path: root/sysdeps/unix/sysv/linux/mips/mips32/sysdep.h

/* Copyright (C) 2000-2019 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
   <https://www.gnu.org/licenses/>.  */

#ifndef _LINUX_MIPS_MIPS32_SYSDEP_H
#define _LINUX_MIPS_MIPS32_SYSDEP_H 1

/* There is some commonality.  */
#include <sysdeps/unix/sysv/linux/sysdep.h>
#include <sysdeps/unix/mips/mips32/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__

/* We don't want the label for the error handler to be visible in the symbol
   table when we define it here.  */
#ifdef __PIC__
# define SYSCALL_ERROR_LABEL 99b
#endif

#else   /* ! __ASSEMBLER__ */

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

#undef INTERNAL_SYSCALL_DECL
#define INTERNAL_SYSCALL_DECL(err) long err __attribute__ ((unused))

#undef INTERNAL_SYSCALL_ERROR_P
#define INTERNAL_SYSCALL_ERROR_P(val, err)   ((void) (val), (long) (err))

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

/* Note that the original Linux syscall restart convention required the
   instruction immediately preceding SYSCALL to initialize $v0 with the
   syscall number.  Then if a restart triggered, $v0 would have been
   clobbered by the syscall interrupted, and needed to be reinititalized.
   The kernel would decrement the PC by 4 before switching back to the
   user mode so that $v0 had been reloaded before SYSCALL was executed
   again.  This implied the place $v0 was loaded from must have been
   preserved across a syscall, e.g. an immediate, static register, stack
   slot, etc.

   The convention was relaxed in Linux with a change applied to the kernel
   GIT repository as commit 96187fb0bc30cd7919759d371d810e928048249d, that
   first appeared in the 2.6.36 release.  Since then the kernel has had
   code that reloads $v0 upon syscall restart and resumes right at the
   SYSCALL instruction, so no special arrangement is needed anymore.

   For backwards compatibility with existing kernel binaries we support
   the old convention by choosing the instruction preceding SYSCALL
   carefully.  This also means we have to force a 32-bit encoding of the
   microMIPS MOVE instruction if one is used.  */

#ifdef __mips_micromips
# define MOVE32 "move32"
#else
# define MOVE32 "move"
#endif

#undef INTERNAL_SYSCALL
#undef INTERNAL_SYSCALL_NCS

#define __nomips16 __attribute__ ((nomips16))

union __mips_syscall_return
  {
    long long val;
    struct
      {
	long v0;
	long v1;
      }
    reg;
  };

#ifdef __mips16
/* There's no MIPS16 syscall instruction, so we go through out-of-line
   standard MIPS wrappers.  These do use inline snippets below though,
   through INTERNAL_SYSCALL_MIPS16.  Spilling the syscall number to
   memory gives the best code in that case, avoiding the need to save
   and restore a static register.  */

# include <mips16-syscall.h>

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

# define INTERNAL_SYSCALL_NCS(number, err, nr, args...)			\
({									\
	union __mips_syscall_return _sc_ret;				\
	_sc_ret.val = __mips16_syscall##nr (args, number);		\
	err = _sc_ret.reg.v1;						\
	_sc_ret.reg.v0;							\
})

# define INTERNAL_SYSCALL_MIPS16(number, err, nr, args...)		\
	internal_syscall##nr ("lw\t%0, %2\n\t",				\
			      "R" (number),				\
			      number, err, args)

#else /* !__mips16 */
# define INTERNAL_SYSCALL(name, err, nr, args...)			\
	internal_syscall##nr ("li\t%0, %2\t\t\t# " #name "\n\t",	\
			      "IK" (SYS_ify (name)),			\
			      SYS_ify (name), err, args)

# define INTERNAL_SYSCALL_NCS(number, err, nr, args...)			\
	internal_syscall##nr (MOVE32 "\t%0, %2\n\t",			\
			      "r" (__s0),				\
			      number, err, args)

