1//===-- sanitizer_syscall_linux_riscv64.inc ---------------------*- C++ -*-===//
2//
3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4// See https://llvm.org/LICENSE.txt for license information.
5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6//
7//===----------------------------------------------------------------------===//
8//
9// Implementations of internal_syscall and internal_iserror for Linux/riscv64.
10//
11//===----------------------------------------------------------------------===//
12
13// About local register variables:
14// https://gcc.gnu.org/onlinedocs/gcc/Local-Register-Variables.html#Local-Register-Variables
15//
16// Kernel ABI...
17// To my surprise I haven't found much information regarding it.
18// Kernel source and internet browsing shows that:
19//  syscall number is passed in a7
20//  (http://man7.org/linux/man-pages/man2/syscall.2.html) results are return in
21//  a0 and a1 (http://man7.org/linux/man-pages/man2/syscall.2.html) arguments
22//  are passed in: a0-a7 (see below)
23//
24//  Regarding the arguments. The only "documentation" I could find is
25//  this comment (!!!) by Bruce Hold on google forums (!!!):
26//    https://groups.google.com/a/groups.riscv.org/forum/#!topic/sw-dev/exbrzM3GZDQ
27//    Confirmed by inspecting glibc sources.
28//  Great way to document things.
29#define SYSCALL(name) __NR_##name
30
31#define INTERNAL_SYSCALL_CLOBBERS "memory"
32
33static uptr __internal_syscall(u64 nr) {
34  register u64 a7 asm("a7") = nr;
35  register u64 a0 asm("a0");
36  __asm__ volatile("ecall\n\t"
37                   : "=r"(a0)
38                   : "r"(a7)
39                   : INTERNAL_SYSCALL_CLOBBERS);
40  return a0;
41}
42#define __internal_syscall0(n) (__internal_syscall)(n)
43
44static uptr __internal_syscall(u64 nr, u64 arg1) {
45  register u64 a7 asm("a7") = nr;
46  register u64 a0 asm("a0") = arg1;
47  __asm__ volatile("ecall\n\t"
48                   : "+r"(a0)
49                   : "r"(a7)
50                   : INTERNAL_SYSCALL_CLOBBERS);
51  return a0;
52}
53#define __internal_syscall1(n, a1) (__internal_syscall)(n, (u64)(a1))
54
55static uptr __internal_syscall(u64 nr, u64 arg1, long arg2) {
56  register u64 a7 asm("a7") = nr;
57  register u64 a0 asm("a0") = arg1;
58  register u64 a1 asm("a1") = arg2;
59  __asm__ volatile("ecall\n\t"
60                   : "+r"(a0)
61                   : "r"(a7), "r"(a1)
62                   : INTERNAL_SYSCALL_CLOBBERS);
63  return a0;
64}
65#define __internal_syscall2(n, a1, a2) \
66  (__internal_syscall)(n, (u64)(a1), (long)(a2))
67
68static uptr __internal_syscall(u64 nr, u64 arg1, long arg2, long arg3) {
69  register u64 a7 asm("a7") = nr;
70  register u64 a0 asm("a0") = arg1;
71  register u64 a1 asm("a1") = arg2;
72  register u64 a2 asm("a2") = arg3;
73  __asm__ volatile("ecall\n\t"
74                   : "+r"(a0)
75                   : "r"(a7), "r"(a1), "r"(a2)
76                   : INTERNAL_SYSCALL_CLOBBERS);
77  return a0;
78}
79#define __internal_syscall3(n, a1, a2, a3) \
80  (__internal_syscall)(n, (u64)(a1), (long)(a2), (long)(a3))
81
82static uptr __internal_syscall(u64 nr, u64 arg1, long arg2, long arg3,
83                               u64 arg4) {
84  register u64 a7 asm("a7") = nr;
85  register u64 a0 asm("a0") = arg1;
86  register u64 a1 asm("a1") = arg2;
87  register u64 a2 asm("a2") = arg3;
88  register u64 a3 asm("a3") = arg4;
89  __asm__ volatile("ecall\n\t"
90                   : "+r"(a0)
