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
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
|
/*
* Emulation of Linux signals
*
* Copyright (c) 2003 Fabrice Bellard
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, see <http://www.gnu.org/licenses/>.
*/
#include "qemu/osdep.h"
#include "qemu.h"
#include "signal-common.h"
#include "linux-user/trace.h"
/* Signal handler invocation must be transparent for the code being
interrupted. Complete CPU (hart) state is saved on entry and restored
before returning from the handler. Process sigmask is also saved to block
signals while the handler is running. The handler gets its own stack,
which also doubles as storage for the CPU state and sigmask.
The code below is qemu re-implementation of arch/riscv/kernel/signal.c */
struct target_sigcontext {
abi_long pc;
abi_long gpr[31]; /* x0 is not present, so all offsets must be -1 */
uint64_t fpr[32];
uint32_t fcsr;
}; /* cf. riscv-linux:arch/riscv/include/uapi/asm/ptrace.h */
struct target_ucontext {
unsigned long uc_flags;
struct target_ucontext *uc_link;
target_stack_t uc_stack;
struct target_sigcontext uc_mcontext;
target_sigset_t uc_sigmask;
};
struct target_rt_sigframe {
uint32_t tramp[2]; /* not in kernel, which uses VDSO instead */
struct target_siginfo info;
struct target_ucontext uc;
};
static abi_ulong get_sigframe(struct target_sigaction *ka,
CPURISCVState *regs, size_t framesize)
{
abi_ulong sp = get_sp_from_cpustate(regs);
/* If we are on the alternate signal stack and would overflow it, don't.
Return an always-bogus address instead so we will die with SIGSEGV. */
if (on_sig_stack(sp) && !likely(on_sig_stack(sp - framesize))) {
return -1L;
}
/* This is the X/Open sanctioned signal stack switching. */
sp = target_sigsp(sp, ka) - framesize;
/* XXX: kernel aligns with 0xf ? */
sp &= ~3UL; /* align sp on 4-byte boundary */
return sp;
}
static void setup_sigcontext(struct target_sigcontext *sc, CPURISCVState *env)
{
int i;
__put_user(env->pc, &sc->pc);
for (i = 1; i < 32; i++) {
__put_user(env->gpr[i], &sc->gpr[i - 1]);
}
for (i = 0; i < 32; i++) {
__put_user(env->fpr[i], &sc->fpr[i]);
}
uint32_t fcsr = riscv_csr_read(env, CSR_FCSR);
__put_user(fcsr, &sc->fcsr);
}
static void setup_ucontext(struct target_ucontext *uc,
CPURISCVState *env, target_sigset_t *set)
{
__put_user(0, &(uc->uc_flags));
__put_user(0, &(uc->uc_link));
target_save_altstack(&uc->uc_stack, env);
int i;
for (i = 0; i < TARGET_NSIG_WORDS; i++) {
__put_user(set->sig[i], &(uc->uc_sigmask.sig[i]));
}
setup_sigcontext(&uc->uc_mcontext, env);
}
static inline void install_sigtramp(uint32_t *tramp)
{
__put_user(0x08b00893, tramp + 0); /* li a7, 139 = __NR_rt_sigreturn */
__put_user(0x00000073, tramp + 1); /* ecall */
}
void setup_rt_frame(int sig, struct target_sigaction *ka,
target_siginfo_t *info,
target_sigset_t *set, CPURISCVState *env)
{
abi_ulong frame_addr;
struct target_rt_sigframe *frame;
frame_addr = get_sigframe(ka, env, sizeof(*frame));
trace_user_setup_rt_frame(env, frame_addr);
if (!lock_user_struct(VERIFY_WRITE, frame, frame_addr, 0)) {
goto badframe;
}
setup_ucontext(&frame->uc, env, set);
tswap_siginfo(&frame->info, info);
install_sigtramp(frame->tramp);
env->pc = ka->_sa_handler;
env->gpr[xSP] = frame_addr;
env->gpr[xA0] = sig;
env->gpr[xA1] = frame_addr + offsetof(struct target_rt_sigframe, info);
env->gpr[xA2] = frame_addr + offsetof(struct target_rt_sigframe, uc);
env->gpr[xRA] = frame_addr + offsetof(struct target_rt_sigframe, tramp);
return;
badframe:
unlock_user_struct(frame, frame_addr, 1);
if (sig == TARGET_SIGSEGV) {
ka->_sa_handler = TARGET_SIG_DFL;
}
force_sig(TARGET_SIGSEGV);
}
static void restore_sigcontext(CPURISCVState *env, struct target_sigcontext *sc)
{
int i;
__get_user(env->pc, &sc->pc);
for (i = 1; i < 32; ++i) {
__get_user(env->gpr[i], &sc->gpr[i - 1]);
}
for (i = 0; i < 32; ++i) {
__get_user(env->fpr[i], &sc->fpr[i]);
}
uint32_t fcsr;
__get_user(fcsr, &sc->fcsr);
riscv_csr_write(env, CSR_FCSR, fcsr);
}
static void restore_ucontext(CPURISCVState *env, struct target_ucontext *uc)
{
sigset_t blocked;
target_sigset_t target_set;
int i;
target_sigemptyset(&target_set);
for (i = 0; i < TARGET_NSIG_WORDS; i++) {
__get_user(target_set.sig[i], &(uc->uc_sigmask.sig[i]));
}
target_to_host_sigset_internal(&blocked, &target_set);
set_sigmask(&blocked);
restore_sigcontext(env, &uc->uc_mcontext);
}
long do_rt_sigreturn(CPURISCVState *env)
{
struct target_rt_sigframe *frame;
abi_ulong frame_addr;
frame_addr = env->gpr[xSP];
trace_user_do_sigreturn(env, frame_addr);
if (!lock_user_struct(VERIFY_READ, frame, frame_addr, 1)) {
goto badframe;
}
restore_ucontext(env, &frame->uc);
if (do_sigaltstack(frame_addr + offsetof(struct target_rt_sigframe,
uc.uc_stack), 0, get_sp_from_cpustate(env)) == -EFAULT) {
goto badframe;
}
unlock_user_struct(frame, frame_addr, 0);
return -TARGET_QEMU_ESIGRETURN;
badframe:
unlock_user_struct(frame, frame_addr, 0);
force_sig(TARGET_SIGSEGV);
return 0;
}
|
