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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
32struct rt_sigframe {
33 struct siginfo info;
34 struct ucontext uc;
35 unsigned char retcode[16]; /* trampoline code */
36};
37
38asmlinkage long _sys_rt_sigreturn(struct pt_regs *regs);
39
40asmlinkage int do_work_pending(struct pt_regs *regs, unsigned int thread_flags,
41 int syscall);
42
43#ifdef CONFIG_FPU
44static 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
58static 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
74static 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
105asmlinkage 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
133badframe:
134 force_sig(SIGSEGV);
135 return 0;
136}
137
138/*
139 * Set up a signal frame.
140 */
141
142static 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
158static 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
168static 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 */
188static 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
242static inline void
243handle_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
264static 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
329asmlinkage int
330do_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}
1/*
2 * OpenRISC signal.c
3 *
4 * Linux architectural port borrowing liberally from similar works of
5 * others. All original copyrights apply as per the original source
6 * declaration.
7 *
8 * Modifications for the OpenRISC architecture:
9 * Copyright (C) 2003 Matjaz Breskvar <phoenix@bsemi.com>
10 * Copyright (C) 2010-2011 Jonas Bonn <jonas@southpole.se>
11 *
12 * This program is free software; you can redistribute it and/or
13 * modify it under the terms of the GNU General Public License
14 * as published by the Free Software Foundation; either version
15 * 2 of the License, or (at your option) any later version.
16 */
17
18#include <linux/sched.h>
19#include <linux/mm.h>
20#include <linux/smp.h>
21#include <linux/kernel.h>
22#include <linux/signal.h>
23#include <linux/errno.h>
24#include <linux/wait.h>
25#include <linux/ptrace.h>
26#include <linux/unistd.h>
27#include <linux/stddef.h>
28#include <linux/tracehook.h>
29
30#include <asm/processor.h>
31#include <asm/ucontext.h>
32#include <asm/uaccess.h>
33
34#define DEBUG_SIG 0
35
36asmlinkage long
37_sys_sigaltstack(const stack_t *uss, stack_t *uoss, struct pt_regs *regs)
38{
39 return do_sigaltstack(uss, uoss, regs->sp);
40}
41
42struct rt_sigframe {
43 struct siginfo *pinfo;
44 void *puc;
45 struct siginfo info;
46 struct ucontext uc;
47 unsigned char retcode[16]; /* trampoline code */
48};
49
50static int restore_sigcontext(struct pt_regs *regs, struct sigcontext *sc)
51{
52 unsigned int err = 0;
53
54 /* Alwys make any pending restarted system call return -EINTR */
55 current_thread_info()->restart_block.fn = do_no_restart_syscall;
56
57 /*
58 * Restore the regs from &sc->regs.
59 * (sc is already checked for VERIFY_READ since the sigframe was
60 * checked in sys_sigreturn previously)
61 */
62 if (__copy_from_user(regs, sc->regs.gpr, 32 * sizeof(unsigned long)))
63 goto badframe;
64 if (__copy_from_user(®s->pc, &sc->regs.pc, sizeof(unsigned long)))
65 goto badframe;
66 if (__copy_from_user(®s->sr, &sc->regs.sr, sizeof(unsigned long)))
67 goto badframe;
68
69 /* make sure the SM-bit is cleared so user-mode cannot fool us */
70 regs->sr &= ~SPR_SR_SM;
71
72 /* TODO: the other ports use regs->orig_XX to disable syscall checks
73 * after this completes, but we don't use that mechanism. maybe we can
74 * use it now ?
75 */
76
77 return err;
78
79badframe:
80 return 1;
81}
82
83asmlinkage long _sys_rt_sigreturn(struct pt_regs *regs)
84{
85 struct rt_sigframe *frame = (struct rt_sigframe __user *)regs->sp;
86 sigset_t set;
87 stack_t st;
88
89 /*
90 * Since we stacked the signal on a dword boundary,
91 * then frame should be dword aligned here. If it's
92 * not, then the user is trying to mess with us.
93 */
94 if (((long)frame) & 3)
95 goto badframe;
96
97 if (!access_ok(VERIFY_READ, frame, sizeof(*frame)))
98 goto badframe;
99 if (__copy_from_user(&set, &frame->uc.uc_sigmask, sizeof(set)))
100 goto badframe;
101
102 set_current_blocked(&set);
103
104 if (restore_sigcontext(regs, &frame->uc.uc_mcontext))
105 goto badframe;
106
107 if (__copy_from_user(&st, &frame->uc.uc_stack, sizeof(st)))
108 goto badframe;
109 /* It is more difficult to avoid calling this function than to
110 call it and ignore errors. */
111 do_sigaltstack(&st, NULL, regs->sp);
112
113 return regs->gpr[11];
114
115badframe:
116 force_sig(SIGSEGV, current);
117 return 0;
118}
119
120/*
121 * Set up a signal frame.
