xref: /openbmc/linux/arch/sh/kernel/signal_32.c (revision 9a87ffc99ec8eb8d35eed7c4f816d75f5cc9662e)
1  // SPDX-License-Identifier: GPL-2.0
2  /*
3   *  linux/arch/sh/kernel/signal.c
4   *
5   *  Copyright (C) 1991, 1992  Linus Torvalds
6   *
7   *  1997-11-28  Modified for POSIX.1b signals by Richard Henderson
8   *
9   *  SuperH version:  Copyright (C) 1999, 2000  Niibe Yutaka & Kaz Kojima
10   *
11   */
12  #include <linux/sched.h>
13  #include <linux/sched/task_stack.h>
14  #include <linux/mm.h>
15  #include <linux/smp.h>
16  #include <linux/kernel.h>
17  #include <linux/signal.h>
18  #include <linux/errno.h>
19  #include <linux/wait.h>
20  #include <linux/ptrace.h>
21  #include <linux/unistd.h>
22  #include <linux/stddef.h>
23  #include <linux/tty.h>
24  #include <linux/elf.h>
25  #include <linux/personality.h>
26  #include <linux/binfmts.h>
27  #include <linux/io.h>
28  #include <linux/resume_user_mode.h>
29  #include <asm/ucontext.h>
30  #include <linux/uaccess.h>
31  #include <asm/cacheflush.h>
32  #include <asm/syscalls.h>
33  #include <asm/fpu.h>
34  
35  struct fdpic_func_descriptor {
36  	unsigned long	text;
37  	unsigned long	GOT;
38  };
39  
40  /*
41   * The following define adds a 64 byte gap between the signal
42   * stack frame and previous contents of the stack.  This allows
43   * frame unwinding in a function epilogue but only if a frame
44   * pointer is used in the function.  This is necessary because
45   * current gcc compilers (<4.3) do not generate unwind info on
46   * SH for function epilogues.
47   */
48  #define UNWINDGUARD 64
49  
50  /*
51   * Do a signal return; undo the signal stack.
52   */
53  
54  #define MOVW(n)	 (0x9300|((n)-2))	/* Move mem word at PC+n to R3 */
55  #if defined(CONFIG_CPU_SH2)
56  #define TRAP_NOARG 0xc320		/* Syscall w/no args (NR in R3) */
57  #else
58  #define TRAP_NOARG 0xc310		/* Syscall w/no args (NR in R3) */
59  #endif
60  #define OR_R0_R0 0x200b			/* or r0,r0 (insert to avoid hardware bug) */
61  
62  struct sigframe
63  {
64  	struct sigcontext sc;
65  	unsigned long extramask[_NSIG_WORDS-1];
66  	u16 retcode[8];
67  };
68  
69  struct rt_sigframe
70  {
71  	struct siginfo info;
72  	struct ucontext uc;
73  	u16 retcode[8];
74  };
75  
76  #ifdef CONFIG_SH_FPU
restore_sigcontext_fpu(struct sigcontext __user * sc)77  static inline int restore_sigcontext_fpu(struct sigcontext __user *sc)
78  {
79  	struct task_struct *tsk = current;
80  
81  	if (!(boot_cpu_data.flags & CPU_HAS_FPU))
82  		return 0;
83  
84  	set_used_math();
85  	return __copy_from_user(&tsk->thread.xstate->hardfpu, &sc->sc_fpregs[0],
86  				sizeof(long)*(16*2+2));
87  }
88  
save_sigcontext_fpu(struct sigcontext __user * sc,struct pt_regs * regs)89  static inline int save_sigcontext_fpu(struct sigcontext __user *sc,
90  				      struct pt_regs *regs)
91  {
92  	struct task_struct *tsk = current;
93  
94  	if (!(boot_cpu_data.flags & CPU_HAS_FPU))
95  		return 0;
96  
97  	if (!used_math())
98  		return __put_user(0, &sc->sc_ownedfp);
99  
100  	if (__put_user(1, &sc->sc_ownedfp))
101  		return -EFAULT;
102  
103  	/* This will cause a "finit" to be triggered by the next
104  	   attempted FPU operation by the 'current' process.
