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. */
  26 static 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  */
  33 static struct page *no_pages[] = { NULL };
  34 static struct vm_special_mapping vdso_vvar_mapping = {
  35         .name = "[vvar]",
  36         .pages = no_pages,
  37 };
  38
  39 static 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
  54 static 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 }
  68 subsys_initcall(init_vdso);
  69
  70 void 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
  90 void 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
  98 int 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
 178 out:
 179         up_write(&mm->mmap_sem);
 180         return ret;
 181 }