Merge tag 'for-3.14' of git://openrisc.net/~jonas/linux

Pull OpenRISC updates from Jonas Bonn:
"The interesting change here is a rework of the OpenRISC signal
handling to make it more like other architectures in the hopes that
this makes it easier for others to comment on and understand. This
rework fixes some real bugs, like the fact that syscall restart did
not work reliably"

* tag 'for-3.14' of git://openrisc.net/~jonas/linux:
openrisc: Use get_signal() signal_setup_done()
openrisc: Rework signal handling

arch/openrisc/kernel/entry.S

···
 
 /* ========================================================[ return ] === */
 
-_work_pending:
-	/*
-	 * if (current_thread_info->flags & _TIF_NEED_RESCHED)
-	 *     schedule();
-	 */
-	l.lwz   r5,TI_FLAGS(r10)
-	l.andi	r3,r5,_TIF_NEED_RESCHED
-	l.sfnei r3,0
-	l.bnf   _work_notifysig
-	 l.nop
-	l.jal   schedule
-	 l.nop
-	l.j	_resume_userspace
-	 l.nop
-
-/* Handle pending signals and notify-resume requests.
- * do_notify_resume must be passed the latest pushed pt_regs, not
- * necessarily the "userspace" ones.  Also, pt_regs->syscallno
- * must be set so that the syscall restart functionality works.
- */
-_work_notifysig:
-	l.jal	do_notify_resume
-	 l.ori	r3,r1,0		  /* pt_regs */
-
 _resume_userspace:
 	DISABLE_INTERRUPTS(r3,r4)
-	l.lwz	r3,TI_FLAGS(r10)
-	l.andi	r3,r3,_TIF_WORK_MASK
-	l.sfnei	r3,0
-	l.bf	_work_pending
+	l.lwz	r4,TI_FLAGS(r10)
+	l.andi	r13,r4,_TIF_WORK_MASK
+	l.sfeqi	r13,0
+	l.bf	_restore_all
 	 l.nop
+
+_work_pending:
+	l.lwz	r5,PT_ORIG_GPR11(r1)
+	l.sfltsi r5,0
+	l.bnf	1f
+	 l.nop
+	l.andi	r5,r5,0
+1:
+	l.jal	do_work_pending
+	 l.ori	r3,r1,0			/* pt_regs */
+
+	l.sfeqi	r11,0
+	l.bf	_restore_all
+	 l.nop
+	l.sfltsi r11,0
+	l.bnf	1f
+	 l.nop
+	l.and	r11,r11,r0
+	l.ori	r11,r11,__NR_restart_syscall
+	l.j	_syscall_check_trace_enter
+	 l.nop
+1:
+	l.lwz	r11,PT_ORIG_GPR11(r1)
+	/* Restore arg registers */
+	l.lwz	r3,PT_GPR3(r1)
+	l.lwz	r4,PT_GPR4(r1)
+	l.lwz	r5,PT_GPR5(r1)
+	l.lwz	r6,PT_GPR6(r1)
+	l.lwz	r7,PT_GPR7(r1)
+	l.j	_syscall_check_trace_enter
+	 l.lwz	r8,PT_GPR8(r1)
 
 _restore_all:
 	RESTORE_ALL

arch/openrisc/kernel/signal.c

···
 #include <linux/tracehook.h>
 
 #include <asm/processor.h>
+#include <asm/syscall.h>
 #include <asm/ucontext.h>
 #include <asm/uaccess.h>
 
 #define DEBUG_SIG 0
 
 struct rt_sigframe {
-	struct siginfo *pinfo;
-	void *puc;
 	struct siginfo info;
 	struct ucontext uc;
 	unsigned char retcode[16];	/* trampoline code */
 };
 
-static int restore_sigcontext(struct pt_regs *regs, struct sigcontext *sc)
+static int restore_sigcontext(struct pt_regs *regs,
+			      struct sigcontext __user *sc)
 {
-	unsigned int err = 0;
+	int err = 0;
 
-	/* Alwys make any pending restarted system call return -EINTR */
+	/* Always make any pending restarted system calls return -EINTR */
 	current_thread_info()->restart_block.fn = do_no_restart_syscall;
 
