1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3 * OpenRISC signal.c
4 *
5 * Linux architectural port borrowing liberally from similar works of
6 * others. All original copyrights apply as per the original source
7 * declaration.
8 *
9 * Modifications for the OpenRISC architecture:
10 * Copyright (C) 2003 Matjaz Breskvar <phoenix@bsemi.com>
11 * Copyright (C) 2010-2011 Jonas Bonn <jonas@southpole.se>
12 */
13
14 #include <linux/sched.h>
15 #include <linux/mm.h>
16 #include <linux/smp.h>
17 #include <linux/kernel.h>
18 #include <linux/signal.h>
19 #include <linux/errno.h>
20 #include <linux/wait.h>
21 #include <linux/ptrace.h>
22 #include <linux/unistd.h>
23 #include <linux/stddef.h>
24 #include <linux/resume_user_mode.h>
25
26 #include <asm/fpu.h>
27 #include <asm/processor.h>
28 #include <asm/syscall.h>
29 #include <asm/ucontext.h>
30 #include <linux/uaccess.h>
31
32 struct rt_sigframe {
33 struct siginfo info;
34 struct ucontext uc;
35 unsigned char retcode[16]; /* trampoline code */
36 };
37
38 asmlinkage long _sys_rt_sigreturn(struct pt_regs *regs);
39
40 asmlinkage int do_work_pending(struct pt_regs *regs, unsigned int thread_flags,
41 int syscall);
42
43 #ifdef CONFIG_FPU
44 static long restore_fp_state(struct sigcontext __user *sc)
45 {
46 long err;
47
48 err = __copy_from_user(¤t->thread.fpcsr, &sc->fpcsr, sizeof(unsigned long));
49 if (unlikely(err))
50 return err;
51
52 /* Restore the FPU state */
53 restore_fpu(current);
54
55 return 0;
56 }
57
58 static long save_fp_state(struct sigcontext __user *sc)
59 {
60 long err;
61
62 /* Sync the user FPU state so we can copy to sigcontext */
63 save_fpu(current);
64
65 err = __copy_to_user(&sc->fpcsr, ¤t->thread.fpcsr, sizeof(unsigned long));
66
67 return err;
68 }
69 #else
70 #define save_fp_state(sc) (0)
71 #define restore_fp_state(sc) (0)
72 #endif
73
74 static int restore_sigcontext(struct pt_regs *regs,
75 struct sigcontext __user *sc)
76 {
77 int err = 0;
78
79 /* Always make any pending restarted system calls return -EINTR */
80 current->restart_block.fn = do_no_restart_syscall;
81
82 /*
83 * Restore the regs from &sc->regs.
84 * (sc is already checked since the sigframe was
85 * checked in sys_sigreturn previously)
86 */
87 err |= __copy_from_user(regs, sc->regs.gpr, 32 * sizeof(unsigned long));
88 err |= __copy_from_user(®s->pc, &sc->regs.pc, sizeof(unsigned long));
89 err |= __copy_from_user(®s->sr, &sc->regs.sr, sizeof(unsigned long));
90 err |= restore_fp_state(sc);
91
92 /* make sure the SM-bit is cleared so user-mode cannot fool us */
93 regs->sr &= ~SPR_SR_SM;
94
95 regs->orig_gpr11 = -1; /* Avoid syscall restart checks */
96
97 /* TODO: the other ports use regs->orig_XX to disable syscall checks
98 * after this completes, but we don't use that mechanism. maybe we can
99 * use it now ?
100 */
101
102 return err;
103 }
104
105 asmlinkage long _sys_rt_sigreturn(struct pt_regs *regs)
106 {
107 struct rt_sigframe __user *frame = (struct rt_sigframe __user *)regs->sp;
108 sigset_t set;
109
110 /*
111 * Since we stacked the signal on a dword boundary,
112 * then frame should be dword aligned here. If it's
113 * not, then the user is trying to mess with us.
