[deliverable/linux.git] / arch / openrisc / kernel / signal.c

/*
 * OpenRISC signal.c
 *
 * Linux architectural port borrowing liberally from similar works of
 * others.  All original copyrights apply as per the original source
 * declaration.
 *
 * Modifications for the OpenRISC architecture:
 * Copyright (C) 2003 Matjaz Breskvar <phoenix@bsemi.com>
 * Copyright (C) 2010-2011 Jonas Bonn <jonas@southpole.se>
 *
 *      This program is free software; you can redistribute it and/or
 *      modify it under the terms of the GNU General Public License
 *      as published by the Free Software Foundation; either version
 *      2 of the License, or (at your option) any later version.
 */

#include <linux/sched.h>
#include <linux/mm.h>
#include <linux/smp.h>
#include <linux/kernel.h>
#include <linux/signal.h>
#include <linux/errno.h>
#include <linux/wait.h>
#include <linux/ptrace.h>
#include <linux/unistd.h>
#include <linux/stddef.h>
#include <linux/tracehook.h>

#include <asm/processor.h>
#include <asm/syscall.h>
#include <asm/ucontext.h>
#include <asm/uaccess.h>

#define DEBUG_SIG 0

struct rt_sigframe {
	struct siginfo info;
	struct ucontext uc;
	unsigned char retcode[16];	/* trampoline code */
};

static int restore_sigcontext(struct pt_regs *regs,
			      struct sigcontext __user *sc)
{
	int err = 0;

	/* Always make any pending restarted system calls return -EINTR */
	current->restart_block.fn = do_no_restart_syscall;

	/*
	 * Restore the regs from &sc->regs.
	 * (sc is already checked for VERIFY_READ since the sigframe was
	 *  checked in sys_sigreturn previously)
	 */
	err |= __copy_from_user(regs, sc->regs.gpr, 32 * sizeof(unsigned long));
	err |= __copy_from_user(&regs->pc, &sc->regs.pc, sizeof(unsigned long));
	err |= __copy_from_user(&regs->sr, &sc->regs.sr, sizeof(unsigned long));

	/* make sure the SM-bit is cleared so user-mode cannot fool us */
	regs->sr &= ~SPR_SR_SM;

	regs->orig_gpr11 = -1;	/* Avoid syscall restart checks */

	/* TODO: the other ports use regs->orig_XX to disable syscall checks
	 * after this completes, but we don't use that mechanism. maybe we can
	 * use it now ?
	 */

	return err;
}

asmlinkage long _sys_rt_sigreturn(struct pt_regs *regs)
{
	struct rt_sigframe *frame = (struct rt_sigframe __user *)regs->sp;
	sigset_t set;

	/*
	 * Since we stacked the signal on a dword boundary,
	 * then frame should be dword aligned here.  If it's
	 * not, then the user is trying to mess with us.
	 */
	if (((long)frame) & 3)
		goto badframe;

	if (!access_ok(VERIFY_READ, frame, sizeof(*frame)))
		goto badframe;
	if (__copy_from_user(&set, &frame->uc.uc_sigmask, sizeof(set)))
		goto badframe;

	set_current_blocked(&set);

	if (restore_sigcontext(regs, &frame->uc.uc_mcontext))
		goto badframe;

	if (restore_altstack(&frame->uc.uc_stack))
		goto badframe;

	return regs->gpr[11];

badframe:
	force_sig(SIGSEGV, current);
	return 0;
}

/*
 * Set up a signal frame.
 */

static int setup_sigcontext(struct pt_regs *regs, struct sigcontext __user *sc)
{
	int err = 0;

	/* copy the regs */
	/* There should be no need to save callee-saved registers here...
	 * ...but we save them anyway.  Revisit this
	 */
	err |= __copy_to_user(sc->regs.gpr, regs, 32 * sizeof(unsigned long));
	err |= __copy_to_user(&sc->regs.pc, &regs->pc, sizeof(unsigned long));
	err |= __copy_to_user(&sc->regs.sr, &regs->sr, sizeof(unsigned long));

	return err;
}

static inline unsigned long align_sigframe(unsigned long sp)
{
	return sp & ~3UL;
}

/*
 * Work out where the signal frame should go.  It's either on the user stack
 * or the alternate stack.
 */

static inline void __user *get_sigframe(struct ksignal *ksig,
					struct pt_regs *regs, size_t frame_size)
{
	unsigned long sp = regs->sp;

