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Re: [PATCH 3/4] Optimize i386 syscall inlining



On 10-09-2015 10:14, H.J. Lu wrote:
> OK for master?
> 
> H.J.
> ---
> Define INLINE_SYSCALL_ERROR_RETURN so that i386 can optimize setting
> errno by branching to the internal __syscall_error without PLT.
> 
> Since GCC 5 and above can properly spill %ebx when needed, we can inline
> syscalls with 6 arguments if GCC 5 or above is used to compile glibc.
> This patch rewrites INTERNAL_SYSCALL macros and skips __libc_do_syscall
> for GCC 5.
> 
> For sysdeps/unix/sysv/linux/i386/brk.c, with -O2 -march=i686
> -mtune=generic, GCC 5.2 now generates:

You can use this refactoring to cleanup some duplicate code as well,
since i386 brk.c, setegid.c, and seteuid.c can be replaces by generic
implementation. 

Also for *stat* implementations i386 could override overflow.h and 
redefine stat_overflow with stat64 logic. 

For lockf64.c I also think it can be feasible to change default
implementation to accommodate i386 requirements (use flock64
instead of flock).

The only implementation is really i386 specific is sigaction.c,
but I can't tell how much of the assembly hackery it requires
nowadays. 

> 
> <__brk>:
>    0:	push   %ebx
>    1:	mov    $0x2d,%eax
>    6:	mov    0x8(%esp),%ebx
>    a:	call   b <__brk+0xb>	b: R_386_PC32	__x86.get_pc_thunk.dx
>    f:	add    $0x2,%edx	11: R_386_GOTPC	_GLOBAL_OFFSET_TABLE_
>   15:	call   *%gs:0x10
>   1c:	mov    0x0(%edx),%edx	1e: R_386_GOT32	__curbrk
>   22:	cmp    %eax,%ebx
>   24:	mov    %eax,(%edx)
>   26:	ja     30 <__brk+0x30>
>   28:	xor    %eax,%eax
>   2a:	pop    %ebx
>   2b:	ret
> 
> instead of
> 
> <__brk>:
>    0:	push   %ebx
>    1:	mov    0x8(%esp),%ecx
>    5:	call   6 <__brk+0x6>	6: R_386_PC32	__x86.get_pc_thunk.bx
>    a:	add    $0x2,%ebx	c: R_386_GOTPC	_GLOBAL_OFFSET_TABLE_
>   10:	xchg   %ecx,%ebx
>   12:	mov    $0x2d,%eax
>   17:	call   *%gs:0x10
>   1e:	xchg   %ecx,%ebx
>   20:	mov    %eax,%edx
>   22:	mov    0x0(%ebx),%eax	24: R_386_GOT32	__curbrk
>   28:	mov    %edx,(%eax)
>   2a:	xor    %eax,%eax
>   2c:	cmp    %edx,%ecx
>   2e:	ja     38 <__brk+0x38>
>   30:	pop    %ebx
>   31:	ret
> 
> The new one is shorter by 2 instructions.
> 
> 	* sysdeps/unix/sysv/linux/i386/Makefile [$(subdir) == csu]
> 	(sysdep-dl-routines): Add sysdep.
> 	[$(subdir) == nptl] (libpthread-routines): Likewise.
> 	[$(subdir) == rt] (librt-routines): Likewise.
> 	* sysdeps/unix/sysv/linux/i386/brk.c (__brk): Add
> 	INTERNAL_SYSCALL_DECL.  Use INLINE_SYSCALL_ERROR_RETURN.
> 	* sysdeps/unix/sysv/linux/i386/clone.S (__clone): Don't check
> 	PIC when branching to SYSCALL_ERROR_LABEL.
> 	* sysdeps/unix/sysv/linux/i386/fxstat.c (__fxstat): Likewise.
> 	* sysdeps/unix/sysv/linux/i386/fxstatat.c (__fxstatat):
> 	Likewise.
> 	* sysdeps/unix/sysv/linux/i386/lockf64.c (lockf64): Likewise.
> 	* sysdeps/unix/sysv/linux/i386/lxstat.c (__lxstat): Likewise.
> 	* sysdeps/unix/sysv/linux/i386/setegid.c (setegid): Likewise.
> 	* sysdeps/unix/sysv/linux/i386/seteuid.c (seteuid): Likewise.
> 	* sysdeps/unix/sysv/linux/i386/sigaction.c (__libc_sigaction):
> 	Likewise.
> 	* sysdeps/unix/sysv/linux/i386/xstat.c (__xstat): Likewise.
> 	* sysdeps/unix/sysv/linux/i386/libc-do-syscall.S
> 	(__libc_do_syscall): Defined only if !__GNUC_PREREQ (5,0).
> 	* sysdeps/unix/sysv/linux/i386/sysdep.S: Removed.
> 	* sysdeps/unix/sysv/linux/i386/sysdep.c: New file.
> 	* sysdeps/unix/sysv/linux/i386/sysdep.h: Define assembler macros
> 	only if !__GNUC_PREREQ (5,0).
> 	(SYSCALL_ERROR_LABEL): Changed to __syscall_error.
> 	(SYSCALL_ERROR_HANDLER): Changed to empty.
