xref: /linux/arch/powerpc/kernel/signal.c (revision 0ea5c948cb64bab5bc7a5516774eb8536f05aa0d)
1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3  * Common signal handling code for both 32 and 64 bits
4  *
5  *    Copyright (c) 2007 Benjamin Herrenschmidt, IBM Corporation
6  *    Extracted from signal_32.c and signal_64.c
7  */
8 
9 #include <linux/resume_user_mode.h>
10 #include <linux/signal.h>
11 #include <linux/uprobes.h>
12 #include <linux/key.h>
13 #include <linux/context_tracking.h>
14 #include <linux/livepatch.h>
15 #include <linux/syscalls.h>
16 #include <asm/hw_breakpoint.h>
17 #include <linux/uaccess.h>
18 #include <asm/switch_to.h>
19 #include <asm/unistd.h>
20 #include <asm/debug.h>
21 #include <asm/tm.h>
22 
23 #include "signal.h"
24 
25 #ifdef CONFIG_VSX
copy_fpr_to_user(void __user * to,struct task_struct * task)26 unsigned long copy_fpr_to_user(void __user *to,
27 			       struct task_struct *task)
28 {
29 	u64 buf[ELF_NFPREG];
30 	int i;
31 
32 	/* save FPR copy to local buffer then write to the thread_struct */
33 	for (i = 0; i < (ELF_NFPREG - 1) ; i++)
34 		buf[i] = task->thread.TS_FPR(i);
35 	buf[i] = task->thread.fp_state.fpscr;
36 	return __copy_to_user(to, buf, ELF_NFPREG * sizeof(double));
37 }
38 
copy_fpr_from_user(struct task_struct * task,void __user * from)39 unsigned long copy_fpr_from_user(struct task_struct *task,
40 				 void __user *from)
41 {
42 	u64 buf[ELF_NFPREG];
43 	int i;
44 
45 	if (__copy_from_user(buf, from, ELF_NFPREG * sizeof(double)))
46 		return 1;
47 	for (i = 0; i < (ELF_NFPREG - 1) ; i++)
48 		task->thread.TS_FPR(i) = buf[i];
49 	task->thread.fp_state.fpscr = buf[i];
50 
51 	return 0;
52 }
53 
copy_vsx_to_user(void __user * to,struct task_struct * task)54 unsigned long copy_vsx_to_user(void __user *to,
55 			       struct task_struct *task)
56 {
57 	u64 buf[ELF_NVSRHALFREG];
58 	int i;
59 
60 	/* save FPR copy to local buffer then write to the thread_struct */
61 	for (i = 0; i < ELF_NVSRHALFREG; i++)
62 		buf[i] = task->thread.fp_state.fpr[i][TS_VSRLOWOFFSET];
63 	return __copy_to_user(to, buf, ELF_NVSRHALFREG * sizeof(double));
64 }
65 
copy_vsx_from_user(struct task_struct * task,void __user * from)66 unsigned long copy_vsx_from_user(struct task_struct *task,
67 				 void __user *from)
68 {
69 	u64 buf[ELF_NVSRHALFREG];
70 	int i;
71 
72 	if (__copy_from_user(buf, from, ELF_NVSRHALFREG * sizeof(double)))
73 		return 1;
74 	for (i = 0; i < ELF_NVSRHALFREG ; i++)
75 		task->thread.fp_state.fpr[i][TS_VSRLOWOFFSET] = buf[i];
76 	return 0;
77 }
78 
79 #ifdef CONFIG_PPC_TRANSACTIONAL_MEM
copy_ckfpr_to_user(void __user * to,struct task_struct * task)80 unsigned long copy_ckfpr_to_user(void __user *to,
81 				  struct task_struct *task)
82 {
83 	u64 buf[ELF_NFPREG];
84 	int i;
85 
86 	/* save FPR copy to local buffer then write to the thread_struct */
87 	for (i = 0; i < (ELF_NFPREG - 1) ; i++)
88 		buf[i] = task->thread.TS_CKFPR(i);
89 	buf[i] = task->thread.ckfp_state.fpscr;
90 	return __copy_to_user(to, buf, ELF_NFPREG * sizeof(double));
91 }
92 
copy_ckfpr_from_user(struct task_struct * task,void __user * from)93 unsigned long copy_ckfpr_from_user(struct task_struct *task,
94 					  void __user *from)
95 {
96 	u64 buf[ELF_NFPREG];
97 	int i;
98 
99 	if (__copy_from_user(buf, from, ELF_NFPREG * sizeof(double)))
