1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3 * Signal support for Hexagon processor
4 *
5 * Copyright (c) 2010-2012, The Linux Foundation. All rights reserved.
6 */
7
8 #include <linux/linkage.h>
9 #include <linux/syscalls.h>
10 #include <linux/sched/task_stack.h>
11
12 #include <asm/registers.h>
13 #include <asm/thread_info.h>
14 #include <asm/unistd.h>
15 #include <linux/uaccess.h>
16 #include <asm/ucontext.h>
17 #include <asm/cacheflush.h>
18 #include <asm/signal.h>
19 #include <asm/vdso.h>
20
21 struct rt_sigframe {
22 unsigned long tramp[2];
23 struct siginfo info;
24 struct ucontext uc;
25 };
26
27 static void __user *get_sigframe(struct ksignal *ksig, struct pt_regs *regs,
28 size_t frame_size)
29 {
30 unsigned long sp = sigsp(regs->r29, ksig);
31
32 return (void __user *)((sp - frame_size) & ~(sizeof(long long) - 1));
33 }
34
35 static int setup_sigcontext(struct pt_regs *regs, struct sigcontext __user *sc)
36 {
37 unsigned long tmp;
38 int err = 0;
39
40 err |= copy_to_user(&sc->sc_regs.r0, ®s->r00,
41 32*sizeof(unsigned long));
42
43 err |= __put_user(regs->sa0, &sc->sc_regs.sa0);
44 err |= __put_user(regs->lc0, &sc->sc_regs.lc0);
45 err |= __put_user(regs->sa1, &sc->sc_regs.sa1);
46 err |= __put_user(regs->lc1, &sc->sc_regs.lc1);
47 err |= __put_user(regs->m0, &sc->sc_regs.m0);
48 err |= __put_user(regs->m1, &sc->sc_regs.m1);
49 err |= __put_user(regs->usr, &sc->sc_regs.usr);
50 err |= __put_user(regs->preds, &sc->sc_regs.p3_0);
51 err |= __put_user(regs->gp, &sc->sc_regs.gp);
52 err |= __put_user(regs->ugp, &sc->sc_regs.ugp);
53 #if CONFIG_HEXAGON_ARCH_VERSION >= 4
54 err |= __put_user(regs->cs0, &sc->sc_regs.cs0);
55 err |= __put_user(regs->cs1, &sc->sc_regs.cs1);
56 #endif
57 tmp = pt_elr(regs); err |= __put_user(tmp, &sc->sc_regs.pc);
58 tmp = pt_cause(regs); err |= __put_user(tmp, &sc->sc_regs.cause);
59 tmp = pt_badva(regs); err |= __put_user(tmp, &sc->sc_regs.badva);
60
61 return err;
62 }
63
64 static int restore_sigcontext(struct pt_regs *regs,
65 struct sigcontext __user *sc)
66 {
67 unsigned long tmp;
68 int err = 0;
69
70 err |= copy_from_user(®s->r00, &sc->sc_regs.r0,
71 32 * sizeof(unsigned long));
72
73 err |= __get_user(regs->sa0, &sc->sc_regs.sa0);
74 err |= __get_user(regs->lc0, &sc->sc_regs.lc0);
75 err |= __get_user(regs->sa1, &sc->sc_regs.sa1);
76 err |= __get_user(regs->lc1, &sc->sc_regs.lc1);
77 err |= __get_user(regs->m0, &sc->sc_regs.m0);
78 err |= __get_user(regs->m1, &sc->sc_regs.m1);
79 err |= __get_user(regs->usr, &sc->sc_regs.usr);
80 err |= __get_user(regs->preds, &sc->sc_regs.p3_0);
81 err |= __get_user(regs->gp, &sc->sc_regs.gp);
82 err |= __get_user(regs->ugp, &sc->sc_regs.ugp);
83 #if CONFIG_HEXAGON_ARCH_VERSION >= 4
84 err |= __get_user(regs->cs0, &sc->sc_regs.cs0);
85 err |= __get_user(regs->cs1, &sc->sc_regs.cs1);
86 #endif
87 err |= __get_user(tmp, &sc->sc_regs.pc); pt_set_elr(regs, tmp);
88
89 return err;
90 }
91
92 /*
93 * Setup signal stack frame with siginfo structure
94 */
95 static int setup_rt_frame(struct ksignal *ksig, sigset_t *set,
96 struct pt_regs *regs)
97 {
98 int err = 0;
99 struct rt_sigframe __user *frame;
100 struct hexagon_vdso *vdso = current->mm->context.vdso;
101
102 frame = get_sigframe(ksig, regs, sizeof(struct rt_sigframe));
103
104 if (!access_ok(frame, sizeof(struct rt_sigframe)))
105 return -EFAULT;
106
107 if (copy_siginfo_to_user(&frame->info, &ksig->info))
108 return -EFAULT;
109
110 /* The on-stack signal trampoline is no longer executed;
111 * however, the libgcc signal frame unwinding code checks for
112 * the presence of these two numeric magic values.