> 	(SYSCALL_ERROR_ERRNO): Removed.
> 	(SYSCALL_ERROR_HANDLER_TLS_STORE): Likewise.
> 	(__syscall_error): New prototype.
> 	[IS_IN (libc)] (INLINE_SYSCALL): New macro.
> 	(INLINE_SYSCALL_ERROR_RETURN): Likewise.
> 	(LOADREGS_0): Likewise.
> 	(ASMARGS_0): Likewise.
> 	(LOADREGS_1): Likewise.
> 	(ASMARGS_1): Likewise.
> 	(LOADREGS_2): Likewise.
> 	(ASMARGS_2): Likewise.
> 	(LOADREGS_3): Likewise.
> 	(ASMARGS_3): Likewise.
> 	(LOADREGS_4): Likewise.
> 	(ASMARGS_4): Likewise.
> 	(LOADREGS_5): Likewise.
> 	(ASMARGS_5): Likewise.
> 	(LOADREGS_6): Likewise.
> 	(ASMARGS_6): Likewise.
> 	(INTERNAL_SYSCALL_MAIN_6): Optimize for GCC 5.
> 	(INTERNAL_SYSCALL_MAIN_INLINE): Likewise.
> 	(INTERNAL_SYSCALL_NCS): Likewise.
> ---
>  sysdeps/unix/sysv/linux/i386/Makefile          |  14 ++
>  sysdeps/unix/sysv/linux/i386/brk.c             |  12 +-
>  sysdeps/unix/sysv/linux/i386/clone.S           |   8 --
>  sysdeps/unix/sysv/linux/i386/fxstat.c          |  10 +-
>  sysdeps/unix/sysv/linux/i386/fxstatat.c        |   9 +-
>  sysdeps/unix/sysv/linux/i386/libc-do-syscall.S |   3 +
>  sysdeps/unix/sysv/linux/i386/lockf64.c         |  13 +-
>  sysdeps/unix/sysv/linux/i386/lxstat.c          |  10 +-
>  sysdeps/unix/sysv/linux/i386/setegid.c         |   5 +-
>  sysdeps/unix/sysv/linux/i386/seteuid.c         |   5 +-
>  sysdeps/unix/sysv/linux/i386/sigaction.c       |  12 +-
>  sysdeps/unix/sysv/linux/i386/sysdep.S          |  40 ------
>  sysdeps/unix/sysv/linux/i386/sysdep.c          |  30 ++++
>  sysdeps/unix/sysv/linux/i386/sysdep.h          | 192 ++++++++++++++++---------
>  sysdeps/unix/sysv/linux/i386/xstat.c           |  10 +-
>  15 files changed, 212 insertions(+), 161 deletions(-)
>  delete mode 100644 sysdeps/unix/sysv/linux/i386/sysdep.S
>  create mode 100644 sysdeps/unix/sysv/linux/i386/sysdep.c
> 
> diff --git a/sysdeps/unix/sysv/linux/i386/Makefile b/sysdeps/unix/sysv/linux/i386/Makefile
> index 80da593..e10d133 100644
> --- a/sysdeps/unix/sysv/linux/i386/Makefile
> +++ b/sysdeps/unix/sysv/linux/i386/Makefile
> @@ -27,3 +27,17 @@ endif
>  ifeq ($(subdir),stdlib)
>  gen-as-const-headers += ucontext_i.sym
>  endif
> +
> +ifeq ($(subdir),csu)
> +sysdep-dl-routines += sysdep
> +endif
> +
> +ifeq ($(subdir),nptl)
> +# pull in __syscall_error routine
> +libpthread-routines += sysdep
> +endif
> +
> +ifeq ($(subdir),rt)
> +# pull in __syscall_error routine
> +librt-routines += sysdep
> +endif
> diff --git a/sysdeps/unix/sysv/linux/i386/brk.c b/sysdeps/unix/sysv/linux/i386/brk.c
> index 5b9a0ce..2d2daa5 100644
> --- a/sysdeps/unix/sysv/linux/i386/brk.c
> +++ b/sysdeps/unix/sysv/linux/i386/brk.c
> @@ -31,19 +31,11 @@ weak_alias (__curbrk, ___brk_addr)
>  int
>  __brk (void *addr)
>  {
> -  void *newbrk;
> -
>    INTERNAL_SYSCALL_DECL (err);
> -  newbrk = (void *) INTERNAL_SYSCALL (brk, err, 1, addr);
> -
> +  void *newbrk = (void *) INTERNAL_SYSCALL (brk, err, 1, addr);
>    __curbrk = newbrk;
> -
>    if (newbrk < addr)
> -    {
> -      __set_errno (ENOMEM);
