/*-
 * SPDX-License-Identifier: BSD-3-Clause
 *
 * Copyright (c) 2008, Juniper Networks, Inc.
 * All rights reserved.
 *
 * 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.
 * 3. Neither the name of the author nor the names of any co-contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``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 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/param.h>
#include <sys/endian.h>
#include <sys/kerneldump.h>
#include <sys/mman.h>

#include <elf.h>
#include <kvm.h>
#include <limits.h>
#include <stdlib.h>
#include <string.h>

#include "kvm_private.h"

struct vmstate {
        void            *map;
        size_t          mapsz;
        size_t          dmphdrsz;
        Elf32_Ehdr      *eh;
        Elf32_Phdr      *ph;
};

static int
valid_elf_header(Elf32_Ehdr *eh)
{

        if (!IS_ELF(*eh))
                return (0);
        if (eh->e_ident[EI_CLASS] != ELFCLASS32)
                return (0);
        if (eh->e_ident[EI_DATA] != ELFDATA2MSB)
                return (0);
        if (eh->e_ident[EI_VERSION] != EV_CURRENT)
                return (0);
        if (eh->e_ident[EI_OSABI] != ELFOSABI_STANDALONE)
                return (0);
        if (be16toh(eh->e_type) != ET_CORE)
                return (0);
        if (be16toh(eh->e_machine) != EM_PPC)
                return (0);
        /* Can't think of anything else to check... */
        return (1);
}

static size_t
dump_header_size(struct kerneldumpheader *dh)
{

        if (strcmp(dh->magic, KERNELDUMPMAGIC) != 0)
                return (0);
        if (strcmp(dh->architecture, "powerpc") != 0)
                return (0);
        /* That should do it... */
        return (sizeof(*dh));
}

/*
 * Map the ELF headers into the process' address space. We do this in two
 * steps: first the ELF header itself and using that information the whole
 * set of headers.
 */
static int
powerpc_maphdrs(kvm_t *kd)
{
        struct vmstate *vm;
        size_t mapsz;

        vm = kd->vmst;

        vm->mapsz = sizeof(*vm->eh) + sizeof(struct kerneldumpheader);
        vm->map = mmap(NULL, vm->mapsz, PROT_READ, MAP_PRIVATE, kd->pmfd, 0);
        if (vm->map == MAP_FAILED) {
                _kvm_err(kd, kd->program, "cannot map corefile");
                return (-1);
        }
        vm->dmphdrsz = 0;
        vm->eh = vm->map;
        if (!valid_elf_header(vm->eh)) {
                /*
                 * Hmmm, no ELF header. Maybe we still have a dump header.
                 * This is normal when the core file wasn't created by
                 * savecore(8), but instead was dumped over TFTP. We can
                 * easily skip the dump header...
                 */
                vm->dmphdrsz = dump_header_size(vm->map);
                if (vm->dmphdrsz == 0)
                        goto inval;
                vm->eh = (void *)((uintptr_t)vm->map + vm->dmphdrsz);
                if (!valid_elf_header(vm->eh))
                        goto inval;
        }
        mapsz = be16toh(vm->eh->e_phentsize) * be16toh(vm->eh->e_phnum) +
            be32toh(vm->eh->e_phoff);
        munmap(vm->map, vm->mapsz);

        /* Map all headers. */
        vm->mapsz = vm->dmphdrsz + mapsz;
        vm->map = mmap(NULL, vm->mapsz, PROT_READ, MAP_PRIVATE, kd->pmfd, 0);
        if (vm->map == MAP_FAILED) {
                _kvm_err(kd, kd->program, "cannot map corefile headers");
                return (-1);
        }
        vm->eh = (void *)((uintptr_t)vm->map + vm->dmphdrsz);
        vm->ph = (void *)((uintptr_t)vm->eh + be32toh(vm->eh->e_phoff));
        return (0);

 inval:
        _kvm_err(kd, kd->program, "invalid corefile");
        return (-1);
}

/*
 * Determine the offset within the corefile corresponding the virtual
 * address. Return the number of contiguous bytes in the corefile or
 * 0 when the virtual address is invalid.
 */
static size_t
powerpc_va2off(kvm_t *kd, kvaddr_t va, off_t *ofs)
{
        struct vmstate *vm = kd->vmst;
        Elf32_Phdr *ph;
        int nph;

        ph = vm->ph;
        nph = be16toh(vm->eh->e_phnum);
        while (nph && (va < be32toh(ph->p_vaddr) ||
            va >= be32toh(ph->p_vaddr) + be32toh(ph->p_memsz))) {
                nph--;
                ph = (void *)((uintptr_t)ph + be16toh(vm->eh->e_phentsize));
        }
        if (nph == 0)
                return (0);

        /* Segment found. Return file offset and range. */
        *ofs = vm->dmphdrsz + be32toh(ph->p_offset) +
            (va - be32toh(ph->p_vaddr));
        return (be32toh(ph->p_memsz) - (va - be32toh(ph->p_vaddr)));
}

static void
_powerpc_freevtop(kvm_t *kd)
{
        struct vmstate *vm = kd->vmst;

        if (vm->eh != MAP_FAILED)
                munmap(vm->eh, vm->mapsz);
        free(vm);
        kd->vmst = NULL;
}

static int
_powerpc_probe(kvm_t *kd)
{

        return (_kvm_probe_elf_kernel(kd, ELFCLASS32, EM_PPC) &&
            kd->nlehdr.e_ident[EI_DATA] == ELFDATA2MSB);
}

static int
_powerpc_initvtop(kvm_t *kd)
{

        kd->vmst = (struct vmstate *)_kvm_malloc(kd, sizeof(*kd->vmst));
        if (kd->vmst == NULL)
                return (-1);

        if (powerpc_maphdrs(kd) == -1)
                return (-1);

        return (0);
}

static int
_powerpc_kvatop(kvm_t *kd, kvaddr_t va, off_t *ofs)
{
        struct vmstate *vm;

        vm = kd->vmst;
        if (be32toh(vm->ph->p_paddr) == 0xffffffff)
                return ((int)powerpc_va2off(kd, va, ofs));

        _kvm_err(kd, kd->program, "Raw corefile not supported");
        return (0);
}

static int
_powerpc_native(kvm_t *kd __unused)
{

#if defined(__powerpc__) && !defined(__powerpc64__)
        return (1);
#else
        return (0);
#endif
}

static struct kvm_arch kvm_powerpc = {
        .ka_probe = _powerpc_probe,
        .ka_initvtop = _powerpc_initvtop,
        .ka_freevtop = _powerpc_freevtop,
        .ka_kvatop = _powerpc_kvatop,
        .ka_native = _powerpc_native,
};

KVM_ARCH(kvm_powerpc);