arch/hexagon/kernel/signal.c - maze/linux - Git at Google

 /*
  * Signal support for Hexagon processor
  *
  * Copyright (c) 2010-2011, Code Aurora Forum. All rights reserved.
  *
  * This program is free software; you can redistribute it and/or modify
  * it under the terms of the GNU General Public License version 2 and
  * only version 2 as published by the Free Software Foundation.
  *
  * This program is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  * GNU General Public License for more details.
  *
  * You should have received a copy of the GNU General Public License
  * along with this program; if not, write to the Free Software
  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
  * 02110-1301, USA.
  */

 #include <linux/linkage.h>
 #include <linux/syscalls.h>
 #include <linux/freezer.h>
 #include <linux/tracehook.h>
 #include <asm/registers.h>
 #include <asm/thread_info.h>
 #include <asm/unistd.h>
 #include <asm/uaccess.h>
 #include <asm/ucontext.h>
 #include <asm/cacheflush.h>
 #include <asm/signal.h>
 #include <asm/vdso.h>

 #define _BLOCKABLE (~(sigmask(SIGKILL) | sigmask(SIGSTOP)))

 struct rt_sigframe {
 	unsigned long tramp[2];
 	struct siginfo info;
 	struct ucontext uc;
 };

 static void __user *get_sigframe(struct k_sigaction *ka, struct pt_regs *regs,
 			  size_t frame_size)
 {
 	unsigned long sp = regs->r29;

 	/* Switch to signal stack if appropriate */
 	if ((ka->sa.sa_flags & SA_ONSTACK) && (sas_ss_flags(sp) == 0))
 		sp = current->sas_ss_sp + current->sas_ss_size;

 	return (void __user *)((sp - frame_size) & ~(sizeof(long long) - 1));
 }

 static int setup_sigcontext(struct pt_regs *regs, struct sigcontext __user *sc)
 {
 	unsigned long tmp;
 	int err = 0;

 	err |= copy_to_user(&sc->sc_regs.r0, &regs->r00,
 			    32*sizeof(unsigned long));

 	err |= __put_user(regs->sa0, &sc->sc_regs.sa0);
 	err |= __put_user(regs->lc0, &sc->sc_regs.lc0);
 	err |= __put_user(regs->sa1, &sc->sc_regs.sa1);
 	err |= __put_user(regs->lc1, &sc->sc_regs.lc1);
 	err |= __put_user(regs->m0, &sc->sc_regs.m0);
 	err |= __put_user(regs->m1, &sc->sc_regs.m1);
 	err |= __put_user(regs->usr, &sc->sc_regs.usr);
 	err |= __put_user(regs->preds, &sc->sc_regs.p3_0);
 	err |= __put_user(regs->gp, &sc->sc_regs.gp);
 	err |= __put_user(regs->ugp, &sc->sc_regs.ugp);

 	tmp = pt_elr(regs); err |= __put_user(tmp, &sc->sc_regs.pc);
 	tmp = pt_cause(regs); err |= __put_user(tmp, &sc->sc_regs.cause);
 	tmp = pt_badva(regs); err |= __put_user(tmp, &sc->sc_regs.badva);

 	return err;
 }

 static int restore_sigcontext(struct pt_regs *regs,
 			      struct sigcontext __user *sc)
 {
 	unsigned long tmp;
 	int err = 0;

 	err |= copy_from_user(&regs->r00, &sc->sc_regs.r0,
 			      32 * sizeof(unsigned long));

 	err |= __get_user(regs->sa0, &sc->sc_regs.sa0);
 	err |= __get_user(regs->lc0, &sc->sc_regs.lc0);
 	err |= __get_user(regs->sa1, &sc->sc_regs.sa1);
 	err |= __get_user(regs->lc1, &sc->sc_regs.lc1);
 	err |= __get_user(regs->m0, &sc->sc_regs.m0);
 	err |= __get_user(regs->m1, &sc->sc_regs.m1);
 	err |= __get_user(regs->usr, &sc->sc_regs.usr);
 	err |= __get_user(regs->preds, &sc->sc_regs.p3_0);
 	err |= __get_user(regs->gp, &sc->sc_regs.gp);
 	err |= __get_user(regs->ugp, &sc->sc_regs.ugp);