105  	   */
106  	clear_used_math();
107  
108  	unlazy_fpu(tsk, regs);
109  	return __copy_to_user(&sc->sc_fpregs[0], &tsk->thread.xstate->hardfpu,
110  			      sizeof(long)*(16*2+2));
111  }
112  #endif /* CONFIG_SH_FPU */
113  
114  static int
restore_sigcontext(struct pt_regs * regs,struct sigcontext __user * sc,int * r0_p)115  restore_sigcontext(struct pt_regs *regs, struct sigcontext __user *sc, int *r0_p)
116  {
117  	unsigned int err = 0;
118  	unsigned int sr = regs->sr & ~SR_USER_MASK;
119  
120  #define COPY(x)		err |= __get_user(regs->x, &sc->sc_##x)
121  			COPY(regs[1]);
122  	COPY(regs[2]);	COPY(regs[3]);
123  	COPY(regs[4]);	COPY(regs[5]);
124  	COPY(regs[6]);	COPY(regs[7]);
125  	COPY(regs[8]);	COPY(regs[9]);
126  	COPY(regs[10]);	COPY(regs[11]);
127  	COPY(regs[12]);	COPY(regs[13]);
128  	COPY(regs[14]);	COPY(regs[15]);
129  	COPY(gbr);	COPY(mach);
130  	COPY(macl);	COPY(pr);
131  	COPY(sr);	COPY(pc);
132  #undef COPY
133  
134  	regs->sr = (regs->sr & SR_USER_MASK) | sr;
135  
136  #ifdef CONFIG_SH_FPU
137  	if (boot_cpu_data.flags & CPU_HAS_FPU) {
138  		int owned_fp;
139  		struct task_struct *tsk = current;
140  
141  		regs->sr |= SR_FD; /* Release FPU */
142  		clear_fpu(tsk, regs);
143  		clear_used_math();
144  		err |= __get_user (owned_fp, &sc->sc_ownedfp);
145  		if (owned_fp)
146  			err |= restore_sigcontext_fpu(sc);
147  	}
148  #endif
149  
150  	regs->tra = -1;		/* disable syscall checks */
151  	err |= __get_user(*r0_p, &sc->sc_regs[0]);
152  	return err;
153  }
154  
sys_sigreturn(void)155  asmlinkage int sys_sigreturn(void)
156  {
157  	struct pt_regs *regs = current_pt_regs();
158  	struct sigframe __user *frame = (struct sigframe __user *)regs->regs[15];
159  	sigset_t set;
160  	int r0;
161  
162          /* Always make any pending restarted system calls return -EINTR */
163  	current->restart_block.fn = do_no_restart_syscall;
164  
165  	if (!access_ok(frame, sizeof(*frame)))
166  		goto badframe;
167  
168  	if (__get_user(set.sig[0], &frame->sc.oldmask)
169  	    || (_NSIG_WORDS > 1
170  		&& __copy_from_user(&set.sig[1], &frame->extramask,
171  				    sizeof(frame->extramask))))
172  		goto badframe;
173  
174  	set_current_blocked(&set);
175  
176  	if (restore_sigcontext(regs, &frame->sc, &r0))
177  		goto badframe;
178  	return r0;
179  
180  badframe:
181  	force_sig(SIGSEGV);
182  	return 0;
183  }
184  
sys_rt_sigreturn(void)185  asmlinkage int sys_rt_sigreturn(void)
186  {
187  	struct pt_regs *regs = current_pt_regs();
188  	struct rt_sigframe __user *frame = (struct rt_sigframe __user *)regs->regs[15];
189  	sigset_t set;
190  	int r0;
191  
192  	/* Always make any pending restarted system calls return -EINTR */
193  	current->restart_block.fn = do_no_restart_syscall;
194  
195  	if (!access_ok(frame, sizeof(*frame)))
196  		goto badframe;
197  
198  	if (__copy_from_user(&set, &frame->uc.uc_sigmask, sizeof(set)))
199  		goto badframe;
200  
201  	set_current_blocked(&set);
202  
203  	if (restore_sigcontext(regs, &frame->uc.uc_mcontext, &r0))
204  		goto badframe;
205  
206  	if (restore_altstack(&frame->uc.uc_stack))
207  		goto badframe;
208  
209  	return r0;
210  
211  badframe:
212  	force_sig(SIGSEGV);
213  	return 0;
214  }
215  
216  /*
217   * Set up a signal frame.
