nios2: Signal handling support

This patch adds support for signal handling.

Signed-off-by: Ley Foon Tan <lftan@altera.com>

diff --git a/arch/nios2/include/asm/signal.h b/arch/nios2/include/asm/signal.h
new file mode 100644 (file)
index 0000000..bbcf11e
--- /dev/null
+++ b/arch/nios2/include/asm/signal.h
@@ -0,0 +1,22 @@
+/*
+ * Copyright Altera Corporation (C) 2013. All rights reserved
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms and conditions of the GNU General Public License,
+ * version 2, as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope 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, see <http://www.gnu.org/licenses/>.
+ *
+ */
+#ifndef _NIOS2_SIGNAL_H
+#define _NIOS2_SIGNAL_H
+
+#include <uapi/asm/signal.h>
+
+#endif /* _NIOS2_SIGNAL_H */

diff --git a/arch/nios2/include/asm/ucontext.h b/arch/nios2/include/asm/ucontext.h
new file mode 100644 (file)
index 0000000..2c87614
--- /dev/null
+++ b/arch/nios2/include/asm/ucontext.h
@@ -0,0 +1,32 @@
+/*
+ * Copyright (C) 2010 Tobias Klauser <tklauser@distanz.ch>
+ * Copyright (C) 2004 Microtronix Datacom Ltd
+ *
+ * This file is subject to the terms and conditions of the GNU General Public
+ * License.  See the file "COPYING" in the main directory of this archive
+ * for more details.
+ */
+
+#ifndef _ASM_NIOS2_UCONTEXT_H
+#define _ASM_NIOS2_UCONTEXT_H
+
+typedef int greg_t;
+#define NGREG 32
+typedef greg_t gregset_t[NGREG];
+
+struct mcontext {
+       int version;
+       gregset_t gregs;
+};
+
+#define MCONTEXT_VERSION 2
+
+struct ucontext {
+       unsigned long     uc_flags;
+       struct ucontext  *uc_link;
+       stack_t           uc_stack;
+       struct mcontext   uc_mcontext;
+       sigset_t          uc_sigmask;   /* mask last for extensibility */
+};
+
+#endif

diff --git a/arch/nios2/include/uapi/asm/sigcontext.h b/arch/nios2/include/uapi/asm/sigcontext.h
new file mode 100644 (file)
index 0000000..7b8bb41
--- /dev/null
+++ b/arch/nios2/include/uapi/asm/sigcontext.h
@@ -0,0 +1,28 @@
+/*
+ * Copyright (C) 2004, Microtronix Datacom Ltd.
+ *
+ * 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 as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * 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, GOOD TITLE or
+ * NON INFRINGEMENT.  See the GNU General Public License for more
+ * details.
+ */
+
+#ifndef _ASM_NIOS2_SIGCONTEXT_H
+#define _ASM_NIOS2_SIGCONTEXT_H
+
+#include <asm/ptrace.h>
+
+struct sigcontext {
+       struct pt_regs regs;
+       unsigned long  sc_mask; /* old sigmask */
+};
+
+#endif

diff --git a/arch/nios2/include/uapi/asm/signal.h b/arch/nios2/include/uapi/asm/signal.h
new file mode 100644 (file)
index 0000000..f29ee63
--- /dev/null
+++ b/arch/nios2/include/uapi/asm/signal.h
@@ -0,0 +1,23 @@
+/*
+ * Copyright Altera Corporation (C) 2013. All rights reserved
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms and conditions of the GNU General Public License,
+ * version 2, as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope 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, see <http://www.gnu.org/licenses/>.
+ *
+ */
+#ifndef _ASM_NIOS2_SIGNAL_H
+#define _ASM_NIOS2_SIGNAL_H
+
+#define SA_RESTORER 0x04000000
+#include <asm-generic/signal.h>
+
+#endif /* _ASM_NIOS2_SIGNAL_H */

