xref: /openbmc/qemu/linux-user/xtensa/signal.c (revision f3bff6c4) 
1 /*
2  *  Emulation of Linux signals
3  *
4  *  Copyright (c) 2003 Fabrice Bellard
5  *
6  *  This program is free software; you can redistribute it and/or modify
7  *  it under the terms of the GNU General Public License as published by
8  *  the Free Software Foundation; either version 2 of the License, or
9  *  (at your option) any later version.
10  *
11  *  This program is distributed in the hope that it will be useful,
12  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
13  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
14  *  GNU General Public License for more details.
15  *
16  *  You should have received a copy of the GNU General Public License
17  *  along with this program; if not, see <http://www.gnu.org/licenses/>.
18  */
19 #include "qemu/osdep.h"
20 #include "qemu.h"
21 #include "user-internals.h"
22 #include "signal-common.h"
23 #include "linux-user/trace.h"
24 
25 struct target_sigcontext {
26     abi_ulong sc_pc;
27     abi_ulong sc_ps;
28     abi_ulong sc_lbeg;
29     abi_ulong sc_lend;
30     abi_ulong sc_lcount;
31     abi_ulong sc_sar;
32     abi_ulong sc_acclo;
33     abi_ulong sc_acchi;
34     abi_ulong sc_a[16];
35     abi_ulong sc_xtregs;
36 };
37 
38 struct target_ucontext {
39     abi_ulong tuc_flags;
40     abi_ulong tuc_link;
41     target_stack_t tuc_stack;
42     struct target_sigcontext tuc_mcontext;
43     target_sigset_t tuc_sigmask;
44 };
45 
46 struct target_rt_sigframe {
47     target_siginfo_t info;
48     struct target_ucontext uc;
49     /* TODO: xtregs */
50     uint8_t retcode[6];
51     abi_ulong window[4];
52 };
53 
54 static abi_ulong get_sigframe(struct target_sigaction *sa,
55                               CPUXtensaState *env,
56                               unsigned long framesize)
57 {
58     abi_ulong sp;
59 
60     sp = target_sigsp(get_sp_from_cpustate(env), sa);
61 
62     return (sp - framesize) & -16;
63 }
64 
65 static int flush_window_regs(CPUXtensaState *env)
66 {
67     uint32_t wb = env->sregs[WINDOW_BASE];
68     uint32_t ws = xtensa_replicate_windowstart(env) >> (wb + 1);
69     unsigned d = ctz32(ws) + 1;
70     unsigned i;
71     int ret = 0;
72 
73     for (i = d; i < env->config->nareg / 4; i += d) {
74         uint32_t ssp, osp;
75         unsigned j;
76 
77         ws >>= d;
78         xtensa_rotate_window(env, d);
79 
80         if (ws & 0x1) {
81             ssp = env->regs[5];
82             d = 1;
83         } else if (ws & 0x2) {
84             ssp = env->regs[9];
85             ret |= get_user_ual(osp, env->regs[1] - 12);
86             osp -= 32;
87             d = 2;
88         } else if (ws & 0x4) {
89             ssp = env->regs[13];
90             ret |= get_user_ual(osp, env->regs[1] - 12);
91             osp -= 48;
92             d = 3;
93         } else {
94             g_assert_not_reached();
95         }
96 
97         for (j = 0; j < 4; ++j) {
98             ret |= put_user_ual(env->regs[j], ssp - 16 + j * 4);
99         }
100         for (j = 4; j < d * 4; ++j) {
101             ret |= put_user_ual(env->regs[j], osp - 16 + j * 4);
102         }
103     }
104     xtensa_rotate_window(env, d);
105     g_assert(env->sregs[WINDOW_BASE] == wb);
106     return ret == 0;
107 }
108 
