path: root/scripts
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authorMarco Elver <>2020-05-21 16:20:38 +0200
committerThomas Gleixner <>2020-06-11 20:04:00 +0200
commit17168f5c1bef4ec7c239e2dd5e3e60b862727dd4 (patch)
tree6f4b678199cac97c93a55922dec568b60b7798bc /scripts
parentea91a1d45d19469001a4955583187b0d75915759 (diff)
kcsan: Avoid inserting __tsan_func_entry/exit if possible
To avoid inserting __tsan_func_{entry,exit}, add option if supported by compiler. Currently only Clang can be told to not emit calls to these functions. It is safe to not emit these, since KCSAN does not rely on them. Note that, if we disable __tsan_func_{entry,exit}(), we need to disable tail-call optimization in sanitized compilation units, as otherwise we may skip frames in the stack trace; in particular when the tail called function is one of the KCSAN's runtime functions, and a report is generated, we might miss the function where the actual access occurred. Since __tsan_func_{entry,exit}() insertion effectively disabled tail-call optimization, there should be no observable change. This was caught and confirmed with kcsan-test & UNWINDER_ORC. Signed-off-by: Marco Elver <> Signed-off-by: Borislav Petkov <> Signed-off-by: Thomas Gleixner <> Acked-by: Will Deacon <> Acked-by: Peter Zijlstra (Intel) <> Link:
Diffstat (limited to 'scripts')
1 files changed, 10 insertions, 1 deletions
diff --git a/scripts/Makefile.kcsan b/scripts/Makefile.kcsan
index caf1111a28ae..20337a7ecf54 100644
--- a/scripts/Makefile.kcsan
+++ b/scripts/Makefile.kcsan
@@ -1,6 +1,15 @@
# SPDX-License-Identifier: GPL-2.0
-CFLAGS_KCSAN := -fsanitize=thread
+# GCC and Clang accept backend options differently. Do not wrap in cc-option,
+# because Clang accepts "--param" even if it is unused.
+cc-param = -mllvm -$(1)
+cc-param = --param -$(1)
+CFLAGS_KCSAN := -fsanitize=thread \
+ $(call cc-option,$(call cc-param,tsan-instrument-func-entry-exit=0) -fno-optimize-sibling-calls)