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/compat.h>
10 #include <linux/signal.h>
11 #include <linux/uaccess.h>
12 #include <linux/syscalls.h>
13 #include <linux/resume_user_mode.h>
14 #include <linux/linkage.h>
15 #include <linux/entry-common.h>
16
17 #include <asm/ucontext.h>
18 #include <asm/vdso.h>
19 #include <asm/signal.h>
20 #include <asm/signal32.h>
21 #include <asm/switch_to.h>
22 #include <asm/vector.h>
23 #include <asm/csr.h>
24 #include <asm/cacheflush.h>
25
26 unsigned long signal_minsigstksz __ro_after_init;
27
28 extern u32 __user_rt_sigreturn[2];
29 static size_t riscv_v_sc_size __ro_after_init;
30
31 #define DEBUG_SIG 0
32
33 struct rt_sigframe {
34 struct siginfo info;
35 struct ucontext uc;
36 #ifndef CONFIG_MMU
37 u32 sigreturn_code[2];
38 #endif
39 };
40
41 #ifdef CONFIG_FPU
42 static long restore_fp_state(struct pt_regs *regs,
43 union __riscv_fp_state __user *sc_fpregs)
44 {
45 long err;
46 struct __riscv_d_ext_state __user *state = &sc_fpregs->d;
47
48 err = __copy_from_user(¤t->thread.fstate, state, sizeof(*state));
49 if (unlikely(err))
50 return err;
51
52 fstate_restore(current, regs);
53 return 0;
54 }
55
56 static long save_fp_state(struct pt_regs *regs,
57 union __riscv_fp_state __user *sc_fpregs)
58 {
59 long err;
60 struct __riscv_d_ext_state __user *state = &sc_fpregs->d;
61
62 fstate_save(current, regs);
63 err = __copy_to_user(state, ¤t->thread.fstate, sizeof(*state));
64 return err;
65 }
66 #else
67 #define save_fp_state(task, regs) (0)
68 #define restore_fp_state(task, regs) (0)
69 #endif
70
71 #ifdef CONFIG_RISCV_ISA_V
72
73 static long save_v_state(struct pt_regs *regs, void __user **sc_vec)
74 {
75 struct __riscv_ctx_hdr __user *hdr;
76 struct __sc_riscv_v_state __user *state;
77 void __user *datap;
78 long err;
79
80 hdr = *sc_vec;
81 /* Place state to the user's signal context space after the hdr */
82 state = (struct __sc_riscv_v_state __user *)(hdr + 1);
83 /* Point datap right after the end of __sc_riscv_v_state */
84 datap = state + 1;
85
86 /* datap is designed to be 16 byte aligned for better performance */
87 WARN_ON(!IS_ALIGNED((unsigned long)datap, 16));
88
89 get_cpu_vector_context();
90 riscv_v_vstate_save(¤t->thread.vstate, regs);
91 put_cpu_vector_context();
92
93 /* Copy everything of vstate but datap. */
94 err = __copy_to_user(&state->v_state, ¤t->thread.vstate,
95 offsetof(struct __riscv_v_ext_state, datap));
96 /* Copy the pointer datap itself. */
97 err |= __put_user((__force void *)datap, &state->v_state.datap);
98 /* Copy the whole vector content to user space datap. */
99 err |= __copy_to_user(datap, current->thread.vstate.datap, riscv_v_vsize);
100 /* Copy magic to the user space after saving all vector conetext */
101 err |= __put_user(RISCV_V_MAGIC, &hdr->magic);
102 err |= __put_user(riscv_v_sc_size, &hdr->size);
103 if (unlikely(err))
104 return err;
105
106 /* Only progress the sv_vec if everything has done successfully */
107 *sc_vec += riscv_v_sc_size;
108 return 0;
109 }
110
111 /*
112 * Restore Vector extension context from the user's signal frame. This function
113 * assumes a valid extension header. So magic and size checking must be done by
114 * the caller.
115 */
116 static long __restore_v_state(struct pt_regs *regs, void __user *sc_vec)
117 {
118 long err;
119 struct __sc_riscv_v_state __user *state = sc_vec;
120 void __user *datap;
121
122 /*
123 * Mark the vstate as clean prior performing the actual copy,
124 * to avoid getting the vstate incorrectly clobbered by the
125 * discarded vector state.
