1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3 * linux/arch/unicore32/kernel/signal.c
4 *
5 * Code specific to PKUnity SoC and UniCore ISA
6 *
7 * Copyright (C) 2001-2010 GUAN Xue-tao
8 */
9 #include <linux/errno.h>
10 #include <linux/signal.h>
11 #include <linux/personality.h>
12 #include <linux/uaccess.h>
13 #include <linux/tracehook.h>
14 #include <linux/elf.h>
15 #include <linux/unistd.h>
16
17 #include <asm/cacheflush.h>
18 #include <asm/ucontext.h>
19
20 /*
21 * For UniCore syscalls, we encode the syscall number into the instruction.
22 */
23 #define SWI_SYS_SIGRETURN (0xff000000) /* error number for new abi */
24 #define SWI_SYS_RT_SIGRETURN (0xff000000 | (__NR_rt_sigreturn))
25 #define SWI_SYS_RESTART (0xff000000 | (__NR_restart_syscall))
26
27 #define KERN_SIGRETURN_CODE (KUSER_VECPAGE_BASE + 0x00000500)
28 #define KERN_RESTART_CODE (KERN_SIGRETURN_CODE + sizeof(sigreturn_codes))
29
30 const unsigned long sigreturn_codes[3] = {
31 SWI_SYS_SIGRETURN, SWI_SYS_RT_SIGRETURN,
32 };
33
34 const unsigned long syscall_restart_code[2] = {
35 SWI_SYS_RESTART, /* swi __NR_restart_syscall */
36 0x69efc004, /* ldr pc, [sp], #4 */
37 };
38
39 /*
40 * Do a signal return; undo the signal stack. These are aligned to 64-bit.
41 */
42 struct sigframe {
43 struct ucontext uc;
44 unsigned long retcode[2];
45 };
46
47 struct rt_sigframe {
48 struct siginfo info;
49 struct sigframe sig;
50 };
51
restore_sigframe(struct pt_regs * regs,struct sigframe __user * sf)52 static int restore_sigframe(struct pt_regs *regs, struct sigframe __user *sf)
53 {
54 sigset_t set;
55 int err;
56
57 err = __copy_from_user(&set, &sf->uc.uc_sigmask, sizeof(set));
58 if (err == 0)
59 set_current_blocked(&set);
60
61 err |= __get_user(regs->UCreg_00, &sf->uc.uc_mcontext.regs.UCreg_00);
62 err |= __get_user(regs->UCreg_01, &sf->uc.uc_mcontext.regs.UCreg_01);
63 err |= __get_user(regs->UCreg_02, &sf->uc.uc_mcontext.regs.UCreg_02);
64 err |= __get_user(regs->UCreg_03, &sf->uc.uc_mcontext.regs.UCreg_03);
65 err |= __get_user(regs->UCreg_04, &sf->uc.uc_mcontext.regs.UCreg_04);
66 err |= __get_user(regs->UCreg_05, &sf->uc.uc_mcontext.regs.UCreg_05);
67 err |= __get_user(regs->UCreg_06, &sf->uc.uc_mcontext.regs.UCreg_06);
68 err |= __get_user(regs->UCreg_07, &sf->uc.uc_mcontext.regs.UCreg_07);
69 err |= __get_user(regs->UCreg_08, &sf->uc.uc_mcontext.regs.UCreg_08);
70 err |= __get_user(regs->UCreg_09, &sf->uc.uc_mcontext.regs.UCreg_09);
71 err |= __get_user(regs->UCreg_10, &sf->uc.uc_mcontext.regs.UCreg_10);
72 err |= __get_user(regs->UCreg_11, &sf->uc.uc_mcontext.regs.UCreg_11);
73 err |= __get_user(regs->UCreg_12, &sf->uc.uc_mcontext.regs.UCreg_12);
74 err |= __get_user(regs->UCreg_13, &sf->uc.uc_mcontext.regs.UCreg_13);
75 err |= __get_user(regs->UCreg_14, &sf->uc.uc_mcontext.regs.UCreg_14);