 	/*
···
 	 * (sc is already checked for VERIFY_READ since the sigframe was
 	 *  checked in sys_sigreturn previously)
 	 */
-	if (__copy_from_user(regs, sc->regs.gpr, 32 * sizeof(unsigned long)))
-		goto badframe;
-	if (__copy_from_user(&regs->pc, &sc->regs.pc, sizeof(unsigned long)))
-		goto badframe;
-	if (__copy_from_user(&regs->sr, &sc->regs.sr, sizeof(unsigned long)))
-		goto badframe;
+	err |= __copy_from_user(regs, sc->regs.gpr, 32 * sizeof(unsigned long));
+	err |= __copy_from_user(&regs->pc, &sc->regs.pc, sizeof(unsigned long));
+	err |= __copy_from_user(&regs->sr, &sc->regs.sr, sizeof(unsigned long));
 
 	/* make sure the SM-bit is cleared so user-mode cannot fool us */
 	regs->sr &= ~SPR_SR_SM;
+
+	regs->orig_gpr11 = -1;	/* Avoid syscall restart checks */
 
 	/* TODO: the other ports use regs->orig_XX to disable syscall checks
 	 * after this completes, but we don't use that mechanism. maybe we can
···
 	 */
 
 	return err;
-
-badframe:
-	return 1;
 }
 
 asmlinkage long _sys_rt_sigreturn(struct pt_regs *regs)
···
  * Set up a signal frame.
  */
 
-static int setup_sigcontext(struct sigcontext *sc, struct pt_regs *regs,
-			    unsigned long mask)
+static int setup_sigcontext(struct pt_regs *regs, struct sigcontext __user *sc)
 {
 	int err = 0;
 
 	/* copy the regs */
-
+	/* There should be no need to save callee-saved registers here...
+	 * ...but we save them anyway.  Revisit this
+	 */
 	err |= __copy_to_user(sc->regs.gpr, regs, 32 * sizeof(unsigned long));
 	err |= __copy_to_user(&sc->regs.pc, &regs->pc, sizeof(unsigned long));
 	err |= __copy_to_user(&sc->regs.sr, &regs->sr, sizeof(unsigned long));
-
-	/* then some other stuff */
-
-	err |= __put_user(mask, &sc->oldmask);
 
 	return err;
 }
···
  * trampoline which performs the syscall sigreturn, or a provided
  * user-mode trampoline.
  */
-static int setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info,
-			  sigset_t *set, struct pt_regs *regs)
+static int setup_rt_frame(struct ksignal *ksig, sigset_t *set,
+			  struct pt_regs *regs)
 {
 	struct rt_sigframe *frame;
 	unsigned long return_ip;
 	int err = 0;
 
-	frame = get_sigframe(ka, regs, sizeof(*frame));
+	frame = get_sigframe(&ksig->ka, regs, sizeof(*frame));
 
 	if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
-		goto give_sigsegv;
+		return -EFAULT;
 
-	err |= __put_user(&frame->info, &frame->pinfo);
-	err |= __put_user(&frame->uc, &frame->puc);
+	/* Create siginfo.  */
+	if (ksig->ka.sa.sa_flags & SA_SIGINFO)
+		err |= copy_siginfo_to_user(&frame->info, &ksig->info);
 
-	if (ka->sa.sa_flags & SA_SIGINFO)
-		err |= copy_siginfo_to_user(&frame->info, info);
-	if (err)
-		goto give_sigsegv;
-
-	/* Clear all the bits of the ucontext we don't use.  */
-	err |= __clear_user(&frame->uc, offsetof(struct ucontext, uc_mcontext));
+	/* Create the ucontext.  */
 	err |= __put_user(0, &frame->uc.uc_flags);
 	err |= __put_user(NULL, &frame->uc.uc_link);
 	err |= __save_altstack(&frame->uc.uc_stack, regs->sp);
-	err |= setup_sigcontext(&frame->uc.uc_mcontext, regs, set->sig[0]);
+	err |= setup_sigcontext(regs, &frame->uc.uc_mcontext);
 
 	err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));
 
 	if (err)
-		goto give_sigsegv;
+		return -EFAULT;
 