109 static int setup_sigcontext(struct target_rt_sigframe *frame,
110                             CPUXtensaState *env)
111 {
112     struct target_sigcontext *sc = &frame->uc.tuc_mcontext;
113     int i;
114 
115     __put_user(env->pc, &sc->sc_pc);
116     __put_user(env->sregs[PS], &sc->sc_ps);
117     __put_user(env->sregs[LBEG], &sc->sc_lbeg);
118     __put_user(env->sregs[LEND], &sc->sc_lend);
119     __put_user(env->sregs[LCOUNT], &sc->sc_lcount);
120     if (!flush_window_regs(env)) {
121         return 0;
122     }
123     for (i = 0; i < 16; ++i) {
124         __put_user(env->regs[i], sc->sc_a + i);
125     }
126     __put_user(0, &sc->sc_xtregs);
127     /* TODO: xtregs */
128     return 1;
129 }
130 
131 static void install_sigtramp(uint8_t *tramp)
132 {
133 #if TARGET_BIG_ENDIAN
134     /* Generate instruction:  MOVI a2, __NR_rt_sigreturn */
135     __put_user(0x22, &tramp[0]);
136     __put_user(0x0a, &tramp[1]);
137     __put_user(TARGET_NR_rt_sigreturn, &tramp[2]);
138     /* Generate instruction:  SYSCALL */
139     __put_user(0x00, &tramp[3]);
140     __put_user(0x05, &tramp[4]);
141     __put_user(0x00, &tramp[5]);
142 #else
143     /* Generate instruction:  MOVI a2, __NR_rt_sigreturn */
144     __put_user(0x22, &tramp[0]);
145     __put_user(0xa0, &tramp[1]);
146     __put_user(TARGET_NR_rt_sigreturn, &tramp[2]);
147     /* Generate instruction:  SYSCALL */
148     __put_user(0x00, &tramp[3]);
149     __put_user(0x50, &tramp[4]);
150     __put_user(0x00, &tramp[5]);
151 #endif
152 }
153 
154 void setup_rt_frame(int sig, struct target_sigaction *ka,
155                     target_siginfo_t *info,
156                     target_sigset_t *set, CPUXtensaState *env)
157 {
158     abi_ulong frame_addr;
159     struct target_rt_sigframe *frame;
160     int is_fdpic = info_is_fdpic(get_task_state(thread_cpu)->info);
161     abi_ulong handler = 0;
162     abi_ulong handler_fdpic_GOT = 0;
163     uint32_t ra;
164     bool abi_call0;
165     unsigned base;
166     int i;
167 
168     frame_addr = get_sigframe(ka, env, sizeof(*frame));
169     trace_user_setup_rt_frame(env, frame_addr);
170 
171     if (is_fdpic) {
172         abi_ulong funcdesc_ptr = ka->_sa_handler;
173 
174         if (get_user_ual(handler, funcdesc_ptr)
175             || get_user_ual(handler_fdpic_GOT, funcdesc_ptr + 4)) {
176             goto give_sigsegv;
177         }
178     } else {
179         handler = ka->_sa_handler;
180     }
181 
182     if (!lock_user_struct(VERIFY_WRITE, frame, frame_addr, 0)) {
183         goto give_sigsegv;
184     }
185 
186     if (ka->sa_flags & SA_SIGINFO) {
187         tswap_siginfo(&frame->info, info);
188     }
189 
190     __put_user(0, &frame->uc.tuc_flags);
191     __put_user(0, &frame->uc.tuc_link);
192     target_save_altstack(&frame->uc.tuc_stack, env);
193     if (!setup_sigcontext(frame, env)) {
194         unlock_user_struct(frame, frame_addr, 0);
195         goto give_sigsegv;
196     }
197     for (i = 0; i < TARGET_NSIG_WORDS; ++i) {
198         __put_user(set->sig[i], &frame->uc.tuc_sigmask.sig[i]);
199     }
200 
201     if (ka->sa_flags & TARGET_SA_RESTORER) {
202         if (is_fdpic) {
203             if (get_user_ual(ra, ka->sa_restorer)) {
204                 unlock_user_struct(frame, frame_addr, 0);
205                 goto give_sigsegv;
206             }
