/*-
 * Copyright (c) 2014, 2015 The FreeBSD Foundation.
 * Copyright (c) 2014, 2017 Andrew Turner.
 * Copyright (c) 2018 Olivier Houchard
 * All rights reserved.
 *
 * This software was developed by Andrew Turner under
 * sponsorship from the FreeBSD Foundation.
 *
 * Portions of this software were developed by Konstantin Belousov
 * under sponsorship from the FreeBSD Foundation.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

#include <sys/cdefs.h>
#define __ELF_WORD_SIZE 32

#include <sys/param.h>
#include <sys/kernel.h>
#include <sys/systm.h>
#include <sys/exec.h>
#include <sys/imgact.h>
#include <sys/linker.h>
#include <sys/proc.h>
#include <sys/reg.h>
#include <sys/sysctl.h>
#include <sys/sysent.h>
#include <sys/imgact_elf.h>
#include <sys/syscall.h>
#include <sys/signalvar.h>
#include <sys/vnode.h>

#include <machine/elf.h>
#include <machine/pcb.h>
#ifdef VFP
#include <machine/vfp.h>
#endif

#include <compat/freebsd32/freebsd32_util.h>

#define FREEBSD32_MINUSER       0x00001000
#define FREEBSD32_MAXUSER       ((1ul << 32) - PAGE_SIZE)
#define FREEBSD32_SHAREDPAGE    (FREEBSD32_MAXUSER - PAGE_SIZE)
#define FREEBSD32_USRSTACK      FREEBSD32_SHAREDPAGE
#define AARCH32_MAXDSIZ         (512 * 1024 * 1024)
#define AARCH32_MAXSSIZ         (64 * 1024 * 1024)
#define AARCH32_MAXVMEM         0

extern const char *freebsd32_syscallnames[];

extern char aarch32_sigcode[];
extern int sz_aarch32_sigcode;

static int freebsd32_fetch_syscall_args(struct thread *td);
static void freebsd32_setregs(struct thread *td, struct image_params *imgp,
    u_long stack);
static void freebsd32_set_syscall_retval(struct thread *, int);

static bool elf32_arm_abi_supported(const struct image_params *,
    const int32_t *, const uint32_t *);
static void elf32_fixlimit(struct rlimit *rl, int which);

extern void freebsd32_sendsig(sig_t catcher, ksiginfo_t *ksi, sigset_t *mask);

u_long __read_frequently elf32_hwcap;
u_long __read_frequently elf32_hwcap2;

static SYSCTL_NODE(_compat, OID_AUTO, aarch32, CTLFLAG_RW | CTLFLAG_MPSAFE, 0,
    "aarch32 mode");

static u_long aarch32_maxdsiz = AARCH32_MAXDSIZ;
SYSCTL_ULONG(_compat_aarch32, OID_AUTO, maxdsiz, CTLFLAG_RWTUN,
    &aarch32_maxdsiz, 0, "");
u_long aarch32_maxssiz = AARCH32_MAXSSIZ;
SYSCTL_ULONG(_compat_aarch32, OID_AUTO, maxssiz, CTLFLAG_RWTUN,
    &aarch32_maxssiz, 0, "");
static u_long aarch32_maxvmem = AARCH32_MAXVMEM;
SYSCTL_ULONG(_compat_aarch32, OID_AUTO, maxvmem, CTLFLAG_RWTUN,
    &aarch32_maxvmem, 0, "");