122 */
123
124static int setup_sigcontext(struct sigcontext *sc, struct pt_regs *regs,
125 unsigned long mask)
126{
127 int err = 0;
128
129 /* copy the regs */
130
131 err |= __copy_to_user(sc->regs.gpr, regs, 32 * sizeof(unsigned long));
132 err |= __copy_to_user(&sc->regs.pc, ®s->pc, sizeof(unsigned long));
133 err |= __copy_to_user(&sc->regs.sr, ®s->sr, sizeof(unsigned long));
134
135 /* then some other stuff */
136
137 err |= __put_user(mask, &sc->oldmask);
138
139 return err;
140}
141
142static inline unsigned long align_sigframe(unsigned long sp)
143{
144 return sp & ~3UL;
145}
146
147/*
148 * Work out where the signal frame should go. It's either on the user stack
149 * or the alternate stack.
150 */
151
152static inline void __user *get_sigframe(struct k_sigaction *ka,
153 struct pt_regs *regs, size_t frame_size)
154{
155 unsigned long sp = regs->sp;
156 int onsigstack = on_sig_stack(sp);
157
158 /* redzone */
159 sp -= STACK_FRAME_OVERHEAD;
160
161 /* This is the X/Open sanctioned signal stack switching. */
162 if ((ka->sa.sa_flags & SA_ONSTACK) && !onsigstack) {
163 if (current->sas_ss_size)
164 sp = current->sas_ss_sp + current->sas_ss_size;
165 }
166
167 sp = align_sigframe(sp - frame_size);
168
169 /*
170 * If we are on the alternate signal stack and would overflow it, don't.
171 * Return an always-bogus address instead so we will die with SIGSEGV.
172 */
173 if (onsigstack && !likely(on_sig_stack(sp)))
174 return (void __user *)-1L;
175
176 return (void __user *)sp;
177}
178
179/* grab and setup a signal frame.
180 *
181 * basically we stack a lot of state info, and arrange for the
182 * user-mode program to return to the kernel using either a
183 * trampoline which performs the syscall sigreturn, or a provided
184 * user-mode trampoline.
185 */
186static int setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info,
187 sigset_t *set, struct pt_regs *regs)
188{
189 struct rt_sigframe *frame;
190 unsigned long return_ip;
191 int err = 0;
192
193 frame = get_sigframe(ka, regs, sizeof(*frame));
194
195 if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
196 goto give_sigsegv;
197
198 err |= __put_user(&frame->info, &frame->pinfo);
199 err |= __put_user(&frame->uc, &frame->puc);
200
201 if (ka->sa.sa_flags & SA_SIGINFO)
202 err |= copy_siginfo_to_user(&frame->info, info);
203 if (err)
204 goto give_sigsegv;
205
206 /* Clear all the bits of the ucontext we don't use. */
207 err |= __clear_user(&frame->uc, offsetof(struct ucontext, uc_mcontext));
208 err |= __put_user(0, &frame->uc.uc_flags);
209 err |= __put_user(NULL, &frame->uc.uc_link);
210 err |= __put_user((void *)current->sas_ss_sp,
211 &frame->uc.uc_stack.ss_sp);
212 err |= __put_user(sas_ss_flags(regs->sp), &frame->uc.uc_stack.ss_flags);
213 err |= __put_user(current->sas_ss_size, &frame->uc.uc_stack.ss_size);
214 err |= setup_sigcontext(&frame->uc.uc_mcontext, regs, set->sig[0]);
215
216 err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));
217
218 if (err)
219 goto give_sigsegv;
220
221 /* trampoline - the desired return ip is the retcode itself */
222 return_ip = (unsigned long)&frame->retcode;
223 /* This is l.ori r11,r0,__NR_sigreturn, l.sys 1 */
224 err |= __put_user(0xa960, (short *)(frame->retcode + 0));
225 err |= __put_user(__NR_rt_sigreturn, (short *)(frame->retcode + 2));
226 err |= __put_user(0x20000001, (unsigned long *)(frame->retcode + 4));
227 err |= __put_user(0x15000000, (unsigned long *)(frame->retcode + 8));
228
229 if (err)
230 goto give_sigsegv;
231
232 /* TODO what is the current->exec_domain stuff and invmap ? */
233
