[Buildroot] [PATCH v2, 1/1] toolchain/toolchain-wrapper: fix gcc -v with relro

[Buildroot] [PATCH v2, 1/1] toolchain/toolchain-wrapper: fix gcc -v with relro

[Fabrice Fontaine]

rhash in version 1.4.0 with relro fails to build because gcc -v raises
the following build failure:

/data/buildroot-test/instance-1/output-1/host/mips64el-buildroot-linux-gnu/sysroot/soft-float/el/usr/lib64/Scrt1.o: In function `__start':
(.text+0x20): undefined reference to `main'
collect2: error: ld returned 1 exit status
Run result: 1

This build failure is raised because the toolchain-wrapper calls gcc with
-Wl,-z,relro and as a result gcc wrongly assumes that some linking must
be done.

Fixes:
 - http://autobuild.buildroot.org/results/8605c16cc28316954ce8b9dcc266974390c5da20

Signed-off-by: Fabrice Fontaine <fontaine.fabrice@gmail.com>
Tested-by: Peter Seiderer <ps.report@gmx.net>
---
Changes v1 -> v2 (after review of Peter Seiderer):
 - Fix typos in commit log and update comment in source code

 toolchain/toolchain-wrapper.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/toolchain/toolchain-wrapper.c b/toolchain/toolchain-wrapper.c
index 0fb6064b1c..2a7dd61729 100644
--- a/toolchain/toolchain-wrapper.c
+++ b/toolchain/toolchain-wrapper.c
@@ -453,10 +453,11 @@ int main(int argc, char **argv)
 			*cur++ = "-pie";
 	}
 #endif
-	/* Are we building the Linux Kernel or U-Boot? */
+	/* Are we building the Linux Kernel or U-Boot or displaying the programs invoked by the compiler? */
 	for (i = 1; i < argc; i++) {
 		if (!strcmp(argv[i], "-D__KERNEL__") ||
-		    !strcmp(argv[i], "-D__UBOOT__"))
+		    !strcmp(argv[i], "-D__UBOOT__") ||
+		    !strcmp(argv[i], "-v"))
 			break;
 	}
 	if (i == argc) {
-- 
2.29.2

[Buildroot] [PATCH v2, 1/1] toolchain/toolchain-wrapper: fix gcc -v with relro

[Yann E. MORIN]

Fabrice, All,

On 2020-12-24 11:18 +0100, Fabrice Fontaine spake thusly:
> rhash in version 1.4.0 with relro fails to build because gcc -v raises
> the following build failure:
> 
> /data/buildroot-test/instance-1/output-1/host/mips64el-buildroot-linux-gnu/sysroot/soft-float/el/usr/lib64/Scrt1.o: In function `__start':
> (.text+0x20): undefined reference to `main'
> collect2: error: ld returned 1 exit status
> Run result: 1
> 
> This build failure is raised because the toolchain-wrapper calls gcc with
> -Wl,-z,relro and as a result gcc wrongly assumes that some linking must
> be done.

Although I do undesrstand the problem, I am not sure this is a good
solution.

Indeed, it is perfectly legit to call gcc -v while doing an acutal
compile or link:

    $ echo 'main() { return 0; }' |gcc -v -Wl,-z,relro -o ess -x c -

Indeed, using -v is a good way to see the actual programs gcc calls in
the various steps, and has already helped me debug some difficult
issues...

So, I think we need to be a little bit smarter in how we detect whether
an actual link is attempted. It is however not trivial to come up with
such a heuristic.

But it might be simpler to "fix" rhash itself, with something like:

    diff -durN rhash-1.4.0.orig/configure rhash-1.4.0/configure
    --- rhash-1.4.0.orig/configure2020-07-14 21:35: 11.000000000 +0200
    +++ rhash-1.4.0/configure2020-12-25 18:07:15.52 9581029 +0100
    @@ -513,8 +513,13 @@
       CC_TMP="$CC"
       test -n "$OPT_CC" && OTHER_CC= || OTHER_CC="gcc cc"
       for CC in "$CC_TMP" $OTHER_CC; do
    +    cc_name_tmp=
         if run_cmd "$CC -v"; then
           cc_name_tmp=$($CC -v 2>&1 | tail -n 1 | cut -d ' ' -f 1)
    +    elif run_cmd "$CC --version"; then
    +      cc_name_tmp=$($CC --version 2>&1 | head -n 1 | cut -d ' ' -f 1)
    +    fi
    +    if test "${cc_name_tmp}"; then
           if test "$cc_name_tmp" = "gcc"; then
             cc_name=$cc_name_tmp
             start_check "$CC version"

This should also be hopefully accpetable upstream (too bad they do not
want to switch a common, well-known buildsystem, and that the cmake
suppot has languished without any comment for more than a year now...)

