/*-
 * SPDX-License-Identifier: BSD-2-Clause
 *
 * Copyright (c) 2013-2021 Dmitry Chagin <dchagin@FreeBSD.org>
 *
 * 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.
 */

#if defined(__i386__) || (defined(__amd64__) && defined(COMPAT_LINUX32))
#define __ELF_WORD_SIZE 32
#else
#define __ELF_WORD_SIZE 64
#endif

#include <sys/param.h>
#include <sys/elf.h>
#include <sys/imgact.h>
#include <sys/lock.h>
#include <sys/proc.h>
#include <sys/rwlock.h>
#include <sys/sysent.h>

#include <vm/pmap.h>
#include <vm/vm_extern.h>
#include <vm/vm_map.h>
#include <vm/vm_object.h>
#include <vm/vm_page.h>
#include <vm/vm_pager.h>
#include <vm/vm_param.h>

#include <compat/linux/linux_vdso.h>

SLIST_HEAD(, linux_vdso_sym) __elfN(linux_vdso_syms) =
    SLIST_HEAD_INITIALIZER(__elfN(linux_vdso_syms));

void
__elfN(linux_vdso_sym_init)(struct linux_vdso_sym *s)
{

        SLIST_INSERT_HEAD(&__elfN(linux_vdso_syms), s, sym);
}

vm_object_t
__elfN(linux_shared_page_init)(char **mapping, vm_size_t size)
{
        vm_page_t m;
        vm_object_t obj;
        vm_offset_t addr;
        size_t n, pages;

        pages = size / PAGE_SIZE;

        addr = kva_alloc(size);
        obj = vm_pager_allocate(OBJT_PHYS, 0, size,
            VM_PROT_DEFAULT, 0, NULL);
        VM_OBJECT_WLOCK(obj);
        for (n = 0; n < pages; n++) {
                m = vm_page_grab(obj, n,
                    VM_ALLOC_ZERO);
                vm_page_valid(m);
                vm_page_xunbusy(m);
                pmap_qenter(addr + n * PAGE_SIZE, &m, 1);
        }
        VM_OBJECT_WUNLOCK(obj);
        *mapping = (char *)addr;
        return (obj);
}

void
__elfN(linux_shared_page_fini)(vm_object_t obj, void *mapping,
    vm_size_t size)
{
        vm_offset_t va;

        va = (vm_offset_t)mapping;
        pmap_qremove(va, size / PAGE_SIZE);
        kva_free(va, size);
        vm_object_deallocate(obj);
}

void
__elfN(linux_vdso_fixup)(char *base, vm_offset_t offset)
{
        struct linux_vdso_sym *lsym;
        const Elf_Shdr *shdr;
        Elf_Ehdr *ehdr;
        Elf_Sym *dsym, *sym;
        char *strtab, *symname;
        int i, symcnt;

        ehdr = (Elf_Ehdr *)base;

        MPASS(IS_ELF(*ehdr));
        MPASS(ehdr->e_ident[EI_CLASS] == ELF_TARG_CLASS);
        MPASS(ehdr->e_ident[EI_DATA] == ELF_TARG_DATA);
        MPASS(ehdr->e_ident[EI_VERSION] == EV_CURRENT);
        MPASS(ehdr->e_shentsize == sizeof(Elf_Shdr));
        MPASS(ehdr->e_shoff != 0);
        MPASS(ehdr->e_type == ET_DYN);

        shdr = (const Elf_Shdr *)(base + ehdr->e_shoff);

        dsym = NULL;
        for (i = 0; i < ehdr->e_shnum; i++) {
                if (shdr[i].sh_size == 0)
                        continue;
                if (shdr[i].sh_type == SHT_DYNSYM) {
                        dsym = (Elf_Sym *)(base + shdr[i].sh_offset);
                        strtab = base + shdr[shdr[i].sh_link].sh_offset;
                        symcnt = shdr[i].sh_size / sizeof(*dsym);
                        break;
                }
        }
        MPASS(dsym != NULL);

        ehdr->e_ident[EI_OSABI] = ELFOSABI_LINUX;

        /*
         * VDSO is readonly mapped to the process VA and
         * can't be relocated by rtld.
         */
        SLIST_FOREACH(lsym, &__elfN(linux_vdso_syms), sym) {
                for (i = 0, sym = dsym; i < symcnt; i++, sym++) {
                        symname = strtab + sym->st_name;
                        if (strncmp(lsym->symname, symname, lsym->size) == 0) {
                                sym->st_value += offset;
                                *lsym->ptr = sym->st_value;
                                break;

                        }
                }
        }
}

int
linux_map_vdso(struct proc *p, vm_object_t obj, vm_offset_t base,
    vm_offset_t size, struct image_params *imgp)
{
        struct vmspace *vmspace;
        vm_map_t map;
        int error;

        MPASS((imgp->sysent->sv_flags & SV_ABI_MASK) == SV_ABI_LINUX);
        MPASS(obj != NULL);

        vmspace = p->p_vmspace;
        map = &vmspace->vm_map;

        vm_object_reference(obj);
        error = vm_map_fixed(map, obj, 0, base, size,
            VM_PROT_READ | VM_PROT_EXECUTE,
            VM_PROT_READ | VM_PROT_EXECUTE,
            MAP_INHERIT_SHARE | MAP_ACC_NO_CHARGE);
        if (error != KERN_SUCCESS) {
                vm_object_deallocate(obj);
                return (vm_mmap_to_errno(error));
        }
        return (0);
}