[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/switch_to.h>
#include <asm/unistd.h>
#include <asm/debug.h>
#include <asm/tm.h>

#include "signal.h"

#ifdef CONFIG_VSX
unsigned long copy_fpr_to_user(void __user *to,
			       struct task_struct *task)
{
	u64 buf[ELF_NFPREG];
	int i;

	/* save FPR copy to local buffer then write to the thread_struct */
	for (i = 0; i < (ELF_NFPREG - 1) ; i++)
		buf[i] = task->thread.TS_FPR(i);
	buf[i] = task->thread.fp_state.fpscr;
	return __copy_to_user(to, buf, ELF_NFPREG * sizeof(double));
}

unsigned long copy_fpr_from_user(struct task_struct *task,
				 void __user *from)
{
	u64 buf[ELF_NFPREG];
	int i;

	if (__copy_from_user(buf, from, ELF_NFPREG * sizeof(double)))
		return 1;
	for (i = 0; i < (ELF_NFPREG - 1) ; i++)
		task->thread.TS_FPR(i) = buf[i];
	task->thread.fp_state.fpscr = buf[i];

	return 0;
}

unsigned long copy_vsx_to_user(void __user *to,
			       struct task_struct *task)
{
	u64 buf[ELF_NVSRHALFREG];
	int i;

	/* save FPR copy to local buffer then write to the thread_struct */
	for (i = 0; i < ELF_NVSRHALFREG; i++)
		buf[i] = task->thread.fp_state.fpr[i][TS_VSRLOWOFFSET];
	return __copy_to_user(to, buf, ELF_NVSRHALFREG * sizeof(double));
}

unsigned long copy_vsx_from_user(struct task_struct *task,
				 void __user *from)
{
	u64 buf[ELF_NVSRHALFREG];
	int i;

	if (__copy_from_user(buf, from, ELF_NVSRHALFREG * sizeof(double)))
		return 1;
	for (i = 0; i < ELF_NVSRHALFREG ; i++)
		task->thread.fp_state.fpr[i][TS_VSRLOWOFFSET] = buf[i];
	return 0;
}

#ifdef CONFIG_PPC_TRANSACTIONAL_MEM
unsigned long copy_ckfpr_to_user(void __user *to,
				  struct task_struct *task)
{
	u64 buf[ELF_NFPREG];
	int i;

	/* save FPR copy to local buffer then write to the thread_struct */
	for (i = 0; i < (ELF_NFPREG - 1) ; i++)
		buf[i] = task->thread.TS_CKFPR(i);
	buf[i] = task->thread.ckfp_state.fpscr;
	return __copy_to_user(to, buf, ELF_NFPREG * sizeof(double));
}

unsigned long copy_ckfpr_from_user(struct task_struct *task,
					  void __user *from)
{
	u64 buf[ELF_NFPREG];
	int i;

	if (__copy_from_user(buf, from, ELF_NFPREG * sizeof(double)))
		return 1;
	for (i = 0; i < (ELF_NFPREG - 1) ; i++)
		task->thread.TS_CKFPR(i) = buf[i];
	task->thread.ckfp_state.fpscr = buf[i];

	return 0;
}

unsigned long copy_ckvsx_to_user(void __user *to,
				  struct task_struct *task)
{
	u64 buf[ELF_NVSRHALFREG];
	int i;

	/* save FPR copy to local buffer then write to the thread_struct */
	for (i = 0; i < ELF_NVSRHALFREG; i++)
		buf[i] = task->thread.ckfp_state.fpr[i][TS_VSRLOWOFFSET];
	return __copy_to_user(to, buf, ELF_NVSRHALFREG * sizeof(double));
}

unsigned long copy_ckvsx_from_user(struct task_struct *task,
					  void __user *from)
{
	u64 buf[ELF_NVSRHALFREG];
	int i;

	if (__copy_from_user(buf, from, ELF_NVSRHALFREG * sizeof(double)))
		return 1;
	for (i = 0; i < ELF_NVSRHALFREG ; i++)
		task->thread.ckfp_state.fpr[i][TS_VSRLOWOFFSET] = buf[i];
	return 0;
}
#endif /* CONFIG_PPC_TRANSACTIONAL_MEM */
#endif