	/* redzone */
	sp -= STACK_FRAME_OVERHEAD;
	sp = sigsp(sp, ksig);
	sp = align_sigframe(sp - frame_size);

	return (void __user *)sp;
}

/* grab and setup a signal frame.
 *
 * basically we stack a lot of state info, and arrange for the
 * user-mode program to return to the kernel using either a
 * trampoline which performs the syscall sigreturn, or a provided
 * user-mode trampoline.
 */
static int setup_rt_frame(struct ksignal *ksig, sigset_t *set,
			  struct pt_regs *regs)
{
	struct rt_sigframe *frame;
	unsigned long return_ip;
	int err = 0;

	frame = get_sigframe(ksig, regs, sizeof(*frame));

	if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
		return -EFAULT;

	/* Create siginfo.  */
	if (ksig->ka.sa.sa_flags & SA_SIGINFO)
		err |= copy_siginfo_to_user(&frame->info, &ksig->info);

	/* Create the ucontext.  */
	err |= __put_user(0, &frame->uc.uc_flags);
	err |= __put_user(NULL, &frame->uc.uc_link);
	err |= __save_altstack(&frame->uc.uc_stack, regs->sp);
	err |= setup_sigcontext(regs, &frame->uc.uc_mcontext);

	err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));

	if (err)
		return -EFAULT;

	/* trampoline - the desired return ip is the retcode itself */
	return_ip = (unsigned long)&frame->retcode;
	/* This is:
		l.ori r11,r0,__NR_sigreturn
		l.sys 1
	 */
	err |= __put_user(0xa960,             (short *)(frame->retcode + 0));
	err |= __put_user(__NR_rt_sigreturn,  (short *)(frame->retcode + 2));
	err |= __put_user(0x20000001, (unsigned long *)(frame->retcode + 4));
	err |= __put_user(0x15000000, (unsigned long *)(frame->retcode + 8));

	if (err)
		return -EFAULT;

	/* TODO what is the current->exec_domain stuff and invmap ? */

	/* Set up registers for signal handler */
	regs->pc = (unsigned long)ksig->ka.sa.sa_handler; /* what we enter NOW */
	regs->gpr[9] = (unsigned long)return_ip;     /* what we enter LATER */
	regs->gpr[3] = (unsigned long)ksig->sig;           /* arg 1: signo */
	regs->gpr[4] = (unsigned long)&frame->info;  /* arg 2: (siginfo_t*) */
	regs->gpr[5] = (unsigned long)&frame->uc;    /* arg 3: ucontext */

	/* actually move the usp to reflect the stacked frame */
	regs->sp = (unsigned long)frame;

	return 0;
}

static inline void
handle_signal(struct ksignal *ksig, struct pt_regs *regs)
{
	int ret;

	ret = setup_rt_frame(ksig, sigmask_to_save(), regs);

	signal_setup_done(ret, ksig, test_thread_flag(TIF_SINGLESTEP));
}

/*
 * Note that 'init' is a special process: it doesn't get signals it doesn't
 * want to handle. Thus you cannot kill init even with a SIGKILL even by
 * mistake.
 *
 * Also note that the regs structure given here as an argument, is the latest
 * pushed pt_regs. It may or may not be the same as the first pushed registers
 * when the initial usermode->kernelmode transition took place. Therefore
 * we can use user_mode(regs) to see if we came directly from kernel or user
 * mode below.
 */

int do_signal(struct pt_regs *regs, int syscall)
{
	struct ksignal ksig;
	unsigned long continue_addr = 0;
	unsigned long restart_addr = 0;
	unsigned long retval = 0;
	int restart = 0;

	if (syscall) {
		continue_addr = regs->pc;
		restart_addr = continue_addr - 4;
		retval = regs->gpr[11];

		/*
		 * Setup syscall restart here so that a debugger will
		 * see the already changed PC.
		 */
		switch (retval) {
		case -ERESTART_RESTARTBLOCK:
			restart = -2;
			/* Fall through */
		case -ERESTARTNOHAND:
		case -ERESTARTSYS:
		case -ERESTARTNOINTR:
			restart++;
			regs->gpr[11] = regs->orig_gpr11;
			regs->pc = restart_addr;
			break;
		}
	}