76 err |= __get_user(regs->UCreg_15, &sf->uc.uc_mcontext.regs.UCreg_15);
77 err |= __get_user(regs->UCreg_16, &sf->uc.uc_mcontext.regs.UCreg_16);
78 err |= __get_user(regs->UCreg_17, &sf->uc.uc_mcontext.regs.UCreg_17);
79 err |= __get_user(regs->UCreg_18, &sf->uc.uc_mcontext.regs.UCreg_18);
80 err |= __get_user(regs->UCreg_19, &sf->uc.uc_mcontext.regs.UCreg_19);
81 err |= __get_user(regs->UCreg_20, &sf->uc.uc_mcontext.regs.UCreg_20);
82 err |= __get_user(regs->UCreg_21, &sf->uc.uc_mcontext.regs.UCreg_21);
83 err |= __get_user(regs->UCreg_22, &sf->uc.uc_mcontext.regs.UCreg_22);
84 err |= __get_user(regs->UCreg_23, &sf->uc.uc_mcontext.regs.UCreg_23);
85 err |= __get_user(regs->UCreg_24, &sf->uc.uc_mcontext.regs.UCreg_24);
86 err |= __get_user(regs->UCreg_25, &sf->uc.uc_mcontext.regs.UCreg_25);
87 err |= __get_user(regs->UCreg_26, &sf->uc.uc_mcontext.regs.UCreg_26);
88 err |= __get_user(regs->UCreg_fp, &sf->uc.uc_mcontext.regs.UCreg_fp);
89 err |= __get_user(regs->UCreg_ip, &sf->uc.uc_mcontext.regs.UCreg_ip);
90 err |= __get_user(regs->UCreg_sp, &sf->uc.uc_mcontext.regs.UCreg_sp);
91 err |= __get_user(regs->UCreg_lr, &sf->uc.uc_mcontext.regs.UCreg_lr);
92 err |= __get_user(regs->UCreg_pc, &sf->uc.uc_mcontext.regs.UCreg_pc);
93 err |= __get_user(regs->UCreg_asr, &sf->uc.uc_mcontext.regs.UCreg_asr);
94
95 err |= !valid_user_regs(regs);
96
97 return err;
98 }
99
__sys_rt_sigreturn(struct pt_regs * regs)100 asmlinkage int __sys_rt_sigreturn(struct pt_regs *regs)
101 {
102 struct rt_sigframe __user *frame;
103
104 /* Always make any pending restarted system calls return -EINTR */
105 current->restart_block.fn = do_no_restart_syscall;
106
107 /*
108 * Since we stacked the signal on a 64-bit boundary,
109 * then 'sp' should be word aligned here. If it's
110 * not, then the user is trying to mess with us.
111 */
112 if (regs->UCreg_sp & 7)
113 goto badframe;
114
115 frame = (struct rt_sigframe __user *)regs->UCreg_sp;
116
117 if (!access_ok(frame, sizeof(*frame)))
118 goto badframe;
119
120 if (restore_sigframe(regs, &frame->sig))
121 goto badframe;
122
123 if (restore_altstack(&frame->sig.uc.uc_stack))
124 goto badframe;
125
126 return regs->UCreg_00;
127
128 badframe:
129 force_sig(SIGSEGV);
130 return 0;
131 }
132
setup_sigframe(struct sigframe __user * sf,struct pt_regs * regs,sigset_t * set)133 static int setup_sigframe(struct sigframe __user *sf, struct pt_regs *regs,
134 sigset_t *set)
135 {
136 int err = 0;
137
138 err |= __put_user(regs->UCreg_00, &sf->uc.uc_mcontext.regs.UCreg_00);
139 err |= __put_user(regs->UCreg_01, &sf->uc.uc_mcontext.regs.UCreg_01);
140 err |= __put_user(regs->UCreg_02, &sf->uc.uc_mcontext.regs.UCreg_02);
141 err |= __put_user(regs->UCreg_03, &sf->uc.uc_mcontext.regs.UCreg_03);
142 err |= __put_user(regs->UCreg_04, &sf->uc.uc_mcontext.regs.UCreg_04);