> -      return -1;
> -    }
> -
> +    return INLINE_SYSCALL_ERROR_RETURN (ENOMEM);
>    return 0;
>  }
>  weak_alias (__brk, brk)
> diff --git a/sysdeps/unix/sysv/linux/i386/clone.S b/sysdeps/unix/sysv/linux/i386/clone.S
> index 243dbfe..2aafb3a 100644
> --- a/sysdeps/unix/sysv/linux/i386/clone.S
> +++ b/sysdeps/unix/sysv/linux/i386/clone.S
> @@ -47,19 +47,11 @@ ENTRY (__clone)
>  	/* Sanity check arguments.  */
>  	movl	$-EINVAL,%eax
>  	movl	FUNC(%esp),%ecx		/* no NULL function pointers */
> -#ifdef PIC
> -	jecxz	SYSCALL_ERROR_LABEL
> -#else
>  	testl	%ecx,%ecx
>  	jz	SYSCALL_ERROR_LABEL
> -#endif
>  	movl	STACK(%esp),%ecx	/* no NULL stack pointers */
> -#ifdef PIC
> -	jecxz	SYSCALL_ERROR_LABEL
> -#else
>  	testl	%ecx,%ecx
>  	jz	SYSCALL_ERROR_LABEL
> -#endif
>  
>  	/* Insert the argument onto the new stack.  Make sure the new
>  	   thread is started with an alignment of (mod 16).  */
> diff --git a/sysdeps/unix/sysv/linux/i386/fxstat.c b/sysdeps/unix/sysv/linux/i386/fxstat.c
> index 2f7a8fe..3919e0c 100644
> --- a/sysdeps/unix/sysv/linux/i386/fxstat.c
> +++ b/sysdeps/unix/sysv/linux/i386/fxstat.c
> @@ -42,10 +42,12 @@ __fxstat (int vers, int fd, struct stat *buf)
>    {
>      struct stat64 buf64;
>  
> -    result = INLINE_SYSCALL (fstat64, 2, fd, &buf64);
> -    if (result == 0)
> -      result = __xstat32_conv (vers, &buf64, buf);
> -    return result;
> +    INTERNAL_SYSCALL_DECL (err);
> +    result = INTERNAL_SYSCALL (fstat64, err, 2, fd, &buf64);
> +    if (__glibc_unlikely (INTERNAL_SYSCALL_ERROR_P (result, )))
> +      return INLINE_SYSCALL_ERROR_RETURN (-result);
> +    else
> +      return __xstat32_conv (vers, &buf64, buf);
>    }
>  }
>  
> diff --git a/sysdeps/unix/sysv/linux/i386/fxstatat.c b/sysdeps/unix/sysv/linux/i386/fxstatat.c
> index 6f3c251..c4be04d 100644
> --- a/sysdeps/unix/sysv/linux/i386/fxstatat.c
> +++ b/sysdeps/unix/sysv/linux/i386/fxstatat.c
> @@ -42,13 +42,10 @@ __fxstatat (int vers, int fd, const char *file, struct stat *st, int flag)
>    struct stat64 st64;
>  
>    result = INTERNAL_SYSCALL (fstatat64, err, 4, fd, file, &st64, flag);
> -  if (!__builtin_expect (INTERNAL_SYSCALL_ERROR_P (result, err), 1))
> -    return __xstat32_conv (vers, &st64, st);
> +  if (__glibc_unlikely (INTERNAL_SYSCALL_ERROR_P (result, )))
> +    return INLINE_SYSCALL_ERROR_RETURN (-result);
>    else
> -    {
> -      __set_errno (INTERNAL_SYSCALL_ERRNO (result, err));
> -      return -1;
> -    }
> +    return __xstat32_conv (vers, &st64, st);
>  }
>  libc_hidden_def (__fxstatat)
>  #ifdef XSTAT_IS_XSTAT64
> diff --git a/sysdeps/unix/sysv/linux/i386/libc-do-syscall.S b/sysdeps/unix/sysv/linux/i386/libc-do-syscall.S
> index af5c6f0..cdef3d5 100644
> --- a/sysdeps/unix/sysv/linux/i386/libc-do-syscall.S
> +++ b/sysdeps/unix/sysv/linux/i386/libc-do-syscall.S
> @@ -18,6 +18,8 @@
>  
>  #include <sysdep.h>
>  
> +#if !__GNUC_PREREQ (5,0)
> +
>  /* %eax, %ecx, %edx and %esi contain the values expected by the kernel.