Regards,
Yann E. MORIN.

> Fixes:
>  - http://autobuild.buildroot.org/results/8605c16cc28316954ce8b9dcc266974390c5da20
> 
> Signed-off-by: Fabrice Fontaine <fontaine.fabrice@gmail.com>
> Tested-by: Peter Seiderer <ps.report@gmx.net>
> ---
> Changes v1 -> v2 (after review of Peter Seiderer):
>  - Fix typos in commit log and update comment in source code
> 
>  toolchain/toolchain-wrapper.c | 5 +++--
>  1 file changed, 3 insertions(+), 2 deletions(-)
> 
> diff --git a/toolchain/toolchain-wrapper.c b/toolchain/toolchain-wrapper.c
> index 0fb6064b1c..2a7dd61729 100644
> --- a/toolchain/toolchain-wrapper.c
> +++ b/toolchain/toolchain-wrapper.c
> @@ -453,10 +453,11 @@ int main(int argc, char **argv)
>  			*cur++ = "-pie";
>  	}
>  #endif
> -	/* Are we building the Linux Kernel or U-Boot? */
> +	/* Are we building the Linux Kernel or U-Boot or displaying the programs invoked by the compiler? */
>  	for (i = 1; i < argc; i++) {
>  		if (!strcmp(argv[i], "-D__KERNEL__") ||
> -		    !strcmp(argv[i], "-D__UBOOT__"))
> +		    !strcmp(argv[i], "-D__UBOOT__") ||
> +		    !strcmp(argv[i], "-v"))
>  			break;
>  	}
>  	if (i == argc) {
> -- 
> 2.29.2
> 
> _______________________________________________
> buildroot mailing list
> buildroot at busybox.net
> http://lists.busybox.net/mailman/listinfo/buildroot

-- 
.-----------------.--------------------.------------------.--------------------.
|  Yann E. MORIN  | Real-Time Embedded | /"\ ASCII RIBBON | Erics' conspiracy: |
| +33 662 376 056 | Software  Designer | \ / CAMPAIGN     |  ___               |
| +33 561 099 427 `------------.-------:  X  AGAINST      |  \e/  There is no  |
| http://ymorin.is-a-geek.org/ | _/*\_ | / \ HTML MAIL    |   v   conspiracy.  |
'------------------------------^-------^------------------^--------------------'

[Buildroot] [PATCH v2, 1/1] toolchain/toolchain-wrapper: fix gcc -v with relro

[Fabrice Fontaine]

