[mirror_ubuntu-hirsute-kernel.git] / arch / powerpc / kernel / signal.c

/*
 * Common signal handling code for both 32 and 64 bits
 *
 *    Copyright (c) 2007 Benjamin Herrenschmidt, IBM Corporation
 *    Extracted from signal_32.c and signal_64.c
 *
 * This file is subject to the terms and conditions of the GNU General
 * Public License.  See the file README.legal in the main directory of
 * this archive for more details.
 */

#include <linux/tracehook.h>
#include <linux/signal.h>
#include <linux/uprobes.h>
#include <linux/key.h>
#include <linux/context_tracking.h>
#include <linux/livepatch.h>
#include <linux/syscalls.h>
#include <asm/hw_breakpoint.h>
#include <linux/uaccess.h>
#include <asm/unistd.h>
#include <asm/debug.h>
#include <asm/tm.h>

#include "signal.h"

/* Log an error when sending an unhandled signal to a process. Controlled
 * through debug.exception-trace sysctl.
 */

int show_unhandled_signals = 1;

/*
 * Allocate space for the signal frame
 */
void __user *get_sigframe(struct ksignal *ksig, unsigned long sp,
			   size_t frame_size, int is_32)
{
        unsigned long oldsp, newsp;

        /* Default to using normal stack */
        oldsp = get_clean_sp(sp, is_32);
	oldsp = sigsp(oldsp, ksig);
	newsp = (oldsp - frame_size) & ~0xFUL;

	/* Check access */
	if (!access_ok((void __user *)newsp, oldsp - newsp))
		return NULL;

        return (void __user *)newsp;
}

static void check_syscall_restart(struct pt_regs *regs, struct k_sigaction *ka,
				  int has_handler)
{
	unsigned long ret = regs->gpr[3];
	int restart = 1;

	/* syscall ? */
	if (TRAP(regs) != 0x0C00)
		return;

	/* error signalled ? */
	if (!(regs->ccr & 0x10000000))
		return;

	switch (ret) {
	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 dont restart.
		 */
		restart = !has_handler;
		break;
	case ERESTARTSYS:
		/* ERESTARTSYS means to restart the syscall if there is no
		 * handler or the handler was registered with SA_RESTART
		 */
		restart = !has_handler || (ka->sa.sa_flags & SA_RESTART) != 0;
		break;
	case ERESTARTNOINTR:
		/* ERESTARTNOINTR means that the syscall should be
		 * called again after the signal handler returns.
		 */
		break;
	default:
		return;
	}
	if (restart) {
		if (ret == ERESTART_RESTARTBLOCK)
			regs->gpr[0] = __NR_restart_syscall;
		else
			regs->gpr[3] = regs->orig_gpr3;
		regs->nip -= 4;
		regs->result = 0;
	} else {
		regs->result = -EINTR;
		regs->gpr[3] = EINTR;
		regs->ccr |= 0x10000000;
	}
}

static void do_signal(struct task_struct *tsk)
{
	sigset_t *oldset = sigmask_to_save();
	struct ksignal ksig = { .sig = 0 };
	int ret;
	int is32 = is_32bit_task();

	BUG_ON(tsk != current);

	get_signal(&ksig);

	/* Is there any syscall restart business here ? */
	check_syscall_restart(tsk->thread.regs, &ksig.ka, ksig.sig > 0);

	if (ksig.sig <= 0) {
		/* No signal to deliver -- put the saved sigmask back */
		restore_saved_sigmask();
		tsk->thread.regs->trap = 0;
		return;               /* no signals delivered */
	}

#ifndef CONFIG_PPC_ADV_DEBUG_REGS
        /*
	 * Reenable the DABR before delivering the signal to
	 * user space. The DABR will have been cleared if it
	 * triggered inside the kernel.
	 */
	if (tsk->thread.hw_brk.address && tsk->thread.hw_brk.type)
		__set_breakpoint(&tsk->thread.hw_brk);
#endif
	/* Re-enable the breakpoints for the signal stack */
	thread_change_pc(tsk, tsk->thread.regs);

	rseq_signal_deliver(&ksig, tsk->thread.regs);

	if (is32) {
        	if (ksig.ka.sa.sa_flags & SA_SIGINFO)
			ret = handle_rt_signal32(&ksig, oldset, tsk);
		else
			ret = handle_signal32(&ksig, oldset, tsk);
	} else {
		ret = handle_rt_signal64(&ksig, oldset, tsk);
	}

	tsk->thread.regs->trap = 0;
	signal_setup_done(ret, &ksig, test_thread_flag(TIF_SINGLESTEP));
}

void do_notify_resume(struct pt_regs *regs, unsigned long thread_info_flags)
{
	user_exit();