>     %edi points to a structure with the values of %ebx, %edi and %ebp.  */
>  
> @@ -48,3 +50,4 @@ ENTRY (__libc_do_syscall)
>  	cfi_restore (ebx)
>  	ret
>  END (__libc_do_syscall)
> +#endif
> diff --git a/sysdeps/unix/sysv/linux/i386/lockf64.c b/sysdeps/unix/sysv/linux/i386/lockf64.c
> index 61fcf22..ae0735c 100644
> --- a/sysdeps/unix/sysv/linux/i386/lockf64.c
> +++ b/sysdeps/unix/sysv/linux/i386/lockf64.c
> @@ -29,6 +29,7 @@ lockf64 (int fd, int cmd, off64_t len64)
>  {
>    struct flock64 fl64;
>    int cmd64;
> +  int result;
>  
>    memset ((char *) &fl64, '\0', sizeof (fl64));
>    fl64.l_whence = SEEK_CUR;
> @@ -41,12 +42,13 @@ lockf64 (int fd, int cmd, off64_t len64)
>        /* Test the lock: return 0 if FD is unlocked or locked by this process;
>  	 return -1, set errno to EACCES, if another process holds the lock.  */
>        fl64.l_type = F_RDLCK;
> -      if (INLINE_SYSCALL (fcntl64, 3, fd, F_GETLK64, &fl64) < 0)
> -        return -1;
> +      INTERNAL_SYSCALL_DECL (err);
> +      result = INTERNAL_SYSCALL (fcntl64, err, 3, fd, F_GETLK64, &fl64);
> +      if (__glibc_unlikely (INTERNAL_SYSCALL_ERROR_P (result, )))
> +	return INLINE_SYSCALL_ERROR_RETURN (-result);
>        if (fl64.l_type == F_UNLCK || fl64.l_pid == __getpid ())
>          return 0;
> -      __set_errno (EACCES);
> -      return -1;
> +      return INLINE_SYSCALL_ERROR_RETURN (EACCES);
>      case F_ULOCK:
>        fl64.l_type = F_UNLCK;
>        cmd64 = F_SETLK64;
> @@ -61,8 +63,7 @@ lockf64 (int fd, int cmd, off64_t len64)
>        break;
>  
>      default:
> -      __set_errno (EINVAL);
> -      return -1;
> +      return INLINE_SYSCALL_ERROR_RETURN (EINVAL);
>      }
>    return INLINE_SYSCALL (fcntl64, 3, fd, cmd64, &fl64);
>  }
> diff --git a/sysdeps/unix/sysv/linux/i386/lxstat.c b/sysdeps/unix/sysv/linux/i386/lxstat.c
> index 0891127..759d240 100644
> --- a/sysdeps/unix/sysv/linux/i386/lxstat.c
> +++ b/sysdeps/unix/sysv/linux/i386/lxstat.c
> @@ -43,10 +43,12 @@ __lxstat (int vers, const char *name, struct stat *buf)
>    {
>      struct stat64 buf64;
>  
> -    result = INLINE_SYSCALL (lstat64, 2, name, &buf64);
> -    if (result == 0)
> -      result = __xstat32_conv (vers, &buf64, buf);
> -    return result;
> +    INTERNAL_SYSCALL_DECL (err);
> +    result = INTERNAL_SYSCALL (lstat64, err, 2, name, &buf64);
> +    if (__glibc_unlikely (INTERNAL_SYSCALL_ERROR_P (result, )))
> +      return INLINE_SYSCALL_ERROR_RETURN (-result);
> +    else
> +      return __xstat32_conv (vers, &buf64, buf);
>    }
>  }
>  
> diff --git a/sysdeps/unix/sysv/linux/i386/setegid.c b/sysdeps/unix/sysv/linux/i386/setegid.c
> index 8c39784..851513e 100644
> --- a/sysdeps/unix/sysv/linux/i386/setegid.c
> +++ b/sysdeps/unix/sysv/linux/i386/setegid.c
> @@ -27,10 +27,7 @@ setegid (gid)
>    int result;
>  
>    if (gid == (gid_t) ~0)
> -    {
> -      __set_errno (EINVAL);
> -      return -1;
> -    }
> +    INLINE_SYSCALL_ERROR_RETURN (EINVAL);
>  
>    result = INLINE_SETXID_SYSCALL (setresgid32, 3, -1, gid, -1);
>  
> diff --git a/sysdeps/unix/sysv/linux/i386/seteuid.c b/sysdeps/unix/sysv/linux/i386/seteuid.c
> index d6a7a27..bebca30 100644
> --- a/sysdeps/unix/sysv/linux/i386/seteuid.c
> +++ b/sysdeps/unix/sysv/linux/i386/seteuid.c
> @@ -26,10 +26,7 @@ seteuid (uid_t uid)
>    int result;
>  
>    if (uid == (uid_t) ~0)
> -    {
> -      __set_errno (EINVAL);
> -      return -1;
> -    }
> +    INLINE_SYSCALL_ERROR_RETURN (EINVAL);
>  
>    result = INLINE_SETXID_SYSCALL (setresuid32, 3, -1, uid, -1);
>  
> diff --git a/sysdeps/unix/sysv/linux/i386/sigaction.c b/sysdeps/unix/sysv/linux/i386/sigaction.c
> index b20a9b9..00df354 100644
> --- a/sysdeps/unix/sysv/linux/i386/sigaction.c
> +++ b/sysdeps/unix/sysv/linux/i386/sigaction.c
> @@ -69,11 +69,13 @@ __libc_sigaction (int sig, const struct sigaction *act, struct sigaction *oact)
>  
>    /* XXX The size argument hopefully will have to be changed to the
>       real size of the user-level sigset_t.  */
> -  result = INLINE_SYSCALL (rt_sigaction, 4,
> -			   sig, act ? &kact : NULL,
> -			   oact ? &koact : NULL, _NSIG / 8);
> -
> -  if (oact && result >= 0)
> +  INTERNAL_SYSCALL_DECL (err);
> +  result = INTERNAL_SYSCALL (rt_sigaction, err, 4,
> +			     sig, act ? &kact : NULL,
> +			     oact ? &koact : NULL, _NSIG / 8);
> +  if (__glibc_unlikely (INTERNAL_SYSCALL_ERROR_P (result, )))
> +     return INLINE_SYSCALL_ERROR_RETURN (-result);
> +  else if (oact && result >= 0)
>      {
>        oact->sa_handler = koact.k_sa_handler;
>        memcpy (&oact->sa_mask, &koact.sa_mask, sizeof (sigset_t));
> diff --git a/sysdeps/unix/sysv/linux/i386/sysdep.S b/sysdeps/unix/sysv/linux/i386/sysdep.S
> deleted file mode 100644
> index 4e6c262..0000000
> --- a/sysdeps/unix/sysv/linux/i386/sysdep.S
> +++ /dev/null
> @@ -1,40 +0,0 @@
> -/* Copyright (C) 1995-2015 Free Software Foundation, Inc.