234 /* Set up registers for signal handler */
235 regs->pc = (unsigned long)ka->sa.sa_handler; /* what we enter NOW */
236 regs->gpr[9] = (unsigned long)return_ip; /* what we enter LATER */
237 regs->gpr[3] = (unsigned long)sig; /* arg 1: signo */
238 regs->gpr[4] = (unsigned long)&frame->info; /* arg 2: (siginfo_t*) */
239 regs->gpr[5] = (unsigned long)&frame->uc; /* arg 3: ucontext */
240
241 /* actually move the usp to reflect the stacked frame */
242 regs->sp = (unsigned long)frame;
243
244 return 0;
245
246give_sigsegv:
247 force_sigsegv(sig, current);
248 return -EFAULT;
249}
250
251static inline void
252handle_signal(unsigned long sig,
253 siginfo_t *info, struct k_sigaction *ka,
254 struct pt_regs *regs)
255{
256 int ret;
257
258 ret = setup_rt_frame(sig, ka, info, sigmask_to_save(), regs);
259 if (ret)
260 return;
261
262 signal_delivered(sig, info, ka, regs,
263 test_thread_flag(TIF_SINGLESTEP));
264}
265
266/*
267 * Note that 'init' is a special process: it doesn't get signals it doesn't
268 * want to handle. Thus you cannot kill init even with a SIGKILL even by
269 * mistake.
270 *
271 * Also note that the regs structure given here as an argument, is the latest
272 * pushed pt_regs. It may or may not be the same as the first pushed registers
273 * when the initial usermode->kernelmode transition took place. Therefore
274 * we can use user_mode(regs) to see if we came directly from kernel or user
275 * mode below.
276 */
277
278void do_signal(struct pt_regs *regs)
279{
280 siginfo_t info;
281 int signr;
282 struct k_sigaction ka;
283
284 /*
285 * We want the common case to go fast, which
286 * is why we may in certain cases get here from
287 * kernel mode. Just return without doing anything
288 * if so.
289 */
290 if (!user_mode(regs))
291 return;
292
293 signr = get_signal_to_deliver(&info, &ka, regs, NULL);
294
295 /* If we are coming out of a syscall then we need
296 * to check if the syscall was interrupted and wants to be
297 * restarted after handling the signal. If so, the original
298 * syscall number is put back into r11 and the PC rewound to
299 * point at the l.sys instruction that resulted in the
300 * original syscall. Syscall results other than the four
301 * below mean that the syscall executed to completion and no
302 * restart is necessary.
303 */
304 if (regs->orig_gpr11) {
305 int restart = 0;
306
307 switch (regs->gpr[11]) {
308 case -ERESTART_RESTARTBLOCK:
309 case -ERESTARTNOHAND:
310 /* Restart if there is no signal handler */
311 restart = (signr <= 0);
312 break;
313 case -ERESTARTSYS:
314 /* Restart if there no signal handler or
315 * SA_RESTART flag is set */
316 restart = (signr <= 0 || (ka.sa.sa_flags & SA_RESTART));
317 break;
318 case -ERESTARTNOINTR:
319 /* Always restart */
320 restart = 1;
321 break;
322 }
323
324 if (restart) {
325 if (regs->gpr[11] == -ERESTART_RESTARTBLOCK)
326 regs->gpr[11] = __NR_restart_syscall;
327 else
328 regs->gpr[11] = regs->orig_gpr11;
329 regs->pc -= 4;
330 } else {
331 regs->gpr[11] = -EINTR;
332 }
333 }
334
335 if (signr <= 0) {
336 /* no signal to deliver so we just put the saved sigmask
337 * back */
338 restore_saved_sigmask();
339 } else { /* signr > 0 */
340 /* Whee! Actually deliver the signal. */
341 handle_signal(signr, &info, &ka, regs);
342 }
343
344 return;
345}
346
347asmlinkage void do_notify_resume(struct pt_regs *regs)
348{
349 if (current_thread_info()->flags & _TIF_SIGPENDING)
350 do_signal(regs);
351
352 if (current_thread_info()->flags & _TIF_NOTIFY_RESUME) {
353 clear_thread_flag(TIF_NOTIFY_RESUME);
354 tracehook_notify_resume(regs);
355 }
356}