	/* Check valid addr_limit, TIF check is done there */
	addr_limit_user_check();

	if (thread_info_flags & _TIF_UPROBE)
		uprobe_notify_resume(regs);

	if (thread_info_flags & _TIF_PATCH_PENDING)
		klp_update_patch_state(current);

	if (thread_info_flags & _TIF_SIGPENDING) {
		BUG_ON(regs != current->thread.regs);
		do_signal(current);
	}

	if (thread_info_flags & _TIF_NOTIFY_RESUME) {
		clear_thread_flag(TIF_NOTIFY_RESUME);
		tracehook_notify_resume(regs);
		rseq_handle_notify_resume(NULL, regs);
	}

	user_enter();
}

unsigned long get_tm_stackpointer(struct task_struct *tsk)
{
	/* When in an active transaction that takes a signal, we need to be
	 * careful with the stack.  It's possible that the stack has moved back
	 * up after the tbegin.  The obvious case here is when the tbegin is
	 * called inside a function that returns before a tend.  In this case,
	 * the stack is part of the checkpointed transactional memory state.
	 * If we write over this non transactionally or in suspend, we are in
	 * trouble because if we get a tm abort, the program counter and stack
	 * pointer will be back at the tbegin but our in memory stack won't be
	 * valid anymore.
	 *
	 * To avoid this, when taking a signal in an active transaction, we
	 * need to use the stack pointer from the checkpointed state, rather
	 * than the speculated state.  This ensures that the signal context
	 * (written tm suspended) will be written below the stack required for
	 * the rollback.  The transaction is aborted because of the treclaim,
	 * so any memory written between the tbegin and the signal will be
	 * rolled back anyway.
	 *
	 * For signals taken in non-TM or suspended mode, we use the
	 * normal/non-checkpointed stack pointer.
	 */

	unsigned long ret = tsk->thread.regs->gpr[1];

#ifdef CONFIG_PPC_TRANSACTIONAL_MEM
	BUG_ON(tsk != current);

	if (MSR_TM_ACTIVE(tsk->thread.regs->msr)) {
		preempt_disable();
		tm_reclaim_current(TM_CAUSE_SIGNAL);
		if (MSR_TM_TRANSACTIONAL(tsk->thread.regs->msr))
			ret = tsk->thread.ckpt_regs.gpr[1];

