[CRIU] [PATCH] Fix gcc9 build failures

[Adrian Reber]

On Thu, Dec 26, 2019 at 10:43:05PM +0100, Salvatore Bonaccorso wrote:
> Hi,
> 
> On Wed, Jan 09, 2019 at 12:49:11PM +0000, Adrian Reber wrote:
> > From: Adrian Reber <areber at redhat.com>
> > 
> > I received this patch from Jeff Law as a fix for build failures with the
> > upcoming GCC 9. The following is Jeff Law's description of the patch:
> > 
> >  Attached you'll find the fix for criu.  You'll see it's just a matter
> >  of dropping the sp/esp clobber from the relevant asm statements.  THe
> >  details:
> > 
> >  criu has a macro which defines an asm which appears to want to set a new
> >  stack pointer, then directly issue a sigreturn call to the kernel.  Some
> >  variants clobber sp (aarch64, arm, x86), others do not (ppc, s390)
> > 
> >  While the asm does indeed set a new stack pointer, we never return from
> >  a sigreturn syscall -- at least not in the normal way.  We actually
> >  return back to the point where the process was interrupted by the
> >  signal.  So describing the affect of the asm on the stack pointer is
> >  pedantically correct, it actually has no real effect and can just be
> >  dropped to avoid the hard error from gcc-9.
> 
> In Debian, with gcc-9 we are seeing as well build failures on ppc64el
> and s390x similarly. See:
> 
> https://buildd.debian.org/status/fetch.php?pkg=criu&arch=s390x&ver=3.12-1&stamp=1570688225&raw=0
> https://buildd.debian.org/status/fetch.php?pkg=criu&arch=ppc64el&ver=3.12-1&stamp=1570688342&raw=0

In Fedora I am building CRIU 3.13 without any errors using GCC 9 on
s390x and ppc64le:

https://koji.fedoraproject.org/koji/buildinfo?buildID=1377921

The error you are seeing is, however, interesting as the file has not
seen any changes for a long time. Curious why it fails on Debian.

		Adrian