LXR linux/arch/mips/kernel/vdso.c

   1/*
   2 * Copyright (C) 2015 Imagination Technologies
   3 * Author: Alex Smith <alex.smith@imgtec.com>
   4 *
   5 * This program is free software; you can redistribute it and/or modify it
   6 * under the terms of the GNU General Public License as published by the
   7 * Free Software Foundation;  either version 2 of the  License, or (at your
   8 * option) any later version.
   9 */
  10
  11#include <linux/binfmts.h>
  12#include <linux/elf.h>
  13#include <linux/err.h>
  14#include <linux/init.h>
  15#include <linux/ioport.h>
  16#include <linux/irqchip/mips-gic.h>
  17#include <linux/mm.h>
  18#include <linux/sched.h>
  19#include <linux/slab.h>
  20#include <linux/timekeeper_internal.h>
  21
  22#include <asm/abi.h>
  23#include <asm/vdso.h>
  24
  25/* Kernel-provided data used by the VDSO. */
  26static union mips_vdso_data vdso_data __page_aligned_data;
  27
  28/*
  29 * Mapping for the VDSO data/GIC pages. The real pages are mapped manually, as
  30 * what we map and where within the area they are mapped is determined at
  31 * runtime.
  32 */
  33static struct page *no_pages[] = { NULL };
  34static struct vm_special_mapping vdso_vvar_mapping = {
  35        .name = "[vvar]",
  36        .pages = no_pages,
  37};
  38
  39static void __init init_vdso_image(struct mips_vdso_image *image)
  40{
  41        unsigned long num_pages, i;
  42        unsigned long data_pfn;
  43
  44        BUG_ON(!PAGE_ALIGNED(image->data));
  45        BUG_ON(!PAGE_ALIGNED(image->size));
  46
  47        num_pages = image->size / PAGE_SIZE;
  48
  49        data_pfn = __phys_to_pfn(__pa_symbol(image->data));
  50        for (i = 0; i < num_pages; i++)
  51                image->mapping.pages[i] = pfn_to_page(data_pfn + i);
  52}
  53
  54static int __init init_vdso(void)
  55{
  56        init_vdso_image(&vdso_image);
  57
  58#ifdef CONFIG_MIPS32_O32
  59        init_vdso_image(&vdso_image_o32);
  60#endif
  61
  62#ifdef CONFIG_MIPS32_N32
  63        init_vdso_image(&vdso_image_n32);
  64#endif
  65
  66        return 0;
  67}
  68subsys_initcall(init_vdso);
  69
  70void update_vsyscall(struct timekeeper *tk)
  71{
  72        vdso_data_write_begin(&vdso_data);
  73
  74        vdso_data.xtime_sec = tk->xtime_sec;
  75        vdso_data.xtime_nsec = tk->tkr_mono.xtime_nsec;
  76        vdso_data.wall_to_mono_sec = tk->wall_to_monotonic.tv_sec;
  77        vdso_data.wall_to_mono_nsec = tk->wall_to_monotonic.tv_nsec;
  78        vdso_data.cs_shift = tk->tkr_mono.shift;
  79
  80        vdso_data.clock_mode = tk->tkr_mono.clock->archdata.vdso_clock_mode;
  81        if (vdso_data.clock_mode != VDSO_CLOCK_NONE) {
  82                vdso_data.cs_mult = tk->tkr_mono.mult;
  83                vdso_data.cs_cycle_last = tk->tkr_mono.cycle_last;
  84                vdso_data.cs_mask = tk->tkr_mono.mask;
  85        }
  86
  87        vdso_data_write_end(&vdso_data);
  88}
  89
  90void update_vsyscall_tz(void)
  91{
  92        if (vdso_data.clock_mode != VDSO_CLOCK_NONE) {
  93                vdso_data.tz_minuteswest = sys_tz.tz_minuteswest;
  94                vdso_data.tz_dsttime = sys_tz.tz_dsttime;
  95        }
  96}
  97
  98int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp)
  99{
 100        struct mips_vdso_image *image = current->thread.abi->vdso;
 101        struct mm_struct *mm = current->mm;
 102        unsigned long gic_size, vvar_size, size, base, data_addr, vdso_addr;
 103        struct vm_area_struct *vma;
 104        struct resource gic_res;
 105        int ret;
 106
 107        if (down_write_killable(&mm->mmap_sem))
 108                return -EINTR;
 109
 110        /* Map delay slot emulation page */
 111        base = mmap_region(NULL, STACK_TOP, PAGE_SIZE,
 112                           VM_READ|VM_WRITE|VM_EXEC|
 113                           VM_MAYREAD|VM_MAYWRITE|VM_MAYEXEC,
 114                           0);
 115        if (IS_ERR_VALUE(base)) {
 116                ret = base;
 117                goto out;
 118        }
 119
 120        /*
 121         * Determine total area size. This includes the VDSO data itself, the
 122         * data page, and the GIC user page if present. Always create a mapping
 123         * for the GIC user area if the GIC is present regardless of whether it
 124         * is the current clocksource, in case it comes into use later on. We
 125         * only map a page even though the total area is 64K, as we only need
 126         * the counter registers at the start.
 127         */
 128        gic_size = gic_present ? PAGE_SIZE : 0;
 129        vvar_size = gic_size + PAGE_SIZE;
 130        size = vvar_size + image->size;
 131
 132        base = get_unmapped_area(NULL, 0, size, 0, 0);
 133        if (IS_ERR_VALUE(base)) {
 134                ret = base;
 135                goto out;
 136        }
 137
 138        data_addr = base + gic_size;
 139        vdso_addr = data_addr + PAGE_SIZE;
 140
 141        vma = _install_special_mapping(mm, base, vvar_size,
 142                                       VM_READ | VM_MAYREAD,
 143                                       &vdso_vvar_mapping);
 144        if (IS_ERR(vma)) {
 145                ret = PTR_ERR(vma);
 146                goto out;
 147        }
 148
 149        /* Map GIC user page. */
 150        if (gic_size) {
 151                ret = gic_get_usm_range(&gic_res);
 152                if (ret)
 153                        goto out;
 154
 155                ret = io_remap_pfn_range(vma, base,
 156                                         gic_res.start >> PAGE_SHIFT,
 157                                         gic_size,
 158                                         pgprot_noncached(PAGE_READONLY));
 159                if (ret)
 160                        goto out;
 161        }
 162
 163        /* Map data page. */
 164        ret = remap_pfn_range(vma, data_addr,
 165                              virt_to_phys(&vdso_data) >> PAGE_SHIFT,
 166                              PAGE_SIZE, PAGE_READONLY);
 167        if (ret)
 168                goto out;
 169
 170        /* Map VDSO image. */
 171        vma = _install_special_mapping(mm, vdso_addr, image->size,
 172                                       VM_READ | VM_EXEC |
 173                                       VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC,
 174                                       &image->mapping);
 175        if (IS_ERR(vma)) {
 176                ret = PTR_ERR(vma);
 177                goto out;
 178        }
 179
 180        mm->context.vdso = (void *)vdso_addr;
 181        ret = 0;
 182
 183out:
 184        up_write(&mm->mmap_sem);
 185        return ret;
 186}
 187