		/*
		 * If we treclaim, we must clear the current thread's TM bits
		 * before re-enabling preemption. Otherwise we might be
		 * preempted and have the live MSR[TS] changed behind our back
		 * (tm_recheckpoint_new_task() would recheckpoint). Besides, we
		 * enter the signal handler in non-transactional state.
		 */
		tsk->thread.regs->msr &= ~MSR_TS_MASK;
		preempt_enable();
	}
#endif
	return ret;
}
Commit	Line	Data
22e38f29 BH	1	/*
	2	* Common signal handling code for both 32 and 64 bits
	3	*
446957ba	4	* Copyright (c) 2007 Benjamin Herrenschmidt, IBM Corporation
22e38f29 BH	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
6558ba2b	12	#include <linux/tracehook.h>
22e38f29	13	#include <linux/signal.h>
8b7b80b9	14	#include <linux/uprobes.h>
18b246fa	15	#include <linux/key.h>
106ed886	16	#include <linux/context_tracking.h>
a768f784	17	#include <linux/livepatch.h>
3e378680	18	#include <linux/syscalls.h>
06532a67	19	#include <asm/hw_breakpoint.h>
7c0f6ba6	20	#include <linux/uaccess.h>
22e38f29	21	#include <asm/unistd.h>
ae3a197e	22	#include <asm/debug.h>
2b3f8e87	23	#include <asm/tm.h>
22e38f29	24
db277e9a CH	25	#include "signal.h"
db277e9a CH	26
d0c3d534 OJ	27	/* Log an error when sending an unhandled signal to a process. Controlled
	28	* through debug.exception-trace sysctl.
	29	*/
	30
e34166ad	31	int show_unhandled_signals = 1;
d0c3d534	32
a3f61dc0 BH	33	/*
	34	* Allocate space for the signal frame
	35	*/
059ade65	36	void __user get_sigframe(struct ksignal ksig, unsigned long sp,
efbda860	37	size_t frame_size, int is_32)
a3f61dc0 BH	38	{
	39	unsigned long oldsp, newsp;
	40
	41	/* Default to using normal stack */
2b3f8e87	42	oldsp = get_clean_sp(sp, is_32);
059ade65	43	oldsp = sigsp(oldsp, ksig);
a3f61dc0 BH	44	newsp = (oldsp - frame_size) & ~0xFUL;
	45
	46	/* Check access */
96d4f267	47	if (!access_ok((void __user *)newsp, oldsp - newsp))
a3f61dc0 BH	48	return NULL;
	49
	50	return (void __user *)newsp;
	51	}
	52
f478f543 CH	53	static void check_syscall_restart(struct pt_regs regs, struct k_sigaction ka,
f478f543 CH	54	int has_handler)
22e38f29 BH	55	{
	56	unsigned long ret = regs->gpr[3];
	57	int restart = 1;
	58
	59	/* syscall ? */
	60	if (TRAP(regs) != 0x0C00)
	61	return;
	62
	63	/* error signalled ? */
	64	if (!(regs->ccr & 0x10000000))
	65	return;
	66
	67	switch (ret) {
	68	case ERESTART_RESTARTBLOCK:
	69	case ERESTARTNOHAND:
	70	/* ERESTARTNOHAND means that the syscall should only be
	71	* restarted if there was no handler for the signal, and since
	72	* we only get here if there is a handler, we dont restart.
	73	*/
	74	restart = !has_handler;
	75	break;
	76	case ERESTARTSYS:
	77	/* ERESTARTSYS means to restart the syscall if there is no
	78	* handler or the handler was registered with SA_RESTART
	79	*/
	80	restart = !has_handler \|\| (ka->sa.sa_flags & SA_RESTART) != 0;
	81	break;
	82	case ERESTARTNOINTR:
	83	/* ERESTARTNOINTR means that the syscall should be
	84	* called again after the signal handler returns.
	85	*/
	86	break;
	87	default:
	88	return;
	89	}
	90	if (restart) {
	91	if (ret == ERESTART_RESTARTBLOCK)
	92	regs->gpr[0] = __NR_restart_syscall;
	93	else
	94	regs->gpr[3] = regs->orig_gpr3;
	95	regs->nip -= 4;
	96	regs->result = 0;
	97	} else {
	98	regs->result = -EINTR;
	99	regs->gpr[3] = EINTR;
	100	regs->ccr \|= 0x10000000;
	101	}
	102	}
69d15f6b	103
d1199431	104	static void do_signal(struct task_struct *tsk)
f478f543	105	{
b7f9a11a	106	sigset_t *oldset = sigmask_to_save();
46725b17	107	struct ksignal ksig = { .sig = 0 };
f478f543 CH	108	int ret;
	109	int is32 = is_32bit_task();
	110
d1199431 CB	111	BUG_ON(tsk != current);
d1199431 CB	112
129b69df	113	get_signal(&ksig);
f478f543	114
f478f543	115	/* Is there any syscall restart business here ? */
d1199431	116	check_syscall_restart(tsk->thread.regs, &ksig.ka, ksig.sig > 0);
f478f543	117
129b69df	118	if (ksig.sig <= 0) {
f478f543	119	/* No signal to deliver -- put the saved sigmask back */
51a7b448	120	restore_saved_sigmask();
d1199431	121	tsk->thread.regs->trap = 0;
129b69df	122	return; /* no signals delivered */
f478f543 CH	123	}
f478f543 CH	124
3bffb652	125	#ifndef CONFIG_PPC_ADV_DEBUG_REGS
