce a lot of false positives.
+config UBSAN_ALIGNMENT
+ def_bool !UBSAN_NO_ALIGNMENT
+
config TEST_UBSAN
tristate "Module for testing for undefined behavior detection"
depends on m && UBSAN