91                   : "r"(a7), "r"(a1), "r"(a2), "r"(a3)
92                   : INTERNAL_SYSCALL_CLOBBERS);
93  return a0;
94}
95#define __internal_syscall4(n, a1, a2, a3, a4) \
96  (__internal_syscall)(n, (u64)(a1), (long)(a2), (long)(a3), (long)(a4))
97
98static uptr __internal_syscall(u64 nr, u64 arg1, long arg2, long arg3, u64 arg4,
99                               long arg5) {
100  register u64 a7 asm("a7") = nr;
101  register u64 a0 asm("a0") = arg1;
102  register u64 a1 asm("a1") = arg2;
103  register u64 a2 asm("a2") = arg3;
104  register u64 a3 asm("a3") = arg4;
105  register u64 a4 asm("a4") = arg5;
106  __asm__ volatile("ecall\n\t"
107                   : "+r"(a0)
108                   : "r"(a7), "r"(a1), "r"(a2), "r"(a3), "r"(a4)
109                   : INTERNAL_SYSCALL_CLOBBERS);
110  return a0;
111}
112#define __internal_syscall5(n, a1, a2, a3, a4, a5)                       \
113  (__internal_syscall)(n, (u64)(a1), (long)(a2), (long)(a3), (long)(a4), \
114                       (u64)(a5))
115
116static uptr __internal_syscall(u64 nr, u64 arg1, long arg2, long arg3, u64 arg4,
117                               long arg5, long arg6) {
118  register u64 a7 asm("a7") = nr;
119  register u64 a0 asm("a0") = arg1;
120  register u64 a1 asm("a1") = arg2;
121  register u64 a2 asm("a2") = arg3;
122  register u64 a3 asm("a3") = arg4;
123  register u64 a4 asm("a4") = arg5;
124  register u64 a5 asm("a5") = arg6;
125  __asm__ volatile("ecall\n\t"
126                   : "+r"(a0)
127                   : "r"(a7), "r"(a1), "r"(a2), "r"(a3), "r"(a4), "r"(a5)
128                   : INTERNAL_SYSCALL_CLOBBERS);
129  return a0;
130}
131#define __internal_syscall6(n, a1, a2, a3, a4, a5, a6)                   \
132  (__internal_syscall)(n, (u64)(a1), (long)(a2), (long)(a3), (long)(a4), \
133                       (u64)(a5), (long)(a6))
134
135static uptr __internal_syscall(u64 nr, u64 arg1, long arg2, long arg3, u64 arg4,
136                               long arg5, long arg6, long arg7) {
137  register u64 a7 asm("a7") = nr;
138  register u64 a0 asm("a0") = arg1;
139  register u64 a1 asm("a1") = arg2;
140  register u64 a2 asm("a2") = arg3;
141  register u64 a3 asm("a3") = arg4;
142  register u64 a4 asm("a4") = arg5;
143  register u64 a5 asm("a5") = arg6;
144  register u64 a6 asm("a6") = arg7;
145  __asm__ volatile("ecall\n\t"
146                   : "+r"(a0)
147                   : "r"(a7), "r"(a1), "r"(a2), "r"(a3), "r"(a4), "r"(a5),
148                     "r"(a6)
149                   : INTERNAL_SYSCALL_CLOBBERS);
150  return a0;
151}
152#define __internal_syscall7(n, a1, a2, a3, a4, a5, a6, a7)               \
153  (__internal_syscall)(n, (u64)(a1), (long)(a2), (long)(a3), (long)(a4), \
154                       (u64)(a5), (long)(a6), (long)(a7))
155
156#define __SYSCALL_NARGS_X(a1, a2, a3, a4, a5, a6, a7, a8, n, ...) n
157#define __SYSCALL_NARGS(...) \
158  __SYSCALL_NARGS_X(__VA_ARGS__, 7, 6, 5, 4, 3, 2, 1, 0, )
159#define __SYSCALL_CONCAT_X(a, b) a##b
160#define __SYSCALL_CONCAT(a, b) __SYSCALL_CONCAT_X(a, b)
161#define __SYSCALL_DISP(b, ...) \
162  __SYSCALL_CONCAT(b, __SYSCALL_NARGS(__VA_ARGS__))(__VA_ARGS__)
163
164#define internal_syscall(...) __SYSCALL_DISP(__internal_syscall, __VA_ARGS__)
165
166// Helper function used to avoid clobbering of errno.
167bool internal_iserror(uptr retval, int *rverrno) {
168  if (retval >= (uptr)-4095) {
169    if (rverrno)
170      *rverrno = -retval;
171    return true;
172  }
173  return false;
174}
175