/*
 * Based on arch/arm/kernel/signal.c
 *
 * Copyright (C) 1995-2009 Russell King
 * Copyright (C) 2012 ARM Ltd.
 * Modified by Will Deacon <will.deacon@arm.com>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 *
 * 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.  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/>.
 */

#include <linux/compat.h>
#include <linux/signal.h>
#include <linux/syscalls.h>
#include <linux/ratelimit.h>

#include <asm/fpsimd.h>
#include <asm/signal32.h>
#include <asm/uaccess.h>
#include <asm/unistd32.h>

struct compat_sigcontext {
        /* We always set these two fields to 0 */
        compat_ulong_t                  trap_no;
        compat_ulong_t                  error_code;

        compat_ulong_t                  oldmask;
        compat_ulong_t                  arm_r0;
        compat_ulong_t                  arm_r1;
        compat_ulong_t                  arm_r2;
        compat_ulong_t                  arm_r3;
        compat_ulong_t                  arm_r4;
        compat_ulong_t                  arm_r5;
        compat_ulong_t                  arm_r6;
        compat_ulong_t                  arm_r7;
        compat_ulong_t                  arm_r8;
        compat_ulong_t                  arm_r9;
        compat_ulong_t                  arm_r10;
        compat_ulong_t                  arm_fp;
        compat_ulong_t                  arm_ip;
        compat_ulong_t                  arm_sp;
        compat_ulong_t                  arm_lr;
        compat_ulong_t                  arm_pc;
        compat_ulong_t                  arm_cpsr;
        compat_ulong_t                  fault_address;
};

struct compat_ucontext {
        compat_ulong_t                  uc_flags;
        compat_uptr_t                   uc_link;
        compat_stack_t                  uc_stack;
        struct compat_sigcontext        uc_mcontext;
        compat_sigset_t                 uc_sigmask;
        int             __unused[32 - (sizeof (compat_sigset_t) / sizeof (int))];
        compat_ulong_t  uc_regspace[128] __attribute__((__aligned__(8)));
};

struct compat_vfp_sigframe {
        compat_ulong_t  magic;
        compat_ulong_t  size;
        struct compat_user_vfp {
                compat_u64      fpregs[32];
                compat_ulong_t  fpscr;
        } ufp;
        struct compat_user_vfp_exc {
                compat_ulong_t  fpexc;
                compat_ulong_t  fpinst;
                compat_ulong_t  fpinst2;
        } ufp_exc;
} __attribute__((__aligned__(8)));

#define VFP_MAGIC               0x56465001
#define VFP_STORAGE_SIZE        sizeof(struct compat_vfp_sigframe)

struct compat_aux_sigframe {
        struct compat_vfp_sigframe      vfp;

        /* Something that isn't a valid magic number for any coprocessor.  */
        unsigned long                   end_magic;
} __attribute__((__aligned__(8)));

struct compat_sigframe {
        struct compat_ucontext  uc;
        compat_ulong_t          retcode[2];
};

struct compat_rt_sigframe {
        struct compat_siginfo info;
        struct compat_sigframe sig;
};

#define _BLOCKABLE (~(sigmask(SIGKILL) | sigmask(SIGSTOP)))

/*
 * For ARM syscalls, the syscall number has to be loaded into r7.
 * We do not support an OABI userspace.
 */
#define MOV_R7_NR_SIGRETURN     (0xe3a07000 | __NR_compat_sigreturn)
#define SVC_SYS_SIGRETURN       (0xef000000 | __NR_compat_sigreturn)
#define MOV_R7_NR_RT_SIGRETURN  (0xe3a07000 | __NR_compat_rt_sigreturn)
#define SVC_SYS_RT_SIGRETURN    (0xef000000 | __NR_compat_rt_sigreturn)

/*
 * For Thumb syscalls, we also pass the syscall number via r7. We therefore
 * need two 16-bit instructions.
 */
#define SVC_THUMB_SIGRETURN     (((0xdf00 | __NR_compat_sigreturn) << 16) | \
                                   0x2700 | __NR_compat_sigreturn)
#define SVC_THUMB_RT_SIGRETURN  (((0xdf00 | __NR_compat_rt_sigreturn) << 16) | \
                                   0x2700 | __NR_compat_rt_sigreturn)

const compat_ulong_t aarch32_sigret_code[6] = {
        /*
         * AArch32 sigreturn code.
         * We don't construct an OABI SWI - instead we just set the imm24 field
         * to the EABI syscall number so that we create a sane disassembly.
         */
        MOV_R7_NR_SIGRETURN,    SVC_SYS_SIGRETURN,    SVC_THUMB_SIGRETURN,
        MOV_R7_NR_RT_SIGRETURN, SVC_SYS_RT_SIGRETURN, SVC_THUMB_RT_SIGRETURN,
};

