// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * Copyright (C) 2015 Imagination Technologies
 * Author: Alex Smith <alex.smith@imgtec.com>
 */

#include <linux/binfmts.h>
#include <linux/elf.h>
#include <linux/err.h>
#include <linux/init.h>
#include <linux/ioport.h>
#include <linux/kernel.h>
#include <linux/mm.h>
#include <linux/random.h>
#include <linux/sched.h>
#include <linux/slab.h>
#include <linux/timekeeper_internal.h>

#include <asm/abi.h>
#include <asm/mips-cps.h>
#include <asm/page.h>
#include <asm/vdso.h>

/* Kernel-provided data used by the VDSO. */
static union mips_vdso_data vdso_data __page_aligned_data;

/*
 * Mapping for the VDSO data/GIC pages. The real pages are mapped manually, as
 * what we map and where within the area they are mapped is determined at
 * runtime.
 */
static struct page *no_pages[] = { NULL };
static struct vm_special_mapping vdso_vvar_mapping = {
        .name = "[vvar]",
        .pages = no_pages,
};

static void __init init_vdso_image(struct mips_vdso_image *image)
{
        unsigned long num_pages, i;
        unsigned long data_pfn;

        BUG_ON(!PAGE_ALIGNED(image->data));
        BUG_ON(!PAGE_ALIGNED(image->size));

        num_pages = image->size / PAGE_SIZE;

        data_pfn = __phys_to_pfn(__pa_symbol(image->data));
        for (i = 0; i < num_pages; i++)
                image->mapping.pages[i] = pfn_to_page(data_pfn + i);
}

static int __init init_vdso(void)
{
        init_vdso_image(&vdso_image);

#ifdef CONFIG_MIPS32_O32
        init_vdso_image(&vdso_image_o32);
#endif

#ifdef CONFIG_MIPS32_N32
        init_vdso_image(&vdso_image_n32);
#endif

        return 0;
}
subsys_initcall(init_vdso);

void update_vsyscall(struct timekeeper *tk)
{
        vdso_data_write_begin(&vdso_data);

        vdso_data.xtime_sec = tk->xtime_sec;
        vdso_data.xtime_nsec = tk->tkr_mono.xtime_nsec;
        vdso_data.wall_to_mono_sec = tk->wall_to_monotonic.tv_sec;
        vdso_data.wall_to_mono_nsec = tk->wall_to_monotonic.tv_nsec;
        vdso_data.cs_shift = tk->tkr_mono.shift;

        vdso_data.clock_mode = tk->tkr_mono.clock->archdata.vdso_clock_mode;
        if (vdso_data.clock_mode != VDSO_CLOCK_NONE) {
                vdso_data.cs_mult = tk->tkr_mono.mult;
                vdso_data.cs_cycle_last = tk->tkr_mono.cycle_last;
                vdso_data.cs_mask = tk->tkr_mono.mask;
        }

        vdso_data_write_end(&vdso_data);
}

void update_vsyscall_tz(void)
{
        if (vdso_data.clock_mode != VDSO_CLOCK_NONE) {
                vdso_data.tz_minuteswest = sys_tz.tz_minuteswest;
                vdso_data.tz_dsttime = sys_tz.tz_dsttime;
        }
}

static unsigned long vdso_base(void)
{
        unsigned long base;

        /* Skip the delay slot emulation page */
        base = STACK_TOP + PAGE_SIZE;

        if (current->flags & PF_RANDOMIZE) {
                base += get_random_int() & (VDSO_RANDOMIZE_SIZE - 1);
                base = PAGE_ALIGN(base);
        }

        return base;
}

int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp)
{
        struct mips_vdso_image *image = current->thread.abi->vdso;
        struct mm_struct *mm = current->mm;
        unsigned long gic_size, vvar_size, size, base, data_addr, vdso_addr, gic_pfn;
        struct vm_area_struct *vma;
        int ret;

        if (down_write_killable(&mm->mmap_sem))
                return -EINTR;

        /* Map delay slot emulation page */
        base = mmap_region(NULL, STACK_TOP, PAGE_SIZE,
                           VM_READ | VM_EXEC |
                           VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC,
                           0, NULL);
        if (IS_ERR_VALUE(base)) {
                ret = base;
                goto out;
        }

        /*
         * Determine total area size. This includes the VDSO data itself, the
         * data page, and the GIC user page if present. Always create a mapping
         * for the GIC user area if the GIC is present regardless of whether it
         * is the current clocksource, in case it comes into use later on. We
         * only map a page even though the total area is 64K, as we only need
         * the counter registers at the start.
         */
        gic_size = mips_gic_present() ? PAGE_SIZE : 0;
        vvar_size = gic_size + PAGE_SIZE;
        size = vvar_size + image->size;

        /*
         * Find a region that's large enough for us to perform the
         * colour-matching alignment below.
         */
        if (cpu_has_dc_aliases)
                size += shm_align_mask + 1;

        base = get_unmapped_area(NULL, vdso_base(), size, 0, 0);
        if (IS_ERR_VALUE(base)) {
                ret = base;
                goto out;
        }

        /*
         * If we suffer from dcache aliasing, ensure that the VDSO data page
         * mapping is coloured the same as the kernel's mapping of that memory.
         * This ensures that when the kernel updates the VDSO data userland
         * will observe it without requiring cache invalidations.
         */
        if (cpu_has_dc_aliases) {
                base = __ALIGN_MASK(base, shm_align_mask);
                base += ((unsigned long)&vdso_data - gic_size) & shm_align_mask;
        }

        data_addr = base + gic_size;
        vdso_addr = data_addr + PAGE_SIZE;

        vma = _install_special_mapping(mm, base, vvar_size,
                                       VM_READ | VM_MAYREAD,
                                       &vdso_vvar_mapping);
        if (IS_ERR(vma)) {
                ret = PTR_ERR(vma);
                goto out;
        }

        /* Map GIC user page. */
        if (gic_size) {
                gic_pfn = virt_to_phys(mips_gic_base + MIPS_GIC_USER_OFS) >> PAGE_SHIFT;

                ret = io_remap_pfn_range(vma, base, gic_pfn, gic_size,
                                         pgprot_noncached(PAGE_READONLY));
                if (ret)
                        goto out;
        }

        /* Map data page. */
        ret = remap_pfn_range(vma, data_addr,
                              virt_to_phys(&vdso_data) >> PAGE_SHIFT,
                              PAGE_SIZE, PAGE_READONLY);
        if (ret)
                goto out;

        /* Map VDSO image. */
        vma = _install_special_mapping(mm, vdso_addr, image->size,
                                       VM_READ | VM_EXEC |
                                       VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC,
                                       &image->mapping);
        if (IS_ERR(vma)) {
                ret = PTR_ERR(vma);
                goto out;
        }

        mm->context.vdso = (void *)vdso_addr;
        ret = 0;

out:
        up_write(&mm->mmap_sem);
        return ret;
}