/* 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
 */
static unsigned long get_tm_stackpointer(struct task_struct *tsk);

void __user *get_sigframe(struct ksignal *ksig, struct task_struct *tsk,
			  size_t frame_size, int is_32)
{
        unsigned long oldsp, newsp;
	unsigned long sp = get_tm_stackpointer(tsk);

        /* Default to using normal stack */
	if (is_32)
		oldsp = sp & 0x0ffffffffUL;
	else
		oldsp = sp;
	oldsp = sigsp(oldsp, ksig);
	newsp = (oldsp - frame_size) & ~0xFUL;

        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_is_syscall(regs))
		return;

	if (trap_norestart(regs))
		return;

	/* error signalled ? */
	if (trap_is_scv(regs)) {
		/* 32-bit compat mode sign extend? */
		if (!IS_ERR_VALUE(ret))
			return;
		ret = -ret;
	} else 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 {
		if (trap_is_scv(regs)) {
			regs->result = -EINTR;
			regs->gpr[3] = -EINTR;
		} 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;

	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();
		set_trap_norestart(tsk->thread.regs);
		return;               /* no signals delivered */
	}

        /*
	 * Reenable the DABR before delivering the signal to
	 * user space. The DABR will have been cleared if it
	 * triggered inside the kernel.
	 */
	if (!IS_ENABLED(CONFIG_PPC_ADV_DEBUG_REGS)) {
		int i;

		for (i = 0; i < nr_wp_slots(); i++) {
			if (tsk->thread.hw_brk[i].address && tsk->thread.hw_brk[i].type)
				__set_breakpoint(i, &tsk->thread.hw_brk[i]);
		}
	}

	/* Re-enable the breakpoints for the signal stack */
	thread_change_pc(tsk, tsk->thread.regs);

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

	if (is_32bit_task()) {
        	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);
	}

	set_trap_norestart(tsk->thread.regs);
	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();

	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 | _TIF_NOTIFY_SIGNAL)) {
		BUG_ON(regs != current->thread.regs);
		do_signal(current);
	}

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

	user_enter();
}

static 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;
}

static const char fm32[] = KERN_INFO "%s[%d]: bad frame in %s: %p nip %08lx lr %08lx\n";
static const char fm64[] = KERN_INFO "%s[%d]: bad frame in %s: %p nip %016lx lr %016lx\n";