static inline int put_sigset_t(compat_sigset_t __user *uset, sigset_t *set)
{
        compat_sigset_t cset;

        cset.sig[0] = set->sig[0] & 0xffffffffull;
        cset.sig[1] = set->sig[0] >> 32;

        return copy_to_user(uset, &cset, sizeof(*uset));
}

static inline int get_sigset_t(sigset_t *set,
                               const compat_sigset_t __user *uset)
{
        compat_sigset_t s32;

        if (copy_from_user(&s32, uset, sizeof(*uset)))
                return -EFAULT;

        set->sig[0] = s32.sig[0] | (((long)s32.sig[1]) << 32);
        return 0;
}

int copy_siginfo_to_user32(compat_siginfo_t __user *to, siginfo_t *from)
{
        int err;

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

        /* If you change siginfo_t structure, please be sure
         * this code is fixed accordingly.
         * It should never copy any pad contained in the structure
         * to avoid security leaks, but must copy the generic
         * 3 ints plus the relevant union member.
         * This routine must convert siginfo from 64bit to 32bit as well
         * at the same time.
         */
        err = __put_user(from->si_signo, &to->si_signo);
        err |= __put_user(from->si_errno, &to->si_errno);
        err |= __put_user((short)from->si_code, &to->si_code);
        if (from->si_code < 0)
                err |= __copy_to_user(&to->_sifields._pad, &from->_sifields._pad,
                                      SI_PAD_SIZE);
        else switch (from->si_code & __SI_MASK) {
        case __SI_KILL:
                err |= __put_user(from->si_pid, &to->si_pid);
                err |= __put_user(from->si_uid, &to->si_uid);
                break;
        case __SI_TIMER:
                 err |= __put_user(from->si_tid, &to->si_tid);
                 err |= __put_user(from->si_overrun, &to->si_overrun);
                 err |= __put_user((compat_uptr_t)(unsigned long)from->si_ptr,
                                   &to->si_ptr);
                break;
        case __SI_POLL:
                err |= __put_user(from->si_band, &to->si_band);
                err |= __put_user(from->si_fd, &to->si_fd);
                break;
        case __SI_FAULT:
                err |= __put_user((compat_uptr_t)(unsigned long)from->si_addr,
                                  &to->si_addr);
#ifdef BUS_MCEERR_AO
                /*
                 * Other callers might not initialize the si_lsb field,
                 * so check explicitely for the right codes here.
                 */
                if (from->si_code == BUS_MCEERR_AR || from->si_code == BUS_MCEERR_AO)
                        err |= __put_user(from->si_addr_lsb, &to->si_addr_lsb);
#endif
                break;
        case __SI_CHLD:
                err |= __put_user(from->si_pid, &to->si_pid);
                err |= __put_user(from->si_uid, &to->si_uid);
                err |= __put_user(from->si_status, &to->si_status);
                err |= __put_user(from->si_utime, &to->si_utime);
                err |= __put_user(from->si_stime, &to->si_stime);
                break;
        case __SI_RT: /* This is not generated by the kernel as of now. */
        case __SI_MESGQ: /* But this is */
                err |= __put_user(from->si_pid, &to->si_pid);
                err |= __put_user(from->si_uid, &to->si_uid);
                err |= __put_user((compat_uptr_t)(unsigned long)from->si_ptr, &to->si_ptr);
                break;
        default: /* this is just in case for now ... */
                err |= __put_user(from->si_pid, &to->si_pid);
                err |= __put_user(from->si_uid, &to->si_uid);
                break;
        }
        return err;
}

int copy_siginfo_from_user32(siginfo_t *to, compat_siginfo_t __user *from)
{
        memset(to, 0, sizeof *to);

        if (copy_from_user(to, from, __ARCH_SI_PREAMBLE_SIZE) ||
            copy_from_user(to->_sifields._pad,
                           from->_sifields._pad, SI_PAD_SIZE))
                return -EFAULT;

        return 0;
}

/*
 * VFP save/restore code.
 */
static int compat_preserve_vfp_context(struct compat_vfp_sigframe __user *frame)
{
        struct fpsimd_state *fpsimd = &current->thread.fpsimd_state;
        compat_ulong_t magic = VFP_MAGIC;
        compat_ulong_t size = VFP_STORAGE_SIZE;
        compat_ulong_t fpscr, fpexc;
        int err = 0;