126 */
127 riscv_v_vstate_set_restore(current, regs);
128
129 /* Copy everything of __sc_riscv_v_state except datap. */
130 err = __copy_from_user(¤t->thread.vstate, &state->v_state,
131 offsetof(struct __riscv_v_ext_state, datap));
132 if (unlikely(err))
133 return err;
134
135 /* Copy the pointer datap itself. */
136 err = __get_user(datap, &state->v_state.datap);
137 if (unlikely(err))
138 return err;
139 /*
140 * Copy the whole vector content from user space datap. Use
141 * copy_from_user to prevent information leak.
142 */
143 return copy_from_user(current->thread.vstate.datap, datap, riscv_v_vsize);
144 }
145 #else
146 #define save_v_state(task, regs) (0)
147 #define __restore_v_state(task, regs) (0)
148 #endif
149
150 static long restore_sigcontext(struct pt_regs *regs,
151 struct sigcontext __user *sc)
152 {
153 void __user *sc_ext_ptr = &sc->sc_extdesc.hdr;
154 __u32 rsvd;
155 long err;
156 /* sc_regs is structured the same as the start of pt_regs */
157 err = __copy_from_user(regs, &sc->sc_regs, sizeof(sc->sc_regs));
158 if (unlikely(err))
159 return err;
160
161 /* Restore the floating-point state. */
162 if (has_fpu()) {
163 err = restore_fp_state(regs, &sc->sc_fpregs);
164 if (unlikely(err))
165 return err;
166 }
167
168 /* Check the reserved word before extensions parsing */
169 err = __get_user(rsvd, &sc->sc_extdesc.reserved);
170 if (unlikely(err))
171 return err;
172 if (unlikely(rsvd))
173 return -EINVAL;
174
175 while (!err) {
176 __u32 magic, size;
177 struct __riscv_ctx_hdr __user *head = sc_ext_ptr;
178
179 err |= __get_user(magic, &head->magic);
180 err |= __get_user(size, &head->size);
181 if (unlikely(err))
182 return err;
183
184 sc_ext_ptr += sizeof(*head);
185 switch (magic) {
186 case END_MAGIC:
187 if (size != END_HDR_SIZE)
188 return -EINVAL;
189
190 return 0;
191 case RISCV_V_MAGIC:
192 if (!has_vector() || !riscv_v_vstate_query(regs) ||
193 size != riscv_v_sc_size)
194 return -EINVAL;
195
196 err = __restore_v_state(regs, sc_ext_ptr);
197 break;
198 default:
199 return -EINVAL;
200 }
201 sc_ext_ptr = (void __user *)head + size;
202 }
203 return err;
204 }
205
206 static size_t get_rt_frame_size(bool cal_all)
207 {
208 struct rt_sigframe __user *frame;
209 size_t frame_size;
210 size_t total_context_size = 0;
211
212 frame_size = sizeof(*frame);
213
214 if (has_vector()) {
215 if (cal_all || riscv_v_vstate_query(task_pt_regs(current)))
216 total_context_size += riscv_v_sc_size;
217 }
218 /*
219 * Preserved a __riscv_ctx_hdr for END signal context header if an
220 * extension uses __riscv_extra_ext_header
221 */
222 if (total_context_size)
223 total_context_size += sizeof(struct __riscv_ctx_hdr);
224
225 frame_size += total_context_size;
226
227 frame_size = round_up(frame_size, 16);
228 return frame_size;
229 }
230
231 SYSCALL_DEFINE0(rt_sigreturn)
232 {
233 struct pt_regs *regs = current_pt_regs();
234 struct rt_sigframe __user *frame;
235 struct task_struct *task;
236 sigset_t set;
237 size_t frame_size = get_rt_frame_size(false);
238
239 /* Always make any pending restarted system calls return -EINTR */
240 current->restart_block.fn = do_no_restart_syscall;
241
242 frame = (struct rt_sigframe __user *)regs->sp;
243
244 if (!access_ok(frame, frame_size))
245 goto badframe;
246
247 if (__copy_from_user(&set, &frame->uc.uc_sigmask, sizeof(set)))
248 goto badframe;
249
250 set_current_blocked(&set);
251
252 if (restore_sigcontext(regs, &frame->uc.uc_mcontext))
253 goto badframe;
254
255 if (restore_altstack(&frame->uc.uc_stack))
256 goto badframe;
257
258 regs->cause = -1UL;
259
260 return regs->a0;
261
262 badframe:
263 task = current;