100 		return 1;
101 	for (i = 0; i < (ELF_NFPREG - 1) ; i++)
102 		task->thread.TS_CKFPR(i) = buf[i];
103 	task->thread.ckfp_state.fpscr = buf[i];
104 
105 	return 0;
106 }
107 
copy_ckvsx_to_user(void __user * to,struct task_struct * task)108 unsigned long copy_ckvsx_to_user(void __user *to,
109 				  struct task_struct *task)
110 {
111 	u64 buf[ELF_NVSRHALFREG];
112 	int i;
113 
114 	/* save FPR copy to local buffer then write to the thread_struct */
115 	for (i = 0; i < ELF_NVSRHALFREG; i++)
116 		buf[i] = task->thread.ckfp_state.fpr[i][TS_VSRLOWOFFSET];
117 	return __copy_to_user(to, buf, ELF_NVSRHALFREG * sizeof(double));
118 }
119 
copy_ckvsx_from_user(struct task_struct * task,void __user * from)120 unsigned long copy_ckvsx_from_user(struct task_struct *task,
121 					  void __user *from)
122 {
123 	u64 buf[ELF_NVSRHALFREG];
124 	int i;
125 
126 	if (__copy_from_user(buf, from, ELF_NVSRHALFREG * sizeof(double)))
127 		return 1;
128 	for (i = 0; i < ELF_NVSRHALFREG ; i++)
129 		task->thread.ckfp_state.fpr[i][TS_VSRLOWOFFSET] = buf[i];
130 	return 0;
131 }
132 #endif /* CONFIG_PPC_TRANSACTIONAL_MEM */
133 #endif
134 
135 /* Log an error when sending an unhandled signal to a process. Controlled
136  * through debug.exception-trace sysctl.
137  */
138 
139 int show_unhandled_signals = 1;
140 
get_min_sigframe_size(void)141 unsigned long get_min_sigframe_size(void)
142 {
143 	if (IS_ENABLED(CONFIG_PPC64))
144 		return get_min_sigframe_size_64();
145 	else
146 		return get_min_sigframe_size_32();
147 }
148 
149 #ifdef CONFIG_COMPAT
get_min_sigframe_size_compat(void)150 unsigned long get_min_sigframe_size_compat(void)
151 {
152 	return get_min_sigframe_size_32();
153 }
154 #endif
155 
156 /*
157  * Allocate space for the signal frame
158  */
159 static unsigned long get_tm_stackpointer(struct task_struct *tsk);
160 
get_sigframe(struct ksignal * ksig,struct task_struct * tsk,size_t frame_size,int is_32)161 void __user *get_sigframe(struct ksignal *ksig, struct task_struct *tsk,
162 			  size_t frame_size, int is_32)
163 {
164         unsigned long oldsp, newsp;
165 	unsigned long sp = get_tm_stackpointer(tsk);
166 
167         /* Default to using normal stack */
168 	if (is_32)
169 		oldsp = sp & 0x0ffffffffUL;
170 	else
171 		oldsp = sp;
172 	oldsp = sigsp(oldsp, ksig);
173 	newsp = (oldsp - frame_size) & ~0xFUL;
174 
175         return (void __user *)newsp;
176 }
177 
check_syscall_restart(struct pt_regs * regs,struct k_sigaction * ka,int has_handler)178 static void check_syscall_restart(struct pt_regs *regs, struct k_sigaction *ka,
179 				  int has_handler)
180 {
181 	unsigned long ret = regs->gpr[3];
182 	int restart = 1;
183 
184 	/* syscall ? */
185 	if (!trap_is_syscall(regs))
186 		return;
187 
188 	if (trap_norestart(regs))
189 		return;
190 
191 	/* error signalled ? */
192 	if (trap_is_scv(regs)) {
193 		/* 32-bit compat mode sign extend? */
194 		if (!IS_ERR_VALUE(ret))
195 			return;
196 		ret = -ret;
197 	} else if (!(regs->ccr & 0x10000000)) {
198 		return;
199 	}
200 
201 	switch (ret) {
202 	case ERESTART_RESTARTBLOCK:
203 	case ERESTARTNOHAND:
204 		/* ERESTARTNOHAND means that the syscall should only be
205 		 * restarted if there was no handler for the signal, and since
206 		 * we only get here if there is a handler, we dont restart.
