Initial import

1 files changed, 326 insertions, 0 deletions

diff --git a/arch/openrisc/kernel/signal.c b/arch/openrisc/kernel/signal.c
new file mode 100644
index 000000000..c82be69b4
--- /dev/null
+++ b/arch/openrisc/kernel/signal.c
@@ -0,0 +1,326 @@
+/*
+ * OpenRISC signal.c
+ *
+ * Linux architectural port borrowing liberally from similar works of
+ * others.  All original copyrights apply as per the original source
+ * declaration.
+ *
+ * Modifications for the OpenRISC architecture:
+ * Copyright (C) 2003 Matjaz Breskvar <phoenix@bsemi.com>
+ * Copyright (C) 2010-2011 Jonas Bonn <jonas@southpole.se>
+ *
+ *      This program is free software; you can redistribute it and/or
+ *      modify it under the terms of the GNU General Public License
+ *      as published by the Free Software Foundation; either version
+ *      2 of the License, or (at your option) any later version.
+ */
+
+#include <linux/sched.h>
+#include <linux/mm.h>
+#include <linux/smp.h>
+#include <linux/kernel.h>
+#include <linux/signal.h>
+#include <linux/errno.h>
+#include <linux/wait.h>
+#include <linux/ptrace.h>
+#include <linux/unistd.h>
+#include <linux/stddef.h>
+#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 info;
+	struct ucontext uc;
+	unsigned char retcode[16];	/* trampoline code */
+};
+
+static int restore_sigcontext(struct pt_regs *regs,
+			      struct sigcontext __user *sc)
+{
+	int err = 0;
+
+	/* Always make any pending restarted system calls return -EINTR */
+	current->restart_block.fn = do_no_restart_syscall;
+
+	/*
+	 * Restore the regs from &sc->regs.
+	 * (sc is already checked for VERIFY_READ since the sigframe was
+	 *  checked in sys_sigreturn previously)
+	 */
+	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
+	 * use it now ?
+	 */
+
+	return err;
+}
+
+asmlinkage long _sys_rt_sigreturn(struct pt_regs *regs)
+{
+	struct rt_sigframe *frame = (struct rt_sigframe __user *)regs->sp;
+	sigset_t set;
+
+	/*
+	 * Since we stacked the signal on a dword boundary,
+	 * then frame should be dword aligned here.  If it's
+	 * not, then the user is trying to mess with us.
+	 */
+	if (((long)frame) & 3)
+		goto badframe;
+
+	if (!access_ok(VERIFY_READ, frame, sizeof(*frame)))
+		goto badframe;
+	if (__copy_from_user(&set, &frame->uc.uc_sigmask, sizeof(set)))
+		goto badframe;
+
+	set_current_blocked(&set);
+
+	if (restore_sigcontext(regs, &frame->uc.uc_mcontext))
+		goto badframe;
+
+	if (restore_altstack(&frame->uc.uc_stack))
+		goto badframe;
+
+	return regs->gpr[11];
+
+badframe:
+	force_sig(SIGSEGV, current);
+	return 0;
+}
+
+/*
+ * Set up a signal frame.
+ */
+
+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));
+
+	return err;
+}
+
+static inline unsigned long align_sigframe(unsigned long sp)
+{
+	return sp & ~3UL;
+}
+
+/*
+ * Work out where the signal frame should go.  It's either on the user stack
+ * or the alternate stack.
+ */
+
+static inline void __user *get_sigframe(struct ksignal *ksig,
+					struct pt_regs *regs, size_t frame_size)
+{
+	unsigned long sp = regs->sp;
+
+	/* redzone */
+	sp -= STACK_FRAME_OVERHEAD;
+	sp = sigsp(sp, ksig);
+	sp = align_sigframe(sp - frame_size);
+
+	return (void __user *)sp;
+}
+
+/* grab and setup a signal frame.
+ *
+ * basically we stack a lot of state info, and arrange for the
+ * user-mode program to return to the kernel using either a
+ * trampoline which performs the syscall sigreturn, or a provided
+ * user-mode trampoline.
+ */
+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(ksig, regs, sizeof(*frame));
+
+	if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
+		return -EFAULT;
+
+	/* Create siginfo.  */
+	if (ksig->ka.sa.sa_flags & SA_SIGINFO)
+		err |= copy_siginfo_to_user(&frame->info, &ksig->info);
+
+	/* 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(regs, &frame->uc.uc_mcontext);
+
+	err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));
+
+	if (err)
+		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));
+	err |= __put_user(0x20000001, (unsigned long *)(frame->retcode + 4));
+	err |= __put_user(0x15000000, (unsigned long *)(frame->retcode + 8));
+
+	if (err)
+		return -EFAULT;
+
+	/* Set up registers for signal handler */
+	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)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 */
+
+	/* actually move the usp to reflect the stacked frame */
+	regs->sp = (unsigned long)frame;
+
+	return 0;
+}
+
+static inline void
+handle_signal(struct ksignal *ksig, struct pt_regs *regs)
+{
+	int ret;
+
+	ret = setup_rt_frame(ksig, sigmask_to_save(), regs);
+
+	signal_setup_done(ret, ksig, test_thread_flag(TIF_SINGLESTEP));
+}
+
+/*
+ * Note that 'init' is a special process: it doesn't get signals it doesn't
+ * want to handle. Thus you cannot kill init even with a SIGKILL even by
+ * mistake.
+ *
+ * Also note that the regs structure given here as an argument, is the latest
+ * pushed pt_regs. It may or may not be the same as the first pushed registers
+ * when the initial usermode->kernelmode transition took place. Therefore
+ * we can use user_mode(regs) to see if we came directly from kernel or user
+ * mode below.
+ */
+
+int do_signal(struct pt_regs *regs, int syscall)
+{
+	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;
+		}
+	}
+
+	/*
+	 * 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 (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;
+			}
+		}
+		handle_signal(&ksig, regs);
+	} else {
+		/* no handler */
+		restore_saved_sigmask();
+		/*
+		 * 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 0;
+}
+
+asmlinkage int
+do_work_pending(struct pt_regs *regs, unsigned int thread_flags, int syscall)
+{
+	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;
+}