f478f543 CH	126	/*
	127	* Reenable the DABR before delivering the signal to
	128	* user space. The DABR will have been cleared if it
	129	* triggered inside the kernel.
	130	*/
d1199431 CB	131	if (tsk->thread.hw_brk.address && tsk->thread.hw_brk.type)
d1199431 CB	132	__set_breakpoint(&tsk->thread.hw_brk);
d6a61bfc	133	#endif
06532a67	134	/* Re-enable the breakpoints for the signal stack */
d1199431	135	thread_change_pc(tsk, tsk->thread.regs);
f478f543	136
784e0300	137	rseq_signal_deliver(&ksig, tsk->thread.regs);
8a417c48	138
f478f543	139	if (is32) {
129b69df	140	if (ksig.ka.sa.sa_flags & SA_SIGINFO)
d1199431	141	ret = handle_rt_signal32(&ksig, oldset, tsk);
f478f543	142	else
d1199431	143	ret = handle_signal32(&ksig, oldset, tsk);
f478f543	144	} else {
d1199431	145	ret = handle_rt_signal64(&ksig, oldset, tsk);
f478f543 CH	146	}
f478f543 CH	147
d1199431	148	tsk->thread.regs->trap = 0;
129b69df	149	signal_setup_done(ret, &ksig, test_thread_flag(TIF_SINGLESTEP));
f478f543 CH	150	}
f478f543 CH	151
18b246fa	152	void do_notify_resume(struct pt_regs *regs, unsigned long thread_info_flags)
7d6d637d	153	{
106ed886 LZ	154	user_exit();
106ed886 LZ	155
3e378680 ME	156	/* Check valid addr_limit, TIF check is done there */
	157	addr_limit_user_check();
	158
f57d56dd	159	if (thread_info_flags & _TIF_UPROBE)
8b7b80b9	160	uprobe_notify_resume(regs);
8b7b80b9	161
43347d56 MB	162	if (thread_info_flags & _TIF_PATCH_PENDING)
	163	klp_update_patch_state(current);
	164
d1199431 CB	165	if (thread_info_flags & _TIF_SIGPENDING) {
	166	BUG_ON(regs != current->thread.regs);
	167	do_signal(current);
	168	}
7d6d637d RM	169
	170	if (thread_info_flags & _TIF_NOTIFY_RESUME) {
	171	clear_thread_flag(TIF_NOTIFY_RESUME);
	172	tracehook_notify_resume(regs);
784e0300	173	rseq_handle_notify_resume(NULL, regs);
7d6d637d	174	}
106ed886 LZ	175
106ed886 LZ	176	user_enter();
7d6d637d	177	}
2b3f8e87	178
d1199431	179	unsigned long get_tm_stackpointer(struct task_struct *tsk)
2b3f8e87 MN	180	{
	181	/* When in an active transaction that takes a signal, we need to be
	182	* careful with the stack. It's possible that the stack has moved back
	183	* up after the tbegin. The obvious case here is when the tbegin is
	184	* called inside a function that returns before a tend. In this case,
	185	* the stack is part of the checkpointed transactional memory state.
	186	* If we write over this non transactionally or in suspend, we are in
	187	* trouble because if we get a tm abort, the program counter and stack
	188	* pointer will be back at the tbegin but our in memory stack won't be
	189	* valid anymore.
	190	*
	191	* To avoid this, when taking a signal in an active transaction, we
	192	* need to use the stack pointer from the checkpointed state, rather
	193	* than the speculated state. This ensures that the signal context
	194	* (written tm suspended) will be written below the stack required for
446957ba	195	* the rollback. The transaction is aborted because of the treclaim,
2b3f8e87 MN	196	* so any memory written between the tbegin and the signal will be
	197	* rolled back anyway.
	198	*
	199	* For signals taken in non-TM or suspended mode, we use the
	200	* normal/non-checkpointed stack pointer.
	201	*/
	202
2464cc4c GLD	203	unsigned long ret = tsk->thread.regs->gpr[1];
2464cc4c GLD	204
2b3f8e87	205	#ifdef CONFIG_PPC_TRANSACTIONAL_MEM
d1199431 CB	206	BUG_ON(tsk != current);
	207
	208	if (MSR_TM_ACTIVE(tsk->thread.regs->msr)) {
2464cc4c	209	preempt_disable();
d31626f7	210	tm_reclaim_current(TM_CAUSE_SIGNAL);
d1199431	211	if (MSR_TM_TRANSACTIONAL(tsk->thread.regs->msr))
2464cc4c GLD	212	ret = tsk->thread.ckpt_regs.gpr[1];
	213
	214	/*
	215	* If we treclaim, we must clear the current thread's TM bits
	216	* before re-enabling preemption. Otherwise we might be
	217	* preempted and have the live MSR[TS] changed behind our back
	218	* (tm_recheckpoint_new_task() would recheckpoint). Besides, we
	219	* enter the signal handler in non-transactional state.
	220	*/
	221	tsk->thread.regs->msr &= ~MSR_TS_MASK;
	222	preempt_enable();
2b3f8e87 MN	223	}
2b3f8e87 MN	224	#endif
2464cc4c	225	return ret;
2b3f8e87	226	}