On Fri, Jan 21, 2022 at 01:57:57PM -0800, H.J. Lu wrote:
> Revert x86 changes in
>
> commit c163647ffbc9a20c8feb6e079dbecccfe016c82e
> Author: Soren Tempel <soe...@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
