/*-
 * Copyright (c) 2004 Tim J. Robbins
 * Copyright (c) 2002 Doug Rabson
 * Copyright (c) 2000 Marcel Moolenaar
 * Copyright (c) 1994-1995 Søren Schmidt
 * 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
 *    in this position and unchanged.
 * 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. The name of the author may not 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/fcntl.h>
#include <sys/file.h>
#include <sys/ktr.h>
#include <sys/lock.h>
#include <sys/malloc.h>
#include <sys/mman.h>
#include <sys/proc.h>
#include <sys/resourcevar.h>
#include <sys/rwlock.h>
#include <sys/syscallsubr.h>
#include <sys/sysent.h>
#include <sys/sysproto.h>

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

#include <compat/linux/linux_emul.h>
#include <compat/linux/linux_mmap.h>
#include <compat/linux/linux_persona.h>
#include <compat/linux/linux_util.h>

#define STACK_SIZE  (2 * 1024 * 1024)
#define GUARD_SIZE  (4 * PAGE_SIZE)

#if defined(__amd64__)
static void linux_fixup_prot(struct thread *td, int *prot);
#endif

static int
linux_mmap_check_fp(struct file *fp, int flags, int prot, int maxprot)
{

        /* Linux mmap() just fails for O_WRONLY files */
        if ((fp->f_flag & FREAD) == 0)
                return (EACCES);

        return (0);
}

int
linux_mmap_common(struct thread *td, uintptr_t addr, size_t len, int prot,
    int flags, int fd, off_t pos)
{
        struct mmap_req mr, mr_fixed;
        struct proc *p = td->td_proc;
        struct vmspace *vms = td->td_proc->p_vmspace;
        int bsd_flags, error;

        LINUX_CTR6(mmap2, "0x%lx, %ld, %ld, 0x%08lx, %ld, 0x%lx",
            addr, len, prot, flags, fd, pos);

        error = 0;
        bsd_flags = 0;

        /*
         * Linux mmap(2):
         * You must specify exactly one of MAP_SHARED and MAP_PRIVATE
         */
        if (!((flags & LINUX_MAP_SHARED) ^ (flags & LINUX_MAP_PRIVATE)))
                return (EINVAL);

        if (flags & LINUX_MAP_SHARED)
                bsd_flags |= MAP_SHARED;
        if (flags & LINUX_MAP_PRIVATE)
                bsd_flags |= MAP_PRIVATE;
        if (flags & LINUX_MAP_FIXED)
                bsd_flags |= MAP_FIXED;
        if (flags & LINUX_MAP_ANON) {
                /* Enforce pos to be on page boundary, then ignore. */
                if ((pos & PAGE_MASK) != 0)
                        return (EINVAL);
                pos = 0;
                bsd_flags |= MAP_ANON;
        } else
                bsd_flags |= MAP_NOSYNC;
        if (flags & LINUX_MAP_GROWSDOWN)
                bsd_flags |= MAP_STACK;

#if defined(__amd64__)
        /*
         * According to the Linux mmap(2) man page, "MAP_32BIT flag
         * is ignored when MAP_FIXED is set."
         */
        if ((flags & LINUX_MAP_32BIT) && (flags & LINUX_MAP_FIXED) == 0)
                bsd_flags |= MAP_32BIT;

        /*
         * PROT_READ, PROT_WRITE, or PROT_EXEC implies PROT_READ and PROT_EXEC
         * on Linux/i386 if the binary requires executable stack.
         * We do this only for IA32 emulation as on native i386 this is does not
         * make sense without PAE.
         *
         * XXX. Linux checks that the file system is not mounted with noexec.
         */
        linux_fixup_prot(td, &prot);
#endif

        /* Linux does not check file descriptor when MAP_ANONYMOUS is set. */
        fd = (bsd_flags & MAP_ANON) ? -1 : fd;
        if (flags & LINUX_MAP_GROWSDOWN) {
                /*
                 * The Linux MAP_GROWSDOWN option does not limit auto
                 * growth of the region.  Linux mmap with this option
                 * takes as addr the initial BOS, and as len, the initial
                 * region size.  It can then grow down from addr without
                 * limit.  However, Linux threads has an implicit internal
                 * limit to stack size of STACK_SIZE.  Its just not
                 * enforced explicitly in Linux.  But, here we impose
                 * a limit of (STACK_SIZE - GUARD_SIZE) on the stack
                 * region, since we can do this with our mmap.
                 *
                 * Our mmap with MAP_STACK takes addr as the maximum
                 * downsize limit on BOS, and as len the max size of
                 * the region.  It then maps the top SGROWSIZ bytes,
                 * and auto grows the region down, up to the limit
                 * in addr.
                 *
                 * If we don't use the MAP_STACK option, the effect
                 * of this code is to allocate a stack region of a
                 * fixed size of (STACK_SIZE - GUARD_SIZE).
                 */

                if ((caddr_t)addr + len > vms->vm_maxsaddr) {
                        /*
                         * Some Linux apps will attempt to mmap
                         * thread stacks near the top of their
                         * address space.  If their TOS is greater
                         * than vm_maxsaddr, vm_map_growstack()
                         * will confuse the thread stack with the
                         * process stack and deliver a SEGV if they
                         * attempt to grow the thread stack past their
                         * current stacksize rlimit.  To avoid this,
                         * adjust vm_maxsaddr upwards to reflect
                         * the current stacksize rlimit rather
                         * than the maximum possible stacksize.
                         * It would be better to adjust the
                         * mmap'ed region, but some apps do not check
                         * mmap's return value.
                         */
                        PROC_LOCK(p);
                        vms->vm_maxsaddr = (char *)round_page(vms->vm_stacktop) -
                            lim_cur_proc(p, RLIMIT_STACK);
                        PROC_UNLOCK(p);
                }