207 		 */
208 		restart = !has_handler;
209 		break;
210 	case ERESTARTSYS:
211 		/* ERESTARTSYS means to restart the syscall if there is no
212 		 * handler or the handler was registered with SA_RESTART
213 		 */
214 		restart = !has_handler || (ka->sa.sa_flags & SA_RESTART) != 0;
215 		break;
216 	case ERESTARTNOINTR:
217 		/* ERESTARTNOINTR means that the syscall should be
218 		 * called again after the signal handler returns.
219 		 */
220 		break;
221 	default:
222 		return;
223 	}
224 	if (restart) {
225 		if (ret == ERESTART_RESTARTBLOCK)
226 			regs->gpr[0] = __NR_restart_syscall;
227 		else
228 			regs->gpr[3] = regs->orig_gpr3;
229 		regs_add_return_ip(regs, -4);
230 		regs->result = 0;
231 	} else {
232 		if (trap_is_scv(regs)) {
233 			regs->result = -EINTR;
234 			regs->gpr[3] = -EINTR;
235 		} else {
236 			regs->result = -EINTR;
237 			regs->gpr[3] = EINTR;
238 			regs->ccr |= 0x10000000;
239 		}
240 	}
241 }
242 
do_signal(struct task_struct * tsk)243 static void do_signal(struct task_struct *tsk)
244 {
245 	sigset_t *oldset = sigmask_to_save();
246 	struct ksignal ksig = { .sig = 0 };
247 	int ret;
248 
249 	BUG_ON(tsk != current);
250 
251 	get_signal(&ksig);
252 
253 	/* Is there any syscall restart business here ? */
254 	check_syscall_restart(tsk->thread.regs, &ksig.ka, ksig.sig > 0);
255 
256 	if (ksig.sig <= 0) {
257 		/* No signal to deliver -- put the saved sigmask back */
258 		restore_saved_sigmask();
259 		set_trap_norestart(tsk->thread.regs);
260 		return;               /* no signals delivered */
261 	}
262 
263         /*
264 	 * Reenable the DABR before delivering the signal to
265 	 * user space. The DABR will have been cleared if it
266 	 * triggered inside the kernel.