Hi Yann,

Le ven. 25 d?c. 2020 ? 18:10, Yann E. MORIN <yann.morin.1998@free.fr> a ?crit :
>
> Fabrice, All,
>
> On 2020-12-24 11:18 +0100, Fabrice Fontaine spake thusly:
> > rhash in version 1.4.0 with relro fails to build because gcc -v raises
> > the following build failure:
> >
> > /data/buildroot-test/instance-1/output-1/host/mips64el-buildroot-linux-gnu/sysroot/soft-float/el/usr/lib64/Scrt1.o: In function `__start':
> > (.text+0x20): undefined reference to `main'
> > collect2: error: ld returned 1 exit status
> > Run result: 1
> >
> > This build failure is raised because the toolchain-wrapper calls gcc with
> > -Wl,-z,relro and as a result gcc wrongly assumes that some linking must
> > be done.
>
> Although I do undesrstand the problem, I am not sure this is a good
> solution.
>
> Indeed, it is perfectly legit to call gcc -v while doing an acutal
> compile or link:
>
>     $ echo 'main() { return 0; }' |gcc -v -Wl,-z,relro -o ess -x c -
>
> Indeed, using -v is a good way to see the actual programs gcc calls in
> the various steps, and has already helped me debug some difficult
> issues...
>
> So, I think we need to be a little bit smarter in how we detect whether
> an actual link is attempted. It is however not trivial to come up with
> such a heuristic.
>
> But it might be simpler to "fix" rhash itself, with something like:
>
>     diff -durN rhash-1.4.0.orig/configure rhash-1.4.0/configure
>     --- rhash-1.4.0.orig/configure2020-07-14 21:35: 11.000000000 +0200
>     +++ rhash-1.4.0/configure2020-12-25 18:07:15.52 9581029 +0100
>     @@ -513,8 +513,13 @@
>        CC_TMP="$CC"
>        test -n "$OPT_CC" && OTHER_CC= || OTHER_CC="gcc cc"
>        for CC in "$CC_TMP" $OTHER_CC; do
>     +    cc_name_tmp=
>          if run_cmd "$CC -v"; then
>            cc_name_tmp=$($CC -v 2>&1 | tail -n 1 | cut -d ' ' -f 1)
>     +    elif run_cmd "$CC --version"; then
>     +      cc_name_tmp=$($CC --version 2>&1 | head -n 1 | cut -d ' ' -f 1)
>     +    fi
>     +    if test "${cc_name_tmp}"; then
>            if test "$cc_name_tmp" = "gcc"; then
>              cc_name=$cc_name_tmp
>              start_check "$CC version"
>
> This should also be hopefully accpetable upstream (too bad they do not
> want to switch a common, well-known buildsystem, and that the cmake
> suppot has languished without any comment for more than a year now...)
I already sent a patch to "fix" rhash here:
https://patchwork.ozlabs.org/project/buildroot/patch/20201203202853.616174-1-fontaine.fabrice at gmail.com/
I'll send it to upstream as soon as I got an answer on a previous PR.
>
> Regards,
> Yann E. MORIN.
>
> > Fixes:
> >  - http://autobuild.buildroot.org/results/8605c16cc28316954ce8b9dcc266974390c5da20
> >
> > Signed-off-by: Fabrice Fontaine <fontaine.fabrice@gmail.com>
> > Tested-by: Peter Seiderer <ps.report@gmx.net>
> > ---
> > Changes v1 -> v2 (after review of Peter Seiderer):
> >  - Fix typos in commit log and update comment in source code
> >
> >  toolchain/toolchain-wrapper.c | 5 +++--
> >  1 file changed, 3 insertions(+), 2 deletions(-)
> >
> > diff --git a/toolchain/toolchain-wrapper.c b/toolchain/toolchain-wrapper.c
> > index 0fb6064b1c..2a7dd61729 100644
> > --- a/toolchain/toolchain-wrapper.c
> > +++ b/toolchain/toolchain-wrapper.c
> > @@ -453,10 +453,11 @@ int main(int argc, char **argv)
> >                       *cur++ = "-pie";
> >       }
> >  #endif
> > -     /* Are we building the Linux Kernel or U-Boot? */
> > +     /* Are we building the Linux Kernel or U-Boot or displaying the programs invoked by the compiler? */
> >       for (i = 1; i < argc; i++) {
> >               if (!strcmp(argv[i], "-D__KERNEL__") ||
> > -                 !strcmp(argv[i], "-D__UBOOT__"))
> > +                 !strcmp(argv[i], "-D__UBOOT__") ||
> > +                 !strcmp(argv[i], "-v"))
> >                       break;
> >       }
> >       if (i == argc) {
> > --
> > 2.29.2
> >
> > _______________________________________________
> > buildroot mailing list
> > buildroot at busybox.net
> > http://lists.busybox.net/mailman/listinfo/buildroot
>
> --
> .-----------------.--------------------.------------------.--------------------.
> |  Yann E. MORIN  | Real-Time Embedded | /"\ ASCII RIBBON | Erics' conspiracy: |
> | +33 662 376 056 | Software  Designer | \ / CAMPAIGN     |  ___               |
> | +33 561 099 427 `------------.-------:  X  AGAINST      |  \e/  There is no  |
> | http://ymorin.is-a-geek.org/ | _/*\_ | / \ HTML MAIL    |   v   conspiracy.  |
> '------------------------------^-------^------------------^--------------------'
Best Regards,

Fabrice

[Buildroot] [PATCH v2, 1/1] toolchain/toolchain-wrapper: fix gcc -v with relro

[Yann E. MORIN]

