glibc/sysdeps/unix/sysv/linux/aarch64/sysdep.h

/* Copyright (C) 2005-2019 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/>.  */

#ifndef _LINUX_AARCH64_SYSDEP_H
#define _LINUX_AARCH64_SYSDEP_H 1

/* Always enable vsyscalls on aarch64 */
#define ALWAYS_USE_VSYSCALL 1

#include <sysdeps/unix/sysdep.h>
#include <sysdeps/aarch64/sysdep.h>
#include <sysdeps/unix/sysv/linux/generic/sysdep.h>

/* Defines RTLD_PRIVATE_ERRNO and USE_DL_SYSINFO.  */
#include <dl-sysdep.h>

#include <tls.h>

/* In order to get __set_errno() definition in INLINE_SYSCALL.  */
#ifndef __ASSEMBLER__
#include <errno.h>
#endif

/* 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.  */
#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 R0
   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 safely
   test with -4095.  */

# undef	PSEUDO
# define PSEUDO(name, syscall_name, args)				      \
  .text;								      \
  ENTRY (name);								      \
    DO_CALL (syscall_name, args);					      \
    cmn x0, #4095;							      \
    b.cs .Lsyscall_error;

# 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)

# define ret_NOERRNO ret

/* The function has to return the error code.  */
# undef	PSEUDO_ERRVAL
# define PSEUDO_ERRVAL(name, syscall_name, args) \
  .text;								      \
  ENTRY (name)								      \
    DO_CALL (syscall_name, args);					      \
    neg x0, x0

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

# define ret_ERRVAL ret

# if !IS_IN (libc)
#  define SYSCALL_ERROR  .Lsyscall_error
#  if RTLD_PRIVATE_ERRNO
#   define SYSCALL_ERROR_HANDLER				\
.Lsyscall_error:						\
	adrp	x1, C_SYMBOL_NAME(rtld_errno);			\
	neg     w0, w0;						\
	str     w0, [x1, :lo12:C_SYMBOL_NAME(rtld_errno)];	\
	mov	x0, -1;						\
	RET;
#  else

#   define SYSCALL_ERROR_HANDLER				\
.Lsyscall_error:						\
	adrp	x1, :gottprel:errno;				\
	neg	w2, w0;						\
	ldr	PTR_REG(1), [x1, :gottprel_lo12:errno];		\
	mrs	x3, tpidr_el0;					\
	mov	x0, -1;						\
	str	w2, [x1, x3];					\
	RET;
#  endif
# else
#  define SYSCALL_ERROR __syscall_error
#  define SYSCALL_ERROR_HANDLER                                 \
.Lsyscall_error:                                                \
	b	__syscall_error;
# endif

/* Linux takes system call args in registers:
	syscall number	x8
	arg 1		x0
	arg 2		x1
	arg 3		x2
	arg 4		x3
	arg 5		x4
	arg 6		x5
	arg 7		x6

   The compiler is going to form a call by coming here, through PSEUDO, with
   arguments
	syscall number	in the DO_CALL macro
	arg 1		x0
	arg 2		x1
	arg 3		x2
	arg 4		x3
	arg 5		x4
	arg 6		x5
	arg 7		x6

*/

# undef	DO_CALL
# define DO_CALL(syscall_name, args)		\
    mov x8, SYS_ify (syscall_name);		\
    svc 0

#else /* not __ASSEMBLER__ */


/* List of system calls which are supported as vsyscalls.  */
# define HAVE_CLOCK_GETRES_VSYSCALL	1
# define HAVE_CLOCK_GETTIME_VSYSCALL	1
# define HAVE_GETTIMEOFDAY_VSYSCALL	1

/* Previously AArch64 used the generic version without the libc_hidden_def
   which lead in a non existent __send symbol in libc.so.  */
# undef HAVE_INTERNAL_SEND_SYMBOL

# define SINGLE_THREAD_BY_GLOBAL		1

/* Define a macro which expands into the inline wrapper code for a system
   call.  */
# undef INLINE_SYSCALL
# define INLINE_SYSCALL(name, nr, args...)				\
  ({ unsigned long _sys_result = INTERNAL_SYSCALL (name, , nr, args);	\
     if (__builtin_expect (INTERNAL_SYSCALL_ERROR_P (_sys_result, ), 0))\
       {								\
	 __set_errno (INTERNAL_SYSCALL_ERRNO (_sys_result, ));		\
	 _sys_result = (unsigned long) -1;				\
       }								\
     (long) _sys_result; })

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

# undef INTERNAL_SYSCALL_RAW
# define INTERNAL_SYSCALL_RAW(name, err, nr, args...)		\
  ({ long _sys_result;						\
     {								\
       LOAD_ARGS_##nr (args)					\
       register long _x8 asm ("x8") = (name);			\
       asm volatile ("svc	0	// syscall " # name     \
		     : "=r" (_x0) : "r"(_x8) ASM_ARGS_##nr : "memory");	\
       _sys_result = _x0;					\
     }								\
     _sys_result; })

# undef INTERNAL_SYSCALL
# define INTERNAL_SYSCALL(name, err, nr, args...)		\
	INTERNAL_SYSCALL_RAW(SYS_ify(name), err, nr, args)

# undef INTERNAL_SYSCALL_AARCH64
# define INTERNAL_SYSCALL_AARCH64(name, err, nr, args...)	\
	INTERNAL_SYSCALL_RAW(__ARM_NR_##name, err, nr, args)

