[musl] Re: [PATCH v2] configure: define TARGET_LIBC_GNUSTACK on musl

[musl] Re: [PATCH v2] configure: define TARGET_LIBC_GNUSTACK on musl

[Dragan Mladjenovic]

Hi,

Looks fine to me. If possible, maybe it should even be back-ported to 
stable branches.

Not sure if MIPS assembly sources (if any) in musl would need explicit 
.note.GNU-stack

to complement this?

Best regards,

Dragan

On 16-Nov-21 06:13, Ilya Lipnitskiy wrote:
> musl only uses PT_GNU_STACK to set default thread stack size and has no
> executable stack support[0], so there is no reason not to emit the
> .note.GNU-stack section on musl builds.
>
> [0]: https://lore.kernel.org/all/20190423192534.GN23599@brightrain.aerifal.cx/T/#u
>
> gcc/ChangeLog:
>
> 	* configure: Regenerate.
> 	* configure.ac: define TARGET_LIBC_GNUSTACK on musl
>
> Signed-off-by: Ilya Lipnitskiy <ilya.lipnitskiy@gmail.com>
> ---
>   gcc/configure    | 3 +++
>   gcc/configure.ac | 3 +++
>   2 files changed, 6 insertions(+)
>
> diff --git a/gcc/configure b/gcc/configure
> index 74b9d9be4c85..7091a838aefa 100755
> --- a/gcc/configure
> +++ b/gcc/configure
> @@ -31275,6 +31275,9 @@ fi
>   # Check if the target LIBC handles PT_GNU_STACK.
>   gcc_cv_libc_gnustack=unknown
>   case "$target" in
> +  mips*-*-linux-musl*)
> +    gcc_cv_libc_gnustack=yes
> +    ;;
>     mips*-*-linux*)
>   
>   if test $glibc_version_major -gt 2 \
> diff --git a/gcc/configure.ac b/gcc/configure.ac
> index c9ee1fb8919e..8a2d34179a75 100644
> --- a/gcc/configure.ac
> +++ b/gcc/configure.ac
> @@ -6961,6 +6961,9 @@ fi
>   # Check if the target LIBC handles PT_GNU_STACK.
>   gcc_cv_libc_gnustack=unknown
>   case "$target" in
> +  mips*-*-linux-musl*)
> +    gcc_cv_libc_gnustack=yes
> +    ;;
>     mips*-*-linux*)
>       GCC_GLIBC_VERSION_GTE_IFELSE([2], [31], [gcc_cv_libc_gnustack=yes], )
>       ;;

Re: [musl] Re: [PATCH v2] configure: define TARGET_LIBC_GNUSTACK on musl

[Rich Felker]

On Tue, Nov 16, 2021 at 03:40:00PM +0100, Dragan Mladjenovic wrote:
> Hi,
> 
> Looks fine to me. If possible, maybe it should even be back-ported
> to stable branches.
> 
> Not sure if MIPS assembly sources (if any) in musl would need
> explicit ..note.GNU-stack
> 
> to complement this?

What are the actual consequences of making this change, and what is
the goal? I'm concerned that it might produce object files which don't
include annotation that they don't need executable stack, in which
case the final executable file will be marked as executable-stack and
the kernel will load it as such. That would be very bad.

Rich


> On 16-Nov-21 06:13, Ilya Lipnitskiy wrote:
> >musl only uses PT_GNU_STACK to set default thread stack size and has no
> >executable stack support[0], so there is no reason not to emit the
> >.note.GNU-stack section on musl builds.
> >
> >[0]: https://lore.kernel.org/all/20190423192534.GN23599@brightrain.aerifal.cx/T/#u
> >
> >gcc/ChangeLog:
> >
> >	* configure: Regenerate.
> >	* configure.ac: define TARGET_LIBC_GNUSTACK on musl
> >
> >Signed-off-by: Ilya Lipnitskiy <ilya.lipnitskiy@gmail.com>
> >---
> >  gcc/configure    | 3 +++
> >  gcc/configure.ac | 3 +++
> >  2 files changed, 6 insertions(+)
> >
> >diff --git a/gcc/configure b/gcc/configure
> >index 74b9d9be4c85..7091a838aefa 100755
> >--- a/gcc/configure
> >+++ b/gcc/configure
> >@@ -31275,6 +31275,9 @@ fi
> >  # Check if the target LIBC handles PT_GNU_STACK.
> >  gcc_cv_libc_gnustack=unknown
> >  case "$target" in
> >+  mips*-*-linux-musl*)
> >+    gcc_cv_libc_gnustack=yes
> >+    ;;
> >    mips*-*-linux*)
> >  if test $glibc_version_major -gt 2 \
> >diff --git a/gcc/configure.ac b/gcc/configure.ac
> >index c9ee1fb8919e..8a2d34179a75 100644
> >--- a/gcc/configure.ac
> >+++ b/gcc/configure.ac
> >@@ -6961,6 +6961,9 @@ fi
> >  # Check if the target LIBC handles PT_GNU_STACK.
> >  gcc_cv_libc_gnustack=unknown
> >  case "$target" in
> >+  mips*-*-linux-musl*)
> >+    gcc_cv_libc_gnustack=yes
> >+    ;;
> >    mips*-*-linux*)
> >      GCC_GLIBC_VERSION_GTE_IFELSE([2], [31], [gcc_cv_libc_gnustack=yes], )
> >      ;;

