/*
 * Copyright (C) 2003 PathScale, Inc.
 * Copyright (C) 2003 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
 * Licensed under the GPL
 */

#include <linux/personality.h>
#include <linux/ptrace.h>
#include <asm/unistd.h>
#include <asm/uaccess.h>
#include <asm/ucontext.h>
#include "frame_kern.h"
#include "skas.h"

void copy_sc(struct uml_pt_regs *regs, void *from)
{
        struct sigcontext *sc = from;

#define GETREG(regs, regno, sc, regname)                                \
        (regs)->gp[(regno) / sizeof(unsigned long)] = (sc)->regname

        GETREG(regs, R8, sc, r8);
        GETREG(regs, R9, sc, r9);
        GETREG(regs, R10, sc, r10);
        GETREG(regs, R11, sc, r11);
        GETREG(regs, R12, sc, r12);
        GETREG(regs, R13, sc, r13);
        GETREG(regs, R14, sc, r14);
        GETREG(regs, R15, sc, r15);
        GETREG(regs, RDI, sc, di);
        GETREG(regs, RSI, sc, si);
        GETREG(regs, RBP, sc, bp);
        GETREG(regs, RBX, sc, bx);
        GETREG(regs, RDX, sc, dx);
        GETREG(regs, RAX, sc, ax);
        GETREG(regs, RCX, sc, cx);
        GETREG(regs, RSP, sc, sp);
        GETREG(regs, RIP, sc, ip);
        GETREG(regs, EFLAGS, sc, flags);
        GETREG(regs, CS, sc, cs);

#undef GETREG
}

static int copy_sc_from_user(struct pt_regs *regs,
                             struct sigcontext __user *from,
                             struct _fpstate __user *fpp)
{
        struct user_i387_struct fp;
        int err = 0;

#define GETREG(regs, regno, sc, regname)                                \
        __get_user((regs)->regs.gp[(regno) / sizeof(unsigned long)],    \
                   &(sc)->regname)

        err |= GETREG(regs, R8, from, r8);
        err |= GETREG(regs, R9, from, r9);
        err |= GETREG(regs, R10, from, r10);
        err |= GETREG(regs, R11, from, r11);
        err |= GETREG(regs, R12, from, r12);
        err |= GETREG(regs, R13, from, r13);
        err |= GETREG(regs, R14, from, r14);
        err |= GETREG(regs, R15, from, r15);
        err |= GETREG(regs, RDI, from, di);
        err |= GETREG(regs, RSI, from, si);
        err |= GETREG(regs, RBP, from, bp);
        err |= GETREG(regs, RBX, from, bx);
        err |= GETREG(regs, RDX, from, dx);
        err |= GETREG(regs, RAX, from, ax);
        err |= GETREG(regs, RCX, from, cx);
        err |= GETREG(regs, RSP, from, sp);
        err |= GETREG(regs, RIP, from, ip);
        err |= GETREG(regs, EFLAGS, from, flags);
        err |= GETREG(regs, CS, from, cs);
        if (err)
                return 1;

#undef GETREG

        err = copy_from_user(&fp, fpp, sizeof(struct user_i387_struct));
        if (err)
                return 1;

        err = restore_fp_registers(userspace_pid[current_thread_info()->cpu],
                                   (unsigned long *) &fp);
        if (err < 0) {
                printk(KERN_ERR "copy_sc_from_user - "
                       "restore_fp_registers failed, errno = %d\n",
                       -err);
                return 1;
        }

        return 0;
}

static int copy_sc_to_user(struct sigcontext __user *to,
                           struct _fpstate __user *to_fp, struct pt_regs *regs,
                           unsigned long mask, unsigned long sp)
{
        struct faultinfo * fi = &current->thread.arch.faultinfo;
        struct user_i387_struct fp;
        int err = 0;

        err |= __put_user(0, &to->gs);
        err |= __put_user(0, &to->fs);

#define PUTREG(regs, regno, sc, regname)                                \
        __put_user((regs)->regs.gp[(regno) / sizeof(unsigned long)],    \
                   &(sc)->regname)

        err |= PUTREG(regs, RDI, to, di);
        err |= PUTREG(regs, RSI, to, si);
        err |= PUTREG(regs, RBP, to, bp);
        /*
         * Must use original RSP, which is passed in, rather than what's in
         * the pt_regs, because that's already been updated to point at the
         * signal frame.
         */
        err |= __put_user(sp, &to->sp);
        err |= PUTREG(regs, RBX, to, bx);
        err |= PUTREG(regs, RDX, to, dx);
        err |= PUTREG(regs, RCX, to, cx);
        err |= PUTREG(regs, RAX, to, ax);
        err |= PUTREG(regs, R8, to, r8);
        err |= PUTREG(regs, R9, to, r9);
        err |= PUTREG(regs, R10, to, r10);
        err |= PUTREG(regs, R11, to, r11);
        err |= PUTREG(regs, R12, to, r12);
        err |= PUTREG(regs, R13, to, r13);
        err |= PUTREG(regs, R14, to, r14);
        err |= PUTREG(regs, R15, to, r15);
        err |= PUTREG(regs, CS, to, cs); /* XXX x86_64 doesn't do this */

        err |= __put_user(fi->cr2, &to->cr2);
        err |= __put_user(fi->error_code, &to->err);
        err |= __put_user(fi->trap_no, &to->trapno);