113 */
114 err |= __put_user(0x7800d166, &frame->tramp[0]);
115 err |= __put_user(0x5400c004, &frame->tramp[1]);
116 err |= setup_sigcontext(regs, &frame->uc.uc_mcontext);
117 err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));
118 err |= __save_altstack(&frame->uc.uc_stack, user_stack_pointer(regs));
119 if (err)
120 return -EFAULT;
121
122 /* Load r0/r1 pair with signumber/siginfo pointer... */
123 regs->r0100 = ((unsigned long long)((unsigned long)&frame->info) << 32)
124 | (unsigned long long)ksig->sig;
125 regs->r02 = (unsigned long) &frame->uc;
126 regs->r31 = (unsigned long) vdso->rt_signal_trampoline;
127 pt_psp(regs) = (unsigned long) frame;
128 pt_set_elr(regs, (unsigned long)ksig->ka.sa.sa_handler);
129
130 return 0;
131 }
132
133 /*
134 * Setup invocation of signal handler
135 */
136 static void handle_signal(struct ksignal *ksig, struct pt_regs *regs)
137 {
138 int ret;
139
140 /*
141 * If we're handling a signal that aborted a system call,
142 * set up the error return value before adding the signal
143 * frame to the stack.
144 */
145
146 if (regs->syscall_nr >= 0) {
147 switch (regs->r00) {
148 case -ERESTART_RESTARTBLOCK:
149 case -ERESTARTNOHAND:
150 regs->r00 = -EINTR;
151 break;
152 case -ERESTARTSYS:
153 if (!(ksig->ka.sa.sa_flags & SA_RESTART)) {
154 regs->r00 = -EINTR;
155 break;
156 }
157 fallthrough;
158 case -ERESTARTNOINTR:
159 regs->r06 = regs->syscall_nr;
160 pt_set_elr(regs, pt_elr(regs) - 4);
161 regs->r00 = regs->restart_r0;
162 break;
163 default:
164 break;
165 }
166 }
167
168 /*
169 * Set up the stack frame; not doing the SA_SIGINFO thing. We
170 * only set up the rt_frame flavor.
171 */
172 /* If there was an error on setup, no signal was delivered. */
173 ret = setup_rt_frame(ksig, sigmask_to_save(), regs);
174
175 signal_setup_done(ret, ksig, test_thread_flag(TIF_SINGLESTEP));
176 }
177
178 /*
179 * Called from return-from-event code.
180 */
181 void do_signal(struct pt_regs *regs)
182 {
183 struct ksignal ksig;
184
185 if (!user_mode(regs))
186 return;
187
188 if (get_signal(&ksig)) {
189 handle_signal(&ksig, regs);
190 return;
191 }
192
193 /*
194 * No (more) signals; if we came from a system call, handle the restart.
195 */
196
197 if (regs->syscall_nr >= 0) {
198 switch (regs->r00) {
199 case -ERESTARTNOHAND:
200 case -ERESTARTSYS:
201 case -ERESTARTNOINTR:
202 regs->r06 = regs->syscall_nr;
203 break;
204 case -ERESTART_RESTARTBLOCK:
205 regs->r06 = __NR_restart_syscall;
206 break;
207 default:
208 goto no_restart;
209 }
210 pt_set_elr(regs, pt_elr(regs) - 4);
211 regs->r00 = regs->restart_r0;
212 }
213
214 no_restart:
215 /* If there's no signal to deliver, put the saved sigmask back */
216 restore_saved_sigmask();
217 }
218
219 /*
220 * Architecture-specific wrappers for signal-related system calls
221 */
222
223 SYSCALL_DEFINE0(rt_sigreturn)
224 {
225 struct pt_regs *regs = current_pt_regs();
226 struct rt_sigframe __user *frame;
227 sigset_t blocked;
228
229 /* Always make any pending restarted system calls return -EINTR */
230 current->restart_block.fn = do_no_restart_syscall;
231
232 frame = (struct rt_sigframe __user *)pt_psp(regs);
233 if (!access_ok(frame, sizeof(*frame)))
234 goto badframe;
235 if (__copy_from_user(&blocked, &frame->uc.uc_sigmask, sizeof(blocked)))
236 goto badframe;
237
238 set_current_blocked(&blocked);
239
240 if (restore_sigcontext(regs, &frame->uc.uc_mcontext))
241 goto badframe;
242
243 /* Restore the user's stack as well */
244 pt_psp(regs) = regs->r29;
245
246 regs->syscall_nr = -1;
247
248 if (restore_altstack(&frame->uc.uc_stack))
249 goto badframe;
250
251 return regs->r00;
252
253 badframe:
254 force_sig(SIGSEGV);
255 return 0;
256 }
257
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