/*
 * Signal handling
 *
 * Copyright (C) 2008-2009 Michal Simek <monstr@monstr.eu>
 * Copyright (C) 2008-2009 PetaLogix
 * Copyright (C) 2003,2004 John Williams <jwilliams@itee.uq.edu.au>
 * Copyright (C) 2001 NEC Corporation
 * Copyright (C) 2001 Miles Bader <miles@gnu.org>
 * Copyright (C) 1999,2000 Niibe Yutaka & Kaz Kojima
 * Copyright (C) 1991,1992 Linus Torvalds
 *
 * 1997-11-28 Modified for POSIX.1b signals by Richard Henderson
 *
 * This file was derived from the sh version, arch/sh/kernel/signal.c
 *
 * 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/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/personality.h>
#include <linux/percpu.h>
#include <linux/linkage.h>
#include <linux/resume_user_mode.h>
#include <asm/entry.h>
#include <asm/ucontext.h>
#include <linux/uaccess.h>
#include <linux/syscalls.h>
#include <asm/cacheflush.h>
#include <asm/syscalls.h>

/*
 * Do a signal return; undo the signal stack.
 */
struct sigframe {
        struct sigcontext sc;
        unsigned long extramask[_NSIG_WORDS-1];
        unsigned long tramp[2]; /* signal trampoline */
};

struct rt_sigframe {
        struct siginfo info;
        struct ucontext uc;
        unsigned long tramp[2]; /* signal trampoline */
};

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

#define COPY(x)         {err |= __get_user(regs->x, &sc->regs.x); }
        COPY(r0);
        COPY(r1);
        COPY(r2);       COPY(r3);       COPY(r4);       COPY(r5);
        COPY(r6);       COPY(r7);       COPY(r8);       COPY(r9);
        COPY(r10);      COPY(r11);      COPY(r12);      COPY(r13);
        COPY(r14);      COPY(r15);      COPY(r16);      COPY(r17);
        COPY(r18);      COPY(r19);      COPY(r20);      COPY(r21);
        COPY(r22);      COPY(r23);      COPY(r24);      COPY(r25);
        COPY(r26);      COPY(r27);      COPY(r28);      COPY(r29);
        COPY(r30);      COPY(r31);
        COPY(pc);       COPY(ear);      COPY(esr);      COPY(fsr);
#undef COPY

        *rval_p = regs->r3;

        return err;
}

asmlinkage long sys_rt_sigreturn(struct pt_regs *regs)
{
        struct rt_sigframe __user *frame =
                (struct rt_sigframe __user *)(regs->r1);

        sigset_t set;
        int rval;

        /* Always make any pending restarted system calls return -EINTR */
        current->restart_block.fn = do_no_restart_syscall;

        if (!access_ok(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, &rval))
                goto badframe;

        if (restore_altstack(&frame->uc.uc_stack))
                goto badframe;

        return rval;

badframe:
        force_sig(SIGSEGV);
        return 0;
}

/*
 * Set up a signal frame.
 */

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

#define COPY(x)         {err |= __put_user(regs->x, &sc->regs.x); }
        COPY(r0);
        COPY(r1);
        COPY(r2);       COPY(r3);       COPY(r4);       COPY(r5);
        COPY(r6);       COPY(r7);       COPY(r8);       COPY(r9);
        COPY(r10);      COPY(r11);      COPY(r12);      COPY(r13);
        COPY(r14);      COPY(r15);      COPY(r16);      COPY(r17);
        COPY(r18);      COPY(r19);      COPY(r20);      COPY(r21);
        COPY(r22);      COPY(r23);      COPY(r24);      COPY(r25);
        COPY(r26);      COPY(r27);      COPY(r28);      COPY(r29);
        COPY(r30);      COPY(r31);
        COPY(pc);       COPY(ear);      COPY(esr);      COPY(fsr);
#undef COPY

        err |= __put_user(mask, &sc->oldmask);

        return err;
}

/*
 * Determine which stack to use..
 */
static inline void __user *
get_sigframe(struct ksignal *ksig, struct pt_regs *regs, size_t frame_size)
{
        /* Default to using normal stack */
        unsigned long sp = sigsp(regs->r1, ksig);

        return (void __user *)((sp - frame_size) & -8UL);
}

static int setup_rt_frame(struct ksignal *ksig, sigset_t *set,
                          struct pt_regs *regs)
{
        struct rt_sigframe __user *frame;
        int err = 0, sig = ksig->sig;
        unsigned long address = 0;
        pmd_t *pmdp;
        pte_t *ptep;

        frame = get_sigframe(ksig, regs, sizeof(*frame));

        if (!access_ok(frame, sizeof(*frame)))
                return -EFAULT;

