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1/* Assembler macros for 64 bit S/390.
2 Copyright (C) 2001-2025 Free Software Foundation, Inc.
3 This file is part of the GNU C Library.
4
5 The GNU C Library is free software; you can redistribute it and/or
6 modify it under the terms of the GNU Lesser General Public
7 License as published by the Free Software Foundation; either
8 version 2.1 of the License, or (at your option) any later version.
9
10 The GNU C Library is distributed in the hope that it will be useful,
11 but WITHOUT ANY WARRANTY; without even the implied warranty of
12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
13 Lesser General Public License for more details.
14
15 You should have received a copy of the GNU Lesser General Public
16 License along with the GNU C Library; if not, see
17 <https://www.gnu.org/licenses/>. */
18
19#ifndef _LINUX_S390_SYSDEP_H
20#define _LINUX_S390_SYSDEP_H
21
22#include <sysdeps/s390/s390-64/sysdep.h>
23#include <sysdeps/unix/sysdep.h>
24#include <sysdeps/unix/sysv/linux/s390/sysdep.h>
25#include <sysdeps/unix/sysv/linux/sysdep.h>
26#include <dl-sysdep.h> /* For RTLD_PRIVATE_ERRNO. */
27#include <tls.h>
28
29/* For Linux we can use the system call table in the header file
30 /usr/include/asm/unistd.h
31 of the kernel. But these symbols do not follow the SYS_* syntax
32 so we have to redefine the `SYS_ify' macro here. */
33/* In newer 2.1 kernels __NR_syscall is missing so we define it here. */
34#define __NR_syscall 0
35
36#undef SYS_ify
37#define SYS_ify(syscall_name) __NR_##syscall_name
38
39#ifdef __ASSEMBLER__
40
41/* Linux uses a negative return value to indicate syscall errors, unlike
42 most Unices, which use the condition codes' carry flag.
43
44 Since version 2.1 the return value of a system call might be negative
45 even if the call succeeded. E.g., the `lseek' system call might return
46 a large offset. Therefore we must not anymore test for < 0, but test
47 for a real error by making sure the value in gpr2 is a real error
48 number. Linus said he will make sure that no syscall returns a value
49 in -1 .. -4095 as a valid result so we can safely test with -4095. */
50
51#undef PSEUDO
52#define PSEUDO(name, syscall_name, args) \
53 .text; \
54 ENTRY (name) \
55 DO_CALL (syscall_name, args); \
56 lghi %r4,-4095 ; \
57 clgr %r2,%r4 ; \
58 jgnl SYSCALL_ERROR_LABEL
59
60#undef PSEUDO_END
61#define PSEUDO_END(name) \
62 SYSCALL_ERROR_HANDLER; \
63 END (name)
64
65#undef PSEUDO_NOERRNO
66#define PSEUDO_NOERRNO(name, syscall_name, args) \
67 .text; \
68 ENTRY (name) \
69 DO_CALL (syscall_name, args)
70
71#undef PSEUDO_END_NOERRNO
72#define PSEUDO_END_NOERRNO(name) \
73 SYSCALL_ERROR_HANDLER; \
74 END (name)
75
76#undef PSEUDO_ERRVAL
77#define PSEUDO_ERRVAL(name, syscall_name, args) \
78 .text; \
79 ENTRY (name) \
80 DO_CALL (syscall_name, args); \
81 lcgr %r2,%r2
82
83#undef PSEUDO_END_ERRVAL
84#define PSEUDO_END_ERRVAL(name) \
85 SYSCALL_ERROR_HANDLER; \
86 END (name)
87
88#undef SYSCALL_ERROR_LABEL
89#ifndef PIC
90# undef SYSCALL_ERROR_LABEL
91# define SYSCALL_ERROR_LABEL syscall_error
92# define SYSCALL_ERROR_HANDLER
93#else
94# if RTLD_PRIVATE_ERRNO
95# undef SYSCALL_ERROR_LABEL
96# define SYSCALL_ERROR_LABEL 0f
97# define SYSCALL_ERROR_HANDLER \
980: larl %r1,rtld_errno; \
99 lcr %r2,%r2; \
100 st %r2,0(%r1); \
101 lghi %r2,-1; \
102 br %r14
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 \
1120: lcr %r0,%r2; \
113 larl %r1,SYSCALL_ERROR_ERRNO@indntpoff; \
114 lg %r1,0(%r1); \
115 ear %r2,%a0; \
116 sllg %r2,%r2,32; \
117 ear %r2,%a1; \
118 st %r0,0(%r1,%r2); \
119 lghi %r2,-1; \
120 br %r14
121# else
122# undef SYSCALL_ERROR_LABEL
123# define SYSCALL_ERROR_LABEL 0f
124# define SYSCALL_ERROR_HANDLER \
1250: larl %r1,_GLOBAL_OFFSET_TABLE_; \
126 lg %r1,errno@GOT(%r1); \
127 lcr %r2,%r2; \
128 st %r2,0(%r1); \
129 lghi %r2,-1; \
130 br %r14
131# endif /* _LIBC_REENTRANT */
132#endif /* PIC */
133
134/* Linux takes system call arguments in registers:
135
136 syscall number 1 call-clobbered
137 arg 1 2 call-clobbered
138 arg 2 3 call-clobbered
139 arg 3 4 call-clobbered
140 arg 4 5 call-clobbered
141 arg 5 6 call-saved
142 arg 6 7 call-saved
143
144 (Of course a function with say 3 arguments does not have entries for
145 arguments 4 and 5.)
146 For system calls with 6 parameters a stack operation is required
147 to load the 6th parameter to register 7. Call saved register 7 is
148 moved to register 0 and back to avoid an additional stack frame.
149 */
150
151#define DO_CALL(syscall, args) \
152 .if args > 5; \
153 lgr %r0,%r7; \
154 lg %r7,160(%r15); \
155 .endif; \
156 lghi %r1,SYS_ify (syscall); \
157 svc 0; \
158 .if args > 5; \
159 lgr %r7,%r0; \
160 .endif
161
162#define ret \
163 br 14
164
165#define ret_NOERRNO \
166 br 14
167
168#define ret_ERRVAL \
169 br 14
170
171#else
172
173# undef HAVE_INTERNAL_BRK_ADDR_SYMBOL
174# define HAVE_INTERNAL_BRK_ADDR_SYMBOL 1
175
176#endif /* __ASSEMBLER__ */
177
178#endif /* _LINUX_S390_SYSDEP_H */