static struct sysentvec elf32_freebsd_sysvec = {
        .sv_size        = SYS_MAXSYSCALL,
        .sv_table       = freebsd32_sysent,
        .sv_fixup       = elf32_freebsd_fixup,
        .sv_sendsig     = freebsd32_sendsig,
        .sv_sigcode     = aarch32_sigcode,
        .sv_szsigcode   = &sz_aarch32_sigcode,
        .sv_name        = "FreeBSD ELF32",
        .sv_coredump    = elf32_coredump,
        .sv_elf_core_osabi = ELFOSABI_FREEBSD,
        .sv_elf_core_abi_vendor = FREEBSD_ABI_VENDOR,
        .sv_elf_core_prepare_notes = elf32_prepare_notes,
        .sv_minsigstksz = MINSIGSTKSZ,
        .sv_minuser     = FREEBSD32_MINUSER,
        .sv_maxuser     = FREEBSD32_MAXUSER,
        .sv_usrstack    = FREEBSD32_USRSTACK,
        .sv_psstrings   = FREEBSD32_PS_STRINGS,
        .sv_psstringssz = sizeof(struct freebsd32_ps_strings),
        .sv_stackprot   = VM_PROT_READ | VM_PROT_WRITE,
        .sv_copyout_auxargs = elf32_freebsd_copyout_auxargs,
        .sv_copyout_strings = freebsd32_copyout_strings,
        .sv_setregs     = freebsd32_setregs,
        .sv_fixlimit    = elf32_fixlimit,
        .sv_maxssiz     = &aarch32_maxssiz,
        .sv_flags       = SV_ABI_FREEBSD | SV_ILP32 | SV_SHP | SV_TIMEKEEP |
            SV_RNG_SEED_VER | SV_SIGSYS,
        .sv_set_syscall_retval = freebsd32_set_syscall_retval,
        .sv_fetch_syscall_args = freebsd32_fetch_syscall_args,
        .sv_syscallnames = freebsd32_syscallnames,
        .sv_shared_page_base = FREEBSD32_SHAREDPAGE,
        .sv_shared_page_len = PAGE_SIZE,
        .sv_schedtail   = NULL,
        .sv_thread_detach = NULL,
        .sv_trap        = NULL,
        .sv_hwcap       = &elf32_hwcap,
        .sv_hwcap2      = &elf32_hwcap2,
        .sv_hwcap3      = NULL,
        .sv_hwcap4      = NULL,
        .sv_onexec_old  = exec_onexec_old,
        .sv_onexit      = exit_onexit,
        .sv_regset_begin = SET_BEGIN(__elfN(regset)),
        .sv_regset_end  = SET_LIMIT(__elfN(regset)),
};
INIT_SYSENTVEC(elf32_sysvec, &elf32_freebsd_sysvec);

static Elf32_Brandinfo freebsd32_brand_info = {
        .brand          = ELFOSABI_FREEBSD,
        .machine        = EM_ARM,
        .compat_3_brand = "FreeBSD",
        .interp_path    = "/libexec/ld-elf.so.1",
        .sysvec         = &elf32_freebsd_sysvec,
        .interp_newpath = "/libexec/ld-elf32.so.1",
        .brand_note     = &elf32_freebsd_brandnote,
        .flags          = BI_CAN_EXEC_DYN | BI_BRAND_NOTE,
        .header_supported= elf32_arm_abi_supported,
};

static void
register_elf32_brand(void *arg)
{
        /* Check if we support AArch32 */
        if (ID_AA64PFR0_EL0_VAL(READ_SPECIALREG(id_aa64pfr0_el1)) ==
            ID_AA64PFR0_EL0_64_32) {
                elf32_insert_brand_entry(&freebsd32_brand_info);
        } else {
                compat_freebsd_32bit = 0;
        }
}
SYSINIT(elf32, SI_SUB_EXEC, SI_ORDER_FIRST, register_elf32_brand, NULL);

static bool
elf32_arm_abi_supported(const struct image_params *imgp,
    const int32_t *osrel __unused, const uint32_t *fctl0 __unused)
{
        const Elf32_Ehdr *hdr;

#define EF_ARM_EABI_FREEBSD_MIN EF_ARM_EABI_VER4
        hdr = (const Elf32_Ehdr *)imgp->image_header;
        if (EF_ARM_EABI_VERSION(hdr->e_flags) < EF_ARM_EABI_FREEBSD_MIN) {
                if (bootverbose)
                        uprintf("Attempting to execute non EABI binary "
                            "(rev %d) image %s",
                            EF_ARM_EABI_VERSION(hdr->e_flags),
                            imgp->args->fname);
                return (false);
        }

        return (true);
}

static int
freebsd32_fetch_syscall_args(struct thread *td)
{
        struct proc *p;
        register_t *ap;
        struct syscall_args *sa;
        int error, i, nap, narg;
        unsigned int args[6];

        nap = 4;
        p = td->td_proc;
        ap = td->td_frame->tf_x;
        sa = &td->td_sa;