264 if (show_unhandled_signals) {
265 pr_info_ratelimited(
266 "%s[%d]: bad frame in %s: frame=%p pc=%p sp=%p\n",
267 task->comm, task_pid_nr(task), __func__,
268 frame, (void *)regs->epc, (void *)regs->sp);
269 }
270 force_sig(SIGSEGV);
271 return 0;
272 }
273
274 static long setup_sigcontext(struct rt_sigframe __user *frame,
275 struct pt_regs *regs)
276 {
277 struct sigcontext __user *sc = &frame->uc.uc_mcontext;
278 struct __riscv_ctx_hdr __user *sc_ext_ptr = &sc->sc_extdesc.hdr;
279 long err;
280
281 /* sc_regs is structured the same as the start of pt_regs */
282 err = __copy_to_user(&sc->sc_regs, regs, sizeof(sc->sc_regs));
283 /* Save the floating-point state. */
284 if (has_fpu())
285 err |= save_fp_state(regs, &sc->sc_fpregs);
286 /* Save the vector state. */
287 if (has_vector() && riscv_v_vstate_query(regs))
288 err |= save_v_state(regs, (void __user **)&sc_ext_ptr);
289 /* Write zero to fp-reserved space and check it on restore_sigcontext */
290 err |= __put_user(0, &sc->sc_extdesc.reserved);
291 /* And put END __riscv_ctx_hdr at the end. */
292 err |= __put_user(END_MAGIC, &sc_ext_ptr->magic);
293 err |= __put_user(END_HDR_SIZE, &sc_ext_ptr->size);
294
295 return err;
296 }
297
298 static inline void __user *get_sigframe(struct ksignal *ksig,
299 struct pt_regs *regs, size_t framesize)
300 {
301 unsigned long sp;
302 /* Default to using normal stack */
303 sp = regs->sp;
304
305 /*
306 * If we are on the alternate signal stack and would overflow it, don't.
307 * Return an always-bogus address instead so we will die with SIGSEGV.
308 */
309 if (on_sig_stack(sp) && !likely(on_sig_stack(sp - framesize)))
310 return (void __user __force *)(-1UL);
311
312 /* This is the X/Open sanctioned signal stack switching. */
313 sp = sigsp(sp, ksig) - framesize;
314
315 /* Align the stack frame. */
316 sp &= ~0xfUL;
317
318 return (void __user *)sp;
319 }
320
321 static int setup_rt_frame(struct ksignal *ksig, sigset_t *set,
322 struct pt_regs *regs)
323 {
324 struct rt_sigframe __user *frame;
325 long err = 0;
326 unsigned long __maybe_unused addr;
327 size_t frame_size = get_rt_frame_size(false);
328
329 frame = get_sigframe(ksig, regs, frame_size);
330 if (!access_ok(frame, frame_size))
331 return -EFAULT;
332
333 err |= copy_siginfo_to_user(&frame->info, &ksig->info);
334
335 /* Create the ucontext. */
336 err |= __put_user(0, &frame->uc.uc_flags);
337 err |= __put_user(NULL, &frame->uc.uc_link);
338 err |= __save_altstack(&frame->uc.uc_stack, regs->sp);
339 err |= setup_sigcontext(frame, regs);
340 err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));
341 if (err)
342 return -EFAULT;
343
344 /* Set up to return from userspace. */
345 #ifdef CONFIG_MMU
346 regs->ra = (unsigned long)VDSO_SYMBOL(
347 current->mm->context.vdso, rt_sigreturn);
348 #else
349 /*
350 * For the nommu case we don't have a VDSO. Instead we push two
351 * instructions to call the rt_sigreturn syscall onto the user stack.
352 */
353 if (copy_to_user(&frame->sigreturn_code, __user_rt_sigreturn,
354 sizeof(frame->sigreturn_code)))
355 return -EFAULT;
356
357 addr = (unsigned long)&frame->sigreturn_code;
358 /* Make sure the two instructions are pushed to icache. */
359 flush_icache_range(addr, addr + sizeof(frame->sigreturn_code));
360
361 regs->ra = addr;
362 #endif /* CONFIG_MMU */
363
364 /*
365 * Set up registers for signal handler.
366 * Registers that we don't modify keep the value they had from
367 * user-space at the time we took the signal.
368 * We always pass siginfo and mcontext, regardless of SA_SIGINFO,
369 * since some things rely on this (e.g. glibc's debug/segfault.c).
