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

/*
 * Signal Handling for ARC
 *
 * Copyright (C) 2004, 2007-2010, 2011-2012 Synopsys, Inc. (www.synopsys.com)
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 *
 * vineetg: Jan 2010 (Restarting of timer related syscalls)
 *
 * vineetg: Nov 2009 (Everything needed for TIF_RESTORE_SIGMASK)
 *  -do_signal() supports TIF_RESTORE_SIGMASK
 *  -do_signal() no loner needs oldset, required by OLD sys_sigsuspend
 *  -sys_rt_sigsuspend() now comes from generic code, so discard arch implemen
 *  -sys_sigsuspend() no longer needs to fudge ptregs, hence that arg removed
 *  -sys_sigsuspend() no longer loops for do_signal(), sets TIF_xxx and leaves
 *   the job to do_signal()
 *
 * vineetg: July 2009
 *  -Modified Code to support the uClibc provided userland sigreturn stub
 *   to avoid kernel synthesing it on user stack at runtime, costing TLB
 *   probes and Cache line flushes.
 *
 * vineetg: July 2009
 *  -In stash_usr_regs( ) and restore_usr_regs( ), save/restore of user regs
 *   in done in block copy rather than one word at a time.
 *   This saves around 2K of code and improves LMBench lat_sig <catch>
 *
 * rajeshwarr: Feb 2009
 *  - Support for Realtime Signals
 *
 * vineetg: Aug 11th 2008: Bug #94183
 *  -ViXS were still seeing crashes when using insmod to load drivers.
 *   It turned out that the code to change Execute permssions for TLB entries
 *   of user was not guarded for interrupts (mod_tlb_permission)
 *   This was cauing TLB entries to be overwritten on unrelated indexes
 *
 * Vineetg: July 15th 2008: Bug #94183
 *  -Exception happens in Delay slot of a JMP, and before user space resumes,
 *   Signal is delivered (Ctrl + C) = >SIGINT.
 *   setup_frame( ) sets up PC,SP,BLINK to enable user space signal handler
 *   to run, but doesn't clear the Delay slot bit from status32. As a result,
 *   on resuming user mode, signal handler branches off to BTA of orig JMP
 *  -FIX: clear the DE bit from status32 in setup_frame( )
 *
 * Rahul Trivedi, Kanika Nema: Codito Technologies 2004
 */

#include <linux/signal.h>
#include <linux/ptrace.h>
#include <linux/personality.h>
#include <linux/uaccess.h>
#include <linux/syscalls.h>
#include <linux/tracehook.h>
#include <asm/ucontext.h>

struct rt_sigframe {
	struct siginfo info;
	struct ucontext uc;
#define MAGIC_SIGALTSTK		0x07302004
	unsigned int sigret_magic;
};

static int
stash_usr_regs(struct rt_sigframe __user *sf, struct pt_regs *regs,
	       sigset_t *set)
{
	int err;
	err = __copy_to_user(&(sf->uc.uc_mcontext.regs.scratch), regs,
			     sizeof(sf->uc.uc_mcontext.regs.scratch));
	err |= __copy_to_user(&sf->uc.uc_sigmask, set, sizeof(sigset_t));

	return err;
}

static int restore_usr_regs(struct pt_regs *regs, struct rt_sigframe __user *sf)
{
	sigset_t set;
	int err;

	err = __copy_from_user(&set, &sf->uc.uc_sigmask, sizeof(set));
	if (!err)
		set_current_blocked(&set);

	err |= __copy_from_user(regs, &(sf->uc.uc_mcontext.regs.scratch),
				sizeof(sf->uc.uc_mcontext.regs.scratch));

	return err;
}

static inline int is_do_ss_needed(unsigned int magic)
{
	if (MAGIC_SIGALTSTK == magic)
		return 1;
	else
		return 0;
}

SYSCALL_DEFINE0(rt_sigreturn)
{
	struct rt_sigframe __user *sf;
	unsigned int magic;
	struct pt_regs *regs = current_pt_regs();

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

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

	sf = (struct rt_sigframe __force __user *)(regs->sp);

	if (!access_ok(VERIFY_READ, sf, sizeof(*sf)))
		goto badframe;

	if (__get_user(magic, &sf->sigret_magic))
		goto badframe;

	if (unlikely(is_do_ss_needed(magic)))
		if (restore_altstack(&sf->uc.uc_stack))
			goto badframe;

	if (restore_usr_regs(regs, sf))
		goto badframe;

