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/mm.h>
  17#include <linux/sched.h>
  18#include <linux/slab.h>
  19#include <linux/timekeeper_internal.h>
  20
  21#include <asm/abi.h>
  22#include <asm/mips-cps.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, gic_pfn;
 103        struct vm_area_struct *vma;
 104        int ret;
 105
 106        if (down_write_killable(&mm->mmap_sem))
 107                return -EINTR;
 108
 109        /* Map delay slot emulation page */
 110        base = mmap_region(NULL, STACK_TOP, PAGE_SIZE,
 111                           VM_READ|VM_WRITE|VM_EXEC|
 112                           VM_MAYREAD|VM_MAYWRITE|VM_MAYEXEC,
 113                           0, NULL);
 114        if (IS_ERR_VALUE(base)) {
 115                ret = base;
 116                goto out;
 117        }
 118
 119        /*
 120         * Determine total area size. This includes the VDSO data itself, the
 121         * data page, and the GIC user page if present. Always create a mapping
 122         * for the GIC user area if the GIC is present regardless of whether it
 123         * is the current clocksource, in case it comes into use later on. We
 124         * only map a page even though the total area is 64K, as we only need
 125         * the counter registers at the start.
 126         */
 127        gic_size = mips_gic_present() ? PAGE_SIZE : 0;
 128        vvar_size = gic_size + PAGE_SIZE;
 129        size = vvar_size + image->size;
 130
 131        base = get_unmapped_area(NULL, 0, size, 0, 0);
 132        if (IS_ERR_VALUE(base)) {
 133                ret = base;
 134                goto out;
 135        }
 136
 137        data_addr = base + gic_size;
 138        vdso_addr = data_addr + PAGE_SIZE;
 139
 140        vma = _install_special_mapping(mm, base, vvar_size,
 141                                       VM_READ | VM_MAYREAD,
 142                                       &vdso_vvar_mapping);
 143        if (IS_ERR(vma)) {
 144                ret = PTR_ERR(vma);
 145                goto out;
 146        }
 147
 148        /* Map GIC user page. */
 149        if (gic_size) {
 150                gic_pfn = virt_to_phys(mips_gic_base + MIPS_GIC_USER_OFS) >> PAGE_SHIFT;
 151
 152                ret = io_remap_pfn_range(vma, base, gic_pfn, gic_size,
 153                                         pgprot_noncached(PAGE_READONLY));
 154                if (ret)
 155                        goto out;
 156        }
 157
 158        /* Map data page. */
 159        ret = remap_pfn_range(vma, data_addr,
 160                              virt_to_phys(&vdso_data) >> PAGE_SHIFT,
 161                              PAGE_SIZE, PAGE_READONLY);
 162        if (ret)
 163                goto out;
 164
 165        /* Map VDSO image. */
 166        vma = _install_special_mapping(mm, vdso_addr, image->size,
 167                                       VM_READ | VM_EXEC |
 168                                       VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC,
 169                                       &image->mapping);
 170        if (IS_ERR(vma)) {
 171                ret = PTR_ERR(vma);
 172                goto out;
 173        }
 174
 175        mm->context.vdso = (void *)vdso_addr;
 176        ret = 0;
 177
 178out:
 179        up_write(&mm->mmap_sem);
 180        return ret;
 181}
 182