diff mbox series

[v2] x86: Properly disable -fsplit-stack support on non-glibc targets

Message ID YessZWWDQr48TLP1@gmail.com
State New
Headers show
Series [v2] x86: Properly disable -fsplit-stack support on non-glibc targets | expand

Commit Message

H.J. Lu Jan. 21, 2022, 9:57 p.m. UTC 
On Fri, Jan 21, 2022 at 10:42:03PM +0100, Jakub Jelinek wrote:
> On Fri, Jan 21, 2022 at 01:31:32PM -0800, H.J. Lu wrote:
> > On Fri, Jan 21, 2022 at 09:18:41PM +0100, Jakub Jelinek via Gcc-patches wrote:
> > > On Fri, Jan 21, 2022 at 08:16:11PM +0100, soeren--- via Gcc-patches wrote:
> > > > gcc/ChangeLog:
> > > > 
> > > > 	* common/config/s390/s390-common.c (s390_supports_split_stack):
> > > > 	Only support split-stack on glibc targets.
> > > > 	* config/i386/gnu-user-common.h (STACK_CHECK_STATIC_BUILTIN): Ditto.
> > > > 	* config/i386/gnu.h (defined): Ditto.
> > > 
> > > Besides breaking bootstrap, this doesn't do what it talks about:
> > > 
> > > > --- a/gcc/config/i386/gnu.h
> > > > +++ b/gcc/config/i386/gnu.h
> > > > @@ -35,7 +35,10 @@ along with GCC.  If not, see <http://www.gnu.org/licenses/>.
> > > >     crti.o%s %{static:crtbeginT.o%s;shared|pie:crtbeginS.o%s;:crtbegin.o%s}"
> > > >  #endif
> > > >  
> > > > -#ifdef TARGET_LIBC_PROVIDES_SSP
> > > > +/* -fsplit-stack uses a field in the TCB at a fixed offset. This
> > > > +   field is only available for glibc.  Disable -fsplit-stack for
> > > > +   other libc implementations to avoid silent TCB corruptions.  */
> > > > +#if defined (TARGET_LIBC_PROVIDES_SSP) && OPTION_GLIBC
> > > >  
> > > >  /* i386 glibc provides __stack_chk_guard in %gs:0x14.  */
> > > >  #define TARGET_THREAD_SSP_OFFSET        0x14
> > > 
> > > Because this doesn't disable just -fsplit-stack support, but also
> > > -fstack-protector*.
> > > Does that one work on musl?
> > > I think common/config/i386/i386-common.c (ix86_supports_split_stack)
> > > should have been changed instead of the config/i386/gnu*.h headers.
> > > 
> > 
> > Like this?
> > 
> > 
> > H.J.
> > ---
> > Revert x86 changes in
> > 
> > commit c163647ffbc9a20c8feb6e079dbecccfe016c82e
> > Author: Soren Tempel <soeren@soeren-tempel.net>
> > Date:   Fri Jan 21 19:22:46 2022 +0000
> > 
> >     Disable -fsplit-stack support on non-glibc targets
> > 
> > and change ix86_supports_split_stack to return true only on glibc.
> > 
> > 	PR bootstrap/104170
> > 	* common/config/i386/i386-common.cc (ix86_supports_split_stack):
> > 	Return true only on glibc.
> > 	* config/i386/gnu-user-common.h (STACK_CHECK_STATIC_BUILTIN):
> > 	Revert commit c163647ffbc.
> > 	* config/i386/gnu.h (TARGET_LIBC_PROVIDES_SSP): Likewise.
> > ---
> >  gcc/common/config/i386/i386-common.cc | 4 ++--
> >  gcc/config/i386/gnu-user-common.h     | 5 ++---
> >  gcc/config/i386/gnu.h                 | 5 +----
> >  3 files changed, 5 insertions(+), 9 deletions(-)
> > 
> > diff --git a/gcc/common/config/i386/i386-common.cc b/gcc/common/config/i386/i386-common.cc
> > index cae0b880d79..78e6ff730aa 100644
> > --- a/gcc/common/config/i386/i386-common.cc
> > +++ b/gcc/common/config/i386/i386-common.cc
> > @@ -1715,9 +1715,9 @@ ix86_option_init_struct (struct gcc_options *opts)
> >  
> >  static bool
> >  ix86_supports_split_stack (bool report ATTRIBUTE_UNUSED,
> > -			   struct gcc_options *opts ATTRIBUTE_UNUSED)
> > +			   struct gcc_options *opts)
> >  {
> > -  bool ret = true;
> > +  bool ret = opts->x_linux_libc == LIBC_GLIBC;
> >  
> >  #ifndef TARGET_THREAD_SPLIT_STACK_OFFSET
> >    if (report)
> 
> Almost.
> I'd think you should honor report and drop ATTRIBUTE_UNUSED from both args.
> 
> So instead:
>   bool ret = true;
> 
>   if (opts->x_linux_libc != LIBC_GLIBC)
>     {
>       if (report)
> 	error ("%<-fsplit-stack%> currently only supported on GNU/Linux");
>       return false;
>     }
> #ifndef TARGET_THREAD_SPLIT_STACK_OFFSET
> ...
> 

Here is the v2 patch.