	/*
	 * Get the signal to deliver.  During the call to get_signal the
	 * debugger may change all our registers so we may need to revert
	 * the decision to restart the syscall; specifically, if the PC is
	 * changed, don't restart the syscall.
	 */
	if (get_signal(&ksig)) {
		if (unlikely(restart) && regs->pc == restart_addr) {
			if (retval == -ERESTARTNOHAND ||
			    retval == -ERESTART_RESTARTBLOCK
			    || (retval == -ERESTARTSYS
			        && !(ksig.ka.sa.sa_flags & SA_RESTART))) {
				/* No automatic restart */
				regs->gpr[11] = -EINTR;
				regs->pc = continue_addr;
			}
		}
		handle_signal(&ksig, regs);
	} else {
		/* no handler */
		restore_saved_sigmask();
		/*
		 * Restore pt_regs PC as syscall restart will be handled by
		 * kernel without return to userspace
		 */
		if (unlikely(restart) && regs->pc == restart_addr) {
			regs->pc = continue_addr;
			return restart;
		}
	}

	return 0;
}

asmlinkage int
do_work_pending(struct pt_regs *regs, unsigned int thread_flags, int syscall)
{
	do {
		if (likely(thread_flags & _TIF_NEED_RESCHED)) {
			schedule();
		} else {
			if (unlikely(!user_mode(regs)))
				return 0;
			local_irq_enable();
			if (thread_flags & _TIF_SIGPENDING) {
				int restart = do_signal(regs, syscall);
				if (unlikely(restart)) {
					/*
					 * Restart without handlers.
					 * Deal with it without leaving
					 * the kernel space.
					 */
					return restart;
				}
				syscall = 0;
			} else {
				clear_thread_flag(TIF_NOTIFY_RESUME);
				tracehook_notify_resume(regs);
			}
		}
		local_irq_disable();
		thread_flags = current_thread_info()->flags;
	} while (thread_flags & _TIF_WORK_MASK);
	return 0;
}
Commit	Line	Data
ac689eb7 JB	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>
10f67dbf	31	#include <asm/syscall.h>
ac689eb7 JB	32	#include <asm/ucontext.h>
	33	#include <asm/uaccess.h>
	34
	35	#define DEBUG_SIG 0
	36
ac689eb7	37	struct rt_sigframe {
ac689eb7 JB	38	struct siginfo info;
	39	struct ucontext uc;
	40	unsigned char retcode[16]; /* trampoline code */
	41	};
	42
10f67dbf JB	43	static int restore_sigcontext(struct pt_regs *regs,
10f67dbf JB	44	struct sigcontext __user *sc)
ac689eb7	45	{
10f67dbf	46	int err = 0;
ac689eb7	47
10f67dbf	48	/* Always make any pending restarted system calls return -EINTR */
f56141e3	49	current->restart_block.fn = do_no_restart_syscall;
ac689eb7	50
d7cb6667 JB	51	/*
d7cb6667 JB	52	* Restore the regs from &sc->regs.
ac689eb7 JB	53	* (sc is already checked for VERIFY_READ since the sigframe was
	54	* checked in sys_sigreturn previously)
	55	*/
10f67dbf JB	56	err \|= __copy_from_user(regs, sc->regs.gpr, 32 * sizeof(unsigned long));
	57	err \|= __copy_from_user(&regs->pc, &sc->regs.pc, sizeof(unsigned long));
	58	err \|= __copy_from_user(&regs->sr, &sc->regs.sr, sizeof(unsigned long));
ac689eb7 JB	59
	60	/* make sure the SM-bit is cleared so user-mode cannot fool us */
	61	regs->sr &= ~SPR_SR_SM;
	62
10f67dbf JB	63	regs->orig_gpr11 = -1; /* Avoid syscall restart checks */
10f67dbf JB	64
ac689eb7 JB	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;
ac689eb7 JB	71	}
	72
	73	asmlinkage long _sys_rt_sigreturn(struct pt_regs *regs)
	74	{
	75	struct rt_sigframe frame = (struct rt_sigframe __user )regs->sp;
	76	sigset_t set;
ac689eb7 JB	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
d8d4b20d	91	set_current_blocked(&set);
ac689eb7 JB	92
	93	if (restore_sigcontext(regs, &frame->uc.uc_mcontext))
	94	goto badframe;
	95
faec5a96	96	if (restore_altstack(&frame->uc.uc_stack))
d26654e5	97	goto badframe;
ac689eb7 JB	98
	99	return regs->gpr[11];
	100
	101	badframe:
	102	force_sig(SIGSEGV, current);
	103	return 0;
	104	}
	105
	106	/*
	107	* Set up a signal frame.
	108	*/
	109
