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1// SPDX-License-Identifier: GPL-2.0-or-later
2/*
3 * Copyright (C) 2009 Sunplus Core Technology Co., Ltd.
4 * Chen Liqin <liqin.chen@sunplusct.com>
5 * Lennox Wu <lennox.wu@sunplusct.com>
6 * Copyright (C) 2012 Regents of the University of California
7 */
8
9#include <linux/signal.h>
10#include <linux/uaccess.h>
11#include <linux/syscalls.h>
12#include <linux/tracehook.h>
13#include <linux/linkage.h>
14
15#include <asm/ucontext.h>
16#include <asm/vdso.h>
17#include <asm/switch_to.h>
18#include <asm/csr.h>
19
20#define DEBUG_SIG 0
21
22struct rt_sigframe {
23 struct siginfo info;
24 struct ucontext uc;
25};
26
27#ifdef CONFIG_FPU
28static long restore_fp_state(struct pt_regs *regs,
29 union __riscv_fp_state __user *sc_fpregs)
30{
31 long err;
32 struct __riscv_d_ext_state __user *state = &sc_fpregs->d;
33 size_t i;
34
35 err = __copy_from_user(¤t->thread.fstate, state, sizeof(*state));
36 if (unlikely(err))
37 return err;
38
39 fstate_restore(current, regs);
40
41 /* We support no other extension state at this time. */
42 for (i = 0; i < ARRAY_SIZE(sc_fpregs->q.reserved); i++) {
43 u32 value;
44
45 err = __get_user(value, &sc_fpregs->q.reserved[i]);
46 if (unlikely(err))
47 break;
48 if (value != 0)
49 return -EINVAL;
50 }
51
52 return err;
53}
54
55static long save_fp_state(struct pt_regs *regs,
56 union __riscv_fp_state __user *sc_fpregs)
57{
58 long err;
59 struct __riscv_d_ext_state __user *state = &sc_fpregs->d;
60 size_t i;
61
62 fstate_save(current, regs);
63 err = __copy_to_user(state, ¤t->thread.fstate, sizeof(*state));
64 if (unlikely(err))
65 return err;
66
67 /* We support no other extension state at this time. */
68 for (i = 0; i < ARRAY_SIZE(sc_fpregs->q.reserved); i++) {
69 err = __put_user(0, &sc_fpregs->q.reserved[i]);
70 if (unlikely(err))
71 break;
72 }
73
74 return err;
75}
76#else
77#define save_fp_state(task, regs) (0)
78#define restore_fp_state(task, regs) (0)
79#endif
80
81static long restore_sigcontext(struct pt_regs *regs,
82 struct sigcontext __user *sc)
83{
84 long err;
85 /* sc_regs is structured the same as the start of pt_regs */
86 err = __copy_from_user(regs, &sc->sc_regs, sizeof(sc->sc_regs));
87 /* Restore the floating-point state. */
88 if (has_fpu)
89 err |= restore_fp_state(regs, &sc->sc_fpregs);
90 return err;
91}
92
93SYSCALL_DEFINE0(rt_sigreturn)
94{
95 struct pt_regs *regs = current_pt_regs();
96 struct rt_sigframe __user *frame;
97 struct task_struct *task;
98 sigset_t set;
99
100 /* Always make any pending restarted system calls return -EINTR */
101 current->restart_block.fn = do_no_restart_syscall;
102
103 frame = (struct rt_sigframe __user *)regs->sp;
104
105 if (!access_ok(frame, sizeof(*frame)))
106 goto badframe;
107
108 if (__copy_from_user(&set, &frame->uc.uc_sigmask, sizeof(set)))
109 goto badframe;
110
111 set_current_blocked(&set);
112
113 if (restore_sigcontext(regs, &frame->uc.uc_mcontext))
114 goto badframe;
115
116 if (restore_altstack(&frame->uc.uc_stack))
117 goto badframe;
118
119 return regs->a0;
120
121badframe:
122 task = current;
123 if (show_unhandled_signals) {
124 pr_info_ratelimited(
125 "%s[%d]: bad frame in %s: frame=%p pc=%p sp=%p\n",
126 task->comm, task_pid_nr(task), __func__,
127 frame, (void *)regs->sepc, (void *)regs->sp);
128 }
129 force_sig(SIGSEGV);
130 return 0;
131}
132
133static long setup_sigcontext(struct rt_sigframe __user *frame,
134 struct pt_regs *regs)
135{
136 struct sigcontext __user *sc = &frame->uc.uc_mcontext;
137 long err;
138 /* sc_regs is structured the same as the start of pt_regs */
139 err = __copy_to_user(&sc->sc_regs, regs, sizeof(sc->sc_regs));
140 /* Save the floating-point state. */
141 if (has_fpu)
142 err |= save_fp_state(regs, &sc->sc_fpregs);
143 return err;
144}
145
146static inline void __user *get_sigframe(struct ksignal *ksig,
147 struct pt_regs *regs, size_t framesize)
148{
149 unsigned long sp;
150 /* Default to using normal stack */
151 sp = regs->sp;
152
153 /*
154 * If we are on the alternate signal stack and would overflow it, don't.
155 * Return an always-bogus address instead so we will die with SIGSEGV.