Fabrice, All,

On 2020-12-25 22:16 +0100, Fabrice Fontaine spake thusly:
> Le ven. 25 d?c. 2020 ? 18:10, Yann E. MORIN <yann.morin.1998@free.fr> a ?crit :
> > On 2020-12-24 11:18 +0100, Fabrice Fontaine spake thusly:
[--SNIP--]
> > > This build failure is raised because the toolchain-wrapper calls gcc with
> > > -Wl,-z,relro and as a result gcc wrongly assumes that some linking must
> > > be done.
> > Although I do undesrstand the problem, I am not sure this is a good
> > solution.
[--SNIP--]
> > But it might be simpler to "fix" rhash itself, with something like:
> >
> >     diff -durN rhash-1.4.0.orig/configure rhash-1.4.0/configure
> >     --- rhash-1.4.0.orig/configure2020-07-14 21:35: 11.000000000 +0200
> >     +++ rhash-1.4.0/configure2020-12-25 18:07:15.52 9581029 +0100
> >     @@ -513,8 +513,13 @@
> >        CC_TMP="$CC"
> >        test -n "$OPT_CC" && OTHER_CC= || OTHER_CC="gcc cc"
> >        for CC in "$CC_TMP" $OTHER_CC; do
> >     +    cc_name_tmp=
> >          if run_cmd "$CC -v"; then
> >            cc_name_tmp=$($CC -v 2>&1 | tail -n 1 | cut -d ' ' -f 1)
> >     +    elif run_cmd "$CC --version"; then
> >     +      cc_name_tmp=$($CC --version 2>&1 | head -n 1 | cut -d ' ' -f 1)
> >     +    fi
> >     +    if test "${cc_name_tmp}"; then
> >            if test "$cc_name_tmp" = "gcc"; then
> >              cc_name=$cc_name_tmp
> >              start_check "$CC version"
> >
> > This should also be hopefully accpetable upstream (too bad they do not
> > want to switch a common, well-known buildsystem, and that the cmake
> > suppot has languished without any comment for more than a year now...)
> I already sent a patch to "fix" rhash here:
> https://patchwork.ozlabs.org/project/buildroot/patch/20201203202853.616174-1-fontaine.fabrice at gmail.com/

Ah right, I see that patch now. It looks like you had a very similar
idea as mine, good. ;-)

Still, I think my proposal is less disuptive, and departs less from the
"inventive" buildsystem from upstream, and thus stands better chance at
being accepted... Well, of course:

> I'll send it to upstream as soon as I got an answer on a previous PR.

Hmm... Looks like that will take time... I know you can be very patient,
but this looks like a lost cause... :-/

Thanks!

Regards,
Yann E. MORIN.

> >
> > Regards,
> > Yann E. MORIN.
> >
> > > Fixes:
> > >  - http://autobuild.buildroot.org/results/8605c16cc28316954ce8b9dcc266974390c5da20
> > >
> > > Signed-off-by: Fabrice Fontaine <fontaine.fabrice@gmail.com>
> > > Tested-by: Peter Seiderer <ps.report@gmx.net>
> > > ---
> > > Changes v1 -> v2 (after review of Peter Seiderer):
> > >  - Fix typos in commit log and update comment in source code
> > >
> > >  toolchain/toolchain-wrapper.c | 5 +++--
> > >  1 file changed, 3 insertions(+), 2 deletions(-)
> > >
> > > diff --git a/toolchain/toolchain-wrapper.c b/toolchain/toolchain-wrapper.c
> > > index 0fb6064b1c..2a7dd61729 100644
> > > --- a/toolchain/toolchain-wrapper.c
> > > +++ b/toolchain/toolchain-wrapper.c
> > > @@ -453,10 +453,11 @@ int main(int argc, char **argv)
> > >                       *cur++ = "-pie";
> > >       }
> > >  #endif
> > > -     /* Are we building the Linux Kernel or U-Boot? */
> > > +     /* Are we building the Linux Kernel or U-Boot or displaying the programs invoked by the compiler? */
> > >       for (i = 1; i < argc; i++) {
> > >               if (!strcmp(argv[i], "-D__KERNEL__") ||
> > > -                 !strcmp(argv[i], "-D__UBOOT__"))
> > > +                 !strcmp(argv[i], "-D__UBOOT__") ||
> > > +                 !strcmp(argv[i], "-v"))
> > >                       break;
> > >       }
> > >       if (i == argc) {
> > > --
> > > 2.29.2
> > >
> > > _______________________________________________
> > > buildroot mailing list
> > > buildroot at busybox.net
> > > http://lists.busybox.net/mailman/listinfo/buildroot
> >
> > --
> > .-----------------.--------------------.------------------.--------------------.
> > |  Yann E. MORIN  | Real-Time Embedded | /"\ ASCII RIBBON | Erics' conspiracy: |
> > | +33 662 376 056 | Software  Designer | \ / CAMPAIGN     |  ___               |
> > | +33 561 099 427 `------------.-------:  X  AGAINST      |  \e/  There is no  |
> > | http://ymorin.is-a-geek.org/ | _/*\_ | / \ HTML MAIL    |   v   conspiracy.  |
> > '------------------------------^-------^------------------^--------------------'
> Best Regards,
> 
> Fabrice

