// SPDX-License-Identifier: GPL-2.0
// Copyright (C) 2012 ARM Limited
// Copyright (C) 2005-2017 Andes Technology Corporation

#include <linux/cache.h>
#include <linux/clocksource.h>
#include <linux/elf.h>
#include <linux/err.h>
#include <linux/errno.h>
#include <linux/gfp.h>
#include <linux/kernel.h>
#include <linux/mm.h>
#include <linux/sched.h>
#include <linux/signal.h>
#include <linux/slab.h>
#include <linux/timekeeper_internal.h>
#include <linux/vmalloc.h>
#include <linux/random.h>

#include <asm/cacheflush.h>
#include <asm/vdso.h>
#include <asm/vdso_datapage.h>
#include <asm/vdso_timer_info.h>
#include <asm/cache_info.h>
extern struct cache_info L1_cache_info[2];
extern char vdso_start[], vdso_end[];
static unsigned long vdso_pages __ro_after_init;
static unsigned long timer_mapping_base;

struct timer_info_t timer_info = {
        .cycle_count_down = true,
        .mapping_base = EMPTY_TIMER_MAPPING,
        .cycle_count_reg_offset = EMPTY_REG_OFFSET
};
/*
 * The vDSO data page.
 */
static struct page *no_pages[] = { NULL };

static union {
        struct vdso_data data;
        u8 page[PAGE_SIZE];
} vdso_data_store __page_aligned_data;
struct vdso_data *vdso_data = &vdso_data_store.data;
static struct vm_special_mapping vdso_spec[2] __ro_after_init = {
        {
         .name = "[vvar]",
         .pages = no_pages,
         },
        {
         .name = "[vdso]",
         },
};

static void get_timer_node_info(void)
{
        timer_mapping_base = timer_info.mapping_base;
        vdso_data->cycle_count_offset =
                timer_info.cycle_count_reg_offset;
        vdso_data->cycle_count_down =
                timer_info.cycle_count_down;
}

static int __init vdso_init(void)
{
        int i;
        struct page **vdso_pagelist;

        if (memcmp(vdso_start, "\177ELF", 4)) {
                pr_err("vDSO is not a valid ELF object!\n");
                return -EINVAL;
        }
        /* Creat a timer io mapping to get clock cycles counter */
        get_timer_node_info();

        vdso_pages = (vdso_end - vdso_start) >> PAGE_SHIFT;
        pr_info("vdso: %ld pages (%ld code @ %p, %ld data @ %p)\n",
                vdso_pages + 1, vdso_pages, vdso_start, 1L, vdso_data);

        /* Allocate the vDSO pagelist */
        vdso_pagelist = kcalloc(vdso_pages, sizeof(struct page *), GFP_KERNEL);
        if (vdso_pagelist == NULL)
                return -ENOMEM;

        for (i = 0; i < vdso_pages; i++)
                vdso_pagelist[i] = virt_to_page(vdso_start + i * PAGE_SIZE);
        vdso_spec[1].pages = &vdso_pagelist[0];

        return 0;
}

arch_initcall(vdso_init);

unsigned long inline vdso_random_addr(unsigned long vdso_mapping_len)
{
        unsigned long start = current->mm->mmap_base, end, offset, addr;
        start = PAGE_ALIGN(start);

        /* Round the lowest possible end address up to a PMD boundary. */
        end = (start + vdso_mapping_len + PMD_SIZE - 1) & PMD_MASK;
        if (end >= TASK_SIZE)
                end = TASK_SIZE;
        end -= vdso_mapping_len;

        if (end > start) {
                offset = get_random_int() % (((end - start) >> PAGE_SHIFT) + 1);
                addr = start + (offset << PAGE_SHIFT);
        } else {
                addr = start;
        }
        return addr;
}

int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp)
{
        struct mm_struct *mm = current->mm;
        unsigned long vdso_base, vdso_text_len, vdso_mapping_len;
        struct vm_area_struct *vma;
        unsigned long addr = 0;
        pgprot_t prot;
        int ret, vvar_page_num = 2;

        vdso_text_len = vdso_pages << PAGE_SHIFT;

        if(timer_mapping_base == EMPTY_VALUE)
                vvar_page_num = 1;
        /* Be sure to map the data page */
        vdso_mapping_len = vdso_text_len + vvar_page_num * PAGE_SIZE;
#ifdef CONFIG_CPU_CACHE_ALIASING
        vdso_mapping_len += L1_cache_info[DCACHE].aliasing_num - 1;
#endif