156 */
157 if (on_sig_stack(sp) && !likely(on_sig_stack(sp - framesize)))
158 return (void __user __force *)(-1UL);
159
160 /* This is the X/Open sanctioned signal stack switching. */
161 sp = sigsp(sp, ksig) - framesize;
162
163 /* Align the stack frame. */
164 sp &= ~0xfUL;
165
166 return (void __user *)sp;
167}
168
169
170static int setup_rt_frame(struct ksignal *ksig, sigset_t *set,
171 struct pt_regs *regs)
172{
173 struct rt_sigframe __user *frame;
174 long err = 0;
175
176 frame = get_sigframe(ksig, regs, sizeof(*frame));
177 if (!access_ok(frame, sizeof(*frame)))
178 return -EFAULT;
179
180 err |= copy_siginfo_to_user(&frame->info, &ksig->info);
181
182 /* Create the ucontext. */
183 err |= __put_user(0, &frame->uc.uc_flags);
184 err |= __put_user(NULL, &frame->uc.uc_link);
185 err |= __save_altstack(&frame->uc.uc_stack, regs->sp);
186 err |= setup_sigcontext(frame, regs);
187 err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));
188 if (err)
189 return -EFAULT;
190
191 /* Set up to return from userspace. */
192 regs->ra = (unsigned long)VDSO_SYMBOL(
193 current->mm->context.vdso, rt_sigreturn);
194
195 /*
196 * Set up registers for signal handler.
197 * Registers that we don't modify keep the value they had from
198 * user-space at the time we took the signal.
199 * We always pass siginfo and mcontext, regardless of SA_SIGINFO,
200 * since some things rely on this (e.g. glibc's debug/segfault.c).
201 */
202 regs->sepc = (unsigned long)ksig->ka.sa.sa_handler;
203 regs->sp = (unsigned long)frame;
204 regs->a0 = ksig->sig; /* a0: signal number */
205 regs->a1 = (unsigned long)(&frame->info); /* a1: siginfo pointer */
206 regs->a2 = (unsigned long)(&frame->uc); /* a2: ucontext pointer */
207
208#if DEBUG_SIG
209 pr_info("SIG deliver (%s:%d): sig=%d pc=%p ra=%p sp=%p\n",
210 current->comm, task_pid_nr(current), ksig->sig,
211 (void *)regs->sepc, (void *)regs->ra, frame);
212#endif
213
214 return 0;
215}
216
217static void handle_signal(struct ksignal *ksig, struct pt_regs *regs)
218{
219 sigset_t *oldset = sigmask_to_save();
220 int ret;
221
222 /* Are we from a system call? */
223 if (regs->scause == EXC_SYSCALL) {
224 /* Avoid additional syscall restarting via ret_from_exception */
225 regs->scause = -1UL;
226
227 /* If so, check system call restarting.. */
228 switch (regs->a0) {
229 case -ERESTART_RESTARTBLOCK:
230 case -ERESTARTNOHAND:
231 regs->a0 = -EINTR;
232 break;
233
234 case -ERESTARTSYS:
235 if (!(ksig->ka.sa.sa_flags & SA_RESTART)) {
236 regs->a0 = -EINTR;
237 break;
238 }
239 /* fallthrough */
240 case -ERESTARTNOINTR:
241 regs->a0 = regs->orig_a0;
242 regs->sepc -= 0x4;
243 break;
244 }
245 }
246
247 /* Set up the stack frame */
248 ret = setup_rt_frame(ksig, oldset, regs);
249
250 signal_setup_done(ret, ksig, 0);
251}
252
253static void do_signal(struct pt_regs *regs)
254{
255 struct ksignal ksig;
256
257 if (get_signal(&ksig)) {
258 /* Actually deliver the signal */
259 handle_signal(&ksig, regs);
260 return;
261 }
262
263 /* Did we come from a system call? */
264 if (regs->scause == EXC_SYSCALL) {
265 /* Avoid additional syscall restarting via ret_from_exception */
266 regs->scause = -1UL;
267
268 /* Restart the system call - no handlers present */
269 switch (regs->a0) {
270 case -ERESTARTNOHAND:
271 case -ERESTARTSYS:
272 case -ERESTARTNOINTR:
273 regs->a0 = regs->orig_a0;
274 regs->sepc -= 0x4;
275 break;
276 case -ERESTART_RESTARTBLOCK:
277 regs->a0 = regs->orig_a0;
278 regs->a7 = __NR_restart_syscall;
279 regs->sepc -= 0x4;
280 break;
281 }
282 }
283
284 /*
285 * If there is no signal to deliver, we just put the saved
286 * sigmask back.
287 */
288 restore_saved_sigmask();
289}
290
291/*
292 * notification of userspace execution resumption
293 * - triggered by the _TIF_WORK_MASK flags
294 */
295asmlinkage __visible void do_notify_resume(struct pt_regs *regs,
296 unsigned long thread_info_flags)
297{
298 /* Handle pending signal delivery */
299 if (thread_info_flags & _TIF_SIGPENDING)
300 do_signal(regs);
301
302 if (thread_info_flags & _TIF_NOTIFY_RESUME) {
303 clear_thread_flag(TIF_NOTIFY_RESUME);
304 tracehook_notify_resume(regs);
305 }
306}