> -   This file is part of the GNU C Library.
> -
> -   The GNU C Library is free software; you can redistribute it and/or
> -   modify it under the terms of the GNU Lesser General Public
> -   License as published by the Free Software Foundation; either
> -   version 2.1 of the License, or (at your option) any later version.
> -
> -   The GNU C Library is distributed in the hope that it will be useful,
> -   but WITHOUT ANY WARRANTY; without even the implied warranty of
> -   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> -   Lesser General Public License for more details.
> -
> -   You should have received a copy of the GNU Lesser General Public
> -   License along with the GNU C Library; if not, see
> -   <http://www.gnu.org/licenses/>.  */
> -
> -#include <sysdep.h>
> -
> -/* The following code is only used in the shared library when we
> -   compile the reentrant version.  Otherwise each system call defines
> -   each own version.  */
> -
> -#ifndef PIC
> -
> -/* The syscall stubs jump here when they detect an error.
> -   The code for Linux is almost identical to the canonical Unix/i386
> -   code, except that the error number in %eax is negated.  */
> -
> -#undef CALL_MCOUNT
> -#define CALL_MCOUNT /* Don't insert the profiling call, it clobbers %eax.  */
> -
> -	.text
> -ENTRY (__syscall_error)
> -	negl %eax
> -
> -#define __syscall_error __syscall_error_1
> -#include <sysdeps/unix/i386/sysdep.S>
> -
> -#endif	/* !PIC */
> diff --git a/sysdeps/unix/sysv/linux/i386/sysdep.c b/sysdeps/unix/sysv/linux/i386/sysdep.c
> new file mode 100644
> index 0000000..141105e
> --- /dev/null
> +++ b/sysdeps/unix/sysv/linux/i386/sysdep.c
> @@ -0,0 +1,30 @@
> +/* Copyright (C) 2015 Free Software Foundation, Inc.
> +   This file is part of the GNU C Library.
> +
> +   The GNU C Library is free software; you can redistribute it and/or
> +   modify it under the terms of the GNU Lesser General Public
> +   License as published by the Free Software Foundation; either
> +   version 2.1 of the License, or (at your option) any later version.
> +
> +   The GNU C Library is distributed in the hope that it will be useful,
> +   but WITHOUT ANY WARRANTY; without even the implied warranty of
> +   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> +   Lesser General Public License for more details.
> +
> +   You should have received a copy of the GNU Lesser General Public
> +   License along with the GNU C Library; if not, see
> +   <http://www.gnu.org/licenses/>.  */
> +
> +#include <errno.h>
> +#include <sysdep.h>
> +
> +/* This routine is jumped to by all the syscall handlers, to stash
> +   an error number into errno.  ERROR is the negative error number
> +   returned from the x86 kernel.  */
> +int
> +__attribute__ ((__regparm__ (1)))
> +__syscall_error (int error)
> +{
> +  __set_errno (-error);
> +  return -1;
> +}
> diff --git a/sysdeps/unix/sysv/linux/i386/sysdep.h b/sysdeps/unix/sysv/linux/i386/sysdep.h
> index aac3e7b..1515fa6 100644
> --- a/sysdeps/unix/sysv/linux/i386/sysdep.h
> +++ b/sysdeps/unix/sysv/linux/i386/sysdep.h
> @@ -56,11 +56,7 @@
>  
>  /* We don't want the label for the error handle to be global when we define
>     it here.  */
> -#ifdef PIC
> -# define SYSCALL_ERROR_LABEL 0f
> -#else
> -# define SYSCALL_ERROR_LABEL syscall_error
> -#endif
> +#define SYSCALL_ERROR_LABEL __syscall_error
>  
>  #undef	PSEUDO
>  #define	PSEUDO(name, syscall_name, args)				      \
> @@ -101,55 +97,7 @@
>  
>  #define ret_ERRVAL ret
>  
> -#ifndef PIC
> -# define SYSCALL_ERROR_HANDLER	/* Nothing here; code in sysdep.S is used.  */
> -#else
> -
> -# if RTLD_PRIVATE_ERRNO
> -#  define SYSCALL_ERROR_HANDLER						      \
> -0:SETUP_PIC_REG(cx);							      \
> -  addl $_GLOBAL_OFFSET_TABLE_, %ecx;					      \
> -  negl %eax;								      \
> -  movl %eax, rtld_errno@GOTOFF(%ecx);					      \
