sysdep.h

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/* Copyright (C) 2000, 2001, 2002, 2003, 2004, 2005, 2006
   Free Software Foundation, Inc.
   Contributed by Martin Schwidefsky ([e-mail]).
   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, write to the Free
   Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
   02111-1307 USA.  */

#ifndef _LINUX_S390_SYSDEP_H
#define _LINUX_S390_SYSDEP_H

#include <sysdeps/s390/s390-32/sysdep.h>
#include <sysdeps/unix/sysdep.h>
#include <dl-sysdep.h>	/* For RTLD_PRIVATE_ERRNO.  */
#include <tls.h>

/* For Linux we can use the system call table in the header file
	/usr/include/asm/unistd.h
   of the kernel.  But these symbols do not follow the SYS_* syntax
   so we have to redefine the `SYS_ify' macro here.  */
/* in newer 2.1 kernels __NR_syscall is missing so we define it here */
#define __NR_syscall 0

#undef SYS_ify
#define SYS_ify(syscall_name)	__NR_##syscall_name

#ifdef __ASSEMBLER__

/* Linux uses a negative return value to indicate syscall errors, unlike
   most Unices, which use the condition codes' carry flag.

   Since version 2.1 the return value of a system call might be negative
   even if the call succeeded.  E.g., the `lseek' system call might return
   a large offset.  Therefore we must not anymore test for < 0, but test
   for a real error by making sure the value in gpr2 is a real error
   number.  Linus said he will make sure the no syscall returns a value
   in -1 .. -4095 as a valid result so we can savely test with -4095.  */

#undef PSEUDO
#define	PSEUDO(name, syscall_name, args)				      \
  .text;                                                                      \
  ENTRY (name)							              \
    DO_CALL (syscall_name, args);                                             \
    lhi  %r4,-4095 ;                                                          \
    clr  %r2,%r4 ;		                                              \
    jnl  SYSCALL_ERROR_LABEL

#undef PSEUDO_END
#define PSEUDO_END(name)						      \
  SYSCALL_ERROR_HANDLER;						      \
  END (name)

#undef PSEUDO_NOERRNO
#define	PSEUDO_NOERRNO(name, syscall_name, args)			      \
  .text;                                                                      \
  ENTRY (name)							              \
    DO_CALL (syscall_name, args)

#undef PSEUDO_END_NOERRNO
#define PSEUDO_END_NOERRNO(name)					      \
  END (name)

#undef PSEUDO_ERRVAL
#define	PSEUDO_ERRVAL(name, syscall_name, args)				      \
  .text;                                                                      \
  ENTRY (name)							              \
    DO_CALL (syscall_name, args);					      \
    lcr %r2,%r2

#undef PSEUDO_END_ERRVAL
#define PSEUDO_END_ERRVAL(name)						      \
  END (name)

#ifndef PIC
# define SYSCALL_ERROR_LABEL 0f
# define SYSCALL_ERROR_HANDLER \
0:  basr  %r1,0;							      \
1:  l     %r1,2f-1b(%r1);						      \
    br    %r1;								      \
2:  .long syscall_error
#else
# if RTLD_PRIVATE_ERRNO
#  define SYSCALL_ERROR_LABEL 0f
#  define SYSCALL_ERROR_HANDLER \
0:  basr  %r1,0;							      \
1:  al    %r1,2f-1b(%r1);						      \
    lcr   %r2,%r2;							      \
    st    %r2,0(%r1);							      \
    lhi   %r2,-1;							      \
    br    %r14;								      \
2:  .long rtld_errno-1b
# elif defined _LIBC_REENTRANT
#  if USE___THREAD
#   ifndef NOT_IN_libc
#    define SYSCALL_ERROR_ERRNO __libc_errno
#   else
#    define SYSCALL_ERROR_ERRNO errno
#   endif
#   define SYSCALL_ERROR_LABEL 0f
#   define SYSCALL_ERROR_HANDLER \
0:  lcr   %r0,%r2;							      \
    basr  %r1,0;							      \
1:  al    %r1,2f-1b(%r1);						      \
    l     %r1,SYSCALL_ERROR_ERRNO@gotntpoff(%r1);			      \
    ear   %r2,%a0;							      \
    st    %r0,0(%r1,%r2);						      \
    lhi   %r2,-1;							      \
    br    %r14;								      \
2:  .long _GLOBAL_OFFSET_TABLE_-1b
#  else
#   define SYSCALL_ERROR_LABEL 0f
#   define SYSCALL_ERROR_HANDLER \
0:  basr  %r1,0;							      \
1:  al    %r1,2f-1b(%r1);						      \
    br    %r1;								      \
2:  .long syscall_error@plt-1b
#  endif
# else
#  define SYSCALL_ERROR_LABEL 0f
#  define SYSCALL_ERROR_HANDLER \
0:  basr  %r1,0;							      \
1:  al    %r1,2f-1b(%r1);						      \
    l     %r1,errno@GOT(%r1);						      \
    lcr   %r2,%r2;							      \
    st    %r2,0(%r1);							      \
    lhi   %r2,-1;							      \
    br    %r14;								      \
2:  .long _GLOBAL_OFFSET_TABLE_-1b
# endif /* _LIBC_REENTRANT */
#endif /* PIC */