H.J.
---
Revert x86 changes in

commit c163647ffbc9a20c8feb6e079dbecccfe016c82e
Author: Soren Tempel <soeren@soeren-tempel.net>
Date:   Fri Jan 21 19:22:46 2022 +0000

    Disable -fsplit-stack support on non-glibc targets

and change ix86_supports_split_stack to return true only on glibc.

	PR bootstrap/104170
	* common/config/i386/i386-common.cc (ix86_supports_split_stack):
	Return true only on glibc.
	* config/i386/gnu-user-common.h (STACK_CHECK_STATIC_BUILTIN):
	Revert commit c163647ffbc.
	* config/i386/gnu.h (TARGET_LIBC_PROVIDES_SSP): Likewise.
---
 gcc/common/config/i386/i386-common.cc | 17 +++++++++++------
 gcc/config/i386/gnu-user-common.h     |  5 ++---
 gcc/config/i386/gnu.h                 |  5 +----
 3 files changed, 14 insertions(+), 13 deletions(-)

Comments

Jakub Jelinek Jan. 21, 2022, 10:14 p.m. UTC | #1 
On Fri, Jan 21, 2022 at 01:57:57PM -0800, H.J. Lu wrote:
> Revert x86 changes in
> 
> commit c163647ffbc9a20c8feb6e079dbecccfe016c82e
> Author: Soren Tempel <soeren@soeren-tempel.net>
> Date:   Fri Jan 21 19:22:46 2022 +0000
> 
>     Disable -fsplit-stack support on non-glibc targets
> 
> and change ix86_supports_split_stack to return true only on glibc.
> 
> 	PR bootstrap/104170
> 	* common/config/i386/i386-common.cc (ix86_supports_split_stack):
> 	Return true only on glibc.
> 	* config/i386/gnu-user-common.h (STACK_CHECK_STATIC_BUILTIN):
> 	Revert commit c163647ffbc.
> 	* config/i386/gnu.h (TARGET_LIBC_PROVIDES_SSP): Likewise.

Ok, thanks.

>  gcc/common/config/i386/i386-common.cc | 17 +++++++++++------
>  gcc/config/i386/gnu-user-common.h     |  5 ++---
>  gcc/config/i386/gnu.h                 |  5 +----
>  3 files changed, 14 insertions(+), 13 deletions(-)
> 
> diff --git a/gcc/common/config/i386/i386-common.cc b/gcc/common/config/i386/i386-common.cc
> index cae0b880d79..7496d179892 100644
> --- a/gcc/common/config/i386/i386-common.cc
> +++ b/gcc/common/config/i386/i386-common.cc
> @@ -1714,16 +1714,21 @@ ix86_option_init_struct (struct gcc_options *opts)
>     field in the TCB, so they cannot be used together.  */
>  
>  static bool
> -ix86_supports_split_stack (bool report ATTRIBUTE_UNUSED,
> +ix86_supports_split_stack (bool report,
>  			   struct gcc_options *opts ATTRIBUTE_UNUSED)
>  {
> +#ifdef TARGET_THREAD_SPLIT_STACK_OFFSET
> +  if (opts->x_linux_libc != LIBC_GLIBC)
> +#endif
> +    {
> +      if (report)
> +	error ("%<-fsplit-stack%> currently only supported on GNU/Linux");
> +      return false;
> +    }
> +
>    bool ret = true;
>  
> -#ifndef TARGET_THREAD_SPLIT_STACK_OFFSET
> -  if (report)
> -    error ("%<-fsplit-stack%> currently only supported on GNU/Linux");
> -  ret = false;
> -#else
> +#ifdef TARGET_THREAD_SPLIT_STACK_OFFSET
>    if (!HAVE_GAS_CFI_PERSONALITY_DIRECTIVE)
>      {
>        if (report)
> diff --git a/gcc/config/i386/gnu-user-common.h b/gcc/config/i386/gnu-user-common.h
> index 7525f788a9c..23b54c5be52 100644
> --- a/gcc/config/i386/gnu-user-common.h
> +++ b/gcc/config/i386/gnu-user-common.h
> @@ -66,8 +66,7 @@ along with GCC; see the file COPYING3.  If not see
>  #define STACK_CHECK_STATIC_BUILTIN 1
>  
>  /* We only build the -fsplit-stack support in libgcc if the
> -   assembler has full support for the CFI directives and
> -   targets glibc.  */
> -#if HAVE_GAS_CFI_PERSONALITY_DIRECTIVE && OPTION_GLIBC
> +   assembler has full support for the CFI directives.  */
> +#if HAVE_GAS_CFI_PERSONALITY_DIRECTIVE
>  #define TARGET_CAN_SPLIT_STACK
>  #endif
> diff --git a/gcc/config/i386/gnu.h b/gcc/config/i386/gnu.h
> index daa505a5d45..401e60c9a02 100644
> --- a/gcc/config/i386/gnu.h
> +++ b/gcc/config/i386/gnu.h
> @@ -35,10 +35,7 @@ along with GCC.  If not, see <http://www.gnu.org/licenses/>.
>     crti.o%s %{static:crtbeginT.o%s;shared|pie:crtbeginS.o%s;:crtbegin.o%s}"
>  #endif
>  
> -/* -fsplit-stack uses a field in the TCB at a fixed offset. This
> -   field is only available for glibc.  Disable -fsplit-stack for
> -   other libc implementations to avoid silent TCB corruptions.  */
> -#if defined (TARGET_LIBC_PROVIDES_SSP) && OPTION_GLIBC
> +#ifdef TARGET_LIBC_PROVIDES_SSP
>  
>  /* i386 glibc provides __stack_chk_guard in %gs:0x14.  */
>  #define TARGET_THREAD_SSP_OFFSET        0x14
> -- 
> 2.34.1

