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
|
#ifndef _BITS_SYSCALLS_H
#define _BITS_SYSCALLS_H
#ifndef _SYSCALL_H
# error "Never use <bits/syscalls.h> directly; include <sys/syscall.h> instead."
#endif
/*
Some of the sneaky macros in the code were taken from
glibc .../sysdeps/unix/sysv/linux/xtensa/sysdep.h
*/
#define SYS_ify(syscall_name) __NR_##syscall_name
#ifdef __ASSEMBLER__
/* The register layout upon entering the function is:
return addr stack ptr arg0, arg1, arg2, arg3, arg4, arg5
----------- --------- ----------------------------------
a0 a1 a2, a3, a4, a5, a6, a7
(Of course a function with say 3 arguments does not have entries for
arguments 4, 5, and 6.)
Linux takes system-call arguments in registers. The ABI and Xtensa
software conventions require the system-call number in a2. We move any
argument that was in a2 to a7, and a7 to a8 if we have all 6 arguments.
Note that for improved efficiency, we do NOT shift all parameters down
one register to maintain the original order.
syscall number arg0, arg1, arg2, arg3, arg4, arg5
-------------- ----------------------------------
a2 a6, a3, a4, a5, a8, a9
Upon return, a2 and a3 are clobbered; all other registers are preserved. */
#undef DO_CALL
#define DO_CALL(syscall_name, nargs) \
DO_ARGS_##nargs \
movi a2, SYS_ify (syscall_name); \
syscall
#define DO_ARGS_0
#define DO_ARGS_1 mov a6, a2;
#define DO_ARGS_2 mov a6, a2;
#define DO_ARGS_3 mov a6, a2;
#define DO_ARGS_4 mov a6, a2;
#define DO_ARGS_5 mov a8, a6; mov a6, a2;
#define DO_ARGS_6 mov a9, a7; mov a8, a6; mov a6, a2;
#else /* not __ASSEMBLER__ */
#include <errno.h>
#define STR(s) #s
#define LD_ARG(n,ar) register int _a##n asm (STR(a##n)) = (int) (ar)
#define LD_ARGS_0()
#define LD_ARGS_1(a0) LD_ARG(6,a0)
#define LD_ARGS_2(a0,a1) LD_ARGS_1(a0); LD_ARG(3,a1)
#define LD_ARGS_3(a0,a1,a2) LD_ARGS_2(a0,a1); LD_ARG(4,a2)
#define LD_ARGS_4(a0,a1,a2,a3) LD_ARGS_3(a0,a1,a2); LD_ARG(5,a3)
#define LD_ARGS_5(a0,a1,a2,a3,a4) LD_ARGS_4(a0,a1,a2,a3); LD_ARG(8,a4)
#define LD_ARGS_6(a0,a1,a2,a3,a4,a5) LD_ARGS_5(a0,a1,a2,a3,a4); LD_ARG(9,a5)
#define ASM_ARGS_0 "r"(_a2)
#define ASM_ARGS_1 ASM_ARGS_0, "r"(_a6)
#define ASM_ARGS_2 ASM_ARGS_1, "r"(_a3)
#define ASM_ARGS_3 ASM_ARGS_2, "r"(_a4)
#define ASM_ARGS_4 ASM_ARGS_3, "r"(_a5)
#define ASM_ARGS_5 ASM_ARGS_4, "r"(_a8)
#define ASM_ARGS_6 ASM_ARGS_5, "r"(_a9)
/* Define a macro which expands into the inline wrapper code for a system
call. */
#undef INLINE_SYSCALL
#define INLINE_SYSCALL(name, nr, args...) \
({ unsigned long resultvar = INTERNAL_SYSCALL (name, , nr, args); \
if (__builtin_expect (INTERNAL_SYSCALL_ERROR_P (resultvar, ), 0)) \
{ \
__set_errno (INTERNAL_SYSCALL_ERRNO (resultvar, )); \
resultvar = (unsigned long) -1; \
} \
(long) resultvar; })
#undef INTERNAL_SYSCALL_DECL
#define INTERNAL_SYSCALL_DECL(err) do { } while (0)
#define INTERNAL_SYSCALL_NCS(name, err, nr, args...) \
({ LD_ARG(2, name); \
LD_ARGS_##nr(args); \
asm volatile ("syscall\n" \
: "=a" (_a2) \
: ASM_ARGS_##nr \
: "memory"); \
(long) _a2; })
#undef INTERNAL_SYSCALL
#define INTERNAL_SYSCALL(name, err, nr, args...) \
INTERNAL_SYSCALL_NCS (__NR_##name, err, nr, ##args)
#undef INTERNAL_SYSCALL_ERROR_P
#define INTERNAL_SYSCALL_ERROR_P(val, err) \
((unsigned long) (val) >= -4095L)
#undef INTERNAL_SYSCALL_ERRNO
#define INTERNAL_SYSCALL_ERRNO(val, err) (-(val))
#define _syscall0(args...) SYSCALL_FUNC (0, args)
#define _syscall1(args...) SYSCALL_FUNC (1, args)
#define _syscall2(args...) SYSCALL_FUNC (2, args)
#define _syscall3(args...) SYSCALL_FUNC (3, args)
#define _syscall4(args...) SYSCALL_FUNC (4, args)
#define _syscall5(args...) SYSCALL_FUNC (5, args)
#define _syscall6(args...) SYSCALL_FUNC (6, args)
#define C_DECL_ARGS_0() void
#define C_DECL_ARGS_1(t, v) t v
#define C_DECL_ARGS_2(t, v, args...) t v, C_DECL_ARGS_1(args)
#define C_DECL_ARGS_3(t, v, args...) t v, C_DECL_ARGS_2(args)
#define C_DECL_ARGS_4(t, v, args...) t v, C_DECL_ARGS_3(args)
#define C_DECL_ARGS_5(t, v, args...) t v, C_DECL_ARGS_4(args)
#define C_DECL_ARGS_6(t, v, args...) t v, C_DECL_ARGS_5(args)
#define C_ARGS_0()
#define C_ARGS_1(t, v) v
#define C_ARGS_2(t, v, args...) v, C_ARGS_1 (args)
#define C_ARGS_3(t, v, args...) v, C_ARGS_2 (args)
#define C_ARGS_4(t, v, args...) v, C_ARGS_3 (args)
#define C_ARGS_5(t, v, args...) v, C_ARGS_4 (args)
#define C_ARGS_6(t, v, args...) v, C_ARGS_5 (args)
#define SYSCALL_FUNC(nargs, type, name, args...) \
type name (C_DECL_ARGS_##nargs (args)) { \
return (type) INLINE_SYSCALL (name, nargs, C_ARGS_##nargs (args)); \
}
#endif /* not __ASSEMBLER__ */
#endif /* _BITS_SYSCALLS_H */
|