143 err |= __put_user(regs->UCreg_05, &sf->uc.uc_mcontext.regs.UCreg_05);
144 err |= __put_user(regs->UCreg_06, &sf->uc.uc_mcontext.regs.UCreg_06);
145 err |= __put_user(regs->UCreg_07, &sf->uc.uc_mcontext.regs.UCreg_07);
146 err |= __put_user(regs->UCreg_08, &sf->uc.uc_mcontext.regs.UCreg_08);
147 err |= __put_user(regs->UCreg_09, &sf->uc.uc_mcontext.regs.UCreg_09);
148 err |= __put_user(regs->UCreg_10, &sf->uc.uc_mcontext.regs.UCreg_10);
149 err |= __put_user(regs->UCreg_11, &sf->uc.uc_mcontext.regs.UCreg_11);
150 err |= __put_user(regs->UCreg_12, &sf->uc.uc_mcontext.regs.UCreg_12);
151 err |= __put_user(regs->UCreg_13, &sf->uc.uc_mcontext.regs.UCreg_13);
152 err |= __put_user(regs->UCreg_14, &sf->uc.uc_mcontext.regs.UCreg_14);
153 err |= __put_user(regs->UCreg_15, &sf->uc.uc_mcontext.regs.UCreg_15);
154 err |= __put_user(regs->UCreg_16, &sf->uc.uc_mcontext.regs.UCreg_16);
155 err |= __put_user(regs->UCreg_17, &sf->uc.uc_mcontext.regs.UCreg_17);
156 err |= __put_user(regs->UCreg_18, &sf->uc.uc_mcontext.regs.UCreg_18);
157 err |= __put_user(regs->UCreg_19, &sf->uc.uc_mcontext.regs.UCreg_19);
158 err |= __put_user(regs->UCreg_20, &sf->uc.uc_mcontext.regs.UCreg_20);
159 err |= __put_user(regs->UCreg_21, &sf->uc.uc_mcontext.regs.UCreg_21);
160 err |= __put_user(regs->UCreg_22, &sf->uc.uc_mcontext.regs.UCreg_22);
161 err |= __put_user(regs->UCreg_23, &sf->uc.uc_mcontext.regs.UCreg_23);
162 err |= __put_user(regs->UCreg_24, &sf->uc.uc_mcontext.regs.UCreg_24);
163 err |= __put_user(regs->UCreg_25, &sf->uc.uc_mcontext.regs.UCreg_25);
164 err |= __put_user(regs->UCreg_26, &sf->uc.uc_mcontext.regs.UCreg_26);
165 err |= __put_user(regs->UCreg_fp, &sf->uc.uc_mcontext.regs.UCreg_fp);
166 err |= __put_user(regs->UCreg_ip, &sf->uc.uc_mcontext.regs.UCreg_ip);
167 err |= __put_user(regs->UCreg_sp, &sf->uc.uc_mcontext.regs.UCreg_sp);
168 err |= __put_user(regs->UCreg_lr, &sf->uc.uc_mcontext.regs.UCreg_lr);
169 err |= __put_user(regs->UCreg_pc, &sf->uc.uc_mcontext.regs.UCreg_pc);
170 err |= __put_user(regs->UCreg_asr, &sf->uc.uc_mcontext.regs.UCreg_asr);
171
172 err |= __put_user(current->thread.trap_no,
173 &sf->uc.uc_mcontext.trap_no);
174 err |= __put_user(current->thread.error_code,
175 &sf->uc.uc_mcontext.error_code);
176 err |= __put_user(current->thread.address,
177 &sf->uc.uc_mcontext.fault_address);
178 err |= __put_user(set->sig[0], &sf->uc.uc_mcontext.oldmask);
179
180 err |= __copy_to_user(&sf->uc.uc_sigmask, set, sizeof(*set));
181
182 return err;
183 }
184
get_sigframe(struct k_sigaction * ka,struct pt_regs * regs,int framesize)185 static inline void __user *get_sigframe(struct k_sigaction *ka,
186 struct pt_regs *regs, int framesize)
187 {
188 unsigned long sp = regs->UCreg_sp;
189 void __user *frame;
190
191 /*
192 * This is the X/Open sanctioned signal stack switching.