	/* Don't restart from sigreturn */
	syscall_wont_restart(regs);

	/*
	 * Ensure that sigreturn always returns to user mode (in case the
	 * regs saved on user stack got fudged between save and sigreturn)
	 * Otherwise it is easy to panic the kernel with a custom
	 * signal handler and/or restorer which clobberes the status32/ret
	 * to return to a bogus location in kernel mode.
	 */
	regs->status32 |= STATUS_U_MASK;

	return regs->r0;

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

/*
 * Determine which stack to use..
 */
static inline void __user *get_sigframe(struct ksignal *ksig,
					struct pt_regs *regs,
					unsigned long framesize)
{
	unsigned long sp = sigsp(regs->sp, ksig);
	void __user *frame;

	/* No matter what happens, 'sp' must be word
	 * aligned otherwise nasty things could happen
	 */

	/* ATPCS B01 mandates 8-byte alignment */
	frame = (void __user *)((sp - framesize) & ~7);

	/* Check that we can actually write to the signal frame */
	if (!access_ok(VERIFY_WRITE, frame, framesize))
		frame = NULL;

	return frame;
}

static int
setup_rt_frame(struct ksignal *ksig, sigset_t *set, struct pt_regs *regs)
{
	struct rt_sigframe __user *sf;
	unsigned int magic = 0;
	int err = 0;

	sf = get_sigframe(ksig, regs, sizeof(struct rt_sigframe));
	if (!sf)
		return 1;

	/*
	 * w/o SA_SIGINFO, struct ucontext is partially populated (only
	 * uc_mcontext/uc_sigmask) for kernel's normal user state preservation
	 * during signal handler execution. This works for SA_SIGINFO as well
	 * although the semantics are now overloaded (the same reg state can be
	 * inspected by userland: but are they allowed to fiddle with it ?
	 */
	err |= stash_usr_regs(sf, regs, set);

	/*
	 * SA_SIGINFO requires 3 args to signal handler:
	 *  #1: sig-no (common to any handler)
	 *  #2: struct siginfo
	 *  #3: struct ucontext (completely populated)
	 */
	if (unlikely(ksig->ka.sa.sa_flags & SA_SIGINFO)) {
		err |= copy_siginfo_to_user(&sf->info, &ksig->info);
		err |= __put_user(0, &sf->uc.uc_flags);
		err |= __put_user(NULL, &sf->uc.uc_link);
		err |= __save_altstack(&sf->uc.uc_stack, regs->sp);

		/* setup args 2 and 3 for user mode handler */
		regs->r1 = (unsigned long)&sf->info;
		regs->r2 = (unsigned long)&sf->uc;

		/*
		 * small optim to avoid unconditonally calling do_sigaltstack
		 * in sigreturn path, now that we only have rt_sigreturn
		 */
		magic = MAGIC_SIGALTSTK;
	}

	err |= __put_user(magic, &sf->sigret_magic);
	if (err)
		return err;

	/* #1 arg to the user Signal handler */
	regs->r0 = ksig->sig;

	/* setup PC of user space signal handler */
	regs->ret = (unsigned long)ksig->ka.sa.sa_handler;

	/*
	 * handler returns using sigreturn stub provided already by userpsace
	 * If not, nuke the process right away
	 */
	if(!(ksig->ka.sa.sa_flags & SA_RESTORER))
		return 1;

	regs->blink = (unsigned long)ksig->ka.sa.sa_restorer;

	/* User Stack for signal handler will be above the frame just carved */
	regs->sp = (unsigned long)sf;

	/*
	 * Bug 94183, Clear the DE bit, so that when signal handler
	 * starts to run, it doesn't use BTA
	 */
	regs->status32 &= ~STATUS_DE_MASK;
	regs->status32 |= STATUS_L_MASK;

	return err;
}

static void arc_restart_syscall(struct k_sigaction *ka, struct pt_regs *regs)
{
	switch (regs->r0) {
	case -ERESTART_RESTARTBLOCK:
	case -ERESTARTNOHAND:
		/*
		 * ERESTARTNOHAND means that the syscall should
		 * only be restarted if there was no handler for
		 * the signal, and since we only get here if there
		 * is a handler, we don't restart
		 */
		regs->r0 = -EINTR;   /* ERESTART_xxx is internal */
		break;