Re: [musl] Re: [PATCH v2] configure: define TARGET_LIBC_GNUSTACK on musl

[Ilya Lipnitskiy]

On Tue, Nov 16, 2021 at 8:41 AM Rich Felker <dalias@libc.org> wrote:
>
> On Tue, Nov 16, 2021 at 03:40:00PM +0100, Dragan Mladjenovic wrote:
> > Hi,
> >
> > Looks fine to me. If possible, maybe it should even be back-ported
> > to stable branches.
The change cherry-picks fine onto 10.x and 11.x branches. Should I
send out separate patches or can the committer of this patch apply it
to 10.x and 11.x?
> >
> > Not sure if MIPS assembly sources (if any) in musl would need
> > explicit ..note.GNU-stack
> >
> > to complement this?
>
> What are the actual consequences of making this change, and what is
> the goal? I'm concerned that it might produce object files which don't
> include annotation that they don't need executable stack, in which
> case the final executable file will be marked as executable-stack and
> the kernel will load it as such. That would be very bad.
It is actually the other way around - for MIPS hard-float targets on
non-glibc (or glibc < 2.31) without this change the .note.GNU-stack
annotation is not emitted by GCC.

Ilya
>
> Rich
>
>
> > On 16-Nov-21 06:13, Ilya Lipnitskiy wrote:
> > >musl only uses PT_GNU_STACK to set default thread stack size and has no
> > >executable stack support[0], so there is no reason not to emit the
> > >.note.GNU-stack section on musl builds.
> > >
> > >[0]: https://lore.kernel.org/all/20190423192534.GN23599@brightrain.aerifal.cx/T/#u
> > >
> > >gcc/ChangeLog:
> > >
> > >     * configure: Regenerate.
> > >     * configure.ac: define TARGET_LIBC_GNUSTACK on musl
> > >
> > >Signed-off-by: Ilya Lipnitskiy <ilya.lipnitskiy@gmail.com>
> > >---
> > >  gcc/configure    | 3 +++
> > >  gcc/configure.ac | 3 +++
> > >  2 files changed, 6 insertions(+)
> > >
> > >diff --git a/gcc/configure b/gcc/configure
> > >index 74b9d9be4c85..7091a838aefa 100755
> > >--- a/gcc/configure
> > >+++ b/gcc/configure
> > >@@ -31275,6 +31275,9 @@ fi
> > >  # Check if the target LIBC handles PT_GNU_STACK.
> > >  gcc_cv_libc_gnustack=unknown
> > >  case "$target" in
> > >+  mips*-*-linux-musl*)
> > >+    gcc_cv_libc_gnustack=yes
> > >+    ;;
> > >    mips*-*-linux*)
> > >  if test $glibc_version_major -gt 2 \
> > >diff --git a/gcc/configure.ac b/gcc/configure.ac
> > >index c9ee1fb8919e..8a2d34179a75 100644
> > >--- a/gcc/configure.ac
> > >+++ b/gcc/configure.ac
> > >@@ -6961,6 +6961,9 @@ fi
> > >  # Check if the target LIBC handles PT_GNU_STACK.
> > >  gcc_cv_libc_gnustack=unknown
> > >  case "$target" in
> > >+  mips*-*-linux-musl*)
> > >+    gcc_cv_libc_gnustack=yes
> > >+    ;;
> > >    mips*-*-linux*)
> > >      GCC_GLIBC_VERSION_GTE_IFELSE([2], [31], [gcc_cv_libc_gnustack=yes], )
> > >      ;;