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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
20extern u32 __user_rt_sigreturn[2];
21
22#define DEBUG_SIG 0
23
24struct rt_sigframe {
25 struct siginfo info;
26 struct ucontext uc;
27#ifndef CONFIG_MMU
28 u32 sigreturn_code[2];
29#endif
30};
31
32#ifdef CONFIG_FPU
33static long restore_fp_state(struct pt_regs *regs,
34 union __riscv_fp_state __user *sc_fpregs)
35{
36 long err;
37 struct __riscv_d_ext_state __user *state = &sc_fpregs->d;
38 size_t i;
39
40 err = __copy_from_user(¤t->thread.fstate, state, sizeof(*state));
41 if (unlikely(err))
42 return err;
43
44 fstate_restore(current, regs);
45
46 /* We support no other extension state at this time. */
47 for (i = 0; i < ARRAY_SIZE(sc_fpregs->q.reserved); i++) {
48 u32 value;
49
50 err = __get_user(value, &sc_fpregs->q.reserved[i]);
51 if (unlikely(err))
52 break;
53 if (value != 0)
54 return -EINVAL;
55 }
56
57 return err;
58}
59
60static long save_fp_state(struct pt_regs *regs,
61 union __riscv_fp_state __user *sc_fpregs)
62{
63 long err;
64 struct __riscv_d_ext_state __user *state = &sc_fpregs->d;
65 size_t i;
66
67 fstate_save(current, regs);
68 err = __copy_to_user(state, ¤t->thread.fstate, sizeof(*state));
69 if (unlikely(err))
70 return err;
71
72 /* We support no other extension state at this time. */
73 for (i = 0; i < ARRAY_SIZE(sc_fpregs->q.reserved); i++) {
74 err = __put_user(0, &sc_fpregs->q.reserved[i]);
75 if (unlikely(err))
76 break;
77 }
78
79 return err;
80}
81#else
82#define save_fp_state(task, regs) (0)
83#define restore_fp_state(task, regs) (0)
84#endif
85
86static long restore_sigcontext(struct pt_regs *regs,
87 struct sigcontext __user *sc)
88{
89 long err;
90 /* sc_regs is structured the same as the start of pt_regs */
91 err = __copy_from_user(regs, &sc->sc_regs, sizeof(sc->sc_regs));
92 /* Restore the floating-point state. */
93 if (has_fpu)
94 err |= restore_fp_state(regs, &sc->sc_fpregs);
95 return err;
96}
97
98SYSCALL_DEFINE0(rt_sigreturn)
99{
100 struct pt_regs *regs = current_pt_regs();
101 struct rt_sigframe __user *frame;
102 struct task_struct *task;
103 sigset_t set;
104
105 /* Always make any pending restarted system calls return -EINTR */
106 current->restart_block.fn = do_no_restart_syscall;
107
108 frame = (struct rt_sigframe __user *)regs->sp;
109
110 if (!access_ok(frame, sizeof(*frame)))
111 goto badframe;
112
113 if (__copy_from_user(&set, &frame->uc.uc_sigmask, sizeof(set)))
114 goto badframe;
115
116 set_current_blocked(&set);
117
118 if (restore_sigcontext(regs, &frame->uc.uc_mcontext))
119 goto badframe;
120
121 if (restore_altstack(&frame->uc.uc_stack))
122 goto badframe;
123
124 return regs->a0;
125
126badframe:
127 task = current;
128 if (show_unhandled_signals) {
129 pr_info_ratelimited(
130 "%s[%d]: bad frame in %s: frame=%p pc=%p sp=%p\n",
131 task->comm, task_pid_nr(task), __func__,
132 frame, (void *)regs->epc, (void *)regs->sp);
133 }
134 force_sig(SIGSEGV);
135 return 0;
136}
137
138static long setup_sigcontext(struct rt_sigframe __user *frame,
139 struct pt_regs *regs)
140{
141 struct sigcontext __user *sc = &frame->uc.uc_mcontext;
142 long err;
143 /* sc_regs is structured the same as the start of pt_regs */
144 err = __copy_to_user(&sc->sc_regs, regs, sizeof(sc->sc_regs));
145 /* Save the floating-point state. */
146 if (has_fpu)
147 err |= save_fp_state(regs, &sc->sc_fpregs);
148 return err;
149}
150
151static inline void __user *get_sigframe(struct ksignal *ksig,
152 struct pt_regs *regs, size_t framesize)
153{
154 unsigned long sp;
155 /* Default to using normal stack */
156 sp = regs->sp;
157
158 /*
159 * If we are on the alternate signal stack and would overflow it, don't.
160 * Return an always-bogus address instead so we will die with SIGSEGV.
