Re: [PATCH 17/28] nios2: Signal handling support

From: Richard Weinberger
Date: Sat Apr 19 2014 - 15:29:45 EST

On Fri, Apr 18, 2014 at 2:27 PM, Ley Foon Tan <lftan@xxxxxxxxxx> wrote:
> This patch adds support for signal handling.
>
> Signed-off-by: Ley Foon Tan <lftan@xxxxxxxxxx>
> ---
> arch/nios2/include/asm/signal.h | 22 ++
> arch/nios2/include/asm/ucontext.h | 34 +++
> arch/nios2/include/uapi/asm/sigcontext.h | 30 +++
> arch/nios2/include/uapi/asm/signal.h | 23 ++
> arch/nios2/kernel/signal.c | 364 +++++++++++++++++++++++++++++++
> 5 files changed, 473 insertions(+)
> create mode 100644 arch/nios2/include/asm/signal.h
> create mode 100644 arch/nios2/include/asm/ucontext.h
> create mode 100644 arch/nios2/include/uapi/asm/sigcontext.h
> create mode 100644 arch/nios2/include/uapi/asm/signal.h
> create mode 100644 arch/nios2/kernel/signal.c
>
> diff --git a/arch/nios2/include/asm/signal.h b/arch/nios2/include/asm/signal.h
> new file mode 100644
> index 0000000..bbcf11eecb0194b7c7b0f9352b0154d67b2dc06a
> --- /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
> index 0000000..5870ef4e92fbaec9137142534ce3c5b23705d43e
> --- /dev/null
> +++ b/arch/nios2/include/asm/ucontext.h
> @@ -0,0 +1,34 @@
> +/*
> + * Copyright (C) 2010 Tobias Klauser <tklauser@xxxxxxxxxx>
> + * Copyright (C) 2004 Microtronix Datacom Ltd
> + *
> + * derived from m68knommu
> + *
> + * 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
> index 0000000..6bfd8807597a7d6abc0ae32f030e44cb4f77809f
> --- /dev/null
> +++ b/arch/nios2/include/uapi/asm/sigcontext.h
> @@ -0,0 +1,30 @@
> +/*
> + * Taken from the m68knommu.
> + *
> + * 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
> index 0000000..f29ee63144817e9798965c0b8279c08844c44e6a
> --- /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
> index 0000000..1c5cbe9c55dde1c3467d727ec66c36b96f3cb9cd
> --- /dev/null
> +++ b/arch/nios2/kernel/signal.c
> @@ -0,0 +1,364 @@
> +/*
> + * Copyright (C) 2013 Altera Corporation
> + * Copyright (C) 2011-2012 Tobias Klauser <tklauser@xxxxxxxxxx>
> + * Copyright (C) 2004 Microtronix Datacom Ltd
> + * Copyright (C) 1991, 1992 Linus Torvalds
> + *
> + * This file is based on kernel/signal.c from m68knommu.
> + *
> + * 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)))
> +
> +static int do_signal(struct pt_regs *regs, sigset_t *oldset, int in_syscall);
> +
> +/*
> + * 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 sigframe {
> + char retcode[12];
> + unsigned long extramask[_NSIG_WORDS-1];
> + struct sigcontext sc;
> +};
> +
> +struct rt_sigframe {
> + char retcode[12];
> + 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;
> +
> + 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->estatus = (regs->estatus & 0xffffffff);
> + 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;
> +
> + sigdelsetmask(&set, ~_BLOCKABLE);
> + spin_lock_irq(&current->sighand->siglock);
> + current->blocked = set;
> + recalc_sigpending();
> + spin_unlock_irq(&current->sighand->siglock);
> +
> + 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 push_cache(unsigned long vaddr)
> +{
> + flush_dcache_range(vaddr, vaddr + 12);
> + flush_icache_range(vaddr, vaddr + 12);
> +}
> +
> +static inline void *get_sigframe(struct k_sigaction *ka, 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. */
> + if ((ka->sa.sa_flags & SA_ONSTACK) && (current->sas_ss_sp != 0)) {
> + if (!on_sig_stack(usp))
> + usp = current->sas_ss_sp + current->sas_ss_size;
> + }

You can use sigsp() here.