267 	 */
268 	if (!IS_ENABLED(CONFIG_PPC_ADV_DEBUG_REGS)) {
269 		int i;
270 
271 		for (i = 0; i < nr_wp_slots(); i++) {
272 			if (tsk->thread.hw_brk[i].address && tsk->thread.hw_brk[i].type)
273 				__set_breakpoint(i, &tsk->thread.hw_brk[i]);
274 		}
275 	}
276 
277 	/* Re-enable the breakpoints for the signal stack */
278 	thread_change_pc(tsk, tsk->thread.regs);
279 
280 	rseq_signal_deliver(&ksig, tsk->thread.regs);
281 
282 	if (is_32bit_task()) {
283         	if (ksig.ka.sa.sa_flags & SA_SIGINFO)
284 			ret = handle_rt_signal32(&ksig, oldset, tsk);
285 		else
286 			ret = handle_signal32(&ksig, oldset, tsk);
287 	} else {
288 		ret = handle_rt_signal64(&ksig, oldset, tsk);
289 	}
290 
291 	set_trap_norestart(tsk->thread.regs);
292 	signal_setup_done(ret, &ksig, test_thread_flag(TIF_SINGLESTEP));
293 }
294 
do_notify_resume(struct pt_regs * regs,unsigned long thread_info_flags)295 void do_notify_resume(struct pt_regs *regs, unsigned long thread_info_flags)
296 {
297 	if (thread_info_flags & _TIF_UPROBE)
298 		uprobe_notify_resume(regs);
299 
300 	if (thread_info_flags & _TIF_PATCH_PENDING)
301 		klp_update_patch_state(current);
302 
303 	if (thread_info_flags & (_TIF_SIGPENDING | _TIF_NOTIFY_SIGNAL)) {
304 		BUG_ON(regs != current->thread.regs);
305 		do_signal(current);
306 	}
307 
308 	if (thread_info_flags & _TIF_NOTIFY_RESUME)
309 		resume_user_mode_work(regs);
310 }
311 
get_tm_stackpointer(struct task_struct * tsk)312 static unsigned long get_tm_stackpointer(struct task_struct *tsk)
313 {
314 	/* When in an active transaction that takes a signal, we need to be
315 	 * careful with the stack.  It's possible that the stack has moved back
316 	 * up after the tbegin.  The obvious case here is when the tbegin is
317 	 * called inside a function that returns before a tend.  In this case,
318 	 * the stack is part of the checkpointed transactional memory state.
319 	 * If we write over this non transactionally or in suspend, we are in
320 	 * trouble because if we get a tm abort, the program counter and stack
321 	 * pointer will be back at the tbegin but our in memory stack won't be
322 	 * valid anymore.
323 	 *
324 	 * To avoid this, when taking a signal in an active transaction, we
325 	 * need to use the stack pointer from the checkpointed state, rather
326 	 * than the speculated state.  This ensures that the signal context
327 	 * (written tm suspended) will be written below the stack required for
328 	 * the rollback.  The transaction is aborted because of the treclaim,
329 	 * so any memory written between the tbegin and the signal will be
330 	 * rolled back anyway.
331 	 *
332 	 * For signals taken in non-TM or suspended mode, we use the
333 	 * normal/non-checkpointed stack pointer.
334 	 */
335 	struct pt_regs *regs = tsk->thread.regs;
336 	unsigned long ret = regs->gpr[1];
337 
338 #ifdef CONFIG_PPC_TRANSACTIONAL_MEM
339 	BUG_ON(tsk != current);
340 
341 	if (MSR_TM_ACTIVE(regs->msr)) {
342 		preempt_disable();
343 		tm_reclaim_current(TM_CAUSE_SIGNAL);
344 		if (MSR_TM_TRANSACTIONAL(regs->msr))
345 			ret = tsk->thread.ckpt_regs.gpr[1];
346 
347 		/*
348 		 * If we treclaim, we must clear the current thread's TM bits
349 		 * before re-enabling preemption. Otherwise we might be
350 		 * preempted and have the live MSR[TS] changed behind our back
351 		 * (tm_recheckpoint_new_task() would recheckpoint). Besides, we
352 		 * enter the signal handler in non-transactional state.
353 		 */
354 		regs_set_return_msr(regs, regs->msr & ~MSR_TS_MASK);
355 		preempt_enable();
356 	}
357 #endif
358 	return ret;
359 }
360 
361 static const char fm32[] = KERN_INFO "%s[%d]: bad frame in %s: %p nip %08lx lr %08lx\n";
362 static const char fm64[] = KERN_INFO "%s[%d]: bad frame in %s: %p nip %016lx lr %016lx\n";
363 
signal_fault(struct task_struct * tsk,struct pt_regs * regs,const char * where,void __user * ptr)364 void signal_fault(struct task_struct *tsk, struct pt_regs *regs,
365 		  const char *where, void __user *ptr)
366 {
367 	if (show_unhandled_signals)
368 		printk_ratelimited(regs->msr & MSR_64BIT ? fm64 : fm32, tsk->comm,
369 				   task_pid_nr(tsk), where, ptr, regs->nip, regs->link);
370 }
371