193 */
194 if ((ka->sa.sa_flags & SA_ONSTACK) && !sas_ss_flags(sp))
195 sp = current->sas_ss_sp + current->sas_ss_size;
196
197 /*
198 * ATPCS B01 mandates 8-byte alignment
199 */
200 frame = (void __user *)((sp - framesize) & ~7);
201
202 /*
203 * Check that we can actually write to the signal frame.
204 */
205 if (!access_ok(frame, framesize))
206 frame = NULL;
207
208 return frame;
209 }
210
setup_return(struct pt_regs * regs,struct k_sigaction * ka,unsigned long __user * rc,void __user * frame,int usig)211 static int setup_return(struct pt_regs *regs, struct k_sigaction *ka,
212 unsigned long __user *rc, void __user *frame, int usig)
213 {
214 unsigned long handler = (unsigned long)ka->sa.sa_handler;
215 unsigned long retcode;
216 unsigned long asr = regs->UCreg_asr & ~PSR_f;
217
218 unsigned int idx = 0;
219
220 if (ka->sa.sa_flags & SA_SIGINFO)
221 idx += 1;
222
223 if (__put_user(sigreturn_codes[idx], rc) ||
224 __put_user(sigreturn_codes[idx+1], rc+1))
225 return 1;
226
227 retcode = KERN_SIGRETURN_CODE + (idx << 2);
228
229 regs->UCreg_00 = usig;
230 regs->UCreg_sp = (unsigned long)frame;
231 regs->UCreg_lr = retcode;
232 regs->UCreg_pc = handler;
233 regs->UCreg_asr = asr;
234
235 return 0;
236 }
237
setup_frame(struct ksignal * ksig,sigset_t * set,struct pt_regs * regs)238 static int setup_frame(struct ksignal *ksig, sigset_t *set,
239 struct pt_regs *regs)
240 {
241 struct sigframe __user *frame = get_sigframe(&ksig->ka, regs, sizeof(*frame));
242 int err = 0;
243
244 if (!frame)
245 return 1;
246
247 /*
248 * Set uc.uc_flags to a value which sc.trap_no would never have.
249 */
250 err |= __put_user(0x5ac3c35a, &frame->uc.uc_flags);
251
252 err |= setup_sigframe(frame, regs, set);
253 if (err == 0)
254 err |= setup_return(regs, &ksig->ka, frame->retcode, frame,
255 ksig->sig);
256
257 return err;
258 }
259
setup_rt_frame(struct ksignal * ksig,sigset_t * set,struct pt_regs * regs)260 static int setup_rt_frame(struct ksignal *ksig, sigset_t *set,
261 struct pt_regs *regs)
262 {
263 struct rt_sigframe __user *frame =
264 get_sigframe(&ksig->ka, regs, sizeof(*frame));
265 int err = 0;
266
267 if (!frame)
268 return 1;
269
270 err |= copy_siginfo_to_user(&frame->info, &ksig->info);
271
272 err |= __put_user(0, &frame->sig.uc.uc_flags);
273 err |= __put_user(NULL, &frame->sig.uc.uc_link);
274 err |= __save_altstack(&frame->sig.uc.uc_stack, regs->UCreg_sp);
275 err |= setup_sigframe(&frame->sig, regs, set);
276 if (err == 0)
277 err |= setup_return(regs, &ksig->ka, frame->sig.retcode, frame,
278 ksig->sig);
279
280 if (err == 0) {
281 /*
282 * For realtime signals we must also set the second and third
283 * arguments for the signal handler.
284 */
285 regs->UCreg_01 = (unsigned long)&frame->info;
286 regs->UCreg_02 = (unsigned long)&frame->sig.uc;
287 }
288
289 return err;
290 }
291
setup_syscall_restart(struct pt_regs * regs)292 static inline void setup_syscall_restart(struct pt_regs *regs)
293 {
294 regs->UCreg_00 = regs->UCreg_ORIG_00;
295 regs->UCreg_pc -= 4;
296 }
297
298 /*
299 * OK, we're invoking a handler
300 */
handle_signal(struct ksignal * ksig,struct pt_regs * regs,int syscall)301 static void handle_signal(struct ksignal *ksig, struct pt_regs *regs,
302 int syscall)
303 {
304 struct thread_info *thread = current_thread_info();
305 sigset_t *oldset = sigmask_to_save();
306 int usig = ksig->sig;
307 int ret;
308
309 /*
310 * If we were from a system call, check for system call restarting...
