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