	Jakub
diff mbox series

Patch

diff --git a/gcc/common/config/i386/i386-common.cc b/gcc/common/config/i386/i386-common.cc
index cae0b880d79..7496d179892 100644
--- a/gcc/common/config/i386/i386-common.cc
+++ b/gcc/common/config/i386/i386-common.cc
@@ -1714,16 +1714,21 @@  ix86_option_init_struct (struct gcc_options *opts)
    field in the TCB, so they cannot be used together.  */
 
 static bool
-ix86_supports_split_stack (bool report ATTRIBUTE_UNUSED,
+ix86_supports_split_stack (bool report,
 			   struct gcc_options *opts ATTRIBUTE_UNUSED)
 {
+#ifdef TARGET_THREAD_SPLIT_STACK_OFFSET
+  if (opts->x_linux_libc != LIBC_GLIBC)
+#endif
+    {
+      if (report)
+	error ("%<-fsplit-stack%> currently only supported on GNU/Linux");
+      return false;
+    }
+
   bool ret = true;
 
-#ifndef TARGET_THREAD_SPLIT_STACK_OFFSET
-  if (report)
-    error ("%<-fsplit-stack%> currently only supported on GNU/Linux");
-  ret = false;
-#else
+#ifdef TARGET_THREAD_SPLIT_STACK_OFFSET
   if (!HAVE_GAS_CFI_PERSONALITY_DIRECTIVE)
     {
       if (report)
diff --git a/gcc/config/i386/gnu-user-common.h b/gcc/config/i386/gnu-user-common.h
index 7525f788a9c..23b54c5be52 100644
--- a/gcc/config/i386/gnu-user-common.h
+++ b/gcc/config/i386/gnu-user-common.h
@@ -66,8 +66,7 @@  along with GCC; see the file COPYING3.  If not see
 #define STACK_CHECK_STATIC_BUILTIN 1
 
 /* We only build the -fsplit-stack support in libgcc if the
-   assembler has full support for the CFI directives and
-   targets glibc.  */
-#if HAVE_GAS_CFI_PERSONALITY_DIRECTIVE && OPTION_GLIBC
+   assembler has full support for the CFI directives.  */
+#if HAVE_GAS_CFI_PERSONALITY_DIRECTIVE
 #define TARGET_CAN_SPLIT_STACK
 #endif
diff --git a/gcc/config/i386/gnu.h b/gcc/config/i386/gnu.h
index daa505a5d45..401e60c9a02 100644
--- a/gcc/config/i386/gnu.h
+++ b/gcc/config/i386/gnu.h
@@ -35,10 +35,7 @@  along with GCC.  If not, see <http://www.gnu.org/licenses/>.
    crti.o%s %{static:crtbeginT.o%s;shared|pie:crtbeginS.o%s;:crtbegin.o%s}"
 #endif
 
-/* -fsplit-stack uses a field in the TCB at a fixed offset. This
-   field is only available for glibc.  Disable -fsplit-stack for
-   other libc implementations to avoid silent TCB corruptions.  */
-#if defined (TARGET_LIBC_PROVIDES_SSP) && OPTION_GLIBC
+#ifdef TARGET_LIBC_PROVIDES_SSP
 
 /* i386 glibc provides __stack_chk_guard in %gs:0x14.  */
 #define TARGET_THREAD_SSP_OFFSET        0x14