# undef INTERNAL_SYSCALL_ERROR_P
# define INTERNAL_SYSCALL_ERROR_P(val, err) \
  ((unsigned long) (val) >= (unsigned long) -4095)

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

# define LOAD_ARGS_0()				\
  register long _x0 asm ("x0");
# define LOAD_ARGS_1(x0)			\
  long _x0tmp = (long) (x0);			\
  LOAD_ARGS_0 ()				\
  _x0 = _x0tmp;
# define LOAD_ARGS_2(x0, x1)			\
  long _x1tmp = (long) (x1);			\
  LOAD_ARGS_1 (x0)				\
  register long _x1 asm ("x1") = _x1tmp;
# define LOAD_ARGS_3(x0, x1, x2)		\
  long _x2tmp = (long) (x2);			\
  LOAD_ARGS_2 (x0, x1)				\
  register long _x2 asm ("x2") = _x2tmp;
# define LOAD_ARGS_4(x0, x1, x2, x3)		\
  long _x3tmp = (long) (x3);			\
  LOAD_ARGS_3 (x0, x1, x2)			\
  register long _x3 asm ("x3") = _x3tmp;
# define LOAD_ARGS_5(x0, x1, x2, x3, x4)	\
  long _x4tmp = (long) (x4);			\
  LOAD_ARGS_4 (x0, x1, x2, x3)			\
  register long _x4 asm ("x4") = _x4tmp;
# define LOAD_ARGS_6(x0, x1, x2, x3, x4, x5)	\
  long _x5tmp = (long) (x5);			\
  LOAD_ARGS_5 (x0, x1, x2, x3, x4)		\
  register long _x5 asm ("x5") = _x5tmp;
# define LOAD_ARGS_7(x0, x1, x2, x3, x4, x5, x6)\
  long _x6tmp = (long) (x6);			\
  LOAD_ARGS_6 (x0, x1, x2, x3, x4, x5)		\
  register long _x6 asm ("x6") = _x6tmp;

# define ASM_ARGS_0
# define ASM_ARGS_1	, "r" (_x0)
# define ASM_ARGS_2	ASM_ARGS_1, "r" (_x1)
# define ASM_ARGS_3	ASM_ARGS_2, "r" (_x2)
# define ASM_ARGS_4	ASM_ARGS_3, "r" (_x3)
# define ASM_ARGS_5	ASM_ARGS_4, "r" (_x4)
# define ASM_ARGS_6	ASM_ARGS_5, "r" (_x5)
# define ASM_ARGS_7	ASM_ARGS_6, "r" (_x6)

# undef INTERNAL_SYSCALL_NCS
# define INTERNAL_SYSCALL_NCS(number, err, nr, args...)	\
	INTERNAL_SYSCALL_RAW (number, err, nr, args)

#endif	/* __ASSEMBLER__ */

/* Pointer mangling is supported for AArch64.  */
#if (IS_IN (rtld) || \
     (!defined SHARED && (IS_IN (libc) \
			  || IS_IN (libpthread))))
# ifdef __ASSEMBLER__
/* Note, dst, src, guard, and tmp are all register numbers rather than
   register names so they will work with both ILP32 and LP64. */
#  define PTR_MANGLE(dst, src, guard, tmp)                                \
  LDST_PCREL (ldr, guard, tmp, C_SYMBOL_NAME(__pointer_chk_guard_local)); \
  PTR_MANGLE2 (dst, src, guard)
/* Use PTR_MANGLE2 for efficiency if guard is already loaded.  */
#  define PTR_MANGLE2(dst, src, guard)\
  eor x##dst, x##src, x##guard
#  define PTR_DEMANGLE(dst, src, guard, tmp)\
  PTR_MANGLE (dst, src, guard, tmp)
#  define PTR_DEMANGLE2(dst, src, guard)\
  PTR_MANGLE2 (dst, src, guard)
# else
extern uintptr_t __pointer_chk_guard_local attribute_relro attribute_hidden;
#  define PTR_MANGLE(var) \
  (var) = (__typeof (var)) ((uintptr_t) (var) ^ __pointer_chk_guard_local)
#  define PTR_DEMANGLE(var)     PTR_MANGLE (var)
# endif
#else
# ifdef __ASSEMBLER__
/* Note, dst, src, guard, and tmp are all register numbers rather than
   register names so they will work with both ILP32 and LP64. */
#  define PTR_MANGLE(dst, src, guard, tmp)                             \
  LDST_GLOBAL (ldr, guard, tmp, C_SYMBOL_NAME(__pointer_chk_guard));   \
  PTR_MANGLE2 (dst, src, guard)
/* Use PTR_MANGLE2 for efficiency if guard is already loaded.  */
#  define PTR_MANGLE2(dst, src, guard)\
  eor x##dst, x##src, x##guard
#  define PTR_DEMANGLE(dst, src, guard, tmp)\
  PTR_MANGLE (dst, src, guard, tmp)
#  define PTR_DEMANGLE2(dst, src, guard)\
  PTR_MANGLE2 (dst, src, guard)
# else
extern uintptr_t __pointer_chk_guard attribute_relro;
#  define PTR_MANGLE(var) \
  (var) = (__typeof (var)) ((uintptr_t) (var) ^ __pointer_chk_guard)
#  define PTR_DEMANGLE(var) PTR_MANGLE (var)
# endif
#endif

#endif /* linux/aarch64/sysdep.h */