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

/* Copyright (C) 2005-2025 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
   <https://www.gnu.org/licenses/>.  */

#ifndef _LINUX_AARCH64_SYSDEP_H
#define _LINUX_AARCH64_SYSDEP_H 1

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

/* Clear ZA state of SME (ASM version).  */
/* The __libc_arm_za_disable function has special calling convention
   that allows to call it without stack manipulation and preserving
   most of the registers.  */
	.macro CALL_LIBC_ARM_ZA_DISABLE
	mov		x13, x30
	.cfi_register	x30, x13
	bl		__libc_arm_za_disable
	mov		x30, x13
	.cfi_register	x13, x30
	.endm

#else /* not __ASSEMBLER__ */

# define VDSO_NAME  "LINUX_2.6.39"
# define VDSO_HASH  123718537

/* List of system calls which are supported as vsyscalls.  */
# define HAVE_CLOCK_GETRES64_VSYSCALL	"__kernel_clock_getres"
# define HAVE_CLOCK_GETTIME64_VSYSCALL	"__kernel_clock_gettime"
# define HAVE_GETTIMEOFDAY_VSYSCALL	"__kernel_gettimeofday"
# define HAVE_GETRANDOM_VSYSCALL        "__kernel_getrandom"

# define HAVE_CLONE3_WRAPPER		1

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

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

# 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, nr, args...)	\
	INTERNAL_SYSCALL_RAW (number, nr, args)

#undef HAVE_INTERNAL_BRK_ADDR_SYMBOL
#define HAVE_INTERNAL_BRK_ADDR_SYMBOL 1

/* Clear ZA state of SME (C version).  */
/* The __libc_arm_za_disable function has special calling convention
   that allows to call it without stack manipulation and preserving
   most of the registers.  */
#define CALL_LIBC_ARM_ZA_DISABLE()			\
({							\
  unsigned long int __tmp;				\
  asm volatile (					\
  "	mov		%0, x30\n"			\
  "	.cfi_register	x30, %0\n"			\
  "	bl		__libc_arm_za_disable\n"	\
  "	mov		x30, %0\n"			\
  "	.cfi_register	%0, x30\n"			\
  : "=r" (__tmp)					\
  :							\
  : "x14", "x15", "x16", "x17", "x18", "memory" );	\
})

/* Do clear ZA state of SME before making normal clone syscall.  */
#define INLINE_CLONE_SYSCALL(a0, a1, a2, a3, a4)	\
({							\
  CALL_LIBC_ARM_ZA_DISABLE ();				\
  INLINE_SYSCALL_CALL (clone, a0, a1, a2, a3, a4);	\
})

#endif	/* __ASSEMBLER__ */

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