void signal_fault(struct task_struct *tsk, struct pt_regs *regs,
		  const char *where, void __user *ptr)
{
	if (show_unhandled_signals)
		printk_ratelimited(regs->msr & MSR_64BIT ? fm64 : fm32, tsk->comm,
				   task_pid_nr(tsk), where, ptr, regs->nip, regs->link);
}
Commit	Line	Data
	1	/*
	2	* Common signal handling code for both 32 and 64 bits
	3	*
	4	* Copyright (c) 2007 Benjamin Herrenschmidt, IBM Corporation
	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
	12	#include <linux/tracehook.h>
	13	#include <linux/signal.h>
	14	#include <linux/uprobes.h>
	15	#include <linux/key.h>
	16	#include <linux/context_tracking.h>
	17	#include <linux/livepatch.h>
	18	#include <linux/syscalls.h>
	19	#include <asm/hw_breakpoint.h>
	20	#include <linux/uaccess.h>
	21	#include <asm/switch_to.h>
	22	#include <asm/unistd.h>
	23	#include <asm/debug.h>
	24	#include <asm/tm.h>
	25
	26	#include "signal.h"
	27
	28	#ifdef CONFIG_VSX
	29	unsigned long copy_fpr_to_user(void __user *to,
	30	struct task_struct *task)
	31	{
	32	u64 buf[ELF_NFPREG];
	33	int i;
	34
	35	/* save FPR copy to local buffer then write to the thread_struct */
	36	for (i = 0; i < (ELF_NFPREG - 1) ; i++)
	37	buf[i] = task->thread.TS_FPR(i);
	38	buf[i] = task->thread.fp_state.fpscr;
	39	return __copy_to_user(to, buf, ELF_NFPREG * sizeof(double));
	40	}
	41
	42	unsigned long copy_fpr_from_user(struct task_struct *task,
	43	void __user *from)
	44	{
	45	u64 buf[ELF_NFPREG];
	46	int i;
	47
	48	if (__copy_from_user(buf, from, ELF_NFPREG * sizeof(double)))
	49	return 1;
	50	for (i = 0; i < (ELF_NFPREG - 1) ; i++)
	51	task->thread.TS_FPR(i) = buf[i];
	52	task->thread.fp_state.fpscr = buf[i];
	53
	54	return 0;
	55	}
	56
	57	unsigned long copy_vsx_to_user(void __user *to,
	58	struct task_struct *task)
	59	{
	60	u64 buf[ELF_NVSRHALFREG];
	61	int i;
	62
	63	/* save FPR copy to local buffer then write to the thread_struct */
	64	for (i = 0; i < ELF_NVSRHALFREG; i++)
	65	buf[i] = task->thread.fp_state.fpr[i][TS_VSRLOWOFFSET];
	66	return __copy_to_user(to, buf, ELF_NVSRHALFREG * sizeof(double));
	67	}
	68
	69	unsigned long copy_vsx_from_user(struct task_struct *task,
	70	void __user *from)
	71	{
	72	u64 buf[ELF_NVSRHALFREG];
	73	int i;
	74
	75	if (__copy_from_user(buf, from, ELF_NVSRHALFREG * sizeof(double)))
	76	return 1;
	77	for (i = 0; i < ELF_NVSRHALFREG ; i++)
	78	task->thread.fp_state.fpr[i][TS_VSRLOWOFFSET] = buf[i];
	79	return 0;
	80	}
	81
	82	#ifdef CONFIG_PPC_TRANSACTIONAL_MEM
	83	unsigned long copy_ckfpr_to_user(void __user *to,
	84	struct task_struct *task)
	85	{
	86	u64 buf[ELF_NFPREG];
	87	int i;
	88
	89	/* save FPR copy to local buffer then write to the thread_struct */
	90	for (i = 0; i < (ELF_NFPREG - 1) ; i++)
	91	buf[i] = task->thread.TS_CKFPR(i);
	92	buf[i] = task->thread.ckfp_state.fpscr;
	93	return __copy_to_user(to, buf, ELF_NFPREG * sizeof(double));
	94	}
	95
	96	unsigned long copy_ckfpr_from_user(struct task_struct *task,
	97	void __user *from)
	98	{
	99	u64 buf[ELF_NFPREG];
	100	int i;
	101
	102	if (__copy_from_user(buf, from, ELF_NFPREG * sizeof(double)))
	103	return 1;
	104	for (i = 0; i < (ELF_NFPREG - 1) ; i++)
	105	task->thread.TS_CKFPR(i) = buf[i];
	106	task->thread.ckfp_state.fpscr = buf[i];
	107
	108	return 0;
	109	}
	110
	111	unsigned long copy_ckvsx_to_user(void __user *to,
	112	struct task_struct *task)
	113	{
	114	u64 buf[ELF_NVSRHALFREG];
	115	int i;
	116
	117	/* save FPR copy to local buffer then write to the thread_struct */
	118	for (i = 0; i < ELF_NVSRHALFREG; i++)
	119	buf[i] = task->thread.ckfp_state.fpr[i][TS_VSRLOWOFFSET];
	120	return __copy_to_user(to, buf, ELF_NVSRHALFREG * sizeof(double));
	121	}
	122
	123	unsigned long copy_ckvsx_from_user(struct task_struct *task,
	124	void __user *from)
	125	{
