1 /*
2 * Common signal handling code for both 32 and 64 bits
3 *
4 * Copyright (c) 2007 Benjamin Herrenschmidt, IBM Corporation
5 * Extracted from signal_32.c and signal_64.c
6 *
7 * This file is subject to the terms and conditions of the GNU General
8 * Public License. See the file README.legal in the main directory of
9 * this archive for more details.
10 */
11
12 #include <linux/resume_user_mode.h>
13 #include <linux/signal.h>
14 #include <linux/uprobes.h>
15 #include <linux/key.h>
16 #include <linux/context_tracking.h>
17 #include <linux/livepatch.h>
18 #include <linux/syscalls.h>
19 #include <asm/hw_breakpoint.h>
20 #include <linux/uaccess.h>
21 #include <asm/switch_to.h>
22 #include <asm/unistd.h>
23 #include <asm/debug.h>
24 #include <asm/tm.h>
25
26 #include "signal.h"
27
28 #ifdef CONFIG_VSX
copy_fpr_to_user(void __user * to,struct task_struct * task)29 unsigned long copy_fpr_to_user(void __user *to,
30 struct task_struct *task)
31 {
32 u64 buf[ELF_NFPREG];
33 int i;
34
35 /* save FPR copy to local buffer then write to the thread_struct */
36 for (i = 0; i < (ELF_NFPREG - 1) ; i++)
37 buf[i] = task->thread.TS_FPR(i);
38 buf[i] = task->thread.fp_state.fpscr;
39 return __copy_to_user(to, buf, ELF_NFPREG * sizeof(double));
40 }
41
copy_fpr_from_user(struct task_struct * task,void __user * from)42 unsigned long copy_fpr_from_user(struct task_struct *task,
43 void __user *from)
44 {
45 u64 buf[ELF_NFPREG];
46 int i;
47
48 if (__copy_from_user(buf, from, ELF_NFPREG * sizeof(double)))
49 return 1;
50 for (i = 0; i < (ELF_NFPREG - 1) ; i++)
51 task->thread.TS_FPR(i) = buf[i];
52 task->thread.fp_state.fpscr = buf[i];
53
54 return 0;
55 }
56
copy_vsx_to_user(void __user * to,struct task_struct * task)57 unsigned long copy_vsx_to_user(void __user *to,
58 struct task_struct *task)
59 {
60 u64 buf[ELF_NVSRHALFREG];
61 int i;
62
63 /* save FPR copy to local buffer then write to the thread_struct */
64 for (i = 0; i < ELF_NVSRHALFREG; i++)
65 buf[i] = task->thread.fp_state.fpr[i][TS_VSRLOWOFFSET];
66 return __copy_to_user(to, buf, ELF_NVSRHALFREG * sizeof(double));
67 }
68
copy_vsx_from_user(struct task_struct * task,void __user * from)69 unsigned long copy_vsx_from_user(struct task_struct *task,
70 void __user *from)
71 {
72 u64 buf[ELF_NVSRHALFREG];
73 int i;
74
75 if (__copy_from_user(buf, from, ELF_NVSRHALFREG * sizeof(double)))
76 return 1;
77 for (i = 0; i < ELF_NVSRHALFREG ; i++)
78 task->thread.fp_state.fpr[i][TS_VSRLOWOFFSET] = buf[i];
79 return 0;
80 }
81
82 #ifdef CONFIG_PPC_TRANSACTIONAL_MEM
copy_ckfpr_to_user(void __user * to,struct task_struct * task)83 unsigned long copy_ckfpr_to_user(void __user *to,
84 struct task_struct *task)
85 {
86 u64 buf[ELF_NFPREG];
87 int i;
88
89 /* save FPR copy to local buffer then write to the thread_struct */
90 for (i = 0; i < (ELF_NFPREG - 1) ; i++)
91 buf[i] = task->thread.TS_CKFPR(i);
92 buf[i] = task->thread.ckfp_state.fpscr;
93 return __copy_to_user(to, buf, ELF_NFPREG * sizeof(double));
94 }
95
copy_ckfpr_from_user(struct task_struct * task,void __user * from)96 unsigned long copy_ckfpr_from_user(struct task_struct *task,
97 void __user *from)
98 {
99 u64 buf[ELF_NFPREG];
100 int i;
101
102 if (__copy_from_user(buf, from, ELF_NFPREG * sizeof(double)))
103 return 1;
104 for (i = 0; i < (ELF_NFPREG - 1) ; i++)
105 task->thread.TS_CKFPR(i) = buf[i];
106 task->thread.ckfp_state.fpscr = buf[i];
107
108 return 0;
109 }
110
copy_ckvsx_to_user(void __user * to,struct task_struct * task)111 unsigned long copy_ckvsx_to_user(void __user *to,
112 struct task_struct *task)
113 {
114 u64 buf[ELF_NVSRHALFREG];
115 int i;
116
117 /* save FPR copy to local buffer then write to the thread_struct */
118 for (i = 0; i < ELF_NVSRHALFREG; i++)
119 buf[i] = task->thread.ckfp_state.fpr[i][TS_VSRLOWOFFSET];
120 return __copy_to_user(to, buf, ELF_NVSRHALFREG * sizeof(double));
121 }
122
copy_ckvsx_from_user(struct task_struct * task,void __user * from)123 unsigned long copy_ckvsx_from_user(struct task_struct *task,
124 void __user *from)
125 {
126 u64 buf[ELF_NVSRHALFREG];
127 int i;
128
129 if (__copy_from_user(buf, from, ELF_NVSRHALFREG * sizeof(double)))
130 return 1;
131 for (i = 0; i < ELF_NVSRHALFREG ; i++)
132 task->thread.ckfp_state.fpr[i][TS_VSRLOWOFFSET] = buf[i];
133 return 0;
134 }
135 #endif /* CONFIG_PPC_TRANSACTIONAL_MEM */
136 #endif
137
138 /* Log an error when sending an unhandled signal to a process. Controlled
139 * through debug.exception-trace sysctl.