-- 
.-----------------.--------------------.------------------.--------------------.
|  Yann E. MORIN  | Real-Time Embedded | /"\ ASCII RIBBON | Erics' conspiracy: |
| +33 662 376 056 | Software  Designer | \ / CAMPAIGN     |  ___               |
| +33 561 099 427 `------------.-------:  X  AGAINST      |  \e/  There is no  |
| http://ymorin.is-a-geek.org/ | _/*\_ | / \ HTML MAIL    |   v   conspiracy.  |
'------------------------------^-------^------------------^--------------------'

[Buildroot] [PATCH v2, 1/1] toolchain/toolchain-wrapper: fix gcc -v with relro

[Yann E. MORIN]

Fabrice, All,

On 2020-12-24 11:18 +0100, Fabrice Fontaine spake thusly:
> rhash in version 1.4.0 with relro fails to build because gcc -v raises
> the following build failure:
> 
> /data/buildroot-test/instance-1/output-1/host/mips64el-buildroot-linux-gnu/sysroot/soft-float/el/usr/lib64/Scrt1.o: In function `__start':
> (.text+0x20): undefined reference to `main'
> collect2: error: ld returned 1 exit status
> Run result: 1
> 
> This build failure is raised because the toolchain-wrapper calls gcc with
> -Wl,-z,relro and as a result gcc wrongly assumes that some linking must
> be done.
> 
> Fixes:
>  - http://autobuild.buildroot.org/results/8605c16cc28316954ce8b9dcc266974390c5da20

I have applied a tweaked version of your previous rhash fix, now.

I still believe this change in the toolchain wrapper to be missing extra
safeguards, as calling -v to do an actual link step is still valid. With
your patch, the link would thus be done without -z relro, which is not
correct.

But since the rhash build has now been fixed with a patch in rhash, I
don;t think we need to investigate further in our toolchain wrapper for
the time being. If there are more packages impacted, we can revisit
later.

Thanks you! :-)

Regards,
Yann E. MORIN.

> Signed-off-by: Fabrice Fontaine <fontaine.fabrice@gmail.com>
> Tested-by: Peter Seiderer <ps.report@gmx.net>
> ---
> Changes v1 -> v2 (after review of Peter Seiderer):
>  - Fix typos in commit log and update comment in source code
> 
>  toolchain/toolchain-wrapper.c | 5 +++--
>  1 file changed, 3 insertions(+), 2 deletions(-)
> 
> diff --git a/toolchain/toolchain-wrapper.c b/toolchain/toolchain-wrapper.c
> index 0fb6064b1c..2a7dd61729 100644
> --- a/toolchain/toolchain-wrapper.c
> +++ b/toolchain/toolchain-wrapper.c
> @@ -453,10 +453,11 @@ int main(int argc, char **argv)
>  			*cur++ = "-pie";
>  	}
>  #endif
> -	/* Are we building the Linux Kernel or U-Boot? */
> +	/* Are we building the Linux Kernel or U-Boot or displaying the programs invoked by the compiler? */
>  	for (i = 1; i < argc; i++) {
>  		if (!strcmp(argv[i], "-D__KERNEL__") ||
> -		    !strcmp(argv[i], "-D__UBOOT__"))
> +		    !strcmp(argv[i], "-D__UBOOT__") ||
> +		    !strcmp(argv[i], "-v"))
>  			break;
>  	}
>  	if (i == argc) {
> -- 
> 2.29.2
> 
> _______________________________________________
> buildroot mailing list
> buildroot at busybox.net
> http://lists.busybox.net/mailman/listinfo/buildroot

-- 
.-----------------.--------------------.------------------.--------------------.
|  Yann E. MORIN  | Real-Time Embedded | /"\ ASCII RIBBON | Erics' conspiracy: |
| +33 662 376 056 | Software  Designer | \ / CAMPAIGN     |  ___               |
| +33 561 099 427 `------------.-------:  X  AGAINST      |  \e/  There is no  |
| http://ymorin.is-a-geek.org/ | _/*\_ | / \ HTML MAIL    |   v   conspiracy.  |
'------------------------------^-------^------------------^--------------------'