diff --git a/arch/nios2/kernel/signal.c b/arch/nios2/kernel/signal.c
new file mode 100644 (file)
index 0000000..f9d2788
--- /dev/null
+++ b/arch/nios2/kernel/signal.c
@@ -0,0 +1,323 @@
+/*
+ * Copyright (C) 2013-2014 Altera Corporation
+ * Copyright (C) 2011-2012 Tobias Klauser <tklauser@distanz.ch>
+ * Copyright (C) 2004 Microtronix Datacom Ltd
+ * Copyright (C) 1991, 1992 Linus Torvalds
+ *
+ * This file is subject to the terms and conditions of the GNU General Public
+ * License.  See the file COPYING in the main directory of this archive
+ * for more details.
+ */
+
+#include <linux/signal.h>
+#include <linux/errno.h>
+#include <linux/ptrace.h>
+#include <linux/uaccess.h>
+#include <linux/unistd.h>
+#include <linux/personality.h>
+#include <linux/tracehook.h>
+
+#include <asm/ucontext.h>
+#include <asm/cacheflush.h>
+
+#define _BLOCKABLE (~(sigmask(SIGKILL) | sigmask(SIGSTOP)))
+
+/*
+ * Do a signal return; undo the signal stack.
+ *
+ * Keep the return code on the stack quadword aligned!
+ * That makes the cache flush below easier.
+ */
+
+struct rt_sigframe {
+       struct siginfo info;
+       struct ucontext uc;
+};
+
+static inline int rt_restore_ucontext(struct pt_regs *regs,
+                                       struct switch_stack *sw,
+                                       struct ucontext *uc, int *pr2)
+{
+       int temp;
+       greg_t *gregs = uc->uc_mcontext.gregs;
+       int err;
+
+       /* Always make any pending restarted system calls return -EINTR */
+       current_thread_info()->restart_block.fn = do_no_restart_syscall;
+
+       err = __get_user(temp, &uc->uc_mcontext.version);
+       if (temp != MCONTEXT_VERSION)
+               goto badframe;
+       /* restore passed registers */
+       err |= __get_user(regs->r1, &gregs[0]);
+       err |= __get_user(regs->r2, &gregs[1]);
+       err |= __get_user(regs->r3, &gregs[2]);
+       err |= __get_user(regs->r4, &gregs[3]);
+       err |= __get_user(regs->r5, &gregs[4]);
+       err |= __get_user(regs->r6, &gregs[5]);
+       err |= __get_user(regs->r7, &gregs[6]);
+       err |= __get_user(regs->r8, &gregs[7]);
+       err |= __get_user(regs->r9, &gregs[8]);
+       err |= __get_user(regs->r10, &gregs[9]);
+       err |= __get_user(regs->r11, &gregs[10]);
+       err |= __get_user(regs->r12, &gregs[11]);
+       err |= __get_user(regs->r13, &gregs[12]);
+       err |= __get_user(regs->r14, &gregs[13]);
+       err |= __get_user(regs->r15, &gregs[14]);
+       err |= __get_user(sw->r16, &gregs[15]);
+       err |= __get_user(sw->r17, &gregs[16]);
+       err |= __get_user(sw->r18, &gregs[17]);
+       err |= __get_user(sw->r19, &gregs[18]);
+       err |= __get_user(sw->r20, &gregs[19]);
+       err |= __get_user(sw->r21, &gregs[20]);
+       err |= __get_user(sw->r22, &gregs[21]);
+       err |= __get_user(sw->r23, &gregs[22]);
+       /* gregs[23] is handled below */
+       err |= __get_user(sw->fp, &gregs[24]);  /* Verify, should this be
+                                                       settable */
+       err |= __get_user(sw->gp, &gregs[25]);  /* Verify, should this be
+                                                       settable */
+
+       err |= __get_user(temp, &gregs[26]);  /* Not really necessary no user
+                                                       settable bits */
+       err |= __get_user(regs->ea, &gregs[27]);
+
+       err |= __get_user(regs->ra, &gregs[23]);
+       err |= __get_user(regs->sp, &gregs[28]);
+
+       regs->orig_r2 = -1;             /* disable syscall checks */
+
