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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; \
44 /* If compiled for profiling, call `_mcount' at the start of each function. */
46 /* The mcount code relies on a normal frame pointer being on the stack
47 to locate our caller, so push one just for its benefit. */
49 move.l %fp, -(%sp); move.l %sp, %fp; \
50 jbsr JUMPTARGET (_mcount); \
53 #define CALL_MCOUNT /* Do nothing. */
57 #define JUMPTARGET(name) name##@PLTPC
59 #define JUMPTARGET(name) name
62 /* Since C identifiers are not normally prefixed with an underscore
63 on this system, the asm identifier `syscall_error' intrudes on the
64 C name space. Make sure we use an innocuous name. */
65 #define syscall_error __syscall_error
67 /* Linux uses a negative return value to indicate syscall errors, unlike
68 most Unices, which use the condition codes' carry flag.
70 Since version 2.1 the return value of a system call might be negative
71 even if the call succeeded. E.g., the `lseek' system call might return
72 a large offset. Therefore we must not anymore test for < 0, but test
73 for a real error by making sure the value in %d0 is a real error
74 number. For now (as of 2.1.1) 122 is the largest defined error number.
75 We allow for a bit of room for development and treat -128 to -1 as
77 #define PSEUDO(name, syscall_name, args) \
79 SYSCALL_ERROR_HANDLER \
81 DO_CALL (&SYS_ify (syscall_name), args); \
87 #define PSEUDO_END(name) .size name, . - name
90 /* Store (- %d0) into errno through the GOT. */
91 #ifdef _LIBC_REENTRANT
92 #define SYSCALL_ERROR_HANDLER \
93 .type syscall_error, @function; \
95 move.l (errno@GOTPC, %pc), %a0; \
99 jbsr __errno_location@PLTPC; \
100 move.l (%sp)+, (%a0); \
102 /* Copy return value to %a0 for syscalls that are declared to return \
103 a pointer (e.g., mmap). */ \
107 #define SYSCALL_ERROR_HANDLER \
108 .type syscall_error, @function; \
110 move.l (errno@GOTPC, %pc), %a0; \
114 /* Copy return value to %a0 for syscalls that are declared to return \
115 a pointer (e.g., mmap). */ \
118 #endif /* _LIBC_REENTRANT */
120 #define SYSCALL_ERROR_HANDLER /* Nothing here; code in sysdep.S is used. */
123 /* Linux takes system call arguments in registers:
125 syscall number %d0 call-clobbered
126 arg 1 %d1 call-clobbered
132 The stack layout upon entering the function is:
141 (Of course a function with say 3 arguments does not have entries for
144 Separate move's are faster than movem, but need more space. Since
145 speed is more important, we don't use movem. Since %a0 and %a1 are
146 scratch registers, we can use them for saving as well. */
148 #define DO_CALL(syscall, args) \
149 move.l syscall, %d0; \
154 #define DOARGS_0 /* No arguments to frob. */
155 #define UNDOARGS_0 /* No arguments to unfrob. */
156 #define _DOARGS_0(n) /* No arguments to frob. */
158 #define DOARGS_1 _DOARGS_1 (4)
159 #define _DOARGS_1(n) move.l n(%sp), %d1; _DOARGS_0 (n)
160 #define UNDOARGS_1 UNDOARGS_0
162 #define DOARGS_2 _DOARGS_2 (8)
163 #define _DOARGS_2(n) move.l %d2, %a0; move.l n(%sp), %d2; _DOARGS_1 (n-4)
164 #define UNDOARGS_2 UNDOARGS_1; move.l %a0, %d2
166 #define DOARGS_3 _DOARGS_3 (12)
167 #define _DOARGS_3(n) move.l %d3, %a1; move.l n(%sp), %d3; _DOARGS_2 (n-4)
168 #define UNDOARGS_3 UNDOARGS_2; move.l %a1, %d3
170 #define DOARGS_4 _DOARGS_4 (16)
171 #define _DOARGS_4(n) move.l %d4, -(%sp); move.l n+4(%sp), %d4; _DOARGS_3 (n)
172 #define UNDOARGS_4 UNDOARGS_3; move.l (%sp)+, %d4
174 #define DOARGS_5 _DOARGS_5 (20)
175 #define _DOARGS_5(n) move.l %d5, -(%sp); move.l n+4(%sp), %d5; _DOARGS_4 (n)
176 #define UNDOARGS_5 UNDOARGS_4; move.l (%sp)+, %d5
180 #if 0 /* Not used by Linux */
183 #define MOVE(x,y) movel x , y
186 #endif /* ASSEMBLER */