 	/* trampoline - the desired return ip is the retcode itself */
 	return_ip = (unsigned long)&frame->retcode;
-	/* This is l.ori r11,r0,__NR_sigreturn, l.sys 1 */
-	err |= __put_user(0xa960, (short *)(frame->retcode + 0));
-	err |= __put_user(__NR_rt_sigreturn, (short *)(frame->retcode + 2));
+	/* This is:
+		l.ori r11,r0,__NR_sigreturn
+		l.sys 1
+	 */
+	err |= __put_user(0xa960,             (short *)(frame->retcode + 0));
+	err |= __put_user(__NR_rt_sigreturn,  (short *)(frame->retcode + 2));
 	err |= __put_user(0x20000001, (unsigned long *)(frame->retcode + 4));
 	err |= __put_user(0x15000000, (unsigned long *)(frame->retcode + 8));
 
 	if (err)
-		goto give_sigsegv;
+		return -EFAULT;
 
 	/* TODO what is the current->exec_domain stuff and invmap ? */
 
 	/* Set up registers for signal handler */
-	regs->pc = (unsigned long)ka->sa.sa_handler; /* what we enter NOW */
+	regs->pc = (unsigned long)ksig->ka.sa.sa_handler; /* what we enter NOW */
 	regs->gpr[9] = (unsigned long)return_ip;     /* what we enter LATER */
-	regs->gpr[3] = (unsigned long)sig;           /* arg 1: signo */
+	regs->gpr[3] = (unsigned long)ksig->sig;           /* arg 1: signo */
 	regs->gpr[4] = (unsigned long)&frame->info;  /* arg 2: (siginfo_t*) */
 	regs->gpr[5] = (unsigned long)&frame->uc;    /* arg 3: ucontext */
 
···
 	regs->sp = (unsigned long)frame;
 
 	return 0;
-
-give_sigsegv:
-	force_sigsegv(sig, current);
-	return -EFAULT;
 }
 
 static inline void
-handle_signal(unsigned long sig,
-	      siginfo_t *info, struct k_sigaction *ka,
-	      struct pt_regs *regs)
+handle_signal(struct ksignal *ksig, struct pt_regs *regs)
 {
 	int ret;
 
-	ret = setup_rt_frame(sig, ka, info, sigmask_to_save(), regs);
-	if (ret)
-		return;
+	ret = setup_rt_frame(ksig, sigmask_to_save(), regs);
 
-	signal_delivered(sig, info, ka, regs,
-				 test_thread_flag(TIF_SINGLESTEP));
+	signal_setup_done(ret, ksig, test_thread_flag(TIF_SINGLESTEP));
 }
 
 /*
···
  * mode below.
  */
 
-void do_signal(struct pt_regs *regs)
+int do_signal(struct pt_regs *regs, int syscall)
 {
-	siginfo_t info;
-	int signr;
-	struct k_sigaction ka;
+	struct ksignal ksig;
+	unsigned long continue_addr = 0;
+	unsigned long restart_addr = 0;
+	unsigned long retval = 0;
+	int restart = 0;
+
+	if (syscall) {
+		continue_addr = regs->pc;
+		restart_addr = continue_addr - 4;
+		retval = regs->gpr[11];
+
+		/*
+		 * Setup syscall restart here so that a debugger will
+		 * see the already changed PC.
+		 */
+		switch (retval) {
+		case -ERESTART_RESTARTBLOCK:
+			restart = -2;
+			/* Fall through */
+		case -ERESTARTNOHAND:
+		case -ERESTARTSYS:
+		case -ERESTARTNOINTR:
+			restart++;
+			regs->gpr[11] = regs->orig_gpr11;
+			regs->pc = restart_addr;
+			break;
+		}
+	}
 