140 */
141
142 int show_unhandled_signals = 1;
143
get_min_sigframe_size(void)144 unsigned long get_min_sigframe_size(void)
145 {
146 if (IS_ENABLED(CONFIG_PPC64))
147 return get_min_sigframe_size_64();
148 else
149 return get_min_sigframe_size_32();
150 }
151
152 #ifdef CONFIG_COMPAT
get_min_sigframe_size_compat(void)153 unsigned long get_min_sigframe_size_compat(void)
154 {
155 return get_min_sigframe_size_32();
156 }
157 #endif
158
159 /*
160 * Allocate space for the signal frame
161 */
162 static unsigned long get_tm_stackpointer(struct task_struct *tsk);
163
get_sigframe(struct ksignal * ksig,struct task_struct * tsk,size_t frame_size,int is_32)164 void __user *get_sigframe(struct ksignal *ksig, struct task_struct *tsk,
165 size_t frame_size, int is_32)
166 {
167 unsigned long oldsp, newsp;
168 unsigned long sp = get_tm_stackpointer(tsk);
169
170 /* Default to using normal stack */
171 if (is_32)
172 oldsp = sp & 0x0ffffffffUL;
173 else
174 oldsp = sp;
175 oldsp = sigsp(oldsp, ksig);
176 newsp = (oldsp - frame_size) & ~0xFUL;
177
178 return (void __user *)newsp;
179 }
180
check_syscall_restart(struct pt_regs * regs,struct k_sigaction * ka,int has_handler)181 static void check_syscall_restart(struct pt_regs *regs, struct k_sigaction *ka,
182 int has_handler)
183 {
184 unsigned long ret = regs->gpr[3];
185 int restart = 1;
186
187 /* syscall ? */
188 if (!trap_is_syscall(regs))
189 return;
190
191 if (trap_norestart(regs))
192 return;
193
194 /* error signalled ? */
195 if (trap_is_scv(regs)) {
196 /* 32-bit compat mode sign extend? */
197 if (!IS_ERR_VALUE(ret))
198 return;
199 ret = -ret;
200 } else if (!(regs->ccr & 0x10000000)) {
201 return;
202 }
203
204 switch (ret) {
205 case ERESTART_RESTARTBLOCK:
206 case ERESTARTNOHAND:
207 /* ERESTARTNOHAND means that the syscall should only be
208 * restarted if there was no handler for the signal, and since
209 * we only get here if there is a handler, we dont restart.
210 */
211 restart = !has_handler;
212 break;
213 case ERESTARTSYS:
214 /* ERESTARTSYS means to restart the syscall if there is no
215 * handler or the handler was registered with SA_RESTART
216 */
217 restart = !has_handler || (ka->sa.sa_flags & SA_RESTART) != 0;
218 break;
219 case ERESTARTNOINTR:
220 /* ERESTARTNOINTR means that the syscall should be
221 * called again after the signal handler returns.
222 */
223 break;
224 default:
225 return;
226 }
227 if (restart) {
228 if (ret == ERESTART_RESTARTBLOCK)
229 regs->gpr[0] = __NR_restart_syscall;
230 else
231 regs->gpr[3] = regs->orig_gpr3;
232 regs_add_return_ip(regs, -4);
233 regs->result = 0;
234 } else {
235 if (trap_is_scv(regs)) {
236 regs->result = -EINTR;
237 regs->gpr[3] = -EINTR;
238 } else {
239 regs->result = -EINTR;
240 regs->gpr[3] = EINTR;
241 regs->ccr |= 0x10000000;
242 }
243 }
244 }
245
do_signal(struct task_struct * tsk)246 static void do_signal(struct task_struct *tsk)
247 {
248 sigset_t *oldset = sigmask_to_save();
249 struct ksignal ksig = { .sig = 0 };
250 int ret;
251
252 BUG_ON(tsk != current);
253
254 get_signal(&ksig);
255
256 /* Is there any syscall restart business here ? */
257 check_syscall_restart(tsk->thread.regs, &ksig.ka, ksig.sig > 0);
258
259 if (ksig.sig <= 0) {
260 /* No signal to deliver -- put the saved sigmask back */
261 restore_saved_sigmask();
262 set_trap_norestart(tsk->thread.regs);
263 return; /* no signals delivered */
264 }
265
266 /*
267 * Reenable the DABR before delivering the signal to
268 * user space. The DABR will have been cleared if it
269 * triggered inside the kernel.