10f67dbf	110	static int setup_sigcontext(struct pt_regs regs, struct sigcontext __user sc)
ac689eb7 JB	111	{
ac689eb7 JB	112	int err = 0;
ac689eb7	113
d7cb6667	114	/* copy the regs */
10f67dbf JB	115	/* There should be no need to save callee-saved registers here...
	116	* ...but we save them anyway. Revisit this
	117	*/
d7cb6667 JB	118	err \|= __copy_to_user(sc->regs.gpr, regs, 32 * sizeof(unsigned long));
	119	err \|= __copy_to_user(&sc->regs.pc, &regs->pc, sizeof(unsigned long));
	120	err \|= __copy_to_user(&sc->regs.sr, &regs->sr, sizeof(unsigned long));
ac689eb7	121
ac689eb7 JB	122	return err;
	123	}
	124
	125	static 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
8e2beafa	135	static inline void __user get_sigframe(struct ksignal ksig,
ac689eb7 JB	136	struct pt_regs *regs, size_t frame_size)
	137	{
	138	unsigned long sp = regs->sp;
ac689eb7 JB	139
	140	/* redzone */
	141	sp -= STACK_FRAME_OVERHEAD;
8e2beafa	142	sp = sigsp(sp, ksig);
ac689eb7 JB	143	sp = align_sigframe(sp - frame_size);
ac689eb7 JB	144
ac689eb7 JB	145	return (void __user *)sp;
	146	}
	147
	148	/* grab and setup a signal frame.
	149	*
	150	* basically we stack a lot of state info, and arrange for the
	151	* user-mode program to return to the kernel using either a
	152	* trampoline which performs the syscall sigreturn, or a provided
	153	* user-mode trampoline.
	154	*/
548dafe8 RW	155	static int setup_rt_frame(struct ksignal ksig, sigset_t set,
548dafe8 RW	156	struct pt_regs *regs)
ac689eb7 JB	157	{
	158	struct rt_sigframe *frame;
	159	unsigned long return_ip;
	160	int err = 0;
	161
8e2beafa	162	frame = get_sigframe(ksig, regs, sizeof(*frame));
548dafe8	163
ac689eb7	164	if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
548dafe8	165	return -EFAULT;
ac689eb7	166
10f67dbf	167	/* Create siginfo. */
548dafe8 RW	168	if (ksig->ka.sa.sa_flags & SA_SIGINFO)
548dafe8 RW	169	err \|= copy_siginfo_to_user(&frame->info, &ksig->info);
ac689eb7	170
10f67dbf	171	/* Create the ucontext. */
ac689eb7 JB	172	err \|= __put_user(0, &frame->uc.uc_flags);
ac689eb7 JB	173	err \|= __put_user(NULL, &frame->uc.uc_link);
faec5a96	174	err \|= __save_altstack(&frame->uc.uc_stack, regs->sp);
10f67dbf	175	err \|= setup_sigcontext(regs, &frame->uc.uc_mcontext);
ac689eb7 JB	176
	177	err \|= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));
	178
	179	if (err)
548dafe8	180	return -EFAULT;
ac689eb7 JB	181
	182	/* trampoline - the desired return ip is the retcode itself */
	183	return_ip = (unsigned long)&frame->retcode;
10f67dbf JB	184	/* This is:
	185	l.ori r11,r0,__NR_sigreturn
	186	l.sys 1
	187	*/
	188	err \|= __put_user(0xa960, (short *)(frame->retcode + 0));
	189	err \|= __put_user(__NR_rt_sigreturn, (short *)(frame->retcode + 2));
ac689eb7 JB	190	err \|= __put_user(0x20000001, (unsigned long *)(frame->retcode + 4));
	191	err \|= __put_user(0x15000000, (unsigned long *)(frame->retcode + 8));
	192
	193	if (err)
548dafe8	194	return -EFAULT;
ac689eb7 JB	195
	196	/* TODO what is the current->exec_domain stuff and invmap ? */
	197
	198	/* Set up registers for signal handler */
548dafe8	199	regs->pc = (unsigned long)ksig->ka.sa.sa_handler; /* what we enter NOW */
ac689eb7	200	regs->gpr[9] = (unsigned long)return_ip; /* what we enter LATER */
548dafe8	201	regs->gpr[3] = (unsigned long)ksig->sig; /* arg 1: signo */
ac689eb7 JB	202	regs->gpr[4] = (unsigned long)&frame->info; /* arg 2: (siginfo_t) /
	203	regs->gpr[5] = (unsigned long)&frame->uc; /* arg 3: ucontext */
	204
	205	/* actually move the usp to reflect the stacked frame */
	206	regs->sp = (unsigned long)frame;
	207
e933c70d	208	return 0;
ac689eb7 JB	209	}
ac689eb7 JB	210
39974d08	211	static inline void