> + /* Verify, is it 32 or 64 bit aligned */
> + return (void *)((usp - frame_size) & -8UL);
> +}
> +
> +static void setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info,
> + sigset_t *set, struct pt_regs *regs)
> +{
> + struct rt_sigframe *frame;
> + int err = 0;
> +
> + frame = get_sigframe(ka, regs, sizeof(*frame));
> +
> + if (info)
> + err |= copy_siginfo_to_user(&frame->info, 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));
> +
> + /* Set up to return from userspace. */
> + regs->ra = (unsigned long) &frame->retcode[0];
> +
> + /* movi r2,__NR_rt_sigreturn */
> + err |= __put_user(0x00800004 + (__NR_rt_sigreturn << 6),
> + (long *)(frame->retcode));
> + /* trap */
> + err |= __put_user(0x003b683a, (long *)(frame->retcode + 4));
> +
> + if (err)
> + goto give_sigsegv;
> +
> + push_cache((unsigned long) &frame->retcode);
> +
> + /* Set up registers for signal handler */
> + regs->sp = (unsigned long) frame;
> + regs->r4 = (unsigned long) (current_thread_info()->exec_domain
> + && current_thread_info()->exec_domain->signal_invmap
> + && sig < 32
> + ? current_thread_info()->exec_domain->signal_invmap[sig]
> + : sig);

Does nios2 really need signal translation and supports execution domains?

> + regs->r5 = (unsigned long) &frame->info;
> + regs->r6 = (unsigned long) &frame->uc;
> + regs->ea = (unsigned long) ka->sa.sa_handler;
> + return;
> +
> +give_sigsegv:
> + force_sigsegv(sig, current);
> +}
> +
> +static inline void handle_restart(struct pt_regs *regs, struct k_sigaction *ka,
> + int has_handler)
> +{
> + switch (regs->r2) {
> + case ERESTART_RESTARTBLOCK:
> + case ERESTARTNOHAND:
> + regs->r2 = EINTR;
> + regs->r7 = 1;
> + break;
> + case ERESTARTSYS:
> + if (has_handler && !(ka->sa.sa_flags & SA_RESTART)) {
> + regs->r2 = EINTR;
> + regs->r7 = 1;
> + break;
> + }
> + /* fallthrough */
> + case ERESTARTNOINTR:
> + regs->r2 = regs->orig_r2;
> + regs->r7 = regs->orig_r7;
> + regs->ea -= 4;
> + break;
> + }
> +}
> +
> +/*
> + * OK, we're invoking a handler
> + */
> +static void handle_signal(int sig, struct k_sigaction *ka, siginfo_t *info,
> + sigset_t *oldset, struct pt_regs *regs)
> +{
> + /* set up the stack frame */
> + if (ka->sa.sa_flags & SA_SIGINFO)
> + setup_rt_frame(sig, ka, info, oldset, regs);
> + else
> + setup_rt_frame(sig, ka, NULL, oldset, regs);
> +
> + if (!(ka->sa.sa_flags & SA_NODEFER)) {
> + spin_lock_irq(&current->sighand->siglock);
> + sigorsets(&current->blocked, &current->blocked,
> + &ka->sa.sa_mask);
> + sigaddset(&current->blocked, sig);
> + recalc_sigpending();
> + spin_unlock_irq(&current->sighand->siglock);
> + }
> +}
> +
> +/*
> + * 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.
> + */

Is this comment still needed? Looks like copy&paste...

> +static int do_signal(struct pt_regs *regs, sigset_t *oldset, int in_syscall)
> +{
> + struct k_sigaction ka;
> + siginfo_t info;
> + int signr;
> +
> + current->thread.kregs = regs;
> +
> + if (!oldset)
> + oldset = &current->blocked;
> +
> + signr = get_signal_to_deliver(&info, &ka, regs, NULL);
> + if (signr > 0) {
> + /*
> + * Are we from a system call? If so, check system call
> + * restarting.
> + */
> + if (in_syscall)
> + handle_restart(regs, &ka, 1);
> + /* Whee! Actually deliver the signal. */
> + handle_signal(signr, &ka, &info, oldset, regs);
> + return 1;
> + }
> +
> + /*
> + * No signal to deliver to the process - restart the syscall.
> + */
> + if (in_syscall) {
> + /* Did the syscall return an error code */
> + if (regs->r7 == 1) {
> + if (regs->r2 == ERESTARTNOHAND ||
> + regs->r2 == ERESTARTSYS ||
> + regs->r2 == ERESTARTNOINTR) {
> + regs->r2 = regs->orig_r2;
> + regs->r7 = regs->orig_r7;
> + regs->ea -= 4;
> + } else if (regs->r2 == ERESTART_RESTARTBLOCK) {
> + regs->r2 = __NR_restart_syscall;
> + regs->ea -= 4;
> + }
> + }
> + }
> +
> + return 0;
> +}
> +
> +asmlinkage void do_notify_resume(struct pt_regs *regs, sigset_t *oldset,
> + int in_syscall)
> +{
> + pr_debug("--> ENTERING %s\n", __func__);

Please remove such printk()s.
If you need to know which functions get called, use ftrace.

> + /*
> + * 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;
> +
> + if (test_thread_flag(TIF_SIGPENDING))
> + do_signal(regs, oldset, in_syscall);
> +
> + if (test_and_clear_thread_flag(TIF_NOTIFY_RESUME))
> + tracehook_notify_resume(regs);
> +}
> --
> 1.8.3.2

--
Thanks,
//richard
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/