 	err |= __get_user(tmp, &sc->sc_regs.pc); pt_set_elr(regs, tmp);

 	return err;
 }

 /*
  * Setup signal stack frame with siginfo structure
  */
 static int setup_rt_frame(int signr, struct k_sigaction *ka, siginfo_t *info,
 			  sigset_t *set,  struct pt_regs *regs)
 {
 	int err = 0;
 	struct rt_sigframe __user *frame;
 	struct hexagon_vdso *vdso = current->mm->context.vdso;

 	frame = get_sigframe(ka, regs, sizeof(struct rt_sigframe));

 	if (!access_ok(VERIFY_WRITE, frame, sizeof(struct rt_sigframe)))
 		goto	sigsegv;

 	if (copy_siginfo_to_user(&frame->info, info))
 		goto	sigsegv;

 	/* The on-stack signal trampoline is no longer executed;
 	 * however, the libgcc signal frame unwinding code checks for
 	 * the presence of these two numeric magic values.
 	 */
 	err |= __put_user(0x7800d166, &frame->tramp[0]);
 	err |= __put_user(0x5400c004, &frame->tramp[1]);
 	err |= setup_sigcontext(regs, &frame->uc.uc_mcontext);
 	err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));
 	if (err)
 		goto sigsegv;

 	/* Load r0/r1 pair with signumber/siginfo pointer... */
 	regs->r0100 = ((unsigned long long)((unsigned long)&frame->info) << 32)
 		| (unsigned long long)signr;
 	regs->r02 = (unsigned long) &frame->uc;
 	regs->r31 = (unsigned long) vdso->rt_signal_trampoline;
 	pt_psp(regs) = (unsigned long) frame;
 	pt_set_elr(regs, (unsigned long)ka->sa.sa_handler);

 	return 0;

 sigsegv:
 	force_sigsegv(signr, current);
 	return -EFAULT;
 }

 /*
  * Setup invocation of signal handler
  */
 static int handle_signal(int sig, siginfo_t *info, struct k_sigaction *ka,
 			 sigset_t *oldset, struct pt_regs *regs)
 {
 	int rc;

 	/*
 	 * If we're handling a signal that aborted a system call,
 	 * set up the error return value before adding the signal
 	 * frame to the stack.
 	 */

 	if (regs->syscall_nr >= 0) {
 		switch (regs->r00) {
 		case -ERESTART_RESTARTBLOCK:
 		case -ERESTARTNOHAND:
 			regs->r00 = -EINTR;
 			break;
 		case -ERESTARTSYS:
 			if (!(ka->sa.sa_flags & SA_RESTART)) {
 				regs->r00 = -EINTR;
 				break;
 			}
 			/* Fall through */
 		case -ERESTARTNOINTR:
 			regs->r06 = regs->syscall_nr;
 			pt_set_elr(regs, pt_elr(regs) - 4);
 			regs->r00 = regs->restart_r0;
 			break;
 		default:
 			break;
 		}
 	}

 	/*
 	 * Set up the stack frame; not doing the SA_SIGINFO thing.  We
 	 * only set up the rt_frame flavor.
 	 */
 	rc = setup_rt_frame(sig, ka, info, oldset, regs);

 	/* If there was an error on setup, no signal was delivered. */
 	if (rc)
 		return rc;

 	spin_lock_irq(&current->sighand->siglock);
 	sigorsets(&current->blocked, &current->blocked, &ka->sa.sa_mask);
 	if (!(ka->sa.sa_flags & SA_NODEFER))
 		sigaddset(&current->blocked, sig);
 	recalc_sigpending();
 	spin_unlock_irq(&current->sighand->siglock);

 	return 0;
 }

 /*
  * Called from return-from-event code.
  */
 static void do_signal(struct pt_regs *regs)
 {
 	struct k_sigaction sigact;
 	siginfo_t info;
 	int signo;

 	if (!user_mode(regs))
 		return;

 	if (try_to_freeze())
 		goto no_signal;

 	signo = get_signal_to_deliver(&info, &sigact, regs, NULL);

 	if (signo > 0) {
 		sigset_t *oldset;

