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

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.

diff --git a/gcc/common/config/i386/i386-common.cc b/gcc/common/config/i386/i386-common.cc
index cae0b88..7496d17 100644 (file)
--- 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 7525f78..23b54c5 100644 (file)
--- 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 daa505a..401e60c 100644 (file)
--- 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