114 */
115 if (((unsigned long)frame) & 3)
116 goto badframe;
117
118 if (!access_ok(frame, sizeof(*frame)))
119 goto badframe;
120 if (__copy_from_user(&set, &frame->uc.uc_sigmask, sizeof(set)))
121 goto badframe;
122
123 set_current_blocked(&set);
124
125 if (restore_sigcontext(regs, &frame->uc.uc_mcontext))
126 goto badframe;
127
128 if (restore_altstack(&frame->uc.uc_stack))
129 goto badframe;
130
131 return regs->gpr[11];
132
133 badframe:
134 force_sig(SIGSEGV);
135 return 0;
136 }
137
138 /*
139 * Set up a signal frame.
140 */
141
142 static int setup_sigcontext(struct pt_regs *regs, struct sigcontext __user *sc)
143 {
144 int err = 0;
145
146 /* copy the regs */
147 /* There should be no need to save callee-saved registers here...
148 * ...but we save them anyway. Revisit this
149 */
150 err |= __copy_to_user(sc->regs.gpr, regs, 32 * sizeof(unsigned long));
151 err |= __copy_to_user(&sc->regs.pc, ®s->pc, sizeof(unsigned long));
152 err |= __copy_to_user(&sc->regs.sr, ®s->sr, sizeof(unsigned long));
153 err |= save_fp_state(sc);
154
155 return err;
156 }
157
158 static inline unsigned long align_sigframe(unsigned long sp)
159 {
160 return sp & ~3UL;
161 }
162
163 /*
164 * Work out where the signal frame should go. It's either on the user stack
165 * or the alternate stack.
166 */
167
168 static inline void __user *get_sigframe(struct ksignal *ksig,
169 struct pt_regs *regs, size_t frame_size)
170 {
171 unsigned long sp = regs->sp;
172
173 /* redzone */
174 sp -= STACK_FRAME_OVERHEAD;
175 sp = sigsp(sp, ksig);
176 sp = align_sigframe(sp - frame_size);
177
178 return (void __user *)sp;
179 }
180
181 /* grab and setup a signal frame.
182 *
183 * basically we stack a lot of state info, and arrange for the
184 * user-mode program to return to the kernel using either a
185 * trampoline which performs the syscall sigreturn, or a provided
186 * user-mode trampoline.
187 */
188 static int setup_rt_frame(struct ksignal *ksig, sigset_t *set,
189 struct pt_regs *regs)
190 {
191 struct rt_sigframe __user *frame;
192 unsigned long return_ip;
193 int err = 0;
194
195 frame = get_sigframe(ksig, regs, sizeof(*frame));
196
197 if (!access_ok(frame, sizeof(*frame)))
198 return -EFAULT;
199
200 /* Create siginfo. */
201 if (ksig->ka.sa.sa_flags & SA_SIGINFO)
202 err |= copy_siginfo_to_user(&frame->info, &ksig->info);
203
204 /* Create the ucontext. */
205 err |= __put_user(0, &frame->uc.uc_flags);
206 err |= __put_user(NULL, &frame->uc.uc_link);
207 err |= __save_altstack(&frame->uc.uc_stack, regs->sp);
208 err |= setup_sigcontext(regs, &frame->uc.uc_mcontext);
209
210 err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));
211
212 if (err)
213 return -EFAULT;
214
215 /* trampoline - the desired return ip is the retcode itself */
216 return_ip = (unsigned long)&frame->retcode;
217 /* This is:
218 l.ori r11,r0,__NR_sigreturn
219 l.sys 1
220 */
221 err |= __put_user(0xa960, (short __user *)(frame->retcode + 0));
222 err |= __put_user(__NR_rt_sigreturn, (short __user *)(frame->retcode + 2));
223 err |= __put_user(0x20000001, (unsigned long __user *)(frame->retcode + 4));
224 err |= __put_user(0x15000000, (unsigned long __user *)(frame->retcode + 8));
225
226 if (err)
227 return -EFAULT;
228
229 /* Set up registers for signal handler */
230 regs->pc = (unsigned long)ksig->ka.sa.sa_handler; /* what we enter NOW */
231 regs->gpr[9] = (unsigned long)return_ip; /* what we enter LATER */
232 regs->gpr[3] = (unsigned long)ksig->sig; /* arg 1: signo */
233 regs->gpr[4] = (unsigned long)&frame->info; /* arg 2: (siginfo_t*) */
234 regs->gpr[5] = (unsigned long)&frame->uc; /* arg 3: ucontext */
235
236 /* actually move the usp to reflect the stacked frame */
237 regs->sp = (unsigned long)frame;
238
239 return 0;
240 }
241
242 static inline void
243 handle_signal(struct ksignal *ksig, struct pt_regs *regs)
244 {
245 int ret;
246
247 ret = setup_rt_frame(ksig, sigmask_to_save(), regs);
248
249 signal_setup_done(ret, ksig, test_thread_flag(TIF_SINGLESTEP));
250 }
251
252 /*
253 * Note that 'init' is a special process: it doesn't get signals it doesn't
254 * want to handle. Thus you cannot kill init even with a SIGKILL even by
255 * mistake.
