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glibc/sysdeps/unix/sysv/linux/aarch64/sysdep.h
Will Newton fede7a5ffa aarch64: Remove inaccurate comment from sysdep.h 
This comment appears to have been copied from the ARM port where it
makes more sense.

2014-03-18  Will Newton  <will.newton@linaro.org>

	* sysdeps/unix/sysv/linux/aarch64/sysdep.h: Remove
	inaccurate comment.
2014-03-18 11:50:39 +00:00

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/* Copyright (C) 2005-2014 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
#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;
/* Notice the use of 'RET' instead of 'ret' the assembler is case
insensitive and eglibc already uses the preprocessor symbol 'ret'
so we use the upper case 'RET' to force through a ret instruction
to the assembler */
# define PSEUDO_RET \
b.cs 1f; \
RET; \
1: \
b SYSCALL_ERROR
# undef ret
# define ret PSEUDO_RET
# 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);
/* Notice the use of 'RET' instead of 'ret' the assembler is case
insensitive and eglibc already uses the preprocessor symbol 'ret'
so we use the upper case 'RET' to force through a ret instruction
to the assembler */
# define PSEUDO_RET_NOERRNO \
RET;
# undef ret_NOERRNO
# define ret_NOERRNO PSEUDO_RET_NOERRNO
# undef PSEUDO_END_NOERRNO
# define PSEUDO_END_NOERRNO(name) \
END (name)
/* 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 PSEUDO_RET_NOERRNO
# if NOT_IN_libc
# define SYSCALL_ERROR __local_syscall_error
# if RTLD_PRIVATE_ERRNO
# define SYSCALL_ERROR_HANDLER \
__local_syscall_error: \
adrp x1, C_SYMBOL_NAME(rtld_errno); \
add x1, x1, #:lo12:C_SYMBOL_NAME(rtld_errno); \
neg w0, w0; \
str w0, [x1]; \
mov x0, -1; \
RET;
# else
# define SYSCALL_ERROR_HANDLER \
__local_syscall_error: \
stp x29, x30, [sp, -32]!; \
cfi_adjust_cfa_offset (32); \
cfi_rel_offset (x29, 0); \
cfi_rel_offset (x30, 8); \
add x29, sp, 0; \
str x19, [sp,16]; \
neg x19, x0; \
bl C_SYMBOL_NAME(__errno_location); \
str w19, [x0]; \
mov x0, -1; \
ldr x19, [sp,16]; \
ldp x29, x30, [sp], 32; \
cfi_adjust_cfa_offset (-32); \
cfi_restore (x29); \
cfi_restore (x30); \
RET;
# endif
# else
# define SYSCALL_ERROR_HANDLER /* Nothing here; code in sysdep.S is used. */
# define SYSCALL_ERROR __syscall_error
# endif
/* Linux takes system call args in registers:
syscall number in the SVC instruction
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) \
DOARGS_##args \
mov x8, SYS_ify (syscall_name); \
svc 0; \
UNDOARGS_##args
# define DOARGS_0 /* nothing */
# define DOARGS_1 /* nothing */
# define DOARGS_2 /* nothing */
# define DOARGS_3 /* nothing */
# define DOARGS_4 /* nothing */
# define DOARGS_5 /* nothing */
# define DOARGS_6 /* nothing */
# define DOARGS_7 /* nothing */
# define UNDOARGS_0 /* nothing */
# define UNDOARGS_1 /* nothing */
# define UNDOARGS_2 /* nothing */
# define UNDOARGS_3 /* nothing */
# define UNDOARGS_4 /* nothing */
# define UNDOARGS_5 /* nothing */
# define UNDOARGS_6 /* nothing */
# define UNDOARGS_7 /* nothing */
#else /* not __ASSEMBLER__ */
# ifdef SHARED
# define INLINE_VSYSCALL(name, nr, args...) \
({ \
__label__ out; \
__label__ iserr; \
long sc_ret; \
INTERNAL_SYSCALL_DECL (sc_err); \
\
if (__vdso_##name != NULL) \
{ \
sc_ret = INTERNAL_VSYSCALL_NCS (__vdso_##name, sc_err, nr, ##args); \