	case -ERESTARTSYS:
		/*
		 * ERESTARTSYS means to restart the syscall if
		 * there is no handler or the handler was
		 * registered with SA_RESTART
		 */
		if (!(ka->sa.sa_flags & SA_RESTART)) {
			regs->r0 = -EINTR;
			break;
		}
		/* fallthrough */

	case -ERESTARTNOINTR:
		/*
		 * ERESTARTNOINTR means that the syscall should
		 * be called again after the signal handler returns.
		 * Setup reg state just as it was before doing the trap
		 * r0 has been clobbered with sys call ret code thus it
		 * needs to be reloaded with orig first arg to syscall
		 * in orig_r0. Rest of relevant reg-file:
		 * r8 (syscall num) and (r1 - r7) will be reset to
		 * their orig user space value when we ret from kernel
		 */
		regs->r0 = regs->orig_r0;
		regs->ret -= 4;
		break;
	}
}

/*
 * OK, we're invoking a handler
 */
static void
handle_signal(struct ksignal *ksig, struct pt_regs *regs)
{
	sigset_t *oldset = sigmask_to_save();
	int failed;

	/* Set up the stack frame */
	failed = setup_rt_frame(ksig, oldset, regs);

	signal_setup_done(failed, ksig, 0);
}

void do_signal(struct pt_regs *regs)
{
	struct ksignal ksig;
	int restart_scall;

	restart_scall = in_syscall(regs) && syscall_restartable(regs);

	if (get_signal(&ksig)) {
		if (restart_scall) {
			arc_restart_syscall(&ksig.ka, regs);
			syscall_wont_restart(regs);	/* No more restarts */
		}
		handle_signal(&ksig, regs);
		return;
	}

	if (restart_scall) {
		/* No handler for syscall: restart it */
		if (regs->r0 == -ERESTARTNOHAND ||
		    regs->r0 == -ERESTARTSYS || regs->r0 == -ERESTARTNOINTR) {
			regs->r0 = regs->orig_r0;
			regs->ret -= 4;
		} else if (regs->r0 == -ERESTART_RESTARTBLOCK) {
			regs->r8 = __NR_restart_syscall;
			regs->ret -= 4;
		}
		syscall_wont_restart(regs);	/* No more restarts */
	}

	/* If there's no signal to deliver, restore the saved sigmask back */
	restore_saved_sigmask();
}

