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0f2a261a | 1 | /* Copyright (C) 1992, 93, 95, 96, 97, 98 Free Software Foundation, Inc. |
c751295f UD |
2 | This file is part of the GNU C Library. |
3 | Contributed by Ulrich Drepper, <drepper@gnu.ai.mit.edu>, August 1995. | |
4 | ARM changes by Philip Blundell, <pjb27@cam.ac.uk>, May 1997. | |
8d2485ed | 5 | |
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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. | |
8d2485ed | 10 | |
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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. | |
8d2485ed | 15 | |
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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 not, | |
18 | write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330, | |
19 | Boston, MA 02111-1307, USA. */ | |
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20 | |
21 | #ifndef _LINUX_ARM_SYSDEP_H | |
22 | #define _LINUX_ARM_SYSDEP_H 1 | |
23 | ||
24 | /* There is some commonality. */ | |
25 | #include <sysdeps/unix/arm/sysdep.h> | |
26 | ||
27 | /* For Linux we can use the system call table in the header file | |
28 | /usr/include/asm/unistd.h | |
29 | of the kernel. But these symbols do not follow the SYS_* syntax | |
30 | so we have to redefine the `SYS_ify' macro here. */ | |
31 | #undef SYS_ify | |
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32 | #define SWI_BASE (0x900000) |
33 | #define SYS_ify(syscall_name) (__NR_##syscall_name) | |
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34 | |
35 | ||
36 | #ifdef ASSEMBLER | |
37 | ||
38 | /* Linux uses a negative return value to indicate syscall errors, | |
39 | unlike most Unices, which use the condition codes' carry flag. | |
40 | ||
41 | Since version 2.1 the return value of a system call might be | |
42 | negative even if the call succeeded. E.g., the `lseek' system call | |
43 | might return a large offset. Therefore we must not anymore test | |
0f2a261a | 44 | for < 0, but test for a real error by making sure the value in R0 |
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45 | is a real error number. Linus said he will make sure the no syscall |
46 | returns a value in -1 .. -4095 as a valid result so we can savely | |
47 | test with -4095. */ | |
ff550b1f | 48 | |
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49 | #undef PSEUDO |
50 | #define PSEUDO(name, syscall_name, args) \ | |
51 | .text; \ | |
24e022cf | 52 | .type syscall_error,%function ; \ |
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53 | ENTRY (name) \ |
54 | DO_CALL (args, syscall_name); \ | |
55 | cmn r0, $4096; \ | |
096031e1 | 56 | bhs PLTJMP(C_SYMBOL_NAME(__syscall_error)); |
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57 | |
58 | #undef PSEUDO_END | |
59 | #define PSEUDO_END(name) \ | |
60 | SYSCALL_ERROR_HANDLER \ | |
61 | END (name) | |
62 | ||
8d2485ed | 63 | #define SYSCALL_ERROR_HANDLER /* Nothing here; code in sysdep.S is used. */ |
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64 | |
65 | /* Linux takes system call args in registers: | |
66 | syscall number in the SWI instruction | |
67 | arg 1 r0 | |
68 | arg 2 r1 | |
69 | arg 3 r2 | |
70 | arg 4 r3 | |
71 | arg 5 r4 (this is different from the APCS convention) | |
72 | ||
73 | The compiler is going to form a call by coming here, through PSEUDO, with | |
74 | arguments | |
75 | syscall number in the DO_CALL macro | |
76 | arg 1 r0 | |
77 | arg 2 r1 | |
78 | arg 3 r2 | |
79 | arg 4 r3 | |
80 | arg 5 [sp] | |
81 | ||
82 | We need to shuffle values between R4 and the stack so that the caller's | |
83 | R4 is not corrupted, and the kernel sees the right argument there. | |
84 | ||
85 | */ | |
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86 | |
87 | #undef DO_CALL | |
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88 | #define DO_CALL(args, syscall_name) \ |
89 | DOARGS_##args \ | |
90 | swi SYS_ify (syscall_name); \ | |
91 | UNDOARGS_##args | |
92 | ||
93 | #define DOARGS_0 /* nothing */ | |
94 | #define DOARGS_1 /* nothing */ | |
95 | #define DOARGS_2 /* nothing */ | |
96 | #define DOARGS_3 /* nothing */ | |
97 | #define DOARGS_4 /* nothing */ | |
98 | #define DOARGS_5 ldr ip, [sp]; str r4, [sp]; mov r4, ip; | |
99 | ||
100 | #define UNDOARGS_0 /* nothing */ | |
101 | #define UNDOARGS_1 /* nothing */ | |
102 | #define UNDOARGS_2 /* nothing */ | |
103 | #define UNDOARGS_3 /* nothing */ | |
104 | #define UNDOARGS_4 /* nothing */ | |
105 | #define UNDOARGS_5 ldr r4, [sp]; | |
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106 | |
107 | #endif /* ASSEMBLER */ | |
108 | ||
109 | #endif /* linux/arm/sysdep.h */ |