207         } else {
208             ra = ka->sa_restorer;
209         }
210     } else {
211         /* Not used, but retain for ABI compatibility. */
212         install_sigtramp(frame->retcode);
213         ra = default_rt_sigreturn;
214     }
215     memset(env->regs, 0, sizeof(env->regs));
216     env->pc = handler;
217     env->regs[1] = frame_addr;
218     env->sregs[WINDOW_BASE] = 0;
219     env->sregs[WINDOW_START] = 1;
220 
221     abi_call0 = (env->sregs[PS] & PS_WOE) == 0;
222     env->sregs[PS] = PS_UM | (3 << PS_RING_SHIFT);
223 
224     if (abi_call0) {
225         base = 0;
226         env->regs[base] = ra;
227     } else {
228         env->sregs[PS] |= PS_WOE | (1 << PS_CALLINC_SHIFT);
229         base = 4;
230         env->regs[base] = (ra & 0x3fffffff) | 0x40000000;
231     }
232     env->regs[base + 2] = sig;
233     env->regs[base + 3] = frame_addr + offsetof(struct target_rt_sigframe,
234                                                 info);
235     env->regs[base + 4] = frame_addr + offsetof(struct target_rt_sigframe, uc);
236     if (is_fdpic) {
237         env->regs[base + 11] = handler_fdpic_GOT;
238     }
239     unlock_user_struct(frame, frame_addr, 1);
240     return;
241 
242 give_sigsegv:
243     force_sigsegv(sig);
244     return;
245 }
246 
247 static void restore_sigcontext(CPUXtensaState *env,
248                                struct target_rt_sigframe *frame)
249 {
250     struct target_sigcontext *sc = &frame->uc.tuc_mcontext;
251     uint32_t ps;
252     int i;
253 
254     __get_user(env->pc, &sc->sc_pc);
255     __get_user(ps, &sc->sc_ps);
256     __get_user(env->sregs[LBEG], &sc->sc_lbeg);
257     __get_user(env->sregs[LEND], &sc->sc_lend);
258     __get_user(env->sregs[LCOUNT], &sc->sc_lcount);
259 
260     env->sregs[WINDOW_BASE] = 0;
261     env->sregs[WINDOW_START] = 1;
262     env->sregs[PS] = deposit32(env->sregs[PS],
263                                PS_CALLINC_SHIFT,
264                                PS_CALLINC_LEN,
265                                extract32(ps, PS_CALLINC_SHIFT,
266                                          PS_CALLINC_LEN));
267     for (i = 0; i < 16; ++i) {
268         __get_user(env->regs[i], sc->sc_a + i);
269     }
270     /* TODO: xtregs */
271 }
272 
273 long do_rt_sigreturn(CPUXtensaState *env)
274 {
275     abi_ulong frame_addr = env->regs[1];
276     struct target_rt_sigframe *frame;
277     sigset_t set;
278 
279     trace_user_do_rt_sigreturn(env, frame_addr);
280     if (!lock_user_struct(VERIFY_READ, frame, frame_addr, 1)) {
281         goto badframe;
282     }
283     target_to_host_sigset(&set, &frame->uc.tuc_sigmask);
284     set_sigmask(&set);
285 
286     restore_sigcontext(env, frame);
287     target_restore_altstack(&frame->uc.tuc_stack, env);
288 
289     unlock_user_struct(frame, frame_addr, 0);
290     return -QEMU_ESIGRETURN;
291 
292 badframe:
293     unlock_user_struct(frame, frame_addr, 0);
294     force_sig(TARGET_SIGSEGV);
295     return -QEMU_ESIGRETURN;
296 }
297 
298 void setup_sigtramp(abi_ulong sigtramp_page)
299 {
300     uint8_t *tramp = lock_user(VERIFY_WRITE, sigtramp_page, 6, 0);
301     assert(tramp != NULL);
302 
303     default_rt_sigreturn = sigtramp_page;
304     install_sigtramp(tramp);
305     unlock_user(tramp, sigtramp_page, 6);
306 }
307