> -  orl $-1, %eax;							      \
> -  ret;
> -
> -# elif defined _LIBC_REENTRANT
> -
> -#  if IS_IN (libc)
> -#   define SYSCALL_ERROR_ERRNO __libc_errno
> -#  else
> -#   define SYSCALL_ERROR_ERRNO errno
> -#  endif
> -#  define SYSCALL_ERROR_HANDLER					      \
> -0:SETUP_PIC_REG (cx);							      \
> -  addl $_GLOBAL_OFFSET_TABLE_, %ecx;					      \
> -  movl SYSCALL_ERROR_ERRNO@GOTNTPOFF(%ecx), %ecx;			      \
> -  negl %eax;								      \
> -  SYSCALL_ERROR_HANDLER_TLS_STORE (%eax, %ecx);				      \
> -  orl $-1, %eax;							      \
> -  ret;
> -#  ifndef NO_TLS_DIRECT_SEG_REFS
> -#   define SYSCALL_ERROR_HANDLER_TLS_STORE(src, destoff)		      \
> -  movl src, %gs:(destoff)
> -#  else
> -#   define SYSCALL_ERROR_HANDLER_TLS_STORE(src, destoff)		      \
> -  addl %gs:0, destoff;							      \
> -  movl src, (destoff)
> -#  endif
> -# else
> -/* Store (- %eax) into errno through the GOT.  */
> -#  define SYSCALL_ERROR_HANDLER						      \
> -0:SETUP_PIC_REG(cx);							      \
> -  addl $_GLOBAL_OFFSET_TABLE_, %ecx;					      \
> -  negl %eax;								      \
> -  movl errno@GOT(%ecx), %ecx;						      \
> -  movl %eax, (%ecx);							      \
> -  orl $-1, %eax;							      \
> -  ret;
> -# endif	/* _LIBC_REENTRANT */
> -#endif	/* PIC */
> -
> +#define SYSCALL_ERROR_HANDLER	/* Nothing here; code in sysdep.c is used.  */
>  
>  /* The original calling convention for system calls on Linux/i386 is
>     to use int $0x80.  */
> @@ -276,6 +224,10 @@
>  
>  #else	/* !__ASSEMBLER__ */
>  
> +extern int __syscall_error (int)
> +  attribute_hidden __attribute__ ((__regparm__ (1)));
> +
> +#if !__GNUC_PREREQ (5,0)
>  /* We need some help from the assembler to generate optimal code.  We
>     define some macros here which later will be used.  */
>  asm (".L__X'%ebx = 1\n\t"
> @@ -315,11 +267,20 @@ struct libc_do_syscall_args
>  {
>    int ebx, edi, ebp;
>  };
> +#endif
>  
>  /* Define a macro which expands inline into the wrapper code for a system
>     call.  */
>  #undef INLINE_SYSCALL
> -#define INLINE_SYSCALL(name, nr, args...) \
> +#if IS_IN (libc)
> +# define INLINE_SYSCALL(name, nr, args...) \
> +  ({									      \
> +    unsigned int resultvar = INTERNAL_SYSCALL (name, , nr, args);	      \
> +    __glibc_unlikely (INTERNAL_SYSCALL_ERROR_P (resultvar, ))		      \
> +    ? __syscall_error (-INTERNAL_SYSCALL_ERRNO (resultvar, ))		      \
> +    : (int) resultvar; })
> +#else
> +# define INLINE_SYSCALL(name, nr, args...) \
>    ({									      \
>      unsigned int resultvar = INTERNAL_SYSCALL (name, , nr, args);	      \
>      if (__glibc_unlikely (INTERNAL_SYSCALL_ERROR_P (resultvar, )))	      \
> @@ -328,6 +289,14 @@ struct libc_do_syscall_args
>  	resultvar = 0xffffffff;						      \
>        }									      \
>      (int) resultvar; })
> +#endif
> +
> +/* Set error number and return -1.  Return the internal function,
> +   __syscall_error, which sets errno from the negative error number
> +   and returns -1, to avoid PIC.  */
> +#undef INLINE_SYSCALL_ERROR_RETURN
> +#define INLINE_SYSCALL_ERROR_RETURN(resultvar) \
> +  __syscall_error (-(resultvar))
>  
>  /* List of system calls which are supported as vsyscalls.  */
>  # define HAVE_CLOCK_GETTIME_VSYSCALL    1
> @@ -355,8 +324,12 @@ struct libc_do_syscall_args
>      INTERNAL_SYSCALL_MAIN_INLINE(name, err, 5, args)
>  /* Each object using 6-argument inline syscalls must include a
>     definition of __libc_do_syscall.  */
> -#define INTERNAL_SYSCALL_MAIN_6(name, err, arg1, arg2, arg3,		\
> -				arg4, arg5, arg6)			\
> +#if __GNUC_PREREQ (5,0)
> +# define INTERNAL_SYSCALL_MAIN_6(name, err, args...) \
> +    INTERNAL_SYSCALL_MAIN_INLINE(name, err, 6, args)
> +#else /* GCC 5  */
> +# define INTERNAL_SYSCALL_MAIN_6(name, err, arg1, arg2, arg3,		\
> +				 arg4, arg5, arg6)			\