218   */
219  
220  static int
setup_sigcontext(struct sigcontext __user * sc,struct pt_regs * regs,unsigned long mask)221  setup_sigcontext(struct sigcontext __user *sc, struct pt_regs *regs,
222  		 unsigned long mask)
223  {
224  	int err = 0;
225  
226  #define COPY(x)		err |= __put_user(regs->x, &sc->sc_##x)
227  	COPY(regs[0]);	COPY(regs[1]);
228  	COPY(regs[2]);	COPY(regs[3]);
229  	COPY(regs[4]);	COPY(regs[5]);
230  	COPY(regs[6]);	COPY(regs[7]);
231  	COPY(regs[8]);	COPY(regs[9]);
232  	COPY(regs[10]);	COPY(regs[11]);
233  	COPY(regs[12]);	COPY(regs[13]);
234  	COPY(regs[14]);	COPY(regs[15]);
235  	COPY(gbr);	COPY(mach);
236  	COPY(macl);	COPY(pr);
237  	COPY(sr);	COPY(pc);
238  #undef COPY
239  
240  #ifdef CONFIG_SH_FPU
241  	err |= save_sigcontext_fpu(sc, regs);
242  #endif
243  
244  	/* non-iBCS2 extensions.. */
245  	err |= __put_user(mask, &sc->oldmask);
246  
247  	return err;
248  }
249  
250  /*
251   * Determine which stack to use..
252   */
253  static inline void __user *
get_sigframe(struct k_sigaction * ka,unsigned long sp,size_t frame_size)254  get_sigframe(struct k_sigaction *ka, unsigned long sp, size_t frame_size)
255  {
256  	if (ka->sa.sa_flags & SA_ONSTACK) {
257  		if (sas_ss_flags(sp) == 0)
258  			sp = current->sas_ss_sp + current->sas_ss_size;
259  	}
260  
261  	return (void __user *)((sp - (frame_size+UNWINDGUARD)) & -8ul);
262  }
263  
264  /* These symbols are defined with the addresses in the vsyscall page.
265     See vsyscall-trapa.S.  */
266  extern void __kernel_sigreturn(void);
267  extern void __kernel_rt_sigreturn(void);
268  
setup_frame(struct ksignal * ksig,sigset_t * set,struct pt_regs * regs)269  static int setup_frame(struct ksignal *ksig, sigset_t *set,
270  		       struct pt_regs *regs)
271  {
272  	struct sigframe __user *frame;
273  	int err = 0, sig = ksig->sig;
274  
275  	frame = get_sigframe(&ksig->ka, regs->regs[15], sizeof(*frame));
276  
277  	if (!access_ok(frame, sizeof(*frame)))
278  		return -EFAULT;
279  
280  	err |= setup_sigcontext(&frame->sc, regs, set->sig[0]);
281  
282  	if (_NSIG_WORDS > 1)
283  		err |= __copy_to_user(frame->extramask, &set->sig[1],
284  				      sizeof(frame->extramask));
285  
286  	/* Set up to return from userspace.  If provided, use a stub
287  	   already in userspace.  */
288  	if (ksig->ka.sa.sa_flags & SA_RESTORER) {
289  		regs->pr = (unsigned long) ksig->ka.sa.sa_restorer;
290  #ifdef CONFIG_VSYSCALL
291  	} else if (likely(current->mm->context.vdso)) {
292  		regs->pr = VDSO_SYM(&__kernel_sigreturn);
293  #endif
294  	} else {
295  		/* Generate return code (system call to sigreturn) */
296  		err |= __put_user(MOVW(7), &frame->retcode[0]);
297  		err |= __put_user(TRAP_NOARG, &frame->retcode[1]);
298  		err |= __put_user(OR_R0_R0, &frame->retcode[2]);
299  		err |= __put_user(OR_R0_R0, &frame->retcode[3]);
300  		err |= __put_user(OR_R0_R0, &frame->retcode[4]);
301  		err |= __put_user(OR_R0_R0, &frame->retcode[5]);
302  		err |= __put_user(OR_R0_R0, &frame->retcode[6]);
303  		err |= __put_user((__NR_sigreturn), &frame->retcode[7]);
304  		regs->pr = (unsigned long) frame->retcode;
305  		flush_icache_range(regs->pr, regs->pr + sizeof(frame->retcode));
306  	}
307  
308  	if (err)
309  		return -EFAULT;
310  
311  	/* Set up registers for signal handler */
312  	regs->regs[15] = (unsigned long) frame;
313  	regs->regs[4] = sig; /* Arg for signal handler */
314  	regs->regs[5] = 0;
315  	regs->regs[6] = (unsigned long) &frame->sc;