        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->r1);
        err |= setup_sigcontext(&frame->uc.uc_mcontext,
                        regs, set->sig[0]);
        err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));

        /* Set up to return from userspace. If provided, use a stub
         already in userspace. */
        /* minus 8 is offset to cater for "rtsd r15,8" */
        /* addi r12, r0, __NR_sigreturn */
        err |= __put_user(0x31800000 | __NR_rt_sigreturn ,
                        frame->tramp + 0);
        /* brki r14, 0x8 */
        err |= __put_user(0xb9cc0008, frame->tramp + 1);

        /* Return from sighandler will jump to the tramp.
         Negative 8 offset because return is rtsd r15, 8 */
        regs->r15 = ((unsigned long)frame->tramp)-8;

        address = ((unsigned long)frame->tramp);
        pmdp = pmd_off(current->mm, address);

        preempt_disable();
        ptep = pte_offset_map(pmdp, address);
        if (ptep && pte_present(*ptep)) {
                address = (unsigned long) page_address(pte_page(*ptep));
                /* MS: I need add offset in page */
                address += ((unsigned long)frame->tramp) & ~PAGE_MASK;
                /* MS address is virtual */
                address = __virt_to_phys(address);
                invalidate_icache_range(address, address + 8);
                flush_dcache_range(address, address + 8);
        }
        if (ptep)
                pte_unmap(ptep);
        preempt_enable();
        if (err)
                return -EFAULT;

        /* Set up registers for signal handler */
        regs->r1 = (unsigned long) frame;

        /* Signal handler args: */
        regs->r5 = sig; /* arg 0: signum */
        regs->r6 = (unsigned long) &frame->info; /* arg 1: siginfo */
        regs->r7 = (unsigned long) &frame->uc; /* arg2: ucontext */
        /* Offset to handle microblaze rtid r14, 0 */
        regs->pc = (unsigned long)ksig->ka.sa.sa_handler;

#ifdef DEBUG_SIG
        pr_info("SIG deliver (%s:%d): sp=%p pc=%08lx\n",
                current->comm, current->pid, frame, regs->pc);
#endif

        return 0;
}

/* Handle restarting system calls */
static inline void
handle_restart(struct pt_regs *regs, struct k_sigaction *ka, int has_handler)
{
        switch (regs->r3) {
        case -ERESTART_RESTARTBLOCK:
        case -ERESTARTNOHAND:
                if (!has_handler)
                        goto do_restart;
                regs->r3 = -EINTR;
                break;
        case -ERESTARTSYS:
                if (has_handler && !(ka->sa.sa_flags & SA_RESTART)) {
                        regs->r3 = -EINTR;
                        break;
        }
                fallthrough;
        case -ERESTARTNOINTR:
do_restart:
                /* offset of 4 bytes to re-execute trap (brki) instruction */
                regs->pc -= 4;
                break;
        }
}

/*
 * OK, we're invoking a handler
 */

static void
handle_signal(struct ksignal *ksig, struct pt_regs *regs)
{
        sigset_t *oldset = sigmask_to_save();
        int ret;

        /* Set up the stack frame */
        ret = setup_rt_frame(ksig, oldset, 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.
 *
 * Note that we go through the signals twice: once to check the signals that
 * the kernel can handle, and then we build all the user-level signal handling
 * stack-frames in one go after that.
 */
static void do_signal(struct pt_regs *regs, int in_syscall)
{
        struct ksignal ksig;

#ifdef DEBUG_SIG
        pr_info("do signal: %p %d\n", regs, in_syscall);
        pr_info("do signal2: %lx %lx %ld [%lx]\n", regs->pc, regs->r1,
                        regs->r12, read_thread_flags());
#endif

        if (get_signal(&ksig)) {
                /* Whee! Actually deliver the signal. */
                if (in_syscall)
                        handle_restart(regs, &ksig.ka, 1);
                handle_signal(&ksig, regs);
                return;
        }

        if (in_syscall)
                handle_restart(regs, NULL, 0);

        /*
         * If there's no signal to deliver, we just put the saved sigmask
         * back.
         */
        restore_saved_sigmask();
}

asmlinkage void do_notify_resume(struct pt_regs *regs, int in_syscall)
{
        if (test_thread_flag(TIF_SIGPENDING) ||
            test_thread_flag(TIF_NOTIFY_SIGNAL))
                do_signal(regs, in_syscall);

        if (test_thread_flag(TIF_NOTIFY_RESUME))
                resume_user_mode_work(regs);
}