	126	u64 buf[ELF_NVSRHALFREG];
	127	int i;
	128
	129	if (__copy_from_user(buf, from, ELF_NVSRHALFREG * sizeof(double)))
	130	return 1;
	131	for (i = 0; i < ELF_NVSRHALFREG ; i++)
	132	task->thread.ckfp_state.fpr[i][TS_VSRLOWOFFSET] = buf[i];
	133	return 0;
	134	}
	135	#endif /* CONFIG_PPC_TRANSACTIONAL_MEM */
	136	#endif
	137
	138	/* Log an error when sending an unhandled signal to a process. Controlled
	139	* through debug.exception-trace sysctl.
	140	*/
	141
	142	int show_unhandled_signals = 1;
	143
	144	/*
	145	* Allocate space for the signal frame
	146	*/
	147	static unsigned long get_tm_stackpointer(struct task_struct *tsk);
	148
	149	void __user get_sigframe(struct ksignal ksig, struct task_struct *tsk,
	150	size_t frame_size, int is_32)
	151	{
	152	unsigned long oldsp, newsp;
	153	unsigned long sp = get_tm_stackpointer(tsk);
	154
	155	/* Default to using normal stack */
	156	if (is_32)
	157	oldsp = sp & 0x0ffffffffUL;
	158	else
	159	oldsp = sp;
	160	oldsp = sigsp(oldsp, ksig);
	161	newsp = (oldsp - frame_size) & ~0xFUL;
	162
	163	return (void __user *)newsp;
	164	}
	165
	166	static void check_syscall_restart(struct pt_regs regs, struct k_sigaction ka,
	167	int has_handler)
	168	{
	169	unsigned long ret = regs->gpr[3];
	170	int restart = 1;
	171
	172	/* syscall ? */
	173	if (!trap_is_syscall(regs))
	174	return;
	175
	176	if (trap_norestart(regs))
	177	return;
	178
	179	/* error signalled ? */
	180	if (trap_is_scv(regs)) {
	181	/* 32-bit compat mode sign extend? */
	182	if (!IS_ERR_VALUE(ret))
	183	return;
	184	ret = -ret;
	185	} else if (!(regs->ccr & 0x10000000)) {
	186	return;
	187	}
	188
	189	switch (ret) {
	190	case ERESTART_RESTARTBLOCK:
	191	case ERESTARTNOHAND:
	192	/* ERESTARTNOHAND means that the syscall should only be
	193	* restarted if there was no handler for the signal, and since
	194	* we only get here if there is a handler, we dont restart.
	195	*/
	196	restart = !has_handler;
	197	break;
	198	case ERESTARTSYS:
	199	/* ERESTARTSYS means to restart the syscall if there is no
	200	* handler or the handler was registered with SA_RESTART
	201	*/
	202	restart = !has_handler \|\| (ka->sa.sa_flags & SA_RESTART) != 0;
	203	break;
	204	case ERESTARTNOINTR:
	205	/* ERESTARTNOINTR means that the syscall should be
	206	* called again after the signal handler returns.
	207	*/
	208	break;
	209	default:
	210	return;
	211	}
	212	if (restart) {
	213	if (ret == ERESTART_RESTARTBLOCK)
	214	regs->gpr[0] = __NR_restart_syscall;
	215	else
	216	regs->gpr[3] = regs->orig_gpr3;
	217	regs->nip -= 4;
	218	regs->result = 0;
	219	} else {
	220	if (trap_is_scv(regs)) {
	221	regs->result = -EINTR;
	222	regs->gpr[3] = -EINTR;
	223	} else {
	224	regs->result = -EINTR;
	225	regs->gpr[3] = EINTR;
	226	regs->ccr \|= 0x10000000;
	227	}
	228	}
	229	}
	230
	231	static void do_signal(struct task_struct *tsk)
	232	{
	233	sigset_t *oldset = sigmask_to_save();
	234	struct ksignal ksig = { .sig = 0 };
	235	int ret;
	236
	237	BUG_ON(tsk != current);
	238
	239	get_signal(&ksig);
	240
	241	/* Is there any syscall restart business here ? */
	242	check_syscall_restart(tsk->thread.regs, &ksig.ka, ksig.sig > 0);
	243
	244	if (ksig.sig <= 0) {
	245	/* No signal to deliver -- put the saved sigmask back */
	246	restore_saved_sigmask();
	247	set_trap_norestart(tsk->thread.regs);
	248	return; /* no signals delivered */
	249	}
	250
	251	/*
	252	* Reenable the DABR before delivering the signal to
	253	* user space. The DABR will have been cleared if it
	254	* triggered inside the kernel.
	255	*/
	256	if (!IS_ENABLED(CONFIG_PPC_ADV_DEBUG_REGS)) {
	257	int i;
	258
	259	for (i = 0; i < nr_wp_slots(); i++) {
	260	if (tsk->thread.hw_brk[i].address && tsk->thread.hw_brk[i].type)
	261	__set_breakpoint(i, &tsk->thread.hw_brk[i]);