#endif /* !__mips16 */

#define internal_syscall0(v0_init, input, number, err, dummy...)	\
({									\
	long _sys_result;						\
									\
	{								\
	register long __s0 asm ("$16") __attribute__ ((unused))		\
	  = (number);							\
	register long __v0 asm ("$2");					\
	register long __a3 asm ("$7");					\
	__asm__ volatile (						\
	".set\tnoreorder\n\t"						\
	v0_init								\
	"syscall\n\t"							\
	".set reorder"							\
	: "=r" (__v0), "=r" (__a3)					\
	: input								\
	: __SYSCALL_CLOBBERS);						\
	err = __a3;							\
	_sys_result = __v0;						\
	}								\
	_sys_result;							\
})

#define internal_syscall1(v0_init, input, number, err, arg1)		\
({									\
	long _sys_result;						\
									\
	{								\
	register long __s0 asm ("$16") __attribute__ ((unused))		\
	  = (number);							\
	register long __v0 asm ("$2");					\
	register long __a0 asm ("$4") = (long) (arg1);			\
	register long __a3 asm ("$7");					\
	__asm__ volatile (						\
	".set\tnoreorder\n\t"						\
	v0_init								\
	"syscall\n\t"							\
	".set reorder"							\
	: "=r" (__v0), "=r" (__a3)					\
	: input, "r" (__a0)						\
	: __SYSCALL_CLOBBERS);						\
	err = __a3;							\
	_sys_result = __v0;						\
	}								\
	_sys_result;							\
})

#define internal_syscall2(v0_init, input, number, err, arg1, arg2)	\
({									\
	long _sys_result;						\
									\
	{								\
	register long __s0 asm ("$16") __attribute__ ((unused))		\
	  = (number);							\
	register long __v0 asm ("$2");					\
	register long __a0 asm ("$4") = (long) (arg1);			\
	register long __a1 asm ("$5") = (long) (arg2);			\
	register long __a3 asm ("$7");					\
	__asm__ volatile (						\
	".set\tnoreorder\n\t"						\
	v0_init								\
	"syscall\n\t"							\
	".set\treorder"							\
	: "=r" (__v0), "=r" (__a3)					\
	: input, "r" (__a0), "r" (__a1)					\
	: __SYSCALL_CLOBBERS);						\
	err = __a3;							\
	_sys_result = __v0;						\
	}								\
	_sys_result;							\
})

#define internal_syscall3(v0_init, input, number, err,			\
			  arg1, arg2, arg3)				\
({									\
	long _sys_result;						\
									\
	{								\
	register long __s0 asm ("$16") __attribute__ ((unused))		\
	  = (number);							\
	register long __v0 asm ("$2");					\
	register long __a0 asm ("$4") = (long) (arg1);			\
	register long __a1 asm ("$5") = (long) (arg2);			\
	register long __a2 asm ("$6") = (long) (arg3);			\
	register long __a3 asm ("$7");					\
	__asm__ volatile (						\
	".set\tnoreorder\n\t"						\
	v0_init								\
	"syscall\n\t"							\
	".set\treorder"							\
	: "=r" (__v0), "=r" (__a3)					\
	: input, "r" (__a0), "r" (__a1), "r" (__a2)			\
	: __SYSCALL_CLOBBERS);						\
	err = __a3;							\
	_sys_result = __v0;						\
	}								\
	_sys_result;							\
})

#define internal_syscall4(v0_init, input, number, err,			\
			  arg1, arg2, arg3, arg4)			\
({									\
	long _sys_result;						\
									\
	{								\
	register long __s0 asm ("$16") __attribute__ ((unused))		\
	  = (number);							\
	register long __v0 asm ("$2");					\
	register long __a0 asm ("$4") = (long) (arg1);			\
	register long __a1 asm ("$5") = (long) (arg2);			\
	register long __a2 asm ("$6") = (long) (arg3);			\
	register long __a3 asm ("$7") = (long) (arg4);			\
	__asm__ volatile (						\
	".set\tnoreorder\n\t"						\
	v0_init								\
	"syscall\n\t"							\
	".set\treorder"							\
	: "=r" (__v0), "+r" (__a3)					\
	: input, "r" (__a0), "r" (__a1), "r" (__a2)			\
	: __SYSCALL_CLOBBERS);						\
	err = __a3;							\
	_sys_result = __v0;						\
	}								\
	_sys_result;							\
})

