1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
|
/* Copyright (C) 1996 Free Software Foundation, Inc.
This file is part of the GNU C Library.
Written by Andreas Schwab, <schwab@issan.informatik.uni-dortmund.de>,
December 1995.
The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Library General Public License as
published by the Free Software Foundation; either version 2 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
Library General Public License for more details.
You should have received a copy of the GNU Library General Public
License along with the GNU C Library; see the file COPYING.LIB. If
not, write to the Free Software Foundation, Inc., 675 Mass Ave,
Cambridge, MA 02139, USA. */
#include <sysdeps/unix/sysdep.h>
/* 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
#ifdef __STDC__
# define SYS_ify(syscall_name) __NR_##syscall_name
#else
# define SYS_ify(syscall_name) __NR_/**/syscall_name
#endif
#ifdef ASSEMBLER
/* Define an entry point visible from C. */
#define ENTRY(name) \
.globl name; \
.type name, @function; \
.align 4; \
C_LABEL(name) \
CALL_MCOUNT
#undef END
#define END(name) .size name, . - name
/* If compiled for profiling, call `_mcount' at the start of each function. */
#ifdef PROF
/* The mcount code relies on a normal frame pointer being on the stack
to locate our caller, so push one just for its benefit. */
#define CALL_MCOUNT \
move.l %fp, -(%sp); move.l %sp, %fp; \
jbsr JUMPTARGET (_mcount); \
move.l (%sp)+, %fp;
#else
#define CALL_MCOUNT /* Do nothing. */
#endif
#ifdef PIC
#define JUMPTARGET(name) name##@PLTPC
#else
#define JUMPTARGET(name) name
#endif
/* Since C identifiers are not normally prefixed with an underscore
on this system, the asm identifier `syscall_error' intrudes on the
C name space. Make sure we use an innocuous name. */
#define syscall_error __syscall_error
/* 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 %d0 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 savely test with -4095. */
#define PSEUDO(name, syscall_name, args) \
.text; \
ENTRY (name) \
DO_CALL (&SYS_ify (syscall_name), args); \
cmp.l &-4095, %d0; \
jcc syscall_error
#undef PSEUDO_END
#define PSEUDO_END(name) \
SYSCALL_ERROR_HANDLER; \
END (name)
#ifdef PIC
/* Store (- %d0) into errno through the GOT. */
#ifdef _LIBC_REENTRANT
#define SYSCALL_ERROR_HANDLER \
syscall_error: \
move.l (errno@GOTPC, %pc), %a0; \
neg.l %d0; \
move.l %d0, (%a0); \
move.l %d0, -(%sp); \
jbsr __errno_location@PLTPC; \
move.l (%sp)+, (%a0); \
move.l &-1, %d0; \
/* Copy return value to %a0 for syscalls that are declared to return \
a pointer (e.g., mmap). */ \
move.l %d0, %a0; \
rts;
#else
#define SYSCALL_ERROR_HANDLER \
syscall_error: \
move.l (errno@GOTPC, %pc), %a0; \
neg.l %d0; \
move.l %d0, (%a0); \
move.l &-1, %d0; \
/* Copy return value to %a0 for syscalls that are declared to return \
a pointer (e.g., mmap). */ \
move.l %d0, %a0; \
rts;
#endif /* _LIBC_REENTRANT */
#else
#define SYSCALL_ERROR_HANDLER /* Nothing here; code in sysdep.S is used. */
#endif /* PIC */
/* Linux takes system call arguments in registers:
syscall number %d0 call-clobbered
arg 1 %d1 call-clobbered
arg 2 %d2 call-saved
arg 3 %d3 call-saved
arg 4 %d4 call-saved
arg 5 %d5 call-saved
The stack layout upon entering the function is:
20(%sp) Arg# 5
16(%sp) Arg# 4
12(%sp) Arg# 3
8(%sp) Arg# 2
4(%sp) Arg# 1
(%sp) Return address
(Of course a function with say 3 arguments does not have entries for
arguments 4 and 5.)
Separate move's are faster than movem, but need more space. Since
speed is more important, we don't use movem. Since %a0 and %a1 are
scratch registers, we can use them for saving as well. */
#define DO_CALL(syscall, args) \
move.l syscall, %d0; \
DOARGS_##args \
trap &0; \
UNDOARGS_##args
#define DOARGS_0 /* No arguments to frob. */
#define UNDOARGS_0 /* No arguments to unfrob. */
#define _DOARGS_0(n) /* No arguments to frob. */
#define DOARGS_1 _DOARGS_1 (4)
#define _DOARGS_1(n) move.l n(%sp), %d1; _DOARGS_0 (n)
#define UNDOARGS_1 UNDOARGS_0
#define DOARGS_2 _DOARGS_2 (8)
#define _DOARGS_2(n) move.l %d2, %a0; move.l n(%sp), %d2; _DOARGS_1 (n-4)
#define UNDOARGS_2 UNDOARGS_1; move.l %a0, %d2
#define DOARGS_3 _DOARGS_3 (12)
#define _DOARGS_3(n) move.l %d3, %a1; move.l n(%sp), %d3; _DOARGS_2 (n-4)
#define UNDOARGS_3 UNDOARGS_2; move.l %a1, %d3
#define DOARGS_4 _DOARGS_4 (16)
#define _DOARGS_4(n) move.l %d4, -(%sp); move.l n+4(%sp), %d4; _DOARGS_3 (n)
#define UNDOARGS_4 UNDOARGS_3; move.l (%sp)+, %d4
#define DOARGS_5 _DOARGS_5 (20)
#define _DOARGS_5(n) move.l %d5, -(%sp); move.l n+4(%sp), %d5; _DOARGS_4 (n)
#define UNDOARGS_5 UNDOARGS_4; move.l (%sp)+, %d5
#define ret rts
#if 0 /* Not used by Linux */
#define r0 %d0
#define r1 %d1
#define MOVE(x,y) movel x , y
#endif
#endif /* ASSEMBLER */
|