/* Linux takes system call arguments in registers:

	syscall number	1	     call-clobbered
	arg 1		2	     call-clobbered
	arg 2		3	     call-clobbered
	arg 3		4	     call-clobbered
	arg 4		5	     call-clobbered
	arg 5		6	     call-saved
	arg 6		7	     call-saved

   (Of course a function with say 3 arguments does not have entries for
   arguments 4 and 5.)
   For system calls with 6 parameters a stack operation is required
   to load the 6th parameter to register 7. Call saved register 7 is
   moved to register 0 and back to avoid an additional stack frame.
 */

#define DO_CALL(syscall, args)						      \
  .if args > 5;								      \
    lr %r0,%r7;								      \
    l %r7,96(%r15);							      \
  .endif;								      \
  .if SYS_ify (syscall) < 256;						      \
    svc SYS_ify (syscall);						      \
  .else;								      \
    lhi %r1,SYS_ify (syscall);						      \
    svc 0;								      \
  .endif;								      \
  .if args > 5;								      \
    lr %r7,%r0;								      \
  .endif

#define ret                                                                   \
    br      14

#define ret_NOERRNO							      \
    br      14

#define ret_ERRVAL							      \
    br      14

#endif /* __ASSEMBLER__ */

#undef INLINE_SYSCALL
#define INLINE_SYSCALL(name, nr, args...)				      \
  ({									      \
    unsigned int _ret = INTERNAL_SYSCALL (name, , nr, args);		      \
    if (__builtin_expect (INTERNAL_SYSCALL_ERROR_P (_ret, ), 0))	      \
     {									      \
       __set_errno (INTERNAL_SYSCALL_ERRNO (_ret, ));			      \
       _ret = 0xffffffff;						      \
     }									      \
    (int) _ret; })

#undef INTERNAL_SYSCALL_DECL
#define INTERNAL_SYSCALL_DECL(err) do { } while (0)

#undef INTERNAL_SYSCALL_DIRECT
#define INTERNAL_SYSCALL_DIRECT(name, err, nr, args...)			      \
  ({									      \
    DECLARGS_##nr(args)							      \
    register int _ret asm("2");						      \
    asm volatile (							      \
    "svc    %b1\n\t"							      \
    : "=d" (_ret)							      \
    : "i" (__NR_##name) ASMFMT_##nr					      \
    : "memory" );							      \
    _ret; })

#undef INTERNAL_SYSCALL_SVC0
#define INTERNAL_SYSCALL_SVC0(name, err, nr, args...)			      \
  ({									      \
    DECLARGS_##nr(args)							      \
    register unsigned long _nr asm("1") = (unsigned long)(__NR_##name);	      \
    register int _ret asm("2");						      \
    asm volatile (							      \
    "svc    0\n\t"							      \
    : "=d" (_ret)							      \
    : "d" (_nr) ASMFMT_##nr						      \
    : "memory" );							      \
    _ret; })