+       err |= restore_altstack(&uc->uc_stack);
+       if (err)
+               goto badframe;
+
+       *pr2 = regs->r2;
+       return err;
+
+badframe:
+       return 1;
+}
+
+asmlinkage int do_rt_sigreturn(struct switch_stack *sw)
+{
+       struct pt_regs *regs = (struct pt_regs *)(sw + 1);
+       /* Verify, can we follow the stack back */
+       struct rt_sigframe *frame = (struct rt_sigframe *) regs->sp;
+       sigset_t set;
+       int rval;
+
+       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 (rt_restore_ucontext(regs, sw, &frame->uc, &rval))
+               goto badframe;
+
+       return rval;
+
+badframe:
+       force_sig(SIGSEGV, current);
+       return 0;
+}
+
+static inline int rt_setup_ucontext(struct ucontext *uc, struct pt_regs *regs)
+{
+       struct switch_stack *sw = (struct switch_stack *)regs - 1;
+       greg_t *gregs = uc->uc_mcontext.gregs;
+       int err = 0;
+
+       err |= __put_user(MCONTEXT_VERSION, &uc->uc_mcontext.version);
+       err |= __put_user(regs->r1, &gregs[0]);
+       err |= __put_user(regs->r2, &gregs[1]);
+       err |= __put_user(regs->r3, &gregs[2]);
+       err |= __put_user(regs->r4, &gregs[3]);
+       err |= __put_user(regs->r5, &gregs[4]);
+       err |= __put_user(regs->r6, &gregs[5]);
+       err |= __put_user(regs->r7, &gregs[6]);
+       err |= __put_user(regs->r8, &gregs[7]);
+       err |= __put_user(regs->r9, &gregs[8]);
+       err |= __put_user(regs->r10, &gregs[9]);
+       err |= __put_user(regs->r11, &gregs[10]);
+       err |= __put_user(regs->r12, &gregs[11]);
+       err |= __put_user(regs->r13, &gregs[12]);
+       err |= __put_user(regs->r14, &gregs[13]);
+       err |= __put_user(regs->r15, &gregs[14]);
+       err |= __put_user(sw->r16, &gregs[15]);
+       err |= __put_user(sw->r17, &gregs[16]);
+       err |= __put_user(sw->r18, &gregs[17]);
+       err |= __put_user(sw->r19, &gregs[18]);
+       err |= __put_user(sw->r20, &gregs[19]);
+       err |= __put_user(sw->r21, &gregs[20]);
+       err |= __put_user(sw->r22, &gregs[21]);
+       err |= __put_user(sw->r23, &gregs[22]);
+       err |= __put_user(regs->ra, &gregs[23]);
+       err |= __put_user(sw->fp, &gregs[24]);
+       err |= __put_user(sw->gp, &gregs[25]);
+       err |= __put_user(regs->ea, &gregs[27]);
+       err |= __put_user(regs->sp, &gregs[28]);
+       return err;
+}
+
+static inline void *get_sigframe(struct ksignal *ksig, struct pt_regs *regs,
+                                size_t frame_size)
+{
+       unsigned long usp;
+
+       /* Default to using normal stack.  */
+       usp = regs->sp;
+
+       /* This is the X/Open sanctioned signal stack switching.  */
+       usp = sigsp(usp, ksig);
+
+       /* Verify, is it 32 or 64 bit aligned */
+       return (void *)((usp - frame_size) & -8UL);
+}
+
+static int setup_rt_frame(struct ksignal *ksig, sigset_t *set,
+                         struct pt_regs *regs)
+{
+       struct rt_sigframe *frame;
+       int err = 0;
+
+       frame = get_sigframe(ksig, regs, sizeof(*frame));
+
+       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(0, &frame->uc.uc_link);
+       err |= __save_altstack(&frame->uc.uc_stack, regs->sp);
+       err |= rt_setup_ucontext(&frame->uc, regs);
+       err |= copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));
+
+       if (err)
+               goto give_sigsegv;
+
+       /* Set up to return from userspace; jump to fixed address sigreturn
+          trampoline on kuser page.  */
+       regs->ra = (unsigned long) (0x1040);
+
+       /* Set up registers for signal handler */