270 */
271 if (!IS_ENABLED(CONFIG_PPC_ADV_DEBUG_REGS)) {
272 int i;
273
274 for (i = 0; i < nr_wp_slots(); i++) {
275 if (tsk->thread.hw_brk[i].address && tsk->thread.hw_brk[i].type)
276 __set_breakpoint(i, &tsk->thread.hw_brk[i]);
277 }
278 }
279
280 /* Re-enable the breakpoints for the signal stack */
281 thread_change_pc(tsk, tsk->thread.regs);
282
283 rseq_signal_deliver(&ksig, tsk->thread.regs);
284
285 if (is_32bit_task()) {
286 if (ksig.ka.sa.sa_flags & SA_SIGINFO)
287 ret = handle_rt_signal32(&ksig, oldset, tsk);
288 else
289 ret = handle_signal32(&ksig, oldset, tsk);
290 } else {
291 ret = handle_rt_signal64(&ksig, oldset, tsk);
292 }
293
294 set_trap_norestart(tsk->thread.regs);
295 signal_setup_done(ret, &ksig, test_thread_flag(TIF_SINGLESTEP));
296 }
297
do_notify_resume(struct pt_regs * regs,unsigned long thread_info_flags)298 void do_notify_resume(struct pt_regs *regs, unsigned long thread_info_flags)
299 {
300 if (thread_info_flags & _TIF_UPROBE)
301 uprobe_notify_resume(regs);
302
303 if (thread_info_flags & _TIF_PATCH_PENDING)
304 klp_update_patch_state(current);
305
306 if (thread_info_flags & (_TIF_SIGPENDING | _TIF_NOTIFY_SIGNAL)) {
307 BUG_ON(regs != current->thread.regs);
308 do_signal(current);
309 }
310
311 if (thread_info_flags & _TIF_NOTIFY_RESUME)
312 resume_user_mode_work(regs);
313 }
314
get_tm_stackpointer(struct task_struct * tsk)315 static unsigned long get_tm_stackpointer(struct task_struct *tsk)
316 {
317 /* When in an active transaction that takes a signal, we need to be
318 * careful with the stack. It's possible that the stack has moved back
319 * up after the tbegin. The obvious case here is when the tbegin is
320 * called inside a function that returns before a tend. In this case,
321 * the stack is part of the checkpointed transactional memory state.
322 * If we write over this non transactionally or in suspend, we are in
323 * trouble because if we get a tm abort, the program counter and stack
324 * pointer will be back at the tbegin but our in memory stack won't be
325 * valid anymore.
326 *
327 * To avoid this, when taking a signal in an active transaction, we
328 * need to use the stack pointer from the checkpointed state, rather
329 * than the speculated state. This ensures that the signal context
330 * (written tm suspended) will be written below the stack required for
331 * the rollback. The transaction is aborted because of the treclaim,
332 * so any memory written between the tbegin and the signal will be
333 * rolled back anyway.
334 *
335 * For signals taken in non-TM or suspended mode, we use the
336 * normal/non-checkpointed stack pointer.
337 */
338 struct pt_regs *regs = tsk->thread.regs;
339 unsigned long ret = regs->gpr[1];
340
341 #ifdef CONFIG_PPC_TRANSACTIONAL_MEM
342 BUG_ON(tsk != current);
343
344 if (MSR_TM_ACTIVE(regs->msr)) {
345 preempt_disable();
346 tm_reclaim_current(TM_CAUSE_SIGNAL);
347 if (MSR_TM_TRANSACTIONAL(regs->msr))
348 ret = tsk->thread.ckpt_regs.gpr[1];
349
350 /*
351 * If we treclaim, we must clear the current thread's TM bits
352 * before re-enabling preemption. Otherwise we might be
353 * preempted and have the live MSR[TS] changed behind our back
354 * (tm_recheckpoint_new_task() would recheckpoint). Besides, we
355 * enter the signal handler in non-transactional state.
356 */
357 regs_set_return_msr(regs, regs->msr & ~MSR_TS_MASK);
358 preempt_enable();
359 }
360 #endif
361 return ret;
362 }
363
364 static const char fm32[] = KERN_INFO "%s[%d]: bad frame in %s: %p nip %08lx lr %08lx\n";
365 static const char fm64[] = KERN_INFO "%s[%d]: bad frame in %s: %p nip %016lx lr %016lx\n";
366
signal_fault(struct task_struct * tsk,struct pt_regs * regs,const char * where,void __user * ptr)367 void signal_fault(struct task_struct *tsk, struct pt_regs *regs,
368 const char *where, void __user *ptr)
369 {
370 if (show_unhandled_signals)
371 printk_ratelimited(regs->msr & MSR_64BIT ? fm64 : fm32, tsk->comm,
372 task_pid_nr(tsk), where, ptr, regs->nip, regs->link);
373 }
374