On 6/3/20 9:23 PM, Marco Elver wrote:
On Wed, 03 Jun 2020, Borislav Petkov wrote:
On Thu, May 14, 2020 at 12:05:38PM +0100, Will Deacon wrote:
Talking off-list, Clang >= 7 is pretty reasonable wrt inlining decisions
and the behaviour for __always_inline is:
* An __always_inline function inlined into a __no_sanitize function is
not instrumented
* An __always_inline function inlined into an instrumented function is
instrumented
* You can't mark a function as both __always_inline __no_sanitize, because
__no_sanitize functions are never inlined
GCC, on the other hand, may still inline __no_sanitize functions and then
subsequently instrument them.
Yeah, about that: I've been looking for a way to trigger this so that
I can show preprocessed source to gcc people. So do you guys have a
.config or somesuch I can try?
For example take this:
int x;
static inline __attribute__((no_sanitize_thread)) void
do_not_sanitize(void) {
x++;
}
void sanitize_this(void) {
do_not_sanitize();
}
Then
gcc-10 -O3 -fsanitize=thread -o example.o -c example.c
objdump -D example.o
Hello.
Thank you for the example. It seems to me that Clang does not inline a
no_sanitize_* function
into one which is instrumented. Is it a documented behavior ([1] doesn't
mention that)?
If so, we can do the same in GCC.
Thanks,
Martin
[1] https://clang.llvm.org/docs/AttributeReference.html#no-sanitize
will show that do_not_sanitize() was inlined into sanitize_this() and is
instrumented. (With Clang this doesn't happen.)
Hope this is enough.
Thanks,
-- Marco