 	/*
-	 * We want the common case to go fast, which
-	 * is why we may in certain cases get here from
-	 * kernel mode. Just return without doing anything
-	 * if so.
+	 * Get the signal to deliver.  During the call to get_signal the
+	 * debugger may change all our registers so we may need to revert
+	 * the decision to restart the syscall; specifically, if the PC is
+	 * changed, don't restart the syscall.
 	 */
-	if (!user_mode(regs))
-		return;
-
-	signr = get_signal_to_deliver(&info, &ka, regs, NULL);
-
-	/* If we are coming out of a syscall then we need
-	 * to check if the syscall was interrupted and wants to be
-	 * restarted after handling the signal.  If so, the original
-	 * syscall number is put back into r11 and the PC rewound to
-	 * point at the l.sys instruction that resulted in the
-	 * original syscall.  Syscall results other than the four
-	 * below mean that the syscall executed to completion and no
-	 * restart is necessary.
-	 */
-	if (regs->orig_gpr11) {
-		int restart = 0;
-
-		switch (regs->gpr[11]) {
-		case -ERESTART_RESTARTBLOCK:
-		case -ERESTARTNOHAND:
-			/* Restart if there is no signal handler */
-			restart = (signr <= 0);
-			break;
-		case -ERESTARTSYS:
-			/* Restart if there no signal handler or
-			 * SA_RESTART flag is set */
-			restart = (signr <= 0 || (ka.sa.sa_flags & SA_RESTART));
-			break;
-		case -ERESTARTNOINTR:
-			/* Always restart */
-			restart = 1;
-			break;
+	if (get_signal(&ksig)) {
+		if (unlikely(restart) && regs->pc == restart_addr) {
+			if (retval == -ERESTARTNOHAND ||
+			    retval == -ERESTART_RESTARTBLOCK
+			    || (retval == -ERESTARTSYS
+			        && !(ksig.ka.sa.sa_flags & SA_RESTART))) {
+				/* No automatic restart */
+				regs->gpr[11] = -EINTR;
+				regs->pc = continue_addr;
+			}
 		}
-
-		if (restart) {
-			if (regs->gpr[11] == -ERESTART_RESTARTBLOCK)
-				regs->gpr[11] = __NR_restart_syscall;
-			else
-				regs->gpr[11] = regs->orig_gpr11;
-			regs->pc -= 4;
-		} else {
-			regs->gpr[11] = -EINTR;
-		}
-	}
-
-	if (signr <= 0) {
-		/* no signal to deliver so we just put the saved sigmask
-		 * back */
+		handle_signal(&ksig, regs);
+	} else {
+		/* no handler */
 		restore_saved_sigmask();
-	} else {		/* signr > 0 */
-		/* Whee!  Actually deliver the signal.  */
-		handle_signal(signr, &info, &ka, regs);
+		/*
+		 * Restore pt_regs PC as syscall restart will be handled by
+		 * kernel without return to userspace
+		 */
+		if (unlikely(restart) && regs->pc == restart_addr) {
+			regs->pc = continue_addr;
+			return restart;
+		}
 	}
 
-	return;
+	return 0;
 }
 
-asmlinkage void do_notify_resume(struct pt_regs *regs)
+asmlinkage int
+do_work_pending(struct pt_regs *regs, unsigned int thread_flags, int syscall)
 {
-	if (current_thread_info()->flags & _TIF_SIGPENDING)
-		do_signal(regs);
-
-	if (current_thread_info()->flags & _TIF_NOTIFY_RESUME) {
-		clear_thread_flag(TIF_NOTIFY_RESUME);
-		tracehook_notify_resume(regs);
-	}
+	do {
+		if (likely(thread_flags & _TIF_NEED_RESCHED)) {
+			schedule();
+		} else {
+			if (unlikely(!user_mode(regs)))
+				return 0;
+			local_irq_enable();
+			if (thread_flags & _TIF_SIGPENDING) {
+				int restart = do_signal(regs, syscall);
+				if (unlikely(restart)) {
+					/*
+					 * Restart without handlers.
+					 * Deal with it without leaving
+					 * the kernel space.
+					 */
+					return restart;
+				}
+				syscall = 0;
+			} else {
+				clear_thread_flag(TIF_NOTIFY_RESUME);
+				tracehook_notify_resume(regs);
+			}
+		}
+		local_irq_disable();
+		thread_flags = current_thread_info()->flags;
+	} while (thread_flags & _TIF_WORK_MASK);
+	return 0;
 }