548dafe8	212	handle_signal(struct ksignal ksig, struct pt_regs regs)
ac689eb7	213	{
e933c70d MF	214	int ret;
e933c70d MF	215
548dafe8	216	ret = setup_rt_frame(ksig, sigmask_to_save(), regs);
ac689eb7	217
548dafe8	218	signal_setup_done(ret, ksig, test_thread_flag(TIF_SINGLESTEP));
ac689eb7 JB	219	}
	220
	221	/*
	222	* Note that 'init' is a special process: it doesn't get signals it doesn't
	223	* want to handle. Thus you cannot kill init even with a SIGKILL even by
	224	* mistake.
	225	*
	226	* Also note that the regs structure given here as an argument, is the latest
	227	* pushed pt_regs. It may or may not be the same as the first pushed registers
	228	* when the initial usermode->kernelmode transition took place. Therefore
	229	* we can use user_mode(regs) to see if we came directly from kernel or user
	230	* mode below.
	231	*/
	232
10f67dbf	233	int do_signal(struct pt_regs *regs, int syscall)
ac689eb7	234	{
548dafe8	235	struct ksignal ksig;
10f67dbf JB	236	unsigned long continue_addr = 0;
	237	unsigned long restart_addr = 0;
	238	unsigned long retval = 0;
	239	int restart = 0;
	240
	241	if (syscall) {
	242	continue_addr = regs->pc;
	243	restart_addr = continue_addr - 4;
	244	retval = regs->gpr[11];
	245
	246	/*
	247	* Setup syscall restart here so that a debugger will
	248	* see the already changed PC.
	249	*/
	250	switch (retval) {
ac689eb7	251	case -ERESTART_RESTARTBLOCK:
10f67dbf JB	252	restart = -2;
10f67dbf JB	253	/* Fall through */
ac689eb7	254	case -ERESTARTNOHAND:
ac689eb7	255	case -ERESTARTSYS:
ac689eb7	256	case -ERESTARTNOINTR:
10f67dbf JB	257	restart++;
	258	regs->gpr[11] = regs->orig_gpr11;
	259	regs->pc = restart_addr;
ac689eb7 JB	260	break;
ac689eb7 JB	261	}
10f67dbf	262	}
ac689eb7	263
10f67dbf	264	/*
548dafe8 RW	265	* Get the signal to deliver. During the call to get_signal the
	266	* debugger may change all our registers so we may need to revert
	267	* the decision to restart the syscall; specifically, if the PC is
	268	* changed, don't restart the syscall.
10f67dbf	269	*/
548dafe8	270	if (get_signal(&ksig)) {
10f67dbf JB	271	if (unlikely(restart) && regs->pc == restart_addr) {
	272	if (retval == -ERESTARTNOHAND \|\|
	273	retval == -ERESTART_RESTARTBLOCK
	274	\|\| (retval == -ERESTARTSYS
548dafe8	275	&& !(ksig.ka.sa.sa_flags & SA_RESTART))) {
10f67dbf JB	276	/* No automatic restart */
	277	regs->gpr[11] = -EINTR;
	278	regs->pc = continue_addr;
	279	}
ac689eb7	280	}
548dafe8	281	handle_signal(&ksig, regs);
10f67dbf JB	282	} else {
	283	/* no handler */
	284	restore_saved_sigmask();
	285	/*
	286	* Restore pt_regs PC as syscall restart will be handled by
	287	* kernel without return to userspace
	288	*/
	289	if (unlikely(restart) && regs->pc == restart_addr) {
	290	regs->pc = continue_addr;
	291	return restart;
	292	}
ac689eb7 JB	293	}
ac689eb7 JB	294
10f67dbf	295	return 0;
ac689eb7 JB	296	}
ac689eb7 JB	297
10f67dbf JB	298	asmlinkage int
10f67dbf JB	299	do_work_pending(struct pt_regs *regs, unsigned int thread_flags, int syscall)
ac689eb7	300	{
10f67dbf JB	301	do {
	302	if (likely(thread_flags & _TIF_NEED_RESCHED)) {
	303	schedule();
	304	} else {
	305	if (unlikely(!user_mode(regs)))
	306	return 0;
	307	local_irq_enable();
	308	if (thread_flags & _TIF_SIGPENDING) {
	309	int restart = do_signal(regs, syscall);
	310	if (unlikely(restart)) {
	311	/*
	312	* Restart without handlers.
	313	* Deal with it without leaving
	314	* the kernel space.
	315	*/
	316	return restart;
	317	}
	318	syscall = 0;
	319	} else {
	320	clear_thread_flag(TIF_NOTIFY_RESUME);
	321	tracehook_notify_resume(regs);
	322	}
	323	}
	324	local_irq_disable();
	325	thread_flags = current_thread_info()->flags;
	326	} while (thread_flags & _TIF_WORK_MASK);
	327	return 0;
ac689eb7	328	}