161 */
162 if (on_sig_stack(sp) && !likely(on_sig_stack(sp - framesize)))
163 return (void __user __force *)(-1UL);
164
165 /* This is the X/Open sanctioned signal stack switching. */
166 sp = sigsp(sp, ksig) - framesize;
167
168 /* Align the stack frame. */
169 sp &= ~0xfUL;
170
171 return (void __user *)sp;
172}
173
174static int setup_rt_frame(struct ksignal *ksig, sigset_t *set,
175 struct pt_regs *regs)
176{
177 struct rt_sigframe __user *frame;
178 long err = 0;
179
180 frame = get_sigframe(ksig, regs, sizeof(*frame));
181 if (!access_ok(frame, sizeof(*frame)))
182 return -EFAULT;
183
184 err |= copy_siginfo_to_user(&frame->info, &ksig->info);
185
186 /* Create the ucontext. */
187 err |= __put_user(0, &frame->uc.uc_flags);
188 err |= __put_user(NULL, &frame->uc.uc_link);
189 err |= __save_altstack(&frame->uc.uc_stack, regs->sp);
190 err |= setup_sigcontext(frame, regs);
191 err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));
192 if (err)
193 return -EFAULT;
194
195 /* Set up to return from userspace. */
196#ifdef CONFIG_MMU
197 regs->ra = (unsigned long)VDSO_SYMBOL(
198 current->mm->context.vdso, rt_sigreturn);
199#else
200 /*
201 * For the nommu case we don't have a VDSO. Instead we push two
202 * instructions to call the rt_sigreturn syscall onto the user stack.
203 */
204 if (copy_to_user(&frame->sigreturn_code, __user_rt_sigreturn,
205 sizeof(frame->sigreturn_code)))
206 return -EFAULT;
207 regs->ra = (unsigned long)&frame->sigreturn_code;
208#endif /* CONFIG_MMU */
209
210 /*
211 * Set up registers for signal handler.
212 * Registers that we don't modify keep the value they had from
213 * user-space at the time we took the signal.
214 * We always pass siginfo and mcontext, regardless of SA_SIGINFO,
215 * since some things rely on this (e.g. glibc's debug/segfault.c).
216 */
217 regs->epc = (unsigned long)ksig->ka.sa.sa_handler;
218 regs->sp = (unsigned long)frame;
219 regs->a0 = ksig->sig; /* a0: signal number */
220 regs->a1 = (unsigned long)(&frame->info); /* a1: siginfo pointer */
221 regs->a2 = (unsigned long)(&frame->uc); /* a2: ucontext pointer */
222
223#if DEBUG_SIG
224 pr_info("SIG deliver (%s:%d): sig=%d pc=%p ra=%p sp=%p\n",
225 current->comm, task_pid_nr(current), ksig->sig,
226 (void *)regs->epc, (void *)regs->ra, frame);
227#endif
228
229 return 0;
230}
231
232static void handle_signal(struct ksignal *ksig, struct pt_regs *regs)
233{
234 sigset_t *oldset = sigmask_to_save();
235 int ret;
236
237 /* Are we from a system call? */
238 if (regs->cause == EXC_SYSCALL) {
239 /* Avoid additional syscall restarting via ret_from_exception */
240 regs->cause = -1UL;
241 /* If so, check system call restarting.. */
242 switch (regs->a0) {
243 case -ERESTART_RESTARTBLOCK:
244 case -ERESTARTNOHAND:
245 regs->a0 = -EINTR;
246 break;
247
248 case -ERESTARTSYS:
249 if (!(ksig->ka.sa.sa_flags & SA_RESTART)) {
250 regs->a0 = -EINTR;
251 break;
252 }
253 fallthrough;
254 case -ERESTARTNOINTR:
255 regs->a0 = regs->orig_a0;
256 regs->epc -= 0x4;
257 break;
258 }
259 }
260
261 /* Set up the stack frame */
262 ret = setup_rt_frame(ksig, oldset, regs);
263
264 signal_setup_done(ret, ksig, 0);
265}
266
267static void do_signal(struct pt_regs *regs)
268{
269 struct ksignal ksig;
270
271 if (get_signal(&ksig)) {
272 /* Actually deliver the signal */
273 handle_signal(&ksig, regs);
274 return;
275 }
276
277 /* Did we come from a system call? */
278 if (regs->cause == EXC_SYSCALL) {
279 /* Avoid additional syscall restarting via ret_from_exception */
280 regs->cause = -1UL;
281
282 /* Restart the system call - no handlers present */
283 switch (regs->a0) {
284 case -ERESTARTNOHAND:
285 case -ERESTARTSYS:
286 case -ERESTARTNOINTR:
287 regs->a0 = regs->orig_a0;
288 regs->epc -= 0x4;
289 break;
290 case -ERESTART_RESTARTBLOCK:
291 regs->a0 = regs->orig_a0;
292 regs->a7 = __NR_restart_syscall;
293 regs->epc -= 0x4;
294 break;
295 }
296 }
297
298 /*
299 * If there is no signal to deliver, we just put the saved
300 * sigmask back.
301 */
302 restore_saved_sigmask();
303}
304
305/*
306 * notification of userspace execution resumption
307 * - triggered by the _TIF_WORK_MASK flags
308 */
309asmlinkage __visible void do_notify_resume(struct pt_regs *regs,
310 unsigned long thread_info_flags)
311{
312 /* Handle pending signal delivery */
313 if (thread_info_flags & _TIF_SIGPENDING)
314 do_signal(regs);
315
316 if (thread_info_flags & _TIF_NOTIFY_RESUME) {
317 clear_thread_flag(TIF_NOTIFY_RESUME);
318 tracehook_notify_resume(regs);
319 }
320}