 		if (test_thread_flag(TIF_RESTORE_SIGMASK))
 			oldset = &current->saved_sigmask;
 		else
 			oldset = &current->blocked;

 		if (handle_signal(signo, &info, &sigact, oldset, regs) == 0) {
 			/*
 			 * Successful delivery case.  The saved sigmask is
 			 * stored in the signal frame, and will be restored
 			 * by sigreturn.  We can clear the TIF flag.
 			 */
 			clear_thread_flag(TIF_RESTORE_SIGMASK);

 			tracehook_signal_handler(signo, &info, &sigact, regs,
 				test_thread_flag(TIF_SINGLESTEP));
 		}
 		return;
 	}

 no_signal:
 	/*
 	 * If we came from a system call, handle the restart.
 	 */
 	if (regs->syscall_nr >= 0) {
 		switch (regs->r00) {
 		case -ERESTARTNOHAND:
 		case -ERESTARTSYS:
 		case -ERESTARTNOINTR:
 			regs->r06 = regs->syscall_nr;
 			break;
 		case -ERESTART_RESTARTBLOCK:
 			regs->r06 = __NR_restart_syscall;
 			break;
 		default:
 			goto no_restart;
 		}
 		pt_set_elr(regs, pt_elr(regs) - 4);
 		regs->r00 = regs->restart_r0;
 	}

 no_restart:
 	/* If there's no signal to deliver, put the saved sigmask back */
 	if (test_thread_flag(TIF_RESTORE_SIGMASK)) {
 		clear_thread_flag(TIF_RESTORE_SIGMASK);
 		sigprocmask(SIG_SETMASK, &current->saved_sigmask, NULL);
 	}
 }

 void do_notify_resume(struct pt_regs *regs, unsigned long thread_info_flags)
 {
 	if (thread_info_flags & _TIF_SIGPENDING)
 		do_signal(regs);

 	if (thread_info_flags & _TIF_NOTIFY_RESUME) {
 		clear_thread_flag(TIF_NOTIFY_RESUME);
 		if (current->replacement_session_keyring)
 			key_replace_session_keyring();
 	}
 }

 /*
  * Architecture-specific wrappers for signal-related system calls
  */
 asmlinkage int sys_sigaltstack(const stack_t __user *uss, stack_t __user *uoss)
 {
 	struct pt_regs *regs = current_thread_info()->regs;

 	return do_sigaltstack(uss, uoss, regs->r29);
 }

 asmlinkage int sys_rt_sigreturn(void)
 {
 	struct pt_regs *regs = current_thread_info()->regs;
 	struct rt_sigframe __user *frame;
 	sigset_t blocked;

 	frame = (struct rt_sigframe __user *)pt_psp(regs);
 	if (!access_ok(VERIFY_READ, frame, sizeof(*frame)))
 		goto badframe;
 	if (__copy_from_user(&blocked, &frame->uc.uc_sigmask, sizeof(blocked)))
 		goto badframe;

 	sigdelsetmask(&blocked, ~_BLOCKABLE);
 	spin_lock_irq(&current->sighand->siglock);
 	current->blocked = blocked;
 	recalc_sigpending();
 	spin_unlock_irq(&current->sighand->siglock);

 	if (restore_sigcontext(regs, &frame->uc.uc_mcontext))
 		goto badframe;

 	/* Restore the user's stack as well */
 	pt_psp(regs) = regs->r29;

 	/*
 	 * Leave a trace in the stack frame that this was a sigreturn.
 	 * If the system call is to replay, we've already restored the
 	 * number in the GPR slot and it will be regenerated on the
 	 * new system call trap entry. Note that if restore_sigcontext()
 	 * did something other than a bulk copy of the pt_regs struct,
 	 * we could avoid this assignment by simply not overwriting
 	 * regs->syscall_nr.
 	 */
 	regs->syscall_nr = __NR_rt_sigreturn;