316  
317  	if (current->personality & FDPIC_FUNCPTRS) {
318  		struct fdpic_func_descriptor __user *funcptr =
319  			(struct fdpic_func_descriptor __user *)ksig->ka.sa.sa_handler;
320  
321  		err |= __get_user(regs->pc, &funcptr->text);
322  		err |= __get_user(regs->regs[12], &funcptr->GOT);
323  	} else
324  		regs->pc = (unsigned long)ksig->ka.sa.sa_handler;
325  
326  	if (err)
327  		return -EFAULT;
328  
329  	pr_debug("SIG deliver (%s:%d): sp=%p pc=%08lx pr=%08lx\n",
330  		 current->comm, task_pid_nr(current), frame, regs->pc, regs->pr);
331  
332  	return 0;
333  }
334  
setup_rt_frame(struct ksignal * ksig,sigset_t * set,struct pt_regs * regs)335  static int setup_rt_frame(struct ksignal *ksig, sigset_t *set,
336  			  struct pt_regs *regs)
337  {
338  	struct rt_sigframe __user *frame;
339  	int err = 0, sig = ksig->sig;
340  
341  	frame = get_sigframe(&ksig->ka, regs->regs[15], sizeof(*frame));
342  
343  	if (!access_ok(frame, sizeof(*frame)))
344  		return -EFAULT;
345  
346  	err |= copy_siginfo_to_user(&frame->info, &ksig->info);
347  
348  	/* Create the ucontext.  */
349  	err |= __put_user(0, &frame->uc.uc_flags);
350  	err |= __put_user(NULL, &frame->uc.uc_link);
351  	err |= __save_altstack(&frame->uc.uc_stack, regs->regs[15]);
352  	err |= setup_sigcontext(&frame->uc.uc_mcontext,
353  			        regs, set->sig[0]);
354  	err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));
355  
356  	/* Set up to return from userspace.  If provided, use a stub
357  	   already in userspace.  */
358  	if (ksig->ka.sa.sa_flags & SA_RESTORER) {
359  		regs->pr = (unsigned long) ksig->ka.sa.sa_restorer;
360  #ifdef CONFIG_VSYSCALL
361  	} else if (likely(current->mm->context.vdso)) {
362  		regs->pr = VDSO_SYM(&__kernel_rt_sigreturn);
363  #endif
364  	} else {
365  		/* Generate return code (system call to rt_sigreturn) */
366  		err |= __put_user(MOVW(7), &frame->retcode[0]);
367  		err |= __put_user(TRAP_NOARG, &frame->retcode[1]);
368  		err |= __put_user(OR_R0_R0, &frame->retcode[2]);
369  		err |= __put_user(OR_R0_R0, &frame->retcode[3]);
370  		err |= __put_user(OR_R0_R0, &frame->retcode[4]);
371  		err |= __put_user(OR_R0_R0, &frame->retcode[5]);
372  		err |= __put_user(OR_R0_R0, &frame->retcode[6]);
373  		err |= __put_user((__NR_rt_sigreturn), &frame->retcode[7]);
374  		regs->pr = (unsigned long) frame->retcode;
375  		flush_icache_range(regs->pr, regs->pr + sizeof(frame->retcode));
376  	}
377  
378  	if (err)
379  		return -EFAULT;
380  
381  	/* Set up registers for signal handler */
382  	regs->regs[15] = (unsigned long) frame;
383  	regs->regs[4] = sig; /* Arg for signal handler */
384  	regs->regs[5] = (unsigned long) &frame->info;
385  	regs->regs[6] = (unsigned long) &frame->uc;
386  
387  	if (current->personality & FDPIC_FUNCPTRS) {
388  		struct fdpic_func_descriptor __user *funcptr =
389  			(struct fdpic_func_descriptor __user *)ksig->ka.sa.sa_handler;
390  
391  		err |= __get_user(regs->pc, &funcptr->text);
392  		err |= __get_user(regs->regs[12], &funcptr->GOT);
393  	} else
394  		regs->pc = (unsigned long)ksig->ka.sa.sa_handler;
395  
396  	if (err)
397  		return -EFAULT;
398  
399  	pr_debug("SIG deliver (%s:%d): sp=%p pc=%08lx pr=%08lx\n",
400  		 current->comm, task_pid_nr(current), frame, regs->pc, regs->pr);
401  
402  	return 0;
403  }
404  
405  static inline void
handle_syscall_restart(unsigned long save_r0,struct pt_regs * regs,struct sigaction * sa)406  handle_syscall_restart(unsigned long save_r0, struct pt_regs *regs,