/* Standalone MIPS wrappers used for 5, 6, and 7 argument syscalls,
   which require stack arguments.  We rely on the compiler arranging
   wrapper's arguments according to the MIPS o32 function calling
   convention, which is reused by syscalls, except for the syscall
   number passed and the error flag returned (taken care of in the
   wrapper called).  This relieves us from relying on non-guaranteed
   compiler specifics required for the stack arguments to be pushed,
   which would be the case if these syscalls were inlined.  */

long long __nomips16 __mips_syscall5 (long arg1, long arg2, long arg3,
				      long arg4, long arg5,
				      long number);
libc_hidden_proto (__mips_syscall5, nomips16)

#define internal_syscall5(v0_init, input, number, err,			\
			  arg1, arg2, arg3, arg4, arg5)			\
({									\
	union __mips_syscall_return _sc_ret;				\
	_sc_ret.val = __mips_syscall5 ((long) (arg1),			\
				       (long) (arg2),			\
				       (long) (arg3),			\
				       (long) (arg4),			\
				       (long) (arg5),			\
				       (long) (number));		\
	err = _sc_ret.reg.v1;						\
	_sc_ret.reg.v0;							\
})

long long __nomips16 __mips_syscall6 (long arg1, long arg2, long arg3,
				      long arg4, long arg5, long arg6,
				      long number);
libc_hidden_proto (__mips_syscall6, nomips16)

#define internal_syscall6(v0_init, input, number, err,			\
			  arg1, arg2, arg3, arg4, arg5, arg6)		\
({									\
	union __mips_syscall_return _sc_ret;				\
	_sc_ret.val = __mips_syscall6 ((long) (arg1),			\
				       (long) (arg2),			\
				       (long) (arg3),			\
				       (long) (arg4),			\
				       (long) (arg5),			\
				       (long) (arg6),			\
				       (long) (number));		\
	err = _sc_ret.reg.v1;						\
	_sc_ret.reg.v0;							\
})

long long __nomips16 __mips_syscall7 (long arg1, long arg2, long arg3,
				      long arg4, long arg5, long arg6,
				      long arg7,
				      long number);
libc_hidden_proto (__mips_syscall7, nomips16)

#define internal_syscall7(v0_init, input, number, err,			\
			  arg1, arg2, arg3, arg4, arg5, arg6, arg7)	\
({									\
	union __mips_syscall_return _sc_ret;				\
	_sc_ret.val = __mips_syscall7 ((long) (arg1),			\
				       (long) (arg2),			\
				       (long) (arg3),			\
				       (long) (arg4),			\
				       (long) (arg5),			\
				       (long) (arg6),			\
				       (long) (arg7),			\
				       (long) (number));		\
	err = _sc_ret.reg.v1;						\
	_sc_ret.reg.v0;							\
})

#define __SYSCALL_CLOBBERS "$1", "$3", "$8", "$9", "$10", "$11", "$12", "$13", \
	"$14", "$15", "$24", "$25", "hi", "lo", "memory"

/* Standard MIPS syscalls have an error flag, and return a positive errno
   when the error flag is set. Emulate this behaviour for vsyscalls so that
   the INTERNAL_SYSCALL_{ERROR_P,ERRNO} macros work correctly.  */
#define INTERNAL_VSYSCALL_CALL(funcptr, err, nr, args...)		\
  ({									\
    long _ret = funcptr (args);						\
    err = ((unsigned long) (_ret) >= (unsigned long) -4095L);		\
    if (err)								\
      _ret = -_ret;							\
    _ret;								\
  })

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

#endif /* __ASSEMBLER__ */

/* Pointer mangling is not yet supported for MIPS.  */
#define PTR_MANGLE(var) (void) (var)
#define PTR_DEMANGLE(var) (void) (var)

#endif /* linux/mips/mips32/sysdep.h */