#undef INTERNAL_SYSCALL_NCS
#define INTERNAL_SYSCALL_NCS(no, err, nr, args...)			      \
  ({									      \
    DECLARGS_##nr(args)							      \
    register unsigned long _nr asm("1") = (unsigned long)(no);		      \
    register int _ret asm("2");						      \
    asm volatile (							      \
    "svc    0\n\t"							      \
    : "=d" (_ret)							      \
    : "d" (_nr) ASMFMT_##nr						      \
    : "memory" );							      \
    _ret; })

#undef INTERNAL_SYSCALL
#define INTERNAL_SYSCALL(name, err, nr, args...)			      \
  (((__NR_##name) < 256) ?						      \
    INTERNAL_SYSCALL_DIRECT(name, err, nr, args) :			      \
    INTERNAL_SYSCALL_SVC0(name, err,nr, args))

#undef INTERNAL_SYSCALL_ERROR_P
#define INTERNAL_SYSCALL_ERROR_P(val, err)				      \
  ((unsigned int) (val) >= 0xfffff001u)

#undef INTERNAL_SYSCALL_ERRNO
#define INTERNAL_SYSCALL_ERRNO(val, err)	(-(val))

#define DECLARGS_0()
#define DECLARGS_1(arg1) \
	register unsigned long gpr2 asm ("2") = (unsigned long)(arg1);
#define DECLARGS_2(arg1, arg2) \
	DECLARGS_1(arg1) \
	register unsigned long gpr3 asm ("3") = (unsigned long)(arg2);
#define DECLARGS_3(arg1, arg2, arg3) \
	DECLARGS_2(arg1, arg2) \
	register unsigned long gpr4 asm ("4") = (unsigned long)(arg3);
#define DECLARGS_4(arg1, arg2, arg3, arg4) \
	DECLARGS_3(arg1, arg2, arg3) \
	register unsigned long gpr5 asm ("5") = (unsigned long)(arg4);
#define DECLARGS_5(arg1, arg2, arg3, arg4, arg5) \
	DECLARGS_4(arg1, arg2, arg3, arg4) \
	register unsigned long gpr6 asm ("6") = (unsigned long)(arg5);
#define DECLARGS_6(arg1, arg2, arg3, arg4, arg5, arg6) \
	DECLARGS_5(arg1, arg2, arg3, arg4, arg5) \
	register unsigned long gpr7 asm ("7") = (unsigned long)(arg6);

#define ASMFMT_0
#define ASMFMT_1 , "0" (gpr2)
#define ASMFMT_2 , "0" (gpr2), "d" (gpr3)
#define ASMFMT_3 , "0" (gpr2), "d" (gpr3), "d" (gpr4)
#define ASMFMT_4 , "0" (gpr2), "d" (gpr3), "d" (gpr4), "d" (gpr5)
#define ASMFMT_5 , "0" (gpr2), "d" (gpr3), "d" (gpr4), "d" (gpr5), "d" (gpr6)
#define ASMFMT_6 , "0" (gpr2), "d" (gpr3), "d" (gpr4), "d" (gpr5), "d" (gpr6), "d" (gpr7)


/* Pointer mangling support.  */
#if defined NOT_IN_libc && defined IS_IN_rtld
/* We cannot use the thread descriptor because in ld.so we use setjmp
   earlier than the descriptor is initialized.  */
#else
/* For the time being just use stack_guard rather than a separate
   pointer_guard.  */
# ifdef __ASSEMBLER__
#  define PTR_MANGLE(reg, tmpreg) \
  ear     tmpreg,%a0;			\
  x       reg,STACK_GUARD(tmpreg)
#  define PTR_MANGLE2(reg, tmpreg) \
  x       reg,STACK_GUARD(tmpreg)
#  define PTR_DEMANGLE(reg, tmpreg) PTR_MANGLE (reg, tmpreg)
# else
#  define PTR_MANGLE(var) \
  (var) = (void *) ((uintptr_t) (var) ^ THREAD_GET_POINTER_GUARD ())
#  define PTR_DEMANGLE(var)	PTR_MANGLE (var)
# endif
#endif

#endif /* _LINUX_S390_SYSDEP_H */