	262	}
	263	}
	264
	265	/* Re-enable the breakpoints for the signal stack */
	266	thread_change_pc(tsk, tsk->thread.regs);
	267
	268	rseq_signal_deliver(&ksig, tsk->thread.regs);
	269
	270	if (is_32bit_task()) {
	271	if (ksig.ka.sa.sa_flags & SA_SIGINFO)
	272	ret = handle_rt_signal32(&ksig, oldset, tsk);
	273	else
	274	ret = handle_signal32(&ksig, oldset, tsk);
	275	} else {
	276	ret = handle_rt_signal64(&ksig, oldset, tsk);
	277	}
	278
	279	set_trap_norestart(tsk->thread.regs);
	280	signal_setup_done(ret, &ksig, test_thread_flag(TIF_SINGLESTEP));
	281	}
	282
	283	void do_notify_resume(struct pt_regs *regs, unsigned long thread_info_flags)
	284	{
	285	user_exit();
	286
	287	if (thread_info_flags & _TIF_UPROBE)
	288	uprobe_notify_resume(regs);
	289
	290	if (thread_info_flags & _TIF_PATCH_PENDING)
	291	klp_update_patch_state(current);
	292
	293	if (thread_info_flags & (_TIF_SIGPENDING \| _TIF_NOTIFY_SIGNAL)) {
	294	BUG_ON(regs != current->thread.regs);
	295	do_signal(current);
	296	}
	297
	298	if (thread_info_flags & _TIF_NOTIFY_RESUME) {
	299	tracehook_notify_resume(regs);
	300	rseq_handle_notify_resume(NULL, regs);
	301	}
	302
	303	user_enter();
	304	}
	305
	306	static unsigned long get_tm_stackpointer(struct task_struct *tsk)
	307	{
	308	/* When in an active transaction that takes a signal, we need to be
	309	* careful with the stack. It's possible that the stack has moved back
	310	* up after the tbegin. The obvious case here is when the tbegin is
	311	* called inside a function that returns before a tend. In this case,
	312	* the stack is part of the checkpointed transactional memory state.
	313	* If we write over this non transactionally or in suspend, we are in
	314	* trouble because if we get a tm abort, the program counter and stack
	315	* pointer will be back at the tbegin but our in memory stack won't be
	316	* valid anymore.
	317	*
	318	* To avoid this, when taking a signal in an active transaction, we
	319	* need to use the stack pointer from the checkpointed state, rather
	320	* than the speculated state. This ensures that the signal context
	321	* (written tm suspended) will be written below the stack required for
	322	* the rollback. The transaction is aborted because of the treclaim,
	323	* so any memory written between the tbegin and the signal will be
	324	* rolled back anyway.
	325	*
	326	* For signals taken in non-TM or suspended mode, we use the
	327	* normal/non-checkpointed stack pointer.
	328	*/
	329
	330	unsigned long ret = tsk->thread.regs->gpr[1];
	331
	332	#ifdef CONFIG_PPC_TRANSACTIONAL_MEM
	333	BUG_ON(tsk != current);
	334
	335	if (MSR_TM_ACTIVE(tsk->thread.regs->msr)) {
	336	preempt_disable();
	337	tm_reclaim_current(TM_CAUSE_SIGNAL);
	338	if (MSR_TM_TRANSACTIONAL(tsk->thread.regs->msr))
	339	ret = tsk->thread.ckpt_regs.gpr[1];
	340
	341	/*
	342	* If we treclaim, we must clear the current thread's TM bits
	343	* before re-enabling preemption. Otherwise we might be
	344	* preempted and have the live MSR[TS] changed behind our back
	345	* (tm_recheckpoint_new_task() would recheckpoint). Besides, we
	346	* enter the signal handler in non-transactional state.
	347	*/
	348	tsk->thread.regs->msr &= ~MSR_TS_MASK;
	349	preempt_enable();
	350	}
	351	#endif
	352	return ret;
	353	}
	354
	355	static const char fm32[] = KERN_INFO "%s[%d]: bad frame in %s: %p nip %08lx lr %08lx\n";
	356	static const char fm64[] = KERN_INFO "%s[%d]: bad frame in %s: %p nip %016lx lr %016lx\n";
	357
	358	void signal_fault(struct task_struct tsk, struct pt_regs regs,
	359	const char where, void __user ptr)
	360	{
	361	if (show_unhandled_signals)
	362	printk_ratelimited(regs->msr & MSR_64BIT ? fm64 : fm32, tsk->comm,
	363	task_pid_nr(tsk), where, ptr, regs->nip, regs->link);
	364	}