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git.ipfire.org Git - thirdparty/glibc.git/blob - sysdeps/unix/sysv/linux/m68k/sysdep.h
1 /* Copyright (C) 1996 Free Software Foundation, Inc.
2 This file is part of the GNU C Library.
3 Written by Andreas Schwab, <schwab@issan.informatik.uni-dortmund.de>,
6 The GNU C Library is free software; you can redistribute it and/or
7 modify it under the terms of the GNU Library General Public License as
8 published by the Free Software Foundation; either version 2 of the
9 License, or (at your option) any later version.
11 The GNU C Library is distributed in the hope that it will be useful,
12 but WITHOUT ANY WARRANTY; without even the implied warranty of
13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
14 Library General Public License for more details.
16 You should have received a copy of the GNU Library General Public
17 License along with the GNU C Library; see the file COPYING.LIB. If
18 not, write to the Free Software Foundation, Inc., 675 Mass Ave,
19 Cambridge, MA 02139, USA. */
21 #include <sysdeps/unix/sysdep.h>
23 /* For Linux we can use the system call table in the header file
24 /usr/include/asm/unistd.h
25 of the kernel. But these symbols do not follow the SYS_* syntax
26 so we have to redefine the `SYS_ify' macro here. */
29 # define SYS_ify(syscall_name) __NR_##syscall_name
31 # define SYS_ify(syscall_name) __NR_/**/syscall_name
36 /* Define an entry point visible from C. */
39 .type name, @function; \
45 #define END(name) .size name, . - name
47 /* If compiled for profiling, call `_mcount' at the start of each function. */
49 /* The mcount code relies on a normal frame pointer being on the stack
50 to locate our caller, so push one just for its benefit. */
52 move.l %fp, -(%sp); move.l %sp, %fp; \
53 jbsr JUMPTARGET (_mcount); \
56 #define CALL_MCOUNT /* Do nothing. */
60 #define JUMPTARGET(name) name##@PLTPC
62 #define JUMPTARGET(name) name
65 /* Since C identifiers are not normally prefixed with an underscore
66 on this system, the asm identifier `syscall_error' intrudes on the
67 C name space. Make sure we use an innocuous name. */
68 #define syscall_error __syscall_error
70 /* Linux uses a negative return value to indicate syscall errors, unlike
71 most Unices, which use the condition codes' carry flag.
73 Since version 2.1 the return value of a system call might be negative
74 even if the call succeeded. E.g., the `lseek' system call might return
75 a large offset. Therefore we must not anymore test for < 0, but test
76 for a real error by making sure the value in %d0 is a real error
77 number. Linus said he will make sure the no syscall returns a value
78 in -1 .. -4095 as a valid result so we can savely test with -4096. */
79 #define PSEUDO(name, syscall_name, args) \
82 DO_CALL (&SYS_ify (syscall_name), args); \
83 moveq.l &-4096, %d1; \
88 #define PSEUDO_END(name) \
89 SYSCALL_ERROR_HANDLER; \
93 /* Store (- %d0) into errno through the GOT. */
94 #ifdef _LIBC_REENTRANT
95 #define SYSCALL_ERROR_HANDLER \
97 move.l (errno@GOTPC, %pc), %a0; \
100 move.l %d0, -(%sp); \
101 jbsr __errno_location@PLTPC; \
102 move.l (%sp)+, (%a0); \
104 /* Copy return value to %a0 for syscalls that are declared to return \
105 a pointer (e.g., mmap). */ \
109 #define SYSCALL_ERROR_HANDLER \
111 move.l (errno@GOTPC, %pc), %a0; \
115 /* Copy return value to %a0 for syscalls that are declared to return \
116 a pointer (e.g., mmap). */ \
119 #endif /* _LIBC_REENTRANT */
121 #define SYSCALL_ERROR_HANDLER /* Nothing here; code in sysdep.S is used. */
124 /* Linux takes system call arguments in registers:
126 syscall number %d0 call-clobbered
127 arg 1 %d1 call-clobbered
133 The stack layout upon entering the function is:
142 (Of course a function with say 3 arguments does not have entries for
145 Separate move's are faster than movem, but need more space. Since
146 speed is more important, we don't use movem. Since %a0 and %a1 are
147 scratch registers, we can use them for saving as well. */
149 #define DO_CALL(syscall, args) \
150 move.l syscall, %d0; \
155 #define DOARGS_0 /* No arguments to frob. */
156 #define UNDOARGS_0 /* No arguments to unfrob. */
157 #define _DOARGS_0(n) /* No arguments to frob. */
159 #define DOARGS_1 _DOARGS_1 (4)
160 #define _DOARGS_1(n) move.l n(%sp), %d1; _DOARGS_0 (n)
161 #define UNDOARGS_1 UNDOARGS_0
163 #define DOARGS_2 _DOARGS_2 (8)
164 #define _DOARGS_2(n) move.l %d2, %a0; move.l n(%sp), %d2; _DOARGS_1 (n-4)
165 #define UNDOARGS_2 UNDOARGS_1; move.l %a0, %d2
167 #define DOARGS_3 _DOARGS_3 (12)
168 #define _DOARGS_3(n) move.l %d3, %a1; move.l n(%sp), %d3; _DOARGS_2 (n-4)
169 #define UNDOARGS_3 UNDOARGS_2; move.l %a1, %d3
171 #define DOARGS_4 _DOARGS_4 (16)
172 #define _DOARGS_4(n) move.l %d4, -(%sp); move.l n+4(%sp), %d4; _DOARGS_3 (n)
173 #define UNDOARGS_4 UNDOARGS_3; move.l (%sp)+, %d4
175 #define DOARGS_5 _DOARGS_5 (20)
176 #define _DOARGS_5(n) move.l %d5, -(%sp); move.l n+4(%sp), %d5; _DOARGS_4 (n)
177 #define UNDOARGS_5 UNDOARGS_4; move.l (%sp)+, %d5
181 #if 0 /* Not used by Linux */
184 #define MOVE(x,y) movel x , y
187 #endif /* ASSEMBLER */