void do_notify_resume(struct pt_regs *regs)
{
	/*
	 * ASM glue gaurantees that this is only called when returning to
	 * user mode
	 */
	if (test_and_clear_thread_flag(TIF_NOTIFY_RESUME))
		tracehook_notify_resume(regs);
}
Commit	Line	Data
c3581039 VG	1	/*
	2	* Signal Handling for ARC
	3	*
	4	* Copyright (C) 2004, 2007-2010, 2011-2012 Synopsys, Inc. (www.synopsys.com)
	5	*
	6	* This program is free software; you can redistribute it and/or modify
	7	* it under the terms of the GNU General Public License version 2 as
	8	* published by the Free Software Foundation.
	9	*
	10	* vineetg: Jan 2010 (Restarting of timer related syscalls)
	11	*
	12	* vineetg: Nov 2009 (Everything needed for TIF_RESTORE_SIGMASK)
	13	* -do_signal() supports TIF_RESTORE_SIGMASK
	14	* -do_signal() no loner needs oldset, required by OLD sys_sigsuspend
	15	* -sys_rt_sigsuspend() now comes from generic code, so discard arch implemen
	16	* -sys_sigsuspend() no longer needs to fudge ptregs, hence that arg removed
	17	* -sys_sigsuspend() no longer loops for do_signal(), sets TIF_xxx and leaves
	18	* the job to do_signal()
	19	*
	20	* vineetg: July 2009
	21	* -Modified Code to support the uClibc provided userland sigreturn stub
	22	* to avoid kernel synthesing it on user stack at runtime, costing TLB
	23	* probes and Cache line flushes.
	24	*
	25	* vineetg: July 2009
	26	* -In stash_usr_regs( ) and restore_usr_regs( ), save/restore of user regs
	27	* in done in block copy rather than one word at a time.
	28	* This saves around 2K of code and improves LMBench lat_sig <catch>
	29	*
	30	* rajeshwarr: Feb 2009
	31	* - Support for Realtime Signals
	32	*
	33	* vineetg: Aug 11th 2008: Bug #94183
	34	* -ViXS were still seeing crashes when using insmod to load drivers.
	35	* It turned out that the code to change Execute permssions for TLB entries
	36	* of user was not guarded for interrupts (mod_tlb_permission)
	37	* This was cauing TLB entries to be overwritten on unrelated indexes
	38	*
	39	* Vineetg: July 15th 2008: Bug #94183
	40	* -Exception happens in Delay slot of a JMP, and before user space resumes,
	41	* Signal is delivered (Ctrl + C) = >SIGINT.
	42	* setup_frame( ) sets up PC,SP,BLINK to enable user space signal handler
	43	* to run, but doesn't clear the Delay slot bit from status32. As a result,
	44	* on resuming user mode, signal handler branches off to BTA of orig JMP
	45	* -FIX: clear the DE bit from status32 in setup_frame( )
	46	*
	47	* Rahul Trivedi, Kanika Nema: Codito Technologies 2004
	48	*/
	49
	50	#include <linux/signal.h>
	51	#include <linux/ptrace.h>
	52	#include <linux/personality.h>
	53	#include <linux/uaccess.h>
	54	#include <linux/syscalls.h>
	55	#include <linux/tracehook.h>
	56	#include <asm/ucontext.h>
	57
	58	struct rt_sigframe {
	59	struct siginfo info;
	60	struct ucontext uc;
	61	#define MAGIC_SIGALTSTK 0x07302004
	62	unsigned int sigret_magic;
	63	};
	64
65	static int
66	stash_usr_regs(struct rt_sigframe __user sf, struct pt_regs regs,
67	sigset_t *set)
68	{
69	int err;
6914e1e3	70	err = __copy_to_user(&(sf->uc.uc_mcontext.regs.scratch), regs,
c3581039 VG	71	sizeof(sf->uc.uc_mcontext.regs.scratch));
	72	err \|= __copy_to_user(&sf->uc.uc_sigmask, set, sizeof(sigset_t));
	73
	74	return err;
	75	}
	76
	77	static int restore_usr_regs(struct pt_regs regs, struct rt_sigframe __user sf)
	78	{
	79	sigset_t set;
	80	int err;
	81
	82	err = __copy_from_user(&set, &sf->uc.uc_sigmask, sizeof(set));
	83	if (!err)
	84	set_current_blocked(&set);
	85
6914e1e3	86	err \|= __copy_from_user(regs, &(sf->uc.uc_mcontext.regs.scratch),
c3581039 VG	87	sizeof(sf->uc.uc_mcontext.regs.scratch));
	88
	89	return err;
	90	}
	91
	92	static inline int is_do_ss_needed(unsigned int magic)
	93	{
	94	if (MAGIC_SIGALTSTK == magic)
	95	return 1;
	96	else
	97	return 0;
	98	}
	99
	100	SYSCALL_DEFINE0(rt_sigreturn)
	101	{
	102	struct rt_sigframe __user *sf;
	103	unsigned int magic;
