1 /* Copyright (C) 2000-2023 Free Software Foundation, Inc.
2 This file is part of the GNU C Library.
3
4 The GNU C Library is free software; you can redistribute it and/or
5 modify it under the terms of the GNU Lesser General Public
6 License as published by the Free Software Foundation; either
7 version 2.1 of the License, or (at your option) any later version.
8
9 The GNU C Library is distributed in the hope that it will be useful,
10 but WITHOUT ANY WARRANTY; without even the implied warranty of
11 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
12 Lesser General Public License for more details.
13
14 You should have received a copy of the GNU Lesser General Public
15 License along with the GNU C Library; if not, see
16 <https://www.gnu.org/licenses/>. */
17
18 #ifndef _LINUX_S390_SYSDEP_H
19 #define _LINUX_S390_SYSDEP_H
20
21 #include <sysdeps/s390/s390-32/sysdep.h>
22 #include <sysdeps/unix/sysdep.h>
23 #include <sysdeps/unix/sysv/linux/s390/sysdep.h>
24 #include <sysdeps/unix/sysv/linux/sysdep.h>
25 #include <dl-sysdep.h> /* For RTLD_PRIVATE_ERRNO. */
26 #include <tls.h>
27
28 /* For Linux we can use the system call table in the header file
29 /usr/include/asm/unistd.h
30 of the kernel. But these symbols do not follow the SYS_* syntax
31 so we have to redefine the `SYS_ify' macro here. */
32 /* in newer 2.1 kernels __NR_syscall is missing so we define it here */
33 #define __NR_syscall 0
34
35 #ifdef __ASSEMBLER__
36
37 /* Linux uses a negative return value to indicate syscall errors, unlike
38 most Unices, which use the condition codes' carry flag.
39
40 Since version 2.1 the return value of a system call might be negative
41 even if the call succeeded. E.g., the `lseek' system call might return
42 a large offset. Therefore we must not anymore test for < 0, but test
43 for a real error by making sure the value in gpr2 is a real error
44 number. Linus said he will make sure that no syscall returns a value
45 in -1 .. -4095 as a valid result so we can safely test with -4095. */
46
47 #undef PSEUDO
48 #define PSEUDO(name, syscall_name, args) \
49 .text; \
50 ENTRY (name) \
51 DO_CALL (syscall_name, args); \
52 lhi %r4,-4095 ; \
53 clr %r2,%r4 ; \
54 jnl SYSCALL_ERROR_LABEL
55
56 #undef PSEUDO_END
57 #define PSEUDO_END(name) \
58 SYSCALL_ERROR_HANDLER; \
59 END (name)
60
61 #undef PSEUDO_NOERRNO
62 #define PSEUDO_NOERRNO(name, syscall_name, args) \
63 .text; \
64 ENTRY (name) \
65 DO_CALL (syscall_name, args)
66
67 #undef PSEUDO_END_NOERRNO
68 #define PSEUDO_END_NOERRNO(name) \
69 END (name)
70
71 #undef PSEUDO_ERRVAL
72 #define PSEUDO_ERRVAL(name, syscall_name, args) \
73 .text; \
74 ENTRY (name) \
75 DO_CALL (syscall_name, args); \
76 lcr %r2,%r2
77
78 #undef PSEUDO_END_ERRVAL
79 #define PSEUDO_END_ERRVAL(name) \
80 END (name)
81
82 #undef SYSCALL_ERROR_LABEL
83 #ifndef PIC
84 # undef SYSCALL_ERROR_LABEL
85 # define SYSCALL_ERROR_LABEL 0f
86 # define SYSCALL_ERROR_HANDLER \
87 0: basr %r1,0; \
88 1: l %r1,2f-1b(%r1); \
89 br %r1; \
90 2: .long syscall_error
91 #else
92 # if RTLD_PRIVATE_ERRNO
93 # undef SYSCALL_ERROR_LABEL
94 # define SYSCALL_ERROR_LABEL 0f
95 # define SYSCALL_ERROR_HANDLER \
96 0: basr %r1,0; \
97 1: al %r1,2f-1b(%r1); \
98 lcr %r2,%r2; \
99 st %r2,0(%r1); \
100 lhi %r2,-1; \
101 br %r14; \
102 2: .long rtld_errno-1b
103 # elif defined _LIBC_REENTRANT
104 # if IS_IN (libc)
105 # define SYSCALL_ERROR_ERRNO __libc_errno
106 # else
107 # define SYSCALL_ERROR_ERRNO errno
108 # endif
109 # undef SYSCALL_ERROR_LABEL
110 # define SYSCALL_ERROR_LABEL 0f
111 # define SYSCALL_ERROR_HANDLER \
112 0: lcr %r0,%r2; \
113 basr %r1,0; \
114 1: al %r1,2f-1b(%r1); \
115 l %r1,SYSCALL_ERROR_ERRNO@gotntpoff(%r1); \
116 ear %r2,%a0; \
117 st %r0,0(%r1,%r2); \
118 lhi %r2,-1; \
119 br %r14; \
120 2: .long _GLOBAL_OFFSET_TABLE_-1b
121 # else
122 # undef SYSCALL_ERROR_LABEL
123 # define SYSCALL_ERROR_LABEL 0f
124 # define SYSCALL_ERROR_HANDLER \
125 0: basr %r1,0; \
126 1: al %r1,2f-1b(%r1); \
127 l %r1,errno@GOT(%r1); \
128 lcr %r2,%r2; \
129 st %r2,0(%r1); \
130 lhi %r2,-1; \
131 br %r14; \
132 2: .long _GLOBAL_OFFSET_TABLE_-1b
133 # endif /* _LIBC_REENTRANT */
134 #endif /* PIC */
135
136 /* Linux takes system call arguments in registers:
137
138 syscall number 1 call-clobbered
139 arg 1 2 call-clobbered
140 arg 2 3 call-clobbered
141 arg 3 4 call-clobbered
142 arg 4 5 call-clobbered
143 arg 5 6 call-saved
144 arg 6 7 call-saved
145
146 (Of course a function with say 3 arguments does not have entries for
147 arguments 4 and 5.)
148 For system calls with 6 parameters a stack operation is required
149 to load the 6th parameter to register 7. Call saved register 7 is
150 moved to register 0 and back to avoid an additional stack frame.
151 */
152
153 #define DO_CALL(syscall, args) \
154 .if args > 5; \
155 lr %r0,%r7; \
156 l %r7,96(%r15); \
157 .endif; \
158 lhi %r1,SYS_ify (syscall); \
159 svc 0; \
160 .if args > 5; \
161 lr %r7,%r0; \
162 .endif
163
164 #define ret \
165 br 14
166
167 #define ret_NOERRNO \
168 br 14
169
170 #define ret_ERRVAL \
171 br 14
172
173 #else
174
175 # undef HAVE_INTERNAL_BRK_ADDR_SYMBOL
176 # define HAVE_INTERNAL_BRK_ADDR_SYMBOL 1
177
178 #endif /* __ASSEMBLER__ */
179
180 #endif /* _LINUX_S390_SYSDEP_H */