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
|
#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
*/
#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. */
#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; })
#define INTERNAL_SYSCALL(name, err, nr, args...) \
INTERNAL_SYSCALL_NCS (__NR_##name, err, nr, ##args)
#endif /* not __ASSEMBLER__ */
#endif /* _BITS_SYSCALLS_H */
|