        /*
         * Save the hardware registers to the fpsimd_state structure.
         * Note that this also saves V16-31, which aren't visible
         * in AArch32.
         */
        fpsimd_save_state(fpsimd);

        /* Place structure header on the stack */
        __put_user_error(magic, &frame->magic, err);
        __put_user_error(size, &frame->size, err);

        /*
         * Now copy the FP registers. Since the registers are packed,
         * we can copy the prefix we want (V0-V15) as it is.
         * FIXME: Won't work if big endian.
         */
        err |= __copy_to_user(&frame->ufp.fpregs, fpsimd->vregs,
                              sizeof(frame->ufp.fpregs));

        /* Create an AArch32 fpscr from the fpsr and the fpcr. */
        fpscr = (fpsimd->fpsr & VFP_FPSCR_STAT_MASK) |
                (fpsimd->fpcr & VFP_FPSCR_CTRL_MASK);
        __put_user_error(fpscr, &frame->ufp.fpscr, err);

        /*
         * The exception register aren't available so we fake up a
         * basic FPEXC and zero everything else.
         */
        fpexc = (1 << 30);
        __put_user_error(fpexc, &frame->ufp_exc.fpexc, err);
        __put_user_error(0, &frame->ufp_exc.fpinst, err);
        __put_user_error(0, &frame->ufp_exc.fpinst2, err);

        return err ? -EFAULT : 0;
}

static int compat_restore_vfp_context(struct compat_vfp_sigframe __user *frame)
{
        struct fpsimd_state fpsimd;
        compat_ulong_t magic = VFP_MAGIC;
        compat_ulong_t size = VFP_STORAGE_SIZE;
        compat_ulong_t fpscr;
        int err = 0;

        __get_user_error(magic, &frame->magic, err);
        __get_user_error(size, &frame->size, err);

        if (err)
                return -EFAULT;
        if (magic != VFP_MAGIC || size != VFP_STORAGE_SIZE)
                return -EINVAL;

        /*
         * Copy the FP registers into the start of the fpsimd_state.
         * FIXME: Won't work if big endian.
         */
        err |= __copy_from_user(fpsimd.vregs, frame->ufp.fpregs,
                                sizeof(frame->ufp.fpregs));

        /* Extract the fpsr and the fpcr from the fpscr */
        __get_user_error(fpscr, &frame->ufp.fpscr, err);
        fpsimd.fpsr = fpscr & VFP_FPSCR_STAT_MASK;
        fpsimd.fpcr = fpscr & VFP_FPSCR_CTRL_MASK;

        /*
         * We don't need to touch the exception register, so
         * reload the hardware state.
         */
        if (!err) {
                preempt_disable();
                fpsimd_load_state(&fpsimd);
                preempt_enable();
        }

        return err ? -EFAULT : 0;
}

static int compat_restore_sigframe(struct pt_regs *regs,
                                   struct compat_sigframe __user *sf)
{
        int err;
        sigset_t set;
        struct compat_aux_sigframe __user *aux;

        err = get_sigset_t(&set, &sf->uc.uc_sigmask);
        if (err == 0) {
                sigdelsetmask(&set, ~_BLOCKABLE);
                set_current_blocked(&set);
        }

        __get_user_error(regs->regs[0], &sf->uc.uc_mcontext.arm_r0, err);
        __get_user_error(regs->regs[1], &sf->uc.uc_mcontext.arm_r1, err);
        __get_user_error(regs->regs[2], &sf->uc.uc_mcontext.arm_r2, err);
        __get_user_error(regs->regs[3], &sf->uc.uc_mcontext.arm_r3, err);
        __get_user_error(regs->regs[4], &sf->uc.uc_mcontext.arm_r4, err);
        __get_user_error(regs->regs[5], &sf->uc.uc_mcontext.arm_r5, err);
        __get_user_error(regs->regs[6], &sf->uc.uc_mcontext.arm_r6, err);
        __get_user_error(regs->regs[7], &sf->uc.uc_mcontext.arm_r7, err);
        __get_user_error(regs->regs[8], &sf->uc.uc_mcontext.arm_r8, err);
        __get_user_error(regs->regs[9], &sf->uc.uc_mcontext.arm_r9, err);
        __get_user_error(regs->regs[10], &sf->uc.uc_mcontext.arm_r10, err);
        __get_user_error(regs->regs[11], &sf->uc.uc_mcontext.arm_fp, err);
        __get_user_error(regs->regs[12], &sf->uc.uc_mcontext.arm_ip, err);
        __get_user_error(regs->compat_sp, &sf->uc.uc_mcontext.arm_sp, err);
        __get_user_error(regs->compat_lr, &sf->uc.uc_mcontext.arm_lr, err);
        __get_user_error(regs->pc, &sf->uc.uc_mcontext.arm_pc, err);
        __get_user_error(regs->pstate, &sf->uc.uc_mcontext.arm_cpsr, err);