311 */
312 if (syscall) {
313 switch (regs->UCreg_00) {
314 case -ERESTART_RESTARTBLOCK:
315 case -ERESTARTNOHAND:
316 regs->UCreg_00 = -EINTR;
317 break;
318 case -ERESTARTSYS:
319 if (!(ksig->ka.sa.sa_flags & SA_RESTART)) {
320 regs->UCreg_00 = -EINTR;
321 break;
322 }
323 /* fallthrough */
324 case -ERESTARTNOINTR:
325 setup_syscall_restart(regs);
326 }
327 }
328
329 /*
330 * Set up the stack frame
331 */
332 if (ksig->ka.sa.sa_flags & SA_SIGINFO)
333 ret = setup_rt_frame(ksig, oldset, regs);
334 else
335 ret = setup_frame(ksig, oldset, regs);
336
337 /*
338 * Check that the resulting registers are actually sane.
339 */
340 ret |= !valid_user_regs(regs);
341
342 signal_setup_done(ret, ksig, 0);
343 }
344
345 /*
346 * Note that 'init' is a special process: it doesn't get signals it doesn't
347 * want to handle. Thus you cannot kill init even with a SIGKILL even by
348 * mistake.
349 *
350 * Note that we go through the signals twice: once to check the signals that
351 * the kernel can handle, and then we build all the user-level signal handling
352 * stack-frames in one go after that.
353 */
do_signal(struct pt_regs * regs,int syscall)354 static void do_signal(struct pt_regs *regs, int syscall)
355 {
356 struct ksignal ksig;
357
358 /*
359 * We want the common case to go fast, which
360 * is why we may in certain cases get here from
361 * kernel mode. Just return without doing anything
362 * if so.
363 */
364 if (!user_mode(regs))
365 return;
366
367 if (get_signal(&ksig)) {
368 handle_signal(&ksig, regs, syscall);
369 return;
370 }
371
372 /*
373 * No signal to deliver to the process - restart the syscall.
374 */
375 if (syscall) {
376 if (regs->UCreg_00 == -ERESTART_RESTARTBLOCK) {
377 u32 __user *usp;
378
379 regs->UCreg_sp -= 4;
380 usp = (u32 __user *)regs->UCreg_sp;
381
382 if (put_user(regs->UCreg_pc, usp) == 0) {
383 regs->UCreg_pc = KERN_RESTART_CODE;
384 } else {
385 regs->UCreg_sp += 4;
386 force_sigsegv(0);
387 }
388 }
389 if (regs->UCreg_00 == -ERESTARTNOHAND ||
390 regs->UCreg_00 == -ERESTARTSYS ||
391 regs->UCreg_00 == -ERESTARTNOINTR) {
392 setup_syscall_restart(regs);
393 }
394 }
395 /* If there's no signal to deliver, we just put the saved
396 * sigmask back.
397 */
398 restore_saved_sigmask();
399 }
400
do_notify_resume(struct pt_regs * regs,unsigned int thread_flags,int syscall)401 asmlinkage void do_notify_resume(struct pt_regs *regs,
402 unsigned int thread_flags, int syscall)
403 {
404 if (thread_flags & _TIF_SIGPENDING)
405 do_signal(regs, syscall);
406
407 if (thread_flags & _TIF_NOTIFY_RESUME) {
408 clear_thread_flag(TIF_NOTIFY_RESUME);
409 tracehook_notify_resume(regs);
410 }
411 }
412
413 /*
414 * Copy signal return handlers into the vector page, and
415 * set sigreturn to be a pointer to these.
416 */
early_signal_init(void)417 void __init early_signal_init(void)
418 {
419 memcpy((void *)kuser_vecpage_to_vectors(KERN_SIGRETURN_CODE),
420 sigreturn_codes, sizeof(sigreturn_codes));
421 memcpy((void *)kuser_vecpage_to_vectors(KERN_RESTART_CODE),
422 syscall_restart_code, sizeof(syscall_restart_code));
423 /* Need not to flush icache, since early_trap_init will do it last. */
424 }
425