if (!INTERNAL_SYSCALL_ERROR_P (sc_ret, sc_err)) \
goto out; \
if (INTERNAL_SYSCALL_ERRNO (sc_ret, sc_err) != ENOSYS) \
goto iserr; \
} \
\
sc_ret = INTERNAL_SYSCALL (name, sc_err, nr, ##args); \
if (INTERNAL_SYSCALL_ERROR_P (sc_ret, sc_err)) \
{ \
iserr: \
__set_errno (INTERNAL_SYSCALL_ERRNO (sc_ret, sc_err)); \
sc_ret = -1L; \
} \
out: \
sc_ret; \
})
# else
# define INLINE_VSYSCALL(name, nr, args...) \
INLINE_SYSCALL (name, nr, ##args)
# endif
# ifdef SHARED
# define INTERNAL_VSYSCALL(name, err, nr, args...) \
({ \
__label__ out; \
long v_ret; \
\
if (__vdso_##name != NULL) \
{ \
v_ret = INTERNAL_VSYSCALL_NCS (__vdso_##name, err, nr, ##args); \
if (!INTERNAL_SYSCALL_ERROR_P (v_ret, err) \
|| INTERNAL_SYSCALL_ERRNO (v_ret, err) != ENOSYS) \
goto out; \
} \
v_ret = INTERNAL_SYSCALL (name, err, nr, ##args); \
out: \
v_ret; \
})
# else
# define INTERNAL_VSYSCALL(name, err, nr, args...) \
INTERNAL_SYSCALL (name, err, nr, ##args)
# endif
/* List of system calls which are supported as vsyscalls. */
# define HAVE_CLOCK_GETRES_VSYSCALL 1
# define HAVE_CLOCK_GETTIME_VSYSCALL 1
# define INTERNAL_VSYSCALL_NCS(funcptr, err, nr, args...) \
({ \
LOAD_ARGS_##nr (args) \
asm volatile ("blr %1" \
: "=r" (_x0) \
: "r" (funcptr), ASM_ARGS_##nr \
: "x30", "memory"); \
(long) _x0; \
})
/* 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...) \
({ unsigned 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", CLOBBER_ARGS_##nr); \
_sys_result = _x0; \
} \
(long) _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 CLOBBER_ARGS_0 CLOBBER_ARGS_1
# define CLOBBER_ARGS_1 "x1", CLOBBER_ARGS_2
# define CLOBBER_ARGS_2 "x2", CLOBBER_ARGS_3
# define CLOBBER_ARGS_3 "x3", CLOBBER_ARGS_4
# define CLOBBER_ARGS_4 "x4", CLOBBER_ARGS_5
# define CLOBBER_ARGS_5 "x5", CLOBBER_ARGS_6
# define CLOBBER_ARGS_6 "x6", CLOBBER_ARGS_7
# define CLOBBER_ARGS_7 \
"x7", "x9", "x10", "x11", "x12", "x13", "x14", "x15", "x16", "x17", "x18"
# define LOAD_ARGS_0() \
register long _x0 asm ("x0");
# define ASM_ARGS_0
# define LOAD_ARGS_1(x0) \
long _x0tmp = (long) (x0); \
LOAD_ARGS_0 () \
_x0 = _x0tmp;
# define ASM_ARGS_1 "r" (_x0)
# define LOAD_ARGS_2(x0, x1) \
long _x1tmp = (long) (x1); \
LOAD_ARGS_1 (x0) \
register long _x1 asm ("x1") = _x1tmp;
# define ASM_ARGS_2 ASM_ARGS_1, "r" (_x1)
# define LOAD_ARGS_3(x0, x1, x2) \
long _x2tmp = (long) (x2); \
LOAD_ARGS_2 (x0, x1) \
register long _x2 asm ("x2") = _x2tmp;
# define ASM_ARGS_3 ASM_ARGS_2, "r" (_x2)
# 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 ASM_ARGS_4 ASM_ARGS_3, "r" (_x3)
# 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 ASM_ARGS_5 ASM_ARGS_4, "r" (_x4)
# 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 ASM_ARGS_6 ASM_ARGS_5, "r" (_x5)
# 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_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 (defined NOT_IN_libc && defined IS_IN_rtld) || \
(!defined SHARED && (!defined NOT_IN_libc || defined IS_IN_libpthread))
# ifdef __ASSEMBLER__
# 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 dst, src, 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__
# 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 dst, src, 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 */
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