256 *
257 * Also note that the regs structure given here as an argument, is the latest
258 * pushed pt_regs. It may or may not be the same as the first pushed registers
259 * when the initial usermode->kernelmode transition took place. Therefore
260 * we can use user_mode(regs) to see if we came directly from kernel or user
261 * mode below.
262 */
263
264 static int do_signal(struct pt_regs *regs, int syscall)
265 {
266 struct ksignal ksig;
267 unsigned long continue_addr = 0;
268 unsigned long restart_addr = 0;
269 unsigned long retval = 0;
270 int restart = 0;
271
272 if (syscall) {
273 continue_addr = regs->pc;
274 restart_addr = continue_addr - 4;
275 retval = regs->gpr[11];
276
277 /*
278 * Setup syscall restart here so that a debugger will
279 * see the already changed PC.
280 */
281 switch (retval) {
282 case -ERESTART_RESTARTBLOCK:
283 restart = -2;
284 fallthrough;
285 case -ERESTARTNOHAND:
286 case -ERESTARTSYS:
287 case -ERESTARTNOINTR:
288 restart++;
289 regs->gpr[11] = regs->orig_gpr11;
290 regs->pc = restart_addr;
291 break;
292 }
293 }
294
295 /*
296 * Get the signal to deliver. During the call to get_signal the
297 * debugger may change all our registers so we may need to revert
298 * the decision to restart the syscall; specifically, if the PC is
299 * changed, don't restart the syscall.
300 */
301 if (get_signal(&ksig)) {
302 if (unlikely(restart) && regs->pc == restart_addr) {
303 if (retval == -ERESTARTNOHAND ||
304 retval == -ERESTART_RESTARTBLOCK
305 || (retval == -ERESTARTSYS
306 && !(ksig.ka.sa.sa_flags & SA_RESTART))) {
307 /* No automatic restart */
308 regs->gpr[11] = -EINTR;
309 regs->pc = continue_addr;
310 }
311 }
312 handle_signal(&ksig, regs);
313 } else {
314 /* no handler */
315 restore_saved_sigmask();
316 /*
317 * Restore pt_regs PC as syscall restart will be handled by
318 * kernel without return to userspace
319 */
320 if (unlikely(restart) && regs->pc == restart_addr) {
321 regs->pc = continue_addr;
322 return restart;
323 }
324 }
325
326 return 0;
327 }
328
329 asmlinkage int
330 do_work_pending(struct pt_regs *regs, unsigned int thread_flags, int syscall)
331 {
332 do {
333 if (likely(thread_flags & _TIF_NEED_RESCHED)) {
334 schedule();
335 } else {
336 if (unlikely(!user_mode(regs)))
337 return 0;
338 local_irq_enable();
339 if (thread_flags & (_TIF_SIGPENDING|_TIF_NOTIFY_SIGNAL)) {
340 int restart = do_signal(regs, syscall);
341 if (unlikely(restart)) {
342 /*
343 * Restart without handlers.
344 * Deal with it without leaving
345 * the kernel space.
346 */
347 return restart;
348 }
349 syscall = 0;
350 } else {
351 resume_user_mode_work(regs);
352 }
353 }
354 local_irq_disable();
355 thread_flags = read_thread_flags();
356 } while (thread_flags & _TIF_WORK_MASK);
357 return 0;
358 }
359
Linux® is a registered trademark of Linus Torvalds in the United States and other countries.
TOMOYO® is a registered trademark of NTT DATA CORPORATION.