        /*
         * Avoid compat_sys_sigreturn() restarting.
         */
        regs->syscallno = ~0UL;

        err |= !valid_user_regs(&regs->user_regs);

        aux = (struct compat_aux_sigframe __user *) sf->uc.uc_regspace;
        if (err == 0)
                err |= compat_restore_vfp_context(&aux->vfp);

        return err;
}

asmlinkage int compat_sys_sigreturn(struct pt_regs *regs)
{
        struct compat_sigframe __user *frame;

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

        /*
         * Since we stacked the signal on a 64-bit boundary,
         * then 'sp' should be word aligned here.  If it's
         * not, then the user is trying to mess with us.
         */
        if (regs->compat_sp & 7)
                goto badframe;

        frame = (struct compat_sigframe __user *)regs->compat_sp;

        if (!access_ok(VERIFY_READ, frame, sizeof (*frame)))
                goto badframe;

        if (compat_restore_sigframe(regs, frame))
                goto badframe;

        return regs->regs[0];

badframe:
        if (show_unhandled_signals)
                pr_info_ratelimited("%s[%d]: bad frame in %s: pc=%08llx sp=%08llx\n",
                                    current->comm, task_pid_nr(current), __func__,
                                    regs->pc, regs->sp);
        force_sig(SIGSEGV, current);
        return 0;
}

asmlinkage int compat_sys_rt_sigreturn(struct pt_regs *regs)
{
        struct compat_rt_sigframe __user *frame;

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

        /*
         * Since we stacked the signal on a 64-bit boundary,
         * then 'sp' should be word aligned here.  If it's
         * not, then the user is trying to mess with us.
         */
        if (regs->compat_sp & 7)
                goto badframe;

        frame = (struct compat_rt_sigframe __user *)regs->compat_sp;

        if (!access_ok(VERIFY_READ, frame, sizeof (*frame)))
                goto badframe;

        if (compat_restore_sigframe(regs, &frame->sig))
                goto badframe;

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

        return regs->regs[0];

badframe:
        if (show_unhandled_signals)
                pr_info_ratelimited("%s[%d]: bad frame in %s: pc=%08llx sp=%08llx\n",
                                    current->comm, task_pid_nr(current), __func__,
                                    regs->pc, regs->sp);
        force_sig(SIGSEGV, current);
        return 0;
}

static void __user *compat_get_sigframe(struct k_sigaction *ka,
                                        struct pt_regs *regs,
                                        int framesize)
{
        compat_ulong_t sp = regs->compat_sp;
        void __user *frame;

        /*
         * This is the X/Open sanctioned signal stack switching.
         */
        if ((ka->sa.sa_flags & SA_ONSTACK) && !sas_ss_flags(sp))
                sp = current->sas_ss_sp + current->sas_ss_size;

        /*
         * ATPCS B01 mandates 8-byte alignment
         */
        frame = compat_ptr((compat_uptr_t)((sp - framesize) & ~7));

        /*
         * Check that we can actually write to the signal frame.
         */
        if (!access_ok(VERIFY_WRITE, frame, framesize))
                frame = NULL;

        return frame;
}

static void compat_setup_return(struct pt_regs *regs, struct k_sigaction *ka,
                                compat_ulong_t __user *rc, void __user *frame,
                                int usig)
{
        compat_ulong_t handler = ptr_to_compat(ka->sa.sa_handler);
        compat_ulong_t retcode;
        compat_ulong_t spsr = regs->pstate & ~PSR_f;
        int thumb;

        /* Check if the handler is written for ARM or Thumb */
        thumb = handler & 1;

        if (thumb) {
                spsr |= COMPAT_PSR_T_BIT;
                spsr &= ~COMPAT_PSR_IT_MASK;
        } else {
                spsr &= ~COMPAT_PSR_T_BIT;
        }

        if (ka->sa.sa_flags & SA_RESTORER) {
                retcode = ptr_to_compat(ka->sa.sa_restorer);
        } else {
                /* Set up sigreturn pointer */
                unsigned int idx = thumb << 1;

                if (ka->sa.sa_flags & SA_SIGINFO)
                        idx += 3;

                retcode = AARCH32_VECTORS_BASE +
                          AARCH32_KERN_SIGRET_CODE_OFFSET +
                          (idx << 2) + thumb;
        }

        regs->regs[0]   = usig;
        regs->compat_sp = ptr_to_compat(frame);
        regs->compat_lr = retcode;
        regs->pc        = handler;
        regs->pstate    = spsr;
}

static int compat_setup_sigframe(struct compat_sigframe __user *sf,
                                 struct pt_regs *regs, sigset_t *set)
{
        struct compat_aux_sigframe __user *aux;
        int err = 0;

