Release 4.14 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 <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(VERIFY_WRITE, (void __user *)newsp, oldsp - newsp))
		return NULL;

        return (void __user *)newsp;
}

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Benjamin Herrenschmidt
70
78.65%
1
25.00%
Josh Boyer
8
8.99%
1
25.00%
Richard Weinberger
7
7.87%
1
25.00%
Michael Neuling
4
4.49%
1
25.00%
Total
89
100.00%
4
100.00%



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;
	}
}

Contributors
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Benjamin Herrenschmidt
176
99.44%
1
50.00%
Christoph Hellwig
1
0.56%
1
50.00%
Total
177
100.00%
2
100.00%



static void do_signal(struct task_struct *tsk)
{
	sigset_t *oldset = sigmask_to_save();
	struct ksignal ksig;
	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);

	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));
}

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Christoph Hellwig
104
47.71%
1
6.67%
Cyril Bur
32
14.68%
1
6.67%
Richard Weinberger
22
10.09%
1
6.67%
Al Viro
17
7.80%
3
20.00%
Michael Neuling
14
6.42%
2
13.33%
Roland McGrath
11
5.05%
2
13.33%
K.Prasad
7
3.21%
1
6.67%
Benjamin Herrenschmidt
5
2.29%
1
6.67%
Dave Kleikamp
3
1.38%
1
6.67%
Luis Machado
2
0.92%
1
6.67%
Paul Gortmaker
1
0.46%
1
6.67%
Total
218
100.00%
15
100.00%



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_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);
	}

	if (thread_info_flags & _TIF_PATCH_PENDING)
		klp_update_patch_state(current);

	user_enter();
}

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CommitProp
Roland McGrath
41
48.81%
1
16.67%
Cyril Bur
14
16.67%
1
16.67%
Josh Poimboeuf
11
13.10%
1
16.67%
Ananth N. Mavinakayanahalli
11
13.10%
1
16.67%
Li Zhong
6
7.14%
1
16.67%
Benjamin Herrenschmidt
1
1.19%
1
16.67%
Total
84
100.00%
6
100.00%



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.
         */

#ifdef CONFIG_PPC_TRANSACTIONAL_MEM
	BUG_ON(tsk != current);

	if (MSR_TM_ACTIVE(tsk->thread.regs->msr)) {
		tm_reclaim_current(TM_CAUSE_SIGNAL);
		if (MSR_TM_TRANSACTIONAL(tsk->thread.regs->msr))
			return tsk->thread.ckpt_regs.gpr[1];
	}
#endif
	return tsk->thread.regs->gpr[1];
}
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Michael Neuling
57
70.37%
1
25.00%
Cyril Bur
22
27.16%
1
25.00%
Paul Mackerras
1
1.23%
1
25.00%
Adam Buchbinder
1
1.23%
1
25.00%
Total
81
100.00%
4
100.00%

Overall Contributors
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Tokens
Prop
Commits
CommitProp
Benjamin Herrenschmidt
267
38.53%
4
13.33%
Christoph Hellwig
108
15.58%
2
6.67%
Michael Neuling
78
11.26%
3
10.00%
Cyril Bur
68
9.81%
1
3.33%
Roland McGrath
53
7.65%
2
6.67%
Richard Weinberger
29
4.18%
2
6.67%
Al Viro
17
2.45%
3
10.00%
Josh Poimboeuf
14
2.02%
1
3.33%
Ananth N. Mavinakayanahalli
14
2.02%
1
3.33%
K.Prasad
10
1.44%
1
3.33%
Li Zhong
9
1.30%
1
3.33%
Josh Boyer
8
1.15%
1
3.33%
Olof Johansson
5
0.72%
1
3.33%
Dave Kleikamp
3
0.43%
1
3.33%
David Howells
3
0.43%
1
3.33%
Luis Machado
2
0.29%
1
3.33%
Adam Buchbinder
2
0.29%
1
3.33%
Paul Mackerras
1
0.14%
1
3.33%
Paul Gortmaker
1
0.14%
1
3.33%
Linus Torvalds
1
0.14%
1
3.33%
Total
693
100.00%
30
100.00%
Directory: arch/powerpc/kernel

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