+       regs->sp = (unsigned long) frame;
+       regs->r4 = (unsigned long) ksig->sig;
+       regs->r5 = (unsigned long) &frame->info;
+       regs->r6 = (unsigned long) &frame->uc;
+       regs->ea = (unsigned long) ksig->ka.sa.sa_handler;
+       return 0;
+
+give_sigsegv:
+       force_sigsegv(ksig->sig, current);
+       return -EFAULT;
+}
+
+/*
+ * OK, we're invoking a handler
+ */
+static void handle_signal(struct ksignal *ksig, struct pt_regs *regs)
+{
+       int ret;
+       sigset_t *oldset = sigmask_to_save();
+
+       /* set up the stack frame */
+       ret = setup_rt_frame(ksig, oldset, regs);
+
+       signal_setup_done(ret, ksig, 0);
+}
+
+static int do_signal(struct pt_regs *regs)
+{
+       unsigned int retval = 0, continue_addr = 0, restart_addr = 0;
+       int restart = 0;
+       struct ksignal ksig;
+
+       current->thread.kregs = regs;
+
+       /*
+        * If we were from a system call, check for system call restarting...
+        */
+       if (regs->orig_r2 >= 0) {
+               continue_addr = regs->ea;
+               restart_addr = continue_addr - 4;
+               retval = regs->r2;
+
+               /*
+                * Prepare for system call restart. We do this here so that a
+                * debugger will see the already changed PC.
+                */
+               switch (retval) {
+               case ERESTART_RESTARTBLOCK:
+                       restart = -2;
+               case ERESTARTNOHAND:
+               case ERESTARTSYS:
+               case ERESTARTNOINTR:
+                       restart++;
+                       regs->r2 = regs->orig_r2;
+                       regs->r7 = regs->orig_r7;
+                       regs->ea = restart_addr;
+                       break;
+               }
+       }
+
+       if (get_signal(&ksig)) {
+               /* handler */
+               if (unlikely(restart && regs->ea == restart_addr)) {
+                       if (retval == ERESTARTNOHAND ||
+                           retval == ERESTART_RESTARTBLOCK ||
+                            (retval == ERESTARTSYS
+                               && !(ksig.ka.sa.sa_flags & SA_RESTART))) {
+                               regs->r2 = EINTR;
+                               regs->r7 = 1;
+                               regs->ea = continue_addr;
+                       }
+               }
+               handle_signal(&ksig, regs);
+               return 0;
+       }
+
+       /*
+        * No handler present
+        */
+       if (unlikely(restart) && regs->ea == restart_addr) {
+               regs->ea = continue_addr;
+               regs->r2 = __NR_restart_syscall;
+       }
+
+       /*
+       * If there's no signal to deliver, we just put the saved sigmask back.
+       */
+       restore_saved_sigmask();
+
+       return restart;
+}
+
+asmlinkage int do_notify_resume(struct pt_regs *regs)
+{
+       /*
+        * 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.
+        */
+       if (!user_mode(regs))
+               return 0;
+
+       if (test_thread_flag(TIF_SIGPENDING)) {
+               int restart = do_signal(regs);
+
+               if (unlikely(restart)) {
+                       /*
+                        * Restart without handlers.
+                        * Deal with it without leaving
+                        * the kernel space.
+                        */
+                       return restart;
+               }
+       } else if (test_and_clear_thread_flag(TIF_NOTIFY_RESUME))
+               tracehook_notify_resume(regs);
+
+       return 0;
+}