2019-11-15 01:02:54 +07:00
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# SPDX-License-Identifier: GPL-2.0
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ifdef CONFIG_KCSAN
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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 <elver@google.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Will Deacon <will@kernel.org>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20200521142047.169334-3-elver@google.com
2020-05-21 21:20:38 +07:00
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# GCC and Clang accept backend options differently. Do not wrap in cc-option,
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# because Clang accepts "--param" even if it is unused.
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ifdef CONFIG_CC_IS_CLANG
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cc-param = -mllvm -$(1)
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else
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cc-param = --param -$(1)
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endif
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2020-05-21 21:20:39 +07:00
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# Keep most options here optional, to allow enabling more compilers if absence
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# of some options does not break KCSAN nor causes false positive reports.
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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 <elver@google.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Will Deacon <will@kernel.org>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20200521142047.169334-3-elver@google.com
2020-05-21 21:20:38 +07:00
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CFLAGS_KCSAN := -fsanitize=thread \
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2020-05-21 21:20:39 +07:00
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$(call cc-option,$(call cc-param,tsan-instrument-func-entry-exit=0) -fno-optimize-sibling-calls) \
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2020-05-21 21:20:40 +07:00
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$(call cc-option,$(call cc-param,tsan-instrument-read-before-write=1)) \
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2020-05-21 21:20:39 +07:00
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$(call cc-param,tsan-distinguish-volatile=1)
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2019-11-15 01:02:54 +07:00
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endif # CONFIG_KCSAN
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