        /* r7 is the syscall id */
        sa->code = td->td_frame->tf_x[7];
        sa->original_code = sa->code;

        if (sa->code == SYS_syscall) {
                sa->code = *ap++;
                nap--;
        } else if (sa->code == SYS___syscall) {
                sa->code = ap[_QUAD_LOWWORD];
                nap -= 2;
                ap += 2;
        }

        if (sa->code >= p->p_sysent->sv_size)
                sa->callp = &nosys_sysent;
        else
                sa->callp = &p->p_sysent->sv_table[sa->code];

        narg = sa->callp->sy_narg;
        for (i = 0; i < nap; i++)
                sa->args[i] = ap[i];
        if (narg > nap) {
                if (narg - nap > nitems(args))
                        panic("Too many system call arguments");
                error = copyin((void *)td->td_frame->tf_x[13], args,
                    (narg - nap) * sizeof(int));
                if (error != 0)
                        return (error);
                for (i = 0; i < (narg - nap); i++)
                        sa->args[i + nap] = args[i];
        }

        td->td_retval[0] = 0;
        td->td_retval[1] = 0;

        return (0);
}

static void
freebsd32_set_syscall_retval(struct thread *td, int error)
{
        struct trapframe *frame;

        frame = td->td_frame;
        switch (error) {
        case 0:
                frame->tf_x[0] = td->td_retval[0];
                frame->tf_x[1] = td->td_retval[1];
                frame->tf_spsr &= ~PSR_C;
                break;
        case ERESTART:
                /*
                 * Reconstruct the pc to point at the swi.
                 */
                if ((frame->tf_spsr & PSR_T) != 0)
                        frame->tf_elr -= 2; //THUMB_INSN_SIZE;
                else
                        frame->tf_elr -= 4; //INSN_SIZE;
                break;
        case EJUSTRETURN:
                /* nothing to do */
                break;
        default:
                frame->tf_x[0] = error;
                frame->tf_spsr |= PSR_C;
                break;
        }
}

static void
freebsd32_setregs(struct thread *td, struct image_params *imgp,
   uintptr_t stack)
{
        struct trapframe *tf = td->td_frame;
        struct pcb *pcb = td->td_pcb;

        memset(tf, 0, sizeof(struct trapframe));

        /*
         * We need to set x0 for init as it doesn't call
         * cpu_set_syscall_retval to copy the value. We also
         * need to set td_retval for the cases where we do.
         */
        tf->tf_x[0] = stack;
        /* SP_usr is mapped to x13 */
        tf->tf_x[13] = stack;
        /* LR_usr is mapped to x14 */
        tf->tf_x[14] = imgp->entry_addr;
        tf->tf_elr = imgp->entry_addr;
        tf->tf_spsr = PSR_M_32;
        if ((uint32_t)imgp->entry_addr & 1)
                tf->tf_spsr |= PSR_T;

#ifdef VFP
        vfp_reset_state(td, pcb);
#endif

        /*
         * Clear debug register state. It is not applicable to the new process.
         */
        bzero(&pcb->pcb_dbg_regs, sizeof(pcb->pcb_dbg_regs));
}

void
elf32_dump_thread(struct thread *td, void *dst, size_t *off)
{
}

static void
elf32_fixlimit(struct rlimit *rl, int which)
{

        switch (which) {
        case RLIMIT_DATA:
                if (aarch32_maxdsiz != 0) {
                        if (rl->rlim_cur > aarch32_maxdsiz)
                                rl->rlim_cur = aarch32_maxdsiz;
                        if (rl->rlim_max > aarch32_maxdsiz)
                                rl->rlim_max = aarch32_maxdsiz;
                }
                break;
        case RLIMIT_STACK:
                if (aarch32_maxssiz != 0) {
                        if (rl->rlim_cur > aarch32_maxssiz)
                                rl->rlim_cur = aarch32_maxssiz;
                        if (rl->rlim_max > aarch32_maxssiz)
                                rl->rlim_max = aarch32_maxssiz;
                }
                break;
        case RLIMIT_VMEM:
                if (aarch32_maxvmem != 0) {
                        if (rl->rlim_cur > aarch32_maxvmem)
                                rl->rlim_cur = aarch32_maxvmem;
                        if (rl->rlim_max > aarch32_maxvmem)
                                rl->rlim_max = aarch32_maxvmem;
                }
                break;
        }
}