 	/*
 	 * If we were meticulous, we'd only call this if we knew that
 	 * we were actually going to use an alternate stack, and we'd
 	 * consider any error to be fatal.  What we do here, in common
 	 * with many other architectures, is call it blindly and only
 	 * consider the -EFAULT return case to be proof of a problem.
 	 */
 	if (do_sigaltstack(&frame->uc.uc_stack, NULL, pt_psp(regs)) == -EFAULT)
 		goto badframe;

 	return 0;

 badframe:
 	force_sig(SIGSEGV, current);
 	return 0;
 }
	/*
	* Signal support for Hexagon processor
	*
	* Copyright (c) 2010-2011, Code Aurora Forum. All rights reserved.
	*
	* This program is free software; you can redistribute it and/or modify
	* it under the terms of the GNU General Public License version 2 and
	* only version 2 as published by the Free Software Foundation.
	*
	* This program is distributed in the hope that it will be useful,
	* but WITHOUT ANY WARRANTY; without even the implied warranty of
	* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
	* GNU General Public License for more details.
	*
	* You should have received a copy of the GNU General Public License
	* along with this program; if not, write to the Free Software
	* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
	* 02110-1301, USA.
	*/

	#include <linux/linkage.h>
	#include <linux/syscalls.h>
	#include <linux/freezer.h>
	#include <linux/tracehook.h>
	#include <asm/registers.h>
	#include <asm/thread_info.h>
	#include <asm/unistd.h>
	#include <asm/uaccess.h>
	#include <asm/ucontext.h>
	#include <asm/cacheflush.h>
	#include <asm/signal.h>
	#include <asm/vdso.h>

	#define _BLOCKABLE (~(sigmask(SIGKILL) \| sigmask(SIGSTOP)))

	struct rt_sigframe {
	unsigned long tramp[2];
	struct siginfo info;
	struct ucontext uc;
	};

	static void __user get_sigframe(struct k_sigaction ka, struct pt_regs *regs,
	size_t frame_size)
	{
	unsigned long sp = regs->r29;

	/* Switch to signal stack if appropriate */
	if ((ka->sa.sa_flags & SA_ONSTACK) && (sas_ss_flags(sp) == 0))
	sp = current->sas_ss_sp + current->sas_ss_size;

	return (void __user *)((sp - frame_size) & ~(sizeof(long long) - 1));
	}

	static int setup_sigcontext(struct pt_regs regs, struct sigcontext __user sc)
	{
	unsigned long tmp;
	int err = 0;

	err \|= copy_to_user(&sc->sc_regs.r0, &regs->r00,
	32*sizeof(unsigned long));

	err \|= __put_user(regs->sa0, &sc->sc_regs.sa0);
	err \|= __put_user(regs->lc0, &sc->sc_regs.lc0);
	err \|= __put_user(regs->sa1, &sc->sc_regs.sa1);
	err \|= __put_user(regs->lc1, &sc->sc_regs.lc1);
	err \|= __put_user(regs->m0, &sc->sc_regs.m0);
	err \|= __put_user(regs->m1, &sc->sc_regs.m1);
	err \|= __put_user(regs->usr, &sc->sc_regs.usr);
	err \|= __put_user(regs->preds, &sc->sc_regs.p3_0);
	err \|= __put_user(regs->gp, &sc->sc_regs.gp);
	err \|= __put_user(regs->ugp, &sc->sc_regs.ugp);

	tmp = pt_elr(regs); err \|= __put_user(tmp, &sc->sc_regs.pc);
	tmp = pt_cause(regs); err \|= __put_user(tmp, &sc->sc_regs.cause);
	tmp = pt_badva(regs); err \|= __put_user(tmp, &sc->sc_regs.badva);

	return err;
	}

	static int restore_sigcontext(struct pt_regs *regs,
	struct sigcontext __user *sc)
	{
	unsigned long tmp;
	int err = 0;

	err \|= copy_from_user(&regs->r00, &sc->sc_regs.r0,
	32 * sizeof(unsigned long));

	err \|= __get_user(regs->sa0, &sc->sc_regs.sa0);
	err \|= __get_user(regs->lc0, &sc->sc_regs.lc0);
	err \|= __get_user(regs->sa1, &sc->sc_regs.sa1);
	err \|= __get_user(regs->lc1, &sc->sc_regs.lc1);
	err \|= __get_user(regs->m0, &sc->sc_regs.m0);
	err \|= __get_user(regs->m1, &sc->sc_regs.m1);
	err \|= __get_user(regs->usr, &sc->sc_regs.usr);
	err \|= __get_user(regs->preds, &sc->sc_regs.p3_0);
	err \|= __get_user(regs->gp, &sc->sc_regs.gp);
	err \|= __get_user(regs->ugp, &sc->sc_regs.ugp);