                /*
                 * This gives us our maximum stack size and a new BOS.
                 * If we're using VM_STACK, then mmap will just map
                 * the top SGROWSIZ bytes, and let the stack grow down
                 * to the limit at BOS.  If we're not using VM_STACK
                 * we map the full stack, since we don't have a way
                 * to autogrow it.
                 */
                if (len <= STACK_SIZE - GUARD_SIZE) {
                        addr = addr - (STACK_SIZE - GUARD_SIZE - len);
                        len = STACK_SIZE - GUARD_SIZE;
                }
        }

        /*
         * FreeBSD is free to ignore the address hint if MAP_FIXED wasn't
         * passed.  However, some Linux applications, like the ART runtime,
         * depend on the hint.  If the MAP_FIXED wasn't passed, but the
         * address is not zero, try with MAP_FIXED and MAP_EXCL first,
         * and fall back to the normal behaviour if that fails.
         */
        mr = (struct mmap_req) {
                .mr_hint = addr,
                .mr_len = len,
                .mr_prot = prot,
                .mr_flags = bsd_flags,
                .mr_fd = fd,
                .mr_pos = pos,
                .mr_check_fp_fn = linux_mmap_check_fp,
        };
        if (addr != 0 && (bsd_flags & MAP_FIXED) == 0 &&
            (bsd_flags & MAP_EXCL) == 0) {
                mr_fixed = mr;
                mr_fixed.mr_flags |= MAP_FIXED | MAP_EXCL;
                error = kern_mmap(td, &mr_fixed);
                if (error == 0)
                        goto out;
        }

        error = kern_mmap(td, &mr);
out:
        LINUX_CTR2(mmap2, "return: %d (%p)", error, td->td_retval[0]);

        return (error);
}

int
linux_mprotect_common(struct thread *td, uintptr_t addr, size_t len, int prot)
{
        int flags = 0;

        /* XXX Ignore PROT_GROWSUP for now. */
        prot &= ~LINUX_PROT_GROWSUP;
        if ((prot & ~(LINUX_PROT_GROWSDOWN | PROT_READ | PROT_WRITE |
            PROT_EXEC)) != 0)
                return (EINVAL);
        if ((prot & LINUX_PROT_GROWSDOWN) != 0) {
                prot &= ~LINUX_PROT_GROWSDOWN;
                flags |= VM_MAP_PROTECT_GROWSDOWN;
        }

#if defined(__amd64__)
        linux_fixup_prot(td, &prot);
#endif
        return (kern_mprotect(td, addr, len, prot, flags));
}

/*
 * Implement Linux madvise(MADV_DONTNEED), which has unusual semantics: for
 * anonymous memory, pages in the range are immediately discarded.
 */
static int
linux_madvise_dontneed(struct thread *td, vm_offset_t start, vm_offset_t end)
{
        vm_map_t map;
        vm_map_entry_t entry;
        vm_object_t backing_object, object;
        vm_offset_t estart, eend;
        vm_pindex_t pstart, pend;
        int error;

        map = &td->td_proc->p_vmspace->vm_map;

        if (!vm_map_range_valid(map, start, end))
                return (EINVAL);
        start = trunc_page(start);
        end = round_page(end);

        error = 0;
        vm_map_lock_read(map);
        if (!vm_map_lookup_entry(map, start, &entry))
                entry = vm_map_entry_succ(entry);
        for (; entry->start < end; entry = vm_map_entry_succ(entry)) {
                if ((entry->eflags & MAP_ENTRY_IS_SUB_MAP) != 0)
                        continue;

                if (entry->wired_count != 0) {
                        error = EINVAL;
                        break;
                }

                object = entry->object.vm_object;
                if (object == NULL)
                        continue;
                if ((object->flags & (OBJ_UNMANAGED | OBJ_FICTITIOUS)) != 0)
                        continue;

                pstart = OFF_TO_IDX(entry->offset);
                if (start > entry->start) {
                        pstart += atop(start - entry->start);
                        estart = start;
                } else {
                        estart = entry->start;
                }
                pend = OFF_TO_IDX(entry->offset) +
                    atop(entry->end - entry->start);
                if (entry->end > end) {
                        pend -= atop(entry->end - end);
                        eend = end;
                } else {
                        eend = entry->end;
                }