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

        addr = vdso_random_addr(vdso_mapping_len);
        vdso_base = get_unmapped_area(NULL, addr, vdso_mapping_len, 0, 0);
        if (IS_ERR_VALUE(vdso_base)) {
                ret = vdso_base;
                goto up_fail;
        }

#ifdef CONFIG_CPU_CACHE_ALIASING
        {
                unsigned int aliasing_mask =
                    L1_cache_info[DCACHE].aliasing_mask;
                unsigned int page_colour_ofs;
                page_colour_ofs = ((unsigned int)vdso_data & aliasing_mask) -
                    (vdso_base & aliasing_mask);
                vdso_base += page_colour_ofs & aliasing_mask;
        }
#endif

        vma = _install_special_mapping(mm, vdso_base, vvar_page_num * PAGE_SIZE,
                                       VM_READ | VM_MAYREAD, &vdso_spec[0]);
        if (IS_ERR(vma)) {
                ret = PTR_ERR(vma);
                goto up_fail;
        }

        /*Map vdata to user space */
        ret = io_remap_pfn_range(vma, vdso_base,
                                 virt_to_phys(vdso_data) >> PAGE_SHIFT,
                                 PAGE_SIZE, vma->vm_page_prot);
        if (ret)
                goto up_fail;

        /*Map timer to user space */
        vdso_base += PAGE_SIZE;
        prot = __pgprot(_PAGE_V | _PAGE_M_UR_KR | _PAGE_D |  _PAGE_C_DEV);
        ret = io_remap_pfn_range(vma, vdso_base, timer_mapping_base >> PAGE_SHIFT,
                                 PAGE_SIZE, prot);
        if (ret)
                goto up_fail;

        /*Map vdso to user space */
        vdso_base += PAGE_SIZE;
        mm->context.vdso = (void *)vdso_base;
        vma = _install_special_mapping(mm, vdso_base, vdso_text_len,
                                       VM_READ | VM_EXEC |
                                       VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC,
                                       &vdso_spec[1]);
        if (IS_ERR(vma)) {
                ret = PTR_ERR(vma);
                goto up_fail;
        }

        up_write(&mm->mmap_sem);
        return 0;

up_fail:
        mm->context.vdso = NULL;
        up_write(&mm->mmap_sem);
        return ret;
}

static void vdso_write_begin(struct vdso_data *vdata)
{
        ++vdso_data->seq_count;
        smp_wmb();              /* Pairs with smp_rmb in vdso_read_retry */
}

static void vdso_write_end(struct vdso_data *vdata)
{
        smp_wmb();              /* Pairs with smp_rmb in vdso_read_begin */
        ++vdso_data->seq_count;
}

void update_vsyscall(struct timekeeper *tk)
{
        vdso_write_begin(vdso_data);
        vdso_data->cs_mask = tk->tkr_mono.mask;
        vdso_data->cs_mult = tk->tkr_mono.mult;
        vdso_data->cs_shift = tk->tkr_mono.shift;
        vdso_data->cs_cycle_last = tk->tkr_mono.cycle_last;
        vdso_data->wtm_clock_sec = tk->wall_to_monotonic.tv_sec;
        vdso_data->wtm_clock_nsec = tk->wall_to_monotonic.tv_nsec;
        vdso_data->xtime_clock_sec = tk->xtime_sec;
        vdso_data->xtime_clock_nsec = tk->tkr_mono.xtime_nsec;
        vdso_data->xtime_coarse_sec = tk->xtime_sec;
        vdso_data->xtime_coarse_nsec = tk->tkr_mono.xtime_nsec >>
            tk->tkr_mono.shift;
        vdso_data->hrtimer_res = hrtimer_resolution;
        vdso_write_end(vdso_data);
}

void update_vsyscall_tz(void)
{
        vdso_data->tz_minuteswest = sys_tz.tz_minuteswest;
        vdso_data->tz_dsttime = sys_tz.tz_dsttime;
}