	err \|= __get_user(tmp, &sc->sc_regs.pc); pt_set_elr(regs, tmp);

	return err;
	}

	/*
	* Setup signal stack frame with siginfo structure
	*/
	static int setup_rt_frame(int signr, struct k_sigaction ka, siginfo_t info,
	sigset_t set, struct pt_regs regs)
	{
	int err = 0;
	struct rt_sigframe __user *frame;
	struct hexagon_vdso *vdso = current->mm->context.vdso;

	frame = get_sigframe(ka, regs, sizeof(struct rt_sigframe));

	if (!access_ok(VERIFY_WRITE, frame, sizeof(struct rt_sigframe)))
	goto sigsegv;

	if (copy_siginfo_to_user(&frame->info, info))
	goto sigsegv;

	/* The on-stack signal trampoline is no longer executed;
	* however, the libgcc signal frame unwinding code checks for
	* the presence of these two numeric magic values.
	*/
	err \|= __put_user(0x7800d166, &frame->tramp[0]);
	err \|= __put_user(0x5400c004, &frame->tramp[1]);
	err \|= setup_sigcontext(regs, &frame->uc.uc_mcontext);
	err \|= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));
	if (err)
	goto sigsegv;

	/* Load r0/r1 pair with signumber/siginfo pointer... */
	regs->r0100 = ((unsigned long long)((unsigned long)&frame->info) << 32)
	\| (unsigned long long)signr;
	regs->r02 = (unsigned long) &frame->uc;
	regs->r31 = (unsigned long) vdso->rt_signal_trampoline;
	pt_psp(regs) = (unsigned long) frame;
	pt_set_elr(regs, (unsigned long)ka->sa.sa_handler);

	return 0;

	sigsegv:
	force_sigsegv(signr, current);
	return -EFAULT;
	}

	/*
	* Setup invocation of signal handler
	*/
	static int handle_signal(int sig, siginfo_t info, struct k_sigaction ka,
	sigset_t oldset, struct pt_regs regs)
	{
	int rc;

	/*
	* If we're handling a signal that aborted a system call,
	* set up the error return value before adding the signal
	* frame to the stack.
	*/

	if (regs->syscall_nr >= 0) {
	switch (regs->r00) {
	case -ERESTART_RESTARTBLOCK:
	case -ERESTARTNOHAND:
	regs->r00 = -EINTR;
	break;
	case -ERESTARTSYS:
	if (!(ka->sa.sa_flags & SA_RESTART)) {
	regs->r00 = -EINTR;
	break;
	}
	/* Fall through */
	case -ERESTARTNOINTR:
	regs->r06 = regs->syscall_nr;
	pt_set_elr(regs, pt_elr(regs) - 4);
	regs->r00 = regs->restart_r0;
	break;
	default:
	break;
	}
	}

	/*
	* Set up the stack frame; not doing the SA_SIGINFO thing. We
	* only set up the rt_frame flavor.
	*/
	rc = setup_rt_frame(sig, ka, info, oldset, regs);

	/* If there was an error on setup, no signal was delivered. */
	if (rc)
	return rc;

	spin_lock_irq(&current->sighand->siglock);
	sigorsets(&current->blocked, &current->blocked, &ka->sa.sa_mask);
	if (!(ka->sa.sa_flags & SA_NODEFER))
	sigaddset(&current->blocked, sig);
	recalc_sigpending();
	spin_unlock_irq(&current->sighand->siglock);

	return 0;
	}

	/*
	* Called from return-from-event code.
	*/
	static void do_signal(struct pt_regs *regs)
	{
	struct k_sigaction sigact;
	siginfo_t info;
	int signo;

	if (!user_mode(regs))
	return;

	if (try_to_freeze())
	goto no_signal;

	signo = get_signal_to_deliver(&info, &sigact, regs, NULL);