370 */
371 regs->epc = (unsigned long)ksig->ka.sa.sa_handler;
372 regs->sp = (unsigned long)frame;
373 regs->a0 = ksig->sig; /* a0: signal number */
374 regs->a1 = (unsigned long)(&frame->info); /* a1: siginfo pointer */
375 regs->a2 = (unsigned long)(&frame->uc); /* a2: ucontext pointer */
376
377 #if DEBUG_SIG
378 pr_info("SIG deliver (%s:%d): sig=%d pc=%p ra=%p sp=%p\n",
379 current->comm, task_pid_nr(current), ksig->sig,
380 (void *)regs->epc, (void *)regs->ra, frame);
381 #endif
382
383 return 0;
384 }
385
386 static void handle_signal(struct ksignal *ksig, struct pt_regs *regs)
387 {
388 sigset_t *oldset = sigmask_to_save();
389 int ret;
390
391 rseq_signal_deliver(ksig, regs);
392
393 /* Set up the stack frame */
394 if (is_compat_task())
395 ret = compat_setup_rt_frame(ksig, oldset, regs);
396 else
397 ret = setup_rt_frame(ksig, oldset, regs);
398
399 signal_setup_done(ret, ksig, 0);
400 }
401
402 void arch_do_signal_or_restart(struct pt_regs *regs)
403 {
404 unsigned long continue_addr = 0, restart_addr = 0;
405 int retval = 0;
406 struct ksignal ksig;
407 bool syscall = (regs->cause == EXC_SYSCALL);
408
409 /* If we were from a system call, check for system call restarting */
410 if (syscall) {
411 continue_addr = regs->epc;
412 restart_addr = continue_addr - 4;
413 retval = regs->a0;
414
415 /* Avoid additional syscall restarting via ret_from_exception */
416 regs->cause = -1UL;
417
418 /*
419 * Prepare for system call restart. We do this here so that a
420 * debugger will see the already changed PC.
421 */
422 switch (retval) {
423 case -ERESTARTNOHAND:
424 case -ERESTARTSYS:
425 case -ERESTARTNOINTR:
426 case -ERESTART_RESTARTBLOCK:
427 regs->a0 = regs->orig_a0;
428 regs->epc = restart_addr;
429 break;
430 }
431 }
432
433 /*
434 * Get the signal to deliver. When running under ptrace, at this point
435 * the debugger may change all of our registers.
436 */
437 if (get_signal(&ksig)) {
438 /*
439 * Depending on the signal settings, we may need to revert the
440 * decision to restart the system call, but skip this if a
441 * debugger has chosen to restart at a different PC.
442 */
443 if (regs->epc == restart_addr &&
444 (retval == -ERESTARTNOHAND ||
445 retval == -ERESTART_RESTARTBLOCK ||
446 (retval == -ERESTARTSYS &&
447 !(ksig.ka.sa.sa_flags & SA_RESTART)))) {
448 regs->a0 = -EINTR;
449 regs->epc = continue_addr;
450 }
451
452 /* Actually deliver the signal */
453 handle_signal(&ksig, regs);
454 return;
455 }
456
457 /*
458 * Handle restarting a different system call. As above, if a debugger
459 * has chosen to restart at a different PC, ignore the restart.
460 */
461 if (syscall && regs->epc == restart_addr && retval == -ERESTART_RESTARTBLOCK)
462 regs->a7 = __NR_restart_syscall;
463
464 /*
465 * If there is no signal to deliver, we just put the saved
466 * sigmask back.
467 */
468 restore_saved_sigmask();
469 }
470
471 void init_rt_signal_env(void);
472 void __init init_rt_signal_env(void)
473 {
474 riscv_v_sc_size = sizeof(struct __riscv_ctx_hdr) +
475 sizeof(struct __sc_riscv_v_state) + riscv_v_vsize;
476 /*
477 * Determine the stack space required for guaranteed signal delivery.
478 * The signal_minsigstksz will be populated into the AT_MINSIGSTKSZ entry
479 * in the auxiliary array at process startup.
480 */
481 signal_minsigstksz = get_rt_frame_size(true);
482 }
483
484 #ifdef CONFIG_DYNAMIC_SIGFRAME
485 bool sigaltstack_size_valid(size_t ss_size)
486 {
487 return ss_size > get_rt_frame_size(false);
488 }
489 #endif /* CONFIG_DYNAMIC_SIGFRAME */
490
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