Re: [PATCH v2 5/7] configure: Unnest detection of -z, relro and -z, now

[Fangrui Song]

On 2019-12-18, Philippe Mathieu-Daudé wrote:
> On 12/18/19 11:34 PM, Richard Henderson wrote:
> > There is nothing about these options that is related to PIE.
> > Use them unconditionally.
> >
> > Signed-off-by: Richard Henderson <address@hidden>
> > ---
> > v2: Do not split into two tests.
> > ---
> >  configure | 9 ++++++---
> >  1 file changed, 6 insertions(+), 3 deletions(-)
> >
> > diff --git a/configure b/configure
> > index 7a646ec007..2503288654 100755
> > --- a/configure
> > +++ b/configure
> > @@ -2040,9 +2040,6 @@ if test "$pie" != "no" ; then
> >      QEMU_CFLAGS="-fPIE -DPIE $QEMU_CFLAGS"
> >      LDFLAGS="-pie $LDFLAGS"
> >      pie="yes"
> > -    if compile_prog "" "-Wl,-z,relro -Wl,-z,now" ; then
> > -      LDFLAGS="-Wl,-z,relro -Wl,-z,now $LDFLAGS"
> > -    fi
> >    else
> >      if test "$pie" = "yes"; then
> >        error_exit "PIE not available due to missing toolchain support"
> > @@ -2053,6 +2050,12 @@ if test "$pie" != "no" ; then
> >    fi
> >  fi
> > +# Detect support for PT_GNU_RELRO + DT_BIND_NOW.
> > +# The combination is known as "full relro", because .got is read-only too.
> > +if compile_prog "" "-Wl,-z,relro -Wl,-z,now" ; then
> > +  LDFLAGS="-Wl,-z,relro -Wl,-z,now $LDFLAGS"
> > +fi
> > +
> >  ##########################################
> >  # __sync_fetch_and_and requires at least -march=i486. Many toolchains
> >  # use i686 as default anyway, but for those that don't, an explicit
>
> Reviewed-by: Philippe Mathieu-Daudé <address@hidden>

One nit, .got is also read-only in partial relro. Full relro makes .got.plt
read-only. (On EM_PPC and EM_PPC64, .got.plt is named .plt (yes,
misnomer)).

Reviewed-by: Fangrui Song <address@hidden>