	if (signo > 0) {
	sigset_t *oldset;

	if (test_thread_flag(TIF_RESTORE_SIGMASK))
	oldset = &current->saved_sigmask;
	else
	oldset = &current->blocked;

	if (handle_signal(signo, &info, &sigact, oldset, regs) == 0) {
	/*
	* Successful delivery case. The saved sigmask is
	* stored in the signal frame, and will be restored
	* by sigreturn. We can clear the TIF flag.
	*/
	clear_thread_flag(TIF_RESTORE_SIGMASK);

	tracehook_signal_handler(signo, &info, &sigact, regs,
	test_thread_flag(TIF_SINGLESTEP));
	}
	return;
	}

	no_signal:
	/*
	* If we came from a system call, handle the restart.
	*/
	if (regs->syscall_nr >= 0) {
	switch (regs->r00) {
	case -ERESTARTNOHAND:
	case -ERESTARTSYS:
	case -ERESTARTNOINTR:
	regs->r06 = regs->syscall_nr;
	break;
	case -ERESTART_RESTARTBLOCK:
	regs->r06 = __NR_restart_syscall;
	break;
	default:
	goto no_restart;
	}
	pt_set_elr(regs, pt_elr(regs) - 4);
	regs->r00 = regs->restart_r0;
	}

	no_restart:
	/* If there's no signal to deliver, put the saved sigmask back */
	if (test_thread_flag(TIF_RESTORE_SIGMASK)) {
	clear_thread_flag(TIF_RESTORE_SIGMASK);
	sigprocmask(SIG_SETMASK, &current->saved_sigmask, NULL);
	}
	}

	void do_notify_resume(struct pt_regs *regs, unsigned long thread_info_flags)
	{
	if (thread_info_flags & _TIF_SIGPENDING)
	do_signal(regs);

	if (thread_info_flags & _TIF_NOTIFY_RESUME) {
	clear_thread_flag(TIF_NOTIFY_RESUME);
	if (current->replacement_session_keyring)
	key_replace_session_keyring();
	}
	}

	/*
	* Architecture-specific wrappers for signal-related system calls
	*/
	asmlinkage int sys_sigaltstack(const stack_t __user uss, stack_t __user uoss)
	{
	struct pt_regs *regs = current_thread_info()->regs;

	return do_sigaltstack(uss, uoss, regs->r29);
	}

	asmlinkage int sys_rt_sigreturn(void)
	{
	struct pt_regs *regs = current_thread_info()->regs;
	struct rt_sigframe __user *frame;
	sigset_t blocked;

	frame = (struct rt_sigframe __user *)pt_psp(regs);
	if (!access_ok(VERIFY_READ, frame, sizeof(*frame)))
	goto badframe;
	if (__copy_from_user(&blocked, &frame->uc.uc_sigmask, sizeof(blocked)))
	goto badframe;

	sigdelsetmask(&blocked, ~_BLOCKABLE);
	spin_lock_irq(&current->sighand->siglock);
	current->blocked = blocked;
	recalc_sigpending();
	spin_unlock_irq(&current->sighand->siglock);

	if (restore_sigcontext(regs, &frame->uc.uc_mcontext))
	goto badframe;

	/* Restore the user's stack as well */
	pt_psp(regs) = regs->r29;

	/*
	* Leave a trace in the stack frame that this was a sigreturn.
	* If the system call is to replay, we've already restored the
	* number in the GPR slot and it will be regenerated on the
	* new system call trap entry. Note that if restore_sigcontext()
	* did something other than a bulk copy of the pt_regs struct,
	* we could avoid this assignment by simply not overwriting
	* regs->syscall_nr.
	*/
	regs->syscall_nr = __NR_rt_sigreturn;

	/*
	* If we were meticulous, we'd only call this if we knew that
	* we were actually going to use an alternate stack, and we'd
	* consider any error to be fatal. What we do here, in common
	* with many other architectures, is call it blindly and only
	* consider the -EFAULT return case to be proof of a problem.
	*/
	if (do_sigaltstack(&frame->uc.uc_stack, NULL, pt_psp(regs)) == -EFAULT)
	goto badframe;

	return 0;

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