[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), 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),
				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;
	int err;
	struct pt_regs *regs = current_pt_regs();

	/* Always make any pending restarted system calls return -EINTR */
	current_thread_info()->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;

	err = restore_usr_regs(regs, sf);
	err |= __get_user(magic, &sf->sigret_magic);
	if (err)
		goto badframe;

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

	return regs->r0;

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

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

	/* This is the X/Open sanctioned signal stack switching */
	if ((ka->sa.sa_flags & SA_ONSTACK) && !sas_ss_flags(sp))
		sp = current->sas_ss_sp + current->sas_ss_size;

	/* 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;
}

/*
 * translate the signal
 */
static inline int map_sig(int sig)
{
	struct thread_info *thread = current_thread_info();
	if (thread->exec_domain && thread->exec_domain->signal_invmap
	    && sig < 32)
		sig = thread->exec_domain->signal_invmap[sig];
	return sig;
}

static int
setup_rt_frame(int signo, struct k_sigaction *ka, siginfo_t *info,
	       sigset_t *set, struct pt_regs *regs)
{
	struct rt_sigframe __user *sf;
	unsigned int magic = 0;
	int err = 0;

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

	/*
	 * 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(ka->sa.sa_flags & SA_SIGINFO)) {
		err |= copy_siginfo_to_user(&sf->info, 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;
	}

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

	/* #1 arg to the user Signal handler */
	regs->r0 = map_sig(signo);

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

	/*
	 * handler returns using sigreturn stub provided already by userpsace
	 */
	BUG_ON(!(ka->sa.sa_flags & SA_RESTORER));
	regs->blink = (unsigned long)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(unsigned long sig, struct k_sigaction *ka, siginfo_t *info,
	      struct pt_regs *regs)
{
	sigset_t *oldset = sigmask_to_save();
	int ret;

	/* Set up the stack frame */
	ret = setup_rt_frame(sig, ka, info, oldset, regs);

	if (ret)
		force_sigsegv(sig, current);
	else
		signal_delivered(sig, info, ka, regs, 0);
}

void do_signal(struct pt_regs *regs)
{
	struct k_sigaction ka;
	siginfo_t info;
	int signr;
	int restart_scall;

	signr = get_signal_to_deliver(&info, &ka, regs, NULL);

	/* Are we from a system call? */
	restart_scall = in_syscall(regs);

	if (signr > 0) {
		if (restart_scall)
			arc_restart_syscall(&ka, regs);

		handle_signal(signr, &ka, &info, 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;
		}
	}