c3581039 VG	104	struct pt_regs *regs = current_pt_regs();
	105
	106	/* Always make any pending restarted system calls return -EINTR */
f56141e3	107	current->restart_block.fn = do_no_restart_syscall;
c3581039 VG	108
	109	/* Since we stacked the signal on a word boundary,
	110	* then 'sp' should be word aligned here. If it's
	111	* not, then the user is trying to mess with us.
	112	*/
	113	if (regs->sp & 3)
	114	goto badframe;
	115
	116	sf = (struct rt_sigframe __force __user *)(regs->sp);
	117
	118	if (!access_ok(VERIFY_READ, sf, sizeof(*sf)))
	119	goto badframe;
	120
10469350	121	if (__get_user(magic, &sf->sigret_magic))
c3581039 VG	122	goto badframe;
	123
	124	if (unlikely(is_do_ss_needed(magic)))
	125	if (restore_altstack(&sf->uc.uc_stack))
	126	goto badframe;
	127
10469350 CR	128	if (restore_usr_regs(regs, sf))
	129	goto badframe;
	130
55bb9480 VG	131	/* Don't restart from sigreturn */
	132	syscall_wont_restart(regs);
	133
e4140819 VG	134	/*
	135	* Ensure that sigreturn always returns to user mode (in case the
	136	* regs saved on user stack got fudged between save and sigreturn)
	137	* Otherwise it is easy to panic the kernel with a custom
	138	* signal handler and/or restorer which clobberes the status32/ret
	139	* to return to a bogus location in kernel mode.
	140	*/
	141	regs->status32 \|= STATUS_U_MASK;
	142
c3581039 VG	143	return regs->r0;
	144
	145	badframe:
	146	force_sig(SIGSEGV, current);
	147	return 0;
	148	}
	149
	150	/*
	151	* Determine which stack to use..
	152	*/
5290dd79	153	static inline void __user get_sigframe(struct ksignal ksig,
c3581039 VG	154	struct pt_regs *regs,
	155	unsigned long framesize)
	156	{
5290dd79	157	unsigned long sp = sigsp(regs->sp, ksig);
c3581039 VG	158	void __user *frame;
c3581039 VG	159
c3581039 VG	160	/* No matter what happens, 'sp' must be word
	161	* aligned otherwise nasty things could happen
	162	*/
	163
	164	/* ATPCS B01 mandates 8-byte alignment */
	165	frame = (void __user *)((sp - framesize) & ~7);
	166
	167	/* Check that we can actually write to the signal frame */
	168	if (!access_ok(VERIFY_WRITE, frame, framesize))
	169	frame = NULL;
	170
	171	return frame;
	172	}
	173
c3581039	174	static int
f6dd2a3f	175	setup_rt_frame(struct ksignal ksig, sigset_t set, struct pt_regs *regs)
c3581039 VG	176	{
	177	struct rt_sigframe __user *sf;
	178	unsigned int magic = 0;
	179	int err = 0;
	180
5290dd79	181	sf = get_sigframe(ksig, regs, sizeof(struct rt_sigframe));
c3581039 VG	182	if (!sf)
	183	return 1;
	184
10469350 CR	185	/*
	186	* w/o SA_SIGINFO, struct ucontext is partially populated (only
	187	* uc_mcontext/uc_sigmask) for kernel's normal user state preservation
	188	* during signal handler execution. This works for SA_SIGINFO as well
	189	* although the semantics are now overloaded (the same reg state can be
	190	* inspected by userland: but are they allowed to fiddle with it ?
	191	*/
	192	err \|= stash_usr_regs(sf, regs, set);
	193
c3581039 VG	194	/*
	195	* SA_SIGINFO requires 3 args to signal handler:
	196	* #1: sig-no (common to any handler)
	197	* #2: struct siginfo
	198	* #3: struct ucontext (completely populated)
	199	*/
f6dd2a3f RW	200	if (unlikely(ksig->ka.sa.sa_flags & SA_SIGINFO)) {
f6dd2a3f RW	201	err \|= copy_siginfo_to_user(&sf->info, &ksig->info);
c3581039 VG	202	err \|= __put_user(0, &sf->uc.uc_flags);
	203	err \|= __put_user(NULL, &sf->uc.uc_link);
	204	err \|= __save_altstack(&sf->uc.uc_stack, regs->sp);
	205
	206	/* setup args 2 and 3 for user mode handler */
	207	regs->r1 = (unsigned long)&sf->info;
	208	regs->r2 = (unsigned long)&sf->uc;
	209
	210	/*
	211	* small optim to avoid unconditonally calling do_sigaltstack
	212	* in sigreturn path, now that we only have rt_sigreturn
	213	*/
	214	magic = MAGIC_SIGALTSTK;
	215	}
	216
c3581039 VG	217	err \|= __put_user(magic, &sf->sigret_magic);
	218	if (err)
	219	return err;
	220
	221	/* #1 arg to the user Signal handler */
e6de3ca9	222	regs->r0 = ksig->sig;