>    struct libc_do_syscall_args _xv =					\
>      {									\
>        (int) (arg1),							\
> @@ -369,14 +342,52 @@ struct libc_do_syscall_args
>      : "=a" (resultvar)							\
>      : "i" (__NR_##name), "c" (arg2), "d" (arg3), "S" (arg4), "D" (&_xv) \
>      : "memory", "cc")
> +#endif /* GCC 5  */
>  #define INTERNAL_SYSCALL(name, err, nr, args...) \
>    ({									      \
>      register unsigned int resultvar;					      \
>      INTERNAL_SYSCALL_MAIN_##nr (name, err, args);			      \
>      (int) resultvar; })
>  #ifdef I386_USE_SYSENTER
> -# ifdef SHARED
> -#  define INTERNAL_SYSCALL_MAIN_INLINE(name, err, nr, args...) \
> +# if __GNUC_PREREQ (5,0)
> +#  ifdef SHARED
> +#   define INTERNAL_SYSCALL_MAIN_INLINE(name, err, nr, args...) \
> +    LOADREGS_##nr(args)							\
> +    asm volatile (							\
> +    "call *%%gs:%P2"							\
> +    : "=a" (resultvar)							\
> +    : "a" (__NR_##name), "i" (offsetof (tcbhead_t, sysinfo))		\
> +      ASMARGS_##nr(args) : "memory", "cc")
> +#   define INTERNAL_SYSCALL_NCS(name, err, nr, args...) \
> +  ({									\
> +    register unsigned int resultvar;					\
> +    LOADREGS_##nr(args)							\
> +    asm volatile (							\
> +    "call *%%gs:%P2"							\
> +    : "=a" (resultvar)							\
> +    : "a" (name), "i" (offsetof (tcbhead_t, sysinfo))			\
> +      ASMARGS_##nr(args) : "memory", "cc");				\
> +    (int) resultvar; })
> +#  else
> +#   define INTERNAL_SYSCALL_MAIN_INLINE(name, err, nr, args...) \
> +    LOADREGS_##nr(args)							\
> +    asm volatile (							\
> +    "call *_dl_sysinfo"							\
> +    : "=a" (resultvar)							\
> +    : "a" (__NR_##name) ASMARGS_##nr(args) : "memory", "cc")
> +#   define INTERNAL_SYSCALL_NCS(name, err, nr, args...) \
> +  ({									\
> +    register unsigned int resultvar;					\
> +    LOADREGS_##nr(args)							\
> +    asm volatile (							\
> +    "call *_dl_sysinfo"							\
> +    : "=a" (resultvar)							\
> +    : "a" (name) ASMARGS_##nr(args) : "memory", "cc");			\
> +    (int) resultvar; })
> +#  endif
> +# else /* GCC 5  */
> +#  ifdef SHARED
> +#   define INTERNAL_SYSCALL_MAIN_INLINE(name, err, nr, args...) \
>      EXTRAVAR_##nr							      \
>      asm volatile (							      \
>      LOADARGS_##nr							      \
> @@ -386,7 +397,7 @@ struct libc_do_syscall_args
>      : "=a" (resultvar)							      \
>      : "i" (__NR_##name), "i" (offsetof (tcbhead_t, sysinfo))		      \
>        ASMFMT_##nr(args) : "memory", "cc")
> -#  define INTERNAL_SYSCALL_NCS(name, err, nr, args...) \
> +#   define INTERNAL_SYSCALL_NCS(name, err, nr, args...) \
>    ({									      \
>      register unsigned int resultvar;					      \
>      EXTRAVAR_##nr							      \
> @@ -398,8 +409,8 @@ struct libc_do_syscall_args
>      : "0" (name), "i" (offsetof (tcbhead_t, sysinfo))			      \
>        ASMFMT_##nr(args) : "memory", "cc");				      \
>      (int) resultvar; })
> -# else
> -#  define INTERNAL_SYSCALL_MAIN_INLINE(name, err, nr, args...) \
> +#  else
> +#   define INTERNAL_SYSCALL_MAIN_INLINE(name, err, nr, args...) \
>      EXTRAVAR_##nr							      \
>      asm volatile (							      \
>      LOADARGS_##nr							      \
> @@ -408,7 +419,7 @@ struct libc_do_syscall_args
>      RESTOREARGS_##nr							      \
>      : "=a" (resultvar)							      \
>      : "i" (__NR_##name) ASMFMT_##nr(args) : "memory", "cc")
> -#  define INTERNAL_SYSCALL_NCS(name, err, nr, args...) \
> +#   define INTERNAL_SYSCALL_NCS(name, err, nr, args...) \
>    ({									      \
>      register unsigned int resultvar;					      \
>      EXTRAVAR_##nr							      \
> @@ -419,9 +430,27 @@ struct libc_do_syscall_args
>      : "=a" (resultvar)							      \
>      : "0" (name) ASMFMT_##nr(args) : "memory", "cc");			      \
>      (int) resultvar; })
> -# endif
> +#  endif
> +# endif /* GCC 5  */
>  #else