        __put_user_error(regs->regs[0], &sf->uc.uc_mcontext.arm_r0, err);
        __put_user_error(regs->regs[1], &sf->uc.uc_mcontext.arm_r1, err);
        __put_user_error(regs->regs[2], &sf->uc.uc_mcontext.arm_r2, err);
        __put_user_error(regs->regs[3], &sf->uc.uc_mcontext.arm_r3, err);
        __put_user_error(regs->regs[4], &sf->uc.uc_mcontext.arm_r4, err);
        __put_user_error(regs->regs[5], &sf->uc.uc_mcontext.arm_r5, err);
        __put_user_error(regs->regs[6], &sf->uc.uc_mcontext.arm_r6, err);
        __put_user_error(regs->regs[7], &sf->uc.uc_mcontext.arm_r7, err);
        __put_user_error(regs->regs[8], &sf->uc.uc_mcontext.arm_r8, err);
        __put_user_error(regs->regs[9], &sf->uc.uc_mcontext.arm_r9, err);
        __put_user_error(regs->regs[10], &sf->uc.uc_mcontext.arm_r10, err);
        __put_user_error(regs->regs[11], &sf->uc.uc_mcontext.arm_fp, err);
        __put_user_error(regs->regs[12], &sf->uc.uc_mcontext.arm_ip, err);
        __put_user_error(regs->compat_sp, &sf->uc.uc_mcontext.arm_sp, err);
        __put_user_error(regs->compat_lr, &sf->uc.uc_mcontext.arm_lr, err);
        __put_user_error(regs->pc, &sf->uc.uc_mcontext.arm_pc, err);
        __put_user_error(regs->pstate, &sf->uc.uc_mcontext.arm_cpsr, err);

        __put_user_error((compat_ulong_t)0, &sf->uc.uc_mcontext.trap_no, err);
        __put_user_error((compat_ulong_t)0, &sf->uc.uc_mcontext.error_code, err);
        __put_user_error(current->thread.fault_address, &sf->uc.uc_mcontext.fault_address, err);
        __put_user_error(set->sig[0], &sf->uc.uc_mcontext.oldmask, err);

        err |= put_sigset_t(&sf->uc.uc_sigmask, set);

        aux = (struct compat_aux_sigframe __user *) sf->uc.uc_regspace;

        if (err == 0)
                err |= compat_preserve_vfp_context(&aux->vfp);
        __put_user_error(0, &aux->end_magic, err);

        return err;
}

/*
 * 32-bit signal handling routines called from signal.c
 */
int compat_setup_rt_frame(int usig, struct k_sigaction *ka, siginfo_t *info,
                          sigset_t *set, struct pt_regs *regs)
{
        struct compat_rt_sigframe __user *frame;
        int err = 0;

        frame = compat_get_sigframe(ka, regs, sizeof(*frame));

        if (!frame)
                return 1;

        err |= copy_siginfo_to_user32(&frame->info, info);

        __put_user_error(0, &frame->sig.uc.uc_flags, err);
        __put_user_error(0, &frame->sig.uc.uc_link, err);

        err |= __compat_save_altstack(&frame->sig.uc.uc_stack, regs->compat_sp);

        err |= compat_setup_sigframe(&frame->sig, regs, set);

        if (err == 0) {
                compat_setup_return(regs, ka, frame->sig.retcode, frame, usig);
                regs->regs[1] = (compat_ulong_t)(unsigned long)&frame->info;
                regs->regs[2] = (compat_ulong_t)(unsigned long)&frame->sig.uc;
        }

        return err;
}

int compat_setup_frame(int usig, struct k_sigaction *ka, sigset_t *set,
                       struct pt_regs *regs)
{
        struct compat_sigframe __user *frame;
        int err = 0;

        frame = compat_get_sigframe(ka, regs, sizeof(*frame));

        if (!frame)
                return 1;

        __put_user_error(0x5ac3c35a, &frame->uc.uc_flags, err);

        err |= compat_setup_sigframe(frame, regs, set);
        if (err == 0)
                compat_setup_return(regs, ka, frame->retcode, frame, usig);

        return err;
}

void compat_setup_restart_syscall(struct pt_regs *regs)
{
       regs->regs[7] = __NR_compat_restart_syscall;
}