407  		       struct sigaction *sa)
408  {
409  	/* If we're not from a syscall, bail out */
410  	if (regs->tra < 0)
411  		return;
412  
413  	/* check for system call restart.. */
414  	switch (regs->regs[0]) {
415  		case -ERESTART_RESTARTBLOCK:
416  		case -ERESTARTNOHAND:
417  		no_system_call_restart:
418  			regs->regs[0] = -EINTR;
419  			break;
420  
421  		case -ERESTARTSYS:
422  			if (!(sa->sa_flags & SA_RESTART))
423  				goto no_system_call_restart;
424  			fallthrough;
425  		case -ERESTARTNOINTR:
426  			regs->regs[0] = save_r0;
427  			regs->pc -= instruction_size(__raw_readw(regs->pc - 4));
428  			break;
429  	}
430  }
431  
432  /*
433   * OK, we're invoking a handler
434   */
435  static void
handle_signal(struct ksignal * ksig,struct pt_regs * regs,unsigned int save_r0)436  handle_signal(struct ksignal *ksig, struct pt_regs *regs, unsigned int save_r0)
437  {
438  	sigset_t *oldset = sigmask_to_save();
439  	int ret;
440  
441  	/* Set up the stack frame */
442  	if (ksig->ka.sa.sa_flags & SA_SIGINFO)
443  		ret = setup_rt_frame(ksig, oldset, regs);
444  	else
445  		ret = setup_frame(ksig, oldset, regs);
446  
447  	signal_setup_done(ret, ksig, test_thread_flag(TIF_SINGLESTEP));
448  }
449  
450  /*
451   * Note that 'init' is a special process: it doesn't get signals it doesn't
452   * want to handle. Thus you cannot kill init even with a SIGKILL even by
453   * mistake.
454   *
455   * Note that we go through the signals twice: once to check the signals that
456   * the kernel can handle, and then we build all the user-level signal handling
457   * stack-frames in one go after that.
458   */
do_signal(struct pt_regs * regs,unsigned int save_r0)459  static void do_signal(struct pt_regs *regs, unsigned int save_r0)
460  {
461  	struct ksignal ksig;
462  
463  	/*
464  	 * We want the common case to go fast, which
465  	 * is why we may in certain cases get here from
466  	 * kernel mode. Just return without doing anything
467  	 * if so.
468  	 */
469  	if (!user_mode(regs))
470  		return;
471  
472  	if (get_signal(&ksig)) {
473  		handle_syscall_restart(save_r0, regs, &ksig.ka.sa);
474  
475  		/* Whee!  Actually deliver the signal.  */
476  		handle_signal(&ksig, regs, save_r0);
477  		return;
478  	}
479  
480  	/* Did we come from a system call? */
481  	if (regs->tra >= 0) {
482  		/* Restart the system call - no handlers present */
483  		if (regs->regs[0] == -ERESTARTNOHAND ||
484  		    regs->regs[0] == -ERESTARTSYS ||
485  		    regs->regs[0] == -ERESTARTNOINTR) {
486  			regs->regs[0] = save_r0;
487  			regs->pc -= instruction_size(__raw_readw(regs->pc - 4));
488  		} else if (regs->regs[0] == -ERESTART_RESTARTBLOCK) {
489  			regs->pc -= instruction_size(__raw_readw(regs->pc - 4));
490  			regs->regs[3] = __NR_restart_syscall;
491  		}
492  	}
493  
494  	/*
495  	 * If there's no signal to deliver, we just put the saved sigmask
496  	 * back.
497  	 */
498  	restore_saved_sigmask();
499  }
500  
do_notify_resume(struct pt_regs * regs,unsigned int save_r0,unsigned long thread_info_flags)501  asmlinkage void do_notify_resume(struct pt_regs *regs, unsigned int save_r0,
502  				 unsigned long thread_info_flags)
503  {
504  	/* deal with pending signal delivery */
505  	if (thread_info_flags & (_TIF_SIGPENDING | _TIF_NOTIFY_SIGNAL))
506  		do_signal(regs, save_r0);
507  
508  	if (thread_info_flags & _TIF_NOTIFY_RESUME)
509  		resume_user_mode_work(regs);
510  }
511