        err |= PUTREG(regs, RIP, to, ip);
        err |= PUTREG(regs, EFLAGS, to, flags);
#undef PUTREG

        err |= __put_user(mask, &to->oldmask);
        if (err)
                return 1;

        err = save_fp_registers(userspace_pid[current_thread_info()->cpu],
                                (unsigned long *) &fp);
        if (err < 0) {
                printk(KERN_ERR "copy_sc_from_user - restore_fp_registers "
                       "failed, errno = %d\n", -err);
                return 1;
        }

        if (copy_to_user(to_fp, &fp, sizeof(struct user_i387_struct)))
                return 1;

        return err;
}

struct rt_sigframe
{
        char __user *pretcode;
        struct ucontext uc;
        struct siginfo info;
        struct _fpstate fpstate;
};

#define round_down(m, n) (((m) / (n)) * (n))

int setup_signal_stack_si(unsigned long stack_top, int sig,
                          struct k_sigaction *ka, struct pt_regs * regs,
                          siginfo_t *info, sigset_t *set)
{
        struct rt_sigframe __user *frame;
        unsigned long save_sp = PT_REGS_RSP(regs);
        int err = 0;
        struct task_struct *me = current;

        frame = (struct rt_sigframe __user *)
                round_down(stack_top - sizeof(struct rt_sigframe), 16);
        /* Subtract 128 for a red zone and 8 for proper alignment */
        frame = (struct rt_sigframe __user *) ((unsigned long) frame - 128 - 8);

        if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
                goto out;

        if (ka->sa.sa_flags & SA_SIGINFO) {
                err |= copy_siginfo_to_user(&frame->info, info);
                if (err)
                        goto out;
        }

        /*
         * Update SP now because the page fault handler refuses to extend
         * the stack if the faulting address is too far below the current
         * SP, which frame now certainly is.  If there's an error, the original
         * value is restored on the way out.
         * When writing the sigcontext to the stack, we have to write the
         * original value, so that's passed to copy_sc_to_user, which does
         * the right thing with it.
         */
        PT_REGS_RSP(regs) = (unsigned long) frame;

        /* Create the ucontext.  */
        err |= __put_user(0, &frame->uc.uc_flags);
        err |= __put_user(0, &frame->uc.uc_link);
        err |= __put_user(me->sas_ss_sp, &frame->uc.uc_stack.ss_sp);
        err |= __put_user(sas_ss_flags(save_sp),
                          &frame->uc.uc_stack.ss_flags);
        err |= __put_user(me->sas_ss_size, &frame->uc.uc_stack.ss_size);
        err |= copy_sc_to_user(&frame->uc.uc_mcontext, &frame->fpstate, regs,
                               set->sig[0], save_sp);
        err |= __put_user(&frame->fpstate, &frame->uc.uc_mcontext.fpstate);
        if (sizeof(*set) == 16) {
                __put_user(set->sig[0], &frame->uc.uc_sigmask.sig[0]);
                __put_user(set->sig[1], &frame->uc.uc_sigmask.sig[1]);
        }
        else
                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.
         */
        /* x86-64 should always use SA_RESTORER. */
        if (ka->sa.sa_flags & SA_RESTORER)
                err |= __put_user(ka->sa.sa_restorer, &frame->pretcode);
        else
                /* could use a vstub here */
                goto restore_sp;

        if (err)
                goto restore_sp;

        /* Set up registers for signal handler */
        {
                struct exec_domain *ed = current_thread_info()->exec_domain;
                if (unlikely(ed && ed->signal_invmap && sig < 32))
                        sig = ed->signal_invmap[sig];
        }

        PT_REGS_RDI(regs) = sig;
        /* In case the signal handler was declared without prototypes */
        PT_REGS_RAX(regs) = 0;

        /*
         * This also works for non SA_SIGINFO handlers because they expect the
         * next argument after the signal number on the stack.
         */
        PT_REGS_RSI(regs) = (unsigned long) &frame->info;
        PT_REGS_RDX(regs) = (unsigned long) &frame->uc;
        PT_REGS_RIP(regs) = (unsigned long) ka->sa.sa_handler;
 out:
        return err;

restore_sp:
        PT_REGS_RSP(regs) = save_sp;
        return err;
}

long sys_rt_sigreturn(struct pt_regs *regs)
{
        unsigned long sp = PT_REGS_SP(&current->thread.regs);
        struct rt_sigframe __user *frame =
                (struct rt_sigframe __user *)(sp - 8);
        struct ucontext __user *uc = &frame->uc;
        sigset_t set;

        if (copy_from_user(&set, &uc->uc_sigmask, sizeof(set)))
                goto segfault;

        sigdelsetmask(&set, ~_BLOCKABLE);

        spin_lock_irq(&current->sighand->siglock);
        current->blocked = set;
        recalc_sigpending();
        spin_unlock_irq(&current->sighand->siglock);

        if (copy_sc_from_user(&current->thread.regs, &uc->uc_mcontext,
                              &frame->fpstate))
                goto segfault;

        /* Avoid ERESTART handling */
        PT_REGS_SYSCALL_NR(&current->thread.regs) = -1;
        return PT_REGS_SYSCALL_RET(&current->thread.regs);

 segfault:
        force_sig(SIGSEGV, current);
        return 0;
}