Re: [PATCH v3] meson: Use -fno-sanitize=function when available

[Thomas Huth]

On 16/08/2024 09.30, Akihiko Odaki wrote:
> On 2024/08/16 16:27, Thomas Huth wrote:
> > On 16/08/2024 09.12, Akihiko Odaki wrote:
> > > On 2024/08/16 16:03, Thomas Huth wrote:
> > > > On 16/08/2024 08.22, Akihiko Odaki wrote:
> > > > > Commit 23ef50ae2d0c (".gitlab-ci.d/buildtest.yml: Use
> > > > > -fno-sanitize=function in the clang-system job") adds
> > > > > -fno-sanitize=function for the CI but doesn't add the flag in the
> > > > > other context. Add it to meson.build for such. It is not removed from
> > > > > .gitlab-ci.d/buildtest.yml because -fno-sanitize=function in meson.build
> > > > > does not affect --extra-cflags due to argument ordering.
> > > > >
> > > > > Signed-off-by: Akihiko Odaki <akihiko.odaki@daynix.com>
> > > > > ---
> > > > > Changes in v3:
> > > > > - I was not properly dropping the change of .gitlab-ci.d/buildtest.yml
> > > > >    but only updated the message. v3 fixes this. (Thomas Huth)
> > > > > - Link to v2: 
> > > > > https://lore.kernel.org/r/20240729-function-v2-1-2401ab18b30b@daynix.com
> > > > > Changes in v2:
> > > > > - Dropped the change of: .gitlab-ci.d/buildtest.yml
> > > > > - Link to v1: 
> > > > > https://lore.kernel.org/r/20240714-function-v1-1-cc2acb4171ba@daynix.com
> > > > > ---
> > > > >   meson.build | 1 +
> > > > >   1 file changed, 1 insertion(+)
> > > > >
> > > > > diff --git a/meson.build b/meson.build
> > > > > index 5613b62a4f42..a4169c572ba9 100644
> > > > > --- a/meson.build
> > > > > +++ b/meson.build
> > > > > @@ -609,6 +609,7 @@ if host_os != 'openbsd' and \
> > > > >   endif
> > > > >   qemu_common_flags += cc.get_supported_arguments(hardening_flags)
> > > > > +qemu_common_flags += cc.get_supported_arguments('-fno-sanitize=function')
> > > > As I mentioned in my last mail: I think it would make sense to move this 
> > > > at the end of the "if get_option('tsan')" block in meson.build, since 
> > > > this apparently only fixes the use of "--enable-sanitizers", and cannot 
> > > > fix the "--extra-cflags" that a user might have specified?
> > > Sorry, I missed it. It cannot fix --extra-cflags, but it should be able 
> > > to fix compiler flags specified by compiler distributor.
> > Oh, you mean that there are distros that enable -fsanitize=function by 
> > default? Can you name one? If so, I think that information should go into 
> > the patch description...?
> No, it is just a precaution.
Ok. I don't think any normal distro will enable this by default since this 
impacts performance of the programs, so it's either the user specifying 
--enable-sanitizers or the user specifying --extra-cflags="-fsanitize=...". 
In the latter case, your patch does not help. In the former case, I think 
this setting should go into the same code block as where we set 
-fsanitize=undefined in our meson.build file, so that it is clear where it 
belongs to.
 Thomas