On Tue, Oct 24, 2023 at 09:22:25AM +0200, Richard Biener wrote: > On Mon, Oct 23, 2023 at 9:26 PM Marek Polacek <pola...@redhat.com> wrote: > > > > On Thu, Oct 19, 2023 at 02:24:11PM +0200, Richard Biener wrote: > > > On Wed, Oct 11, 2023 at 10:48 PM Marek Polacek <pola...@redhat.com> wrote: > > > > > > > > On Tue, Sep 19, 2023 at 10:58:19AM -0400, Marek Polacek wrote: > > > > > On Mon, Sep 18, 2023 at 08:57:39AM +0200, Richard Biener wrote: > > > > > > On Fri, Sep 15, 2023 at 5:09 PM Marek Polacek via Gcc-patches > > > > > > <gcc-patches@gcc.gnu.org> wrote: > > > > > > > > > > > > > > Bootstrapped/regtested on x86_64-pc-linux-gnu, > > > > > > > powerpc64le-unknown-linux-gnu, > > > > > > > and aarch64-unknown-linux-gnu; ok for trunk? > > > > > > > > > > > > > > -- >8 -- > > > > > > > In > > > > > > > <https://gcc.gnu.org/pipermail/gcc-patches/2023-August/628748.html> > > > > > > > I proposed -fhardened, a new umbrella option that enables a > > > > > > > reasonable set > > > > > > > of hardening flags. The read of the room seems to be that the > > > > > > > option > > > > > > > would be useful. So here's a patch implementing that option. > > > > > > > > > > > > > > Currently, -fhardened enables: > > > > > > > > > > > > > > -D_FORTIFY_SOURCE=3 (or =2 for older glibcs) > > > > > > > -D_GLIBCXX_ASSERTIONS > > > > > > > -ftrivial-auto-var-init=pattern > > > > > > I think =zero is much better here given the overhead is way > > > cheaper and pointers get a more reliable behavior. > > > > Ok, changed now. > > > > > > > > > -fPIE -pie -Wl,-z,relro,-z,now > > > > > > > -fstack-protector-strong > > > > > > > -fstack-clash-protection > > > > > > > -fcf-protection=full (x86 GNU/Linux only) > > > > > > > > > > > > > > -fhardened will not override options that were specified on the > > > > > > > command line > > > > > > > (before or after -fhardened). For example, > > > > > > > > > > > > > > -D_FORTIFY_SOURCE=1 -fhardened > > > > > > > > > > > > > > means that _FORTIFY_SOURCE=1 will be used. Similarly, > > > > > > > > > > > > > > -fhardened -fstack-protector > > > > > > > > > > > > > > will not enable -fstack-protector-strong. > > > > > > > > > > > > > > In DW_AT_producer it is reflected only as -fhardened; it doesn't > > > > > > > expand > > > > > > > to anything. I think we need a better way to show what it > > > > > > > actually > > > > > > > enables. > > > > > > > > > > > > I do think we need to find a solution here to solve asserting > > > > > > compliance. > > > > > > > > > > Fair enough. > > > > > > > > > > > Maybe we can have -Whardened that will diagnose any altering of > > > > > > -fhardened by other options on the command-line or by missed target > > > > > > implementations? People might for example use -fstack-protector > > > > > > but don't really want to make protection lower than requested with > > > > > > -fhardened. > > > > > > > > > > > > Any such conflict is much less appearant than when you use the > > > > > > flags -fhardened composes. > > > > > > > > > > How about: --help=hardened says which options -fhardened attempts to > > > > > enable, and -Whardened warns when it didn't enable an option? E.g., > > > > > > > > > > -fstack-protector -fhardened -Whardened > > > > > > > > > > would say that it didn't enable -fstack-protector-strong because > > > > > -fstack-protector was specified on the command line? > > > > > > > > > > If !HAVE_LD_NOW_SUPPORT, --help=hardened probably doesn't even have to > > > > > list -z now, likewise for -z relro. > > > > > > > > > > Unclear if -Whardened should be enabled by default, but probably yes? > > > > > > > > Here's v2 which adds -Whardened (enabled by default). > > > > > > > > Bootstrapped/regtested on x86_64-pc-linux-gnu, ok for trunk? > > > > > > I think it's OK but I'd like to see a second ACK here. > > > > Thanks! > > > > > Can you see how our > > > primary and secondary targets (+ host OS) behave here? > > > > That's very reasonable. I tried to build gcc on Compile Farm 119 (AIX) but > > that fails with: > > > > ar -X64 x ../ppc64/libgcc/libgcc_s.a shr.o > > ar: 0707-100 ../ppc64/libgcc/libgcc_s.a does not exist. > > make[2]: *** [/home/polacek/gcc/libgcc/config/rs6000/t-slibgcc-aix:98: all] > > Error 1 > > make[2]: Leaving directory > > '/home/polacek/x/trunk/powerpc-ibm-aix7.3.1.0/libgcc' > > > > and I tried Darwin (104) and that fails with > > > > *** Configuration aarch64-apple-darwin21.6.0 not supported > > > > Is anyone else able to build gcc on those machines, or test the attached > > patch? > > > > > I think the > > > documentation should elaborate a bit on expectations for non-Linux/GNU > > > targets, specifically I think the default configuration for a target > > > should > > > with -fhardened _not_ have any -Whardened diagnostics. Maybe we can > > > have a testcase for this? > > > > Sorry, I'm not sure how to test that. I suppose if -fhardened enables > > something not supported on those systems, and it's something for which > > we have a configure test, then we shouldn't warn. This is already the > > case for -pie, -z relro, and -z now. > > I was thinking of > > /* { dg-do compile } */ > /* { dg-additional-options "-fhardened -Whardened" } */ > > int main () {} > > and excess errors should catch "misconfigurations"?
I see. fhardened-3.c is basically just like this (-Whardened is on by default). > > Should the docs say something like the following for features without > > configure checks? > > > > @option{-fhardened} can, on certain systems, attempt to enable features > > not supported on that particular system. In that case, it's possible to > > prevent the warning using the @option{-Wno-hardened} option. > > Yeah, but ideally > > @option{-fhardened} can, on certain systems, not enable features not > available on those systems and @option{-Whardened} will not diagnose > those as missing. > > But I understand it doesn't work like that? Right. It will not diagnose missing features if they have a configure check, otherwise it will. And I don't know if we want a configure check for every feature. Maybe we can add them in the future if the current patch turns out to be problematical in practice? Thanks, Marek