                if ((object->flags & (OBJ_ANON | OBJ_ONEMAPPING)) ==
                    (OBJ_ANON | OBJ_ONEMAPPING)) {
                        /*
                         * Singly-mapped anonymous memory is discarded.  This
                         * does not match Linux's semantics when the object
                         * belongs to a shadow chain of length > 1, since
                         * subsequent faults may retrieve pages from an
                         * intermediate anonymous object.  However, handling
                         * this case correctly introduces a fair bit of
                         * complexity.
                         */
                        VM_OBJECT_WLOCK(object);
                        if ((object->flags & OBJ_ONEMAPPING) != 0) {
                                vm_object_collapse(object);
                                vm_object_page_remove(object, pstart, pend, 0);
                                backing_object = object->backing_object;
                                if (backing_object != NULL &&
                                    (backing_object->flags & OBJ_ANON) != 0)
                                        linux_msg(td,
                                            "possibly incorrect MADV_DONTNEED");
                                VM_OBJECT_WUNLOCK(object);
                                continue;
                        }
                        VM_OBJECT_WUNLOCK(object);
                }

                /*
                 * Handle shared mappings.  Remove them outright instead of
                 * calling pmap_advise(), for consistency with Linux.
                 */
                pmap_remove(map->pmap, estart, eend);
                vm_object_madvise(object, pstart, pend, MADV_DONTNEED);
        }
        vm_map_unlock_read(map);

        return (error);
}

int
linux_madvise_common(struct thread *td, uintptr_t addr, size_t len, int behav)
{

        switch (behav) {
        case LINUX_MADV_NORMAL:
                return (kern_madvise(td, addr, len, MADV_NORMAL));
        case LINUX_MADV_RANDOM:
                return (kern_madvise(td, addr, len, MADV_RANDOM));
        case LINUX_MADV_SEQUENTIAL:
                return (kern_madvise(td, addr, len, MADV_SEQUENTIAL));
        case LINUX_MADV_WILLNEED:
                return (kern_madvise(td, addr, len, MADV_WILLNEED));
        case LINUX_MADV_DONTNEED:
                return (linux_madvise_dontneed(td, addr, addr + len));
        case LINUX_MADV_FREE:
                return (kern_madvise(td, addr, len, MADV_FREE));
        case LINUX_MADV_REMOVE:
                linux_msg(curthread, "unsupported madvise MADV_REMOVE");
                return (EINVAL);
        case LINUX_MADV_DONTFORK:
                return (kern_minherit(td, addr, len, INHERIT_NONE));
        case LINUX_MADV_DOFORK:
                return (kern_minherit(td, addr, len, INHERIT_COPY));
        case LINUX_MADV_MERGEABLE:
                linux_msg(curthread, "unsupported madvise MADV_MERGEABLE");
                return (EINVAL);
        case LINUX_MADV_UNMERGEABLE:
                /* We don't merge anyway. */
                return (0);
        case LINUX_MADV_HUGEPAGE:
                /* Ignored; on FreeBSD huge pages are always on. */
                return (0);
        case LINUX_MADV_NOHUGEPAGE:
#if 0
                /*
                 * Don't warn - Firefox uses it a lot, and in real Linux it's
                 * an optional feature.
                 */
                linux_msg(curthread, "unsupported madvise MADV_NOHUGEPAGE");
#endif
                return (EINVAL);
        case LINUX_MADV_DONTDUMP:
                return (kern_madvise(td, addr, len, MADV_NOCORE));
        case LINUX_MADV_DODUMP:
                return (kern_madvise(td, addr, len, MADV_CORE));
        case LINUX_MADV_WIPEONFORK:
                return (kern_minherit(td, addr, len, INHERIT_ZERO));
        case LINUX_MADV_KEEPONFORK:
                return (kern_minherit(td, addr, len, INHERIT_COPY));
        case LINUX_MADV_HWPOISON:
                linux_msg(curthread, "unsupported madvise MADV_HWPOISON");
                return (EINVAL);
        case LINUX_MADV_SOFT_OFFLINE:
                linux_msg(curthread, "unsupported madvise MADV_SOFT_OFFLINE");
                return (EINVAL);
        case -1:
                /*
                 * -1 is sometimes used as a dummy value to detect simplistic
                 * madvise(2) stub implementations.  This safeguard is used by
                 * BoringSSL, for example, before assuming MADV_WIPEONFORK is
                 * safe to use.  Don't produce an "unsupported" error message
                 * for this special dummy value, which is unlikely to be used
                 * by any new advisory behavior feature.
                 */
                return (EINVAL);
        default:
                linux_msg(curthread, "unsupported madvise behav %d", behav);
                return (EINVAL);
        }
}

#if defined(__amd64__)
static void
linux_fixup_prot(struct thread *td, int *prot)
{
        struct linux_pemuldata *pem;

        if (SV_PROC_FLAG(td->td_proc, SV_ILP32) && *prot & PROT_READ) {
                pem = pem_find(td->td_proc);
                if (pem->persona & LINUX_READ_IMPLIES_EXEC)
                        *prot |= PROT_EXEC;
        }

}
#endif