	/* 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;
70	err = __copy_to_user(&(sf->uc.uc_mcontext.regs), regs,
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
86	err \|= __copy_from_user(regs, &(sf->uc.uc_mcontext.regs),
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;
104	int err;
105	struct pt_regs *regs = current_pt_regs();
106
107	/* Always make any pending restarted system calls return -EINTR */
108	current_thread_info()->restart_block.fn = do_no_restart_syscall;
109
110	/* Since we stacked the signal on a word boundary,
111	* then 'sp' should be word aligned here. If it's
112	* not, then the user is trying to mess with us.
113	*/
114	if (regs->sp & 3)
115	goto badframe;
116
117	sf = (struct rt_sigframe __force __user *)(regs->sp);
118
119	if (!access_ok(VERIFY_READ, sf, sizeof(*sf)))
120	goto badframe;
121
122	err = restore_usr_regs(regs, sf);
123	err \|= __get_user(magic, &sf->sigret_magic);
124	if (err)
125	goto badframe;
126
127	if (unlikely(is_do_ss_needed(magic)))
128	if (restore_altstack(&sf->uc.uc_stack))
129	goto badframe;
130
131	return regs->r0;
132
133	badframe:
134	force_sig(SIGSEGV, current);
135	return 0;
136	}
137
138	/*
139	* Determine which stack to use..
140	*/
141	static inline void __user get_sigframe(struct k_sigaction ka,
142	struct pt_regs *regs,
143	unsigned long framesize)
144	{
145	unsigned long sp = regs->sp;
146	void __user *frame;
147
148	/* This is the X/Open sanctioned signal stack switching */
149	if ((ka->sa.sa_flags & SA_ONSTACK) && !sas_ss_flags(sp))
150	sp = current->sas_ss_sp + current->sas_ss_size;
151
152	/* No matter what happens, 'sp' must be word
153	* aligned otherwise nasty things could happen
154	*/
155
156	/* ATPCS B01 mandates 8-byte alignment */
157	frame = (void __user *)((sp - framesize) & ~7);
158
159	/* Check that we can actually write to the signal frame */
160	if (!access_ok(VERIFY_WRITE, frame, framesize))
161	frame = NULL;
162
163	return frame;
164	}
165
166	/*
167	* translate the signal
168	*/
169	static inline int map_sig(int sig)
170	{
171	struct thread_info *thread = current_thread_info();
172	if (thread->exec_domain && thread->exec_domain->signal_invmap
173	&& sig < 32)
174	sig = thread->exec_domain->signal_invmap[sig];
175	return sig;
176	}
177
178	static int
179	setup_rt_frame(int signo, struct k_sigaction ka, siginfo_t info,
180	sigset_t set, struct pt_regs regs)
181	{
182	struct rt_sigframe __user *sf;
183	unsigned int magic = 0;
184	int err = 0;
185
186	sf = get_sigframe(ka, regs, sizeof(struct rt_sigframe));
187	if (!sf)
188	return 1;
189
190	/*
191	* SA_SIGINFO requires 3 args to signal handler:
192	* #1: sig-no (common to any handler)
193	* #2: struct siginfo
194	* #3: struct ucontext (completely populated)
195	*/
196	if (unlikely(ka->sa.sa_flags & SA_SIGINFO)) {
197	err \|= copy_siginfo_to_user(&sf->info, info);
198	err \|= __put_user(0, &sf->uc.uc_flags);
199	err \|= __put_user(NULL, &sf->uc.uc_link);
200	err \|= __save_altstack(&sf->uc.uc_stack, regs->sp);
201
202	/* setup args 2 and 3 for user mode handler */
203	regs->r1 = (unsigned long)&sf->info;
204	regs->r2 = (unsigned long)&sf->uc;
205
206	/*
207	* small optim to avoid unconditonally calling do_sigaltstack
208	* in sigreturn path, now that we only have rt_sigreturn
209	*/
210	magic = MAGIC_SIGALTSTK;
211	}
212
213	/*
214	* w/o SA_SIGINFO, struct ucontext is partially populated (only
215	* uc_mcontext/uc_sigmask) for kernel's normal user state preservation
216	* during signal handler execution. This works for SA_SIGINFO as well
217	* although the semantics are now overloaded (the same reg state can be
218	* inspected by userland: but are they allowed to fiddle with it ?
219	*/
220	err \|= stash_usr_regs(sf, regs, set);
221	err \|= __put_user(magic, &sf->sigret_magic);
222	if (err)
223	return err;
224
225	/* #1 arg to the user Signal handler */
226	regs->r0 = map_sig(signo);
227
228	/* setup PC of user space signal handler */
229	regs->ret = (unsigned long)ka->sa.sa_handler;
230
231	/*
232	* handler returns using sigreturn stub provided already by userpsace
233	*/
234	BUG_ON(!(ka->sa.sa_flags & SA_RESTORER));
235	regs->blink = (unsigned long)ka->sa.sa_restorer;
236
237	/* User Stack for signal handler will be above the frame just carved */
238	regs->sp = (unsigned long)sf;
239
240	/*
241	* Bug 94183, Clear the DE bit, so that when signal handler
242	* starts to run, it doesn't use BTA
243	*/
244	regs->status32 &= ~STATUS_DE_MASK;
245	regs->status32 \|= STATUS_L_MASK;
246
247	return err;
248	}
249
250	static void arc_restart_syscall(struct k_sigaction ka, struct pt_regs regs)
251	{
252	switch (regs->r0) {
253	case -ERESTART_RESTARTBLOCK:
254	case -ERESTARTNOHAND:
255	/*
256	* ERESTARTNOHAND means that the syscall should
257	* only be restarted if there was no handler for
258	* the signal, and since we only get here if there
259	* is a handler, we don't restart
260	*/
261	regs->r0 = -EINTR; /* ERESTART_xxx is internal */
262	break;
263
264	case -ERESTARTSYS:
265	/*
266	* ERESTARTSYS means to restart the syscall if
267	* there is no handler or the handler was
268	* registered with SA_RESTART
269	*/
270	if (!(ka->sa.sa_flags & SA_RESTART)) {
271	regs->r0 = -EINTR;
272	break;
273	}
274	/* fallthrough */
275
276	case -ERESTARTNOINTR:
277	/*
278	* ERESTARTNOINTR means that the syscall should
279	* be called again after the signal handler returns.
280	* Setup reg state just as it was before doing the trap
281	* r0 has been clobbered with sys call ret code thus it
282	* needs to be reloaded with orig first arg to syscall
283	* in orig_r0. Rest of relevant reg-file:
284	* r8 (syscall num) and (r1 - r7) will be reset to
285	* their orig user space value when we ret from kernel
286	*/
287	regs->r0 = regs->orig_r0;
288	regs->ret -= 4;
289	break;
290	}
291	}
292
293	/*
294	* OK, we're invoking a handler
295	*/
296	static void
297	handle_signal(unsigned long sig, struct k_sigaction ka, siginfo_t info,
298	struct pt_regs *regs)
299	{
300	sigset_t *oldset = sigmask_to_save();
301	int ret;
302
303	/* Set up the stack frame */
304	ret = setup_rt_frame(sig, ka, info, oldset, regs);
305
306	if (ret)
307	force_sigsegv(sig, current);
308	else
309	signal_delivered(sig, info, ka, regs, 0);
310	}
311
312	void do_signal(struct pt_regs *regs)
313	{
314	struct k_sigaction ka;
315	siginfo_t info;
316	int signr;
317	int restart_scall;
318
319	signr = get_signal_to_deliver(&info, &ka, regs, NULL);
320
321	/* Are we from a system call? */
322	restart_scall = in_syscall(regs);
323
324	if (signr > 0) {
325	if (restart_scall)
326	arc_restart_syscall(&ka, regs);
327
328	handle_signal(signr, &ka, &info, regs);
329	return;
330	}
331
332	if (restart_scall) {
333	/* No handler for syscall: restart it */
334	if (regs->r0 == -ERESTARTNOHAND \|\|
335	regs->r0 == -ERESTARTSYS \|\| regs->r0 == -ERESTARTNOINTR) {
336	regs->r0 = regs->orig_r0;
337	regs->ret -= 4;
338	} else if (regs->r0 == -ERESTART_RESTARTBLOCK) {
339	regs->r8 = __NR_restart_syscall;
340	regs->ret -= 4;
341	}
342	}
343
344	/* If there's no signal to deliver, restore the saved sigmask back */
345	restore_saved_sigmask();
346	}
347
348	void do_notify_resume(struct pt_regs *regs)
349	{
350	/*
351	* ASM glue gaurantees that this is only called when returning to
352	* user mode
353	*/
354	if (test_and_clear_thread_flag(TIF_NOTIFY_RESUME))
355	tracehook_notify_resume(regs);
356	}