> -# define INTERNAL_SYSCALL_MAIN_INLINE(name, err, nr, args...) \
> +# if __GNUC_PREREQ (5,0)
> +#  define INTERNAL_SYSCALL_MAIN_INLINE(name, err, nr, args...) \
> +    LOADREGS_##nr(args)							\
> +    asm volatile (							\
> +    "int $0x80"								\
> +    : "=a" (resultvar)							\
> +    : "a" (__NR_##name) ASMARGS_##nr(args) : "memory", "cc")
> +#  define INTERNAL_SYSCALL_NCS(name, err, nr, args...) \
> +  ({									\
> +    register unsigned int resultvar;					\
> +    LOADREGS_##nr(args)							\
> +    asm volatile (							\
> +    "int $0x80"								\
> +    : "=a" (resultvar)							\
> +    : "a" (name) ASMARGS_##nr(args) : "memory", "cc");			\
> +    (int) resultvar; })
> +# else /* GCC 5  */
> +#  define INTERNAL_SYSCALL_MAIN_INLINE(name, err, nr, args...) \
>      EXTRAVAR_##nr							      \
>      asm volatile (							      \
>      LOADARGS_##nr							      \
> @@ -430,7 +459,7 @@ struct libc_do_syscall_args
>      RESTOREARGS_##nr							      \
>      : "=a" (resultvar)							      \
>      : "i" (__NR_##name) ASMFMT_##nr(args) : "memory", "cc")
> -# define INTERNAL_SYSCALL_NCS(name, err, nr, args...) \
> +#  define INTERNAL_SYSCALL_NCS(name, err, nr, args...) \
>    ({									      \
>      register unsigned int resultvar;					      \
>      EXTRAVAR_##nr							      \
> @@ -441,6 +470,7 @@ struct libc_do_syscall_args
>      : "=a" (resultvar)							      \
>      : "0" (name) ASMFMT_##nr(args) : "memory", "cc");			      \
>      (int) resultvar; })
> +# endif /* GCC 5  */
>  #endif
>  
>  #undef INTERNAL_SYSCALL_DECL
> @@ -505,6 +535,36 @@ struct libc_do_syscall_args
>  # define RESTOREARGS_5
>  #endif
>  
> +#if __GNUC_PREREQ (5,0)
> +# define LOADREGS_0()
> +# define ASMARGS_0()
> +# define LOADREGS_1(arg1) \
> +	LOADREGS_0 ()
> +# define ASMARGS_1(arg1) \
> +	ASMARGS_0 (), "b" ((unsigned int) (arg1))
> +# define LOADREGS_2(arg1, arg2) \
> +	LOADREGS_1 (arg1)
> +# define ASMARGS_2(arg1, arg2) \
> +	ASMARGS_1 (arg1), "c" ((unsigned int) (arg2))
> +# define LOADREGS_3(arg1, arg2, arg3) \
> +	LOADREGS_2 (arg1, arg2)
> +# define ASMARGS_3(arg1, arg2, arg3) \
> +	ASMARGS_2 (arg1, arg2), "d" ((unsigned int) (arg3))
> +# define LOADREGS_4(arg1, arg2, arg3, arg4) \
> +	LOADREGS_3 (arg1, arg2, arg3)
> +# define ASMARGS_4(arg1, arg2, arg3, arg4) \
> +	ASMARGS_3 (arg1, arg2, arg3), "S" ((unsigned int) (arg4))
> +# define LOADREGS_5(arg1, arg2, arg3, arg4, arg5) \
> +	LOADREGS_4 (arg1, arg2, arg3, arg4)
> +# define ASMARGS_5(arg1, arg2, arg3, arg4, arg5) \
> +	ASMARGS_4 (arg1, arg2, arg3, arg4), "D" ((unsigned int) (arg5))
> +# define LOADREGS_6(arg1, arg2, arg3, arg4, arg5, arg6) \
> +	register unsigned int _a6 asm ("ebp") = (unsigned int) (arg6); \
> +	LOADREGS_5 (arg1, arg2, arg3, arg4, arg5)
> +# define ASMARGS_6(arg1, arg2, arg3, arg4, arg5, arg6) \
> +	ASMARGS_5 (arg1, arg2, arg3, arg4, arg5), "r" (_a6)
> +#endif /* GCC 5  */
> +
>  #define ASMFMT_0()
>  #ifdef __PIC__
>  # define ASMFMT_1(arg1) \
> diff --git a/sysdeps/unix/sysv/linux/i386/xstat.c b/sysdeps/unix/sysv/linux/i386/xstat.c
> index 2424434..4dce122 100644
> --- a/sysdeps/unix/sysv/linux/i386/xstat.c
> +++ b/sysdeps/unix/sysv/linux/i386/xstat.c
> @@ -43,10 +43,12 @@ __xstat (int vers, const char *name, struct stat *buf)
>    {
>      struct stat64 buf64;
>  
> -    result = INLINE_SYSCALL (stat64, 2, name, &buf64);
> -    if (result == 0)
> -      result = __xstat32_conv (vers, &buf64, buf);
> -    return result;
> +    INTERNAL_SYSCALL_DECL (err);
> +    result = INTERNAL_SYSCALL (stat64, err, 2, name, &buf64);
> +    if (__glibc_unlikely (INTERNAL_SYSCALL_ERROR_P (result, )))
> +      return INLINE_SYSCALL_ERROR_RETURN (-result);
> +    else
> +      return __xstat32_conv (vers, &buf64, buf);
>    }
>  }
>  hidden_def (__xstat)
> 


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