c3581039 VG	223
c3581039 VG	224	/* setup PC of user space signal handler */
f6dd2a3f	225	regs->ret = (unsigned long)ksig->ka.sa.sa_handler;
c3581039 VG	226
	227	/*
	228	* handler returns using sigreturn stub provided already by userpsace
e4140819	229	* If not, nuke the process right away
c3581039	230	*/
e4140819 VG	231	if(!(ksig->ka.sa.sa_flags & SA_RESTORER))
	232	return 1;
	233
f6dd2a3f	234	regs->blink = (unsigned long)ksig->ka.sa.sa_restorer;
c3581039 VG	235
	236	/* User Stack for signal handler will be above the frame just carved */
	237	regs->sp = (unsigned long)sf;
	238
	239	/*
	240	* Bug 94183, Clear the DE bit, so that when signal handler
	241	* starts to run, it doesn't use BTA
	242	*/
	243	regs->status32 &= ~STATUS_DE_MASK;
	244	regs->status32 \|= STATUS_L_MASK;
	245
	246	return err;
	247	}
	248
	249	static void arc_restart_syscall(struct k_sigaction ka, struct pt_regs regs)
	250	{
	251	switch (regs->r0) {
	252	case -ERESTART_RESTARTBLOCK:
	253	case -ERESTARTNOHAND:
	254	/*
	255	* ERESTARTNOHAND means that the syscall should
	256	* only be restarted if there was no handler for
	257	* the signal, and since we only get here if there
	258	* is a handler, we don't restart
	259	*/
	260	regs->r0 = -EINTR; /* ERESTART_xxx is internal */
	261	break;
	262
	263	case -ERESTARTSYS:
	264	/*
	265	* ERESTARTSYS means to restart the syscall if
	266	* there is no handler or the handler was
	267	* registered with SA_RESTART
	268	*/
	269	if (!(ka->sa.sa_flags & SA_RESTART)) {
	270	regs->r0 = -EINTR;
	271	break;
	272	}
	273	/* fallthrough */
	274
	275	case -ERESTARTNOINTR:
	276	/*
	277	* ERESTARTNOINTR means that the syscall should
	278	* be called again after the signal handler returns.
	279	* Setup reg state just as it was before doing the trap
	280	* r0 has been clobbered with sys call ret code thus it
	281	* needs to be reloaded with orig first arg to syscall
	282	* in orig_r0. Rest of relevant reg-file:
	283	* r8 (syscall num) and (r1 - r7) will be reset to
	284	* their orig user space value when we ret from kernel
	285	*/
	286	regs->r0 = regs->orig_r0;
	287	regs->ret -= 4;
	288	break;
	289	}
	290	}
	291
	292	/*
	293	* OK, we're invoking a handler
	294	*/
	295	static void
f6dd2a3f	296	handle_signal(struct ksignal ksig, struct pt_regs regs)
c3581039 VG	297	{
c3581039 VG	298	sigset_t *oldset = sigmask_to_save();
e4140819	299	int failed;
c3581039 VG	300
c3581039 VG	301	/* Set up the stack frame */
e4140819	302	failed = setup_rt_frame(ksig, oldset, regs);
c3581039	303
e4140819	304	signal_setup_done(failed, ksig, 0);
c3581039 VG	305	}
	306
	307	void do_signal(struct pt_regs *regs)
	308	{
f6dd2a3f	309	struct ksignal ksig;
c3581039 VG	310	int restart_scall;
c3581039 VG	311
55bb9480	312	restart_scall = in_syscall(regs) && syscall_restartable(regs);
c3581039	313
f6dd2a3f	314	if (get_signal(&ksig)) {
55bb9480	315	if (restart_scall) {
f6dd2a3f	316	arc_restart_syscall(&ksig.ka, regs);
55bb9480 VG	317	syscall_wont_restart(regs); /* No more restarts */
55bb9480 VG	318	}
f6dd2a3f	319	handle_signal(&ksig, regs);
c3581039 VG	320	return;
	321	}
	322
	323	if (restart_scall) {
	324	/* No handler for syscall: restart it */
	325	if (regs->r0 == -ERESTARTNOHAND \|\|
	326	regs->r0 == -ERESTARTSYS \|\| regs->r0 == -ERESTARTNOINTR) {
	327	regs->r0 = regs->orig_r0;
	328	regs->ret -= 4;
	329	} else if (regs->r0 == -ERESTART_RESTARTBLOCK) {
	330	regs->r8 = __NR_restart_syscall;
	331	regs->ret -= 4;
	332	}
55bb9480	333	syscall_wont_restart(regs); /* No more restarts */
c3581039 VG	334	}
	335
	336	/* If there's no signal to deliver, restore the saved sigmask back */
	337	restore_saved_sigmask();
	338	}
	339
	340	void do_notify_resume(struct pt_regs *regs)
	341	{
	342	/*
	343	* ASM glue gaurantees that this is only called when returning to
	344	* user mode
	345	*/
	346	if (test_and_clear_thread_flag(TIF_NOTIFY_RESUME))
	347	tracehook_notify_resume(regs);
	348	}