root/arch/nds32/kernel/vdso.c

DEFINITIONS

1. get_timer_node_info
2. vdso_init
3. vdso_random_addr
4. arch_setup_additional_pages
5. vdso_write_begin
6. vdso_write_end
7. update_vsyscall
8. update_vsyscall_tz

   1 // SPDX-License-Identifier: GPL-2.0
   2 // Copyright (C) 2012 ARM Limited
   3 // Copyright (C) 2005-2017 Andes Technology Corporation
   4 
   5 #include <linux/cache.h>
   6 #include <linux/clocksource.h>
   7 #include <linux/elf.h>
   8 #include <linux/err.h>
   9 #include <linux/errno.h>
  10 #include <linux/gfp.h>
  11 #include <linux/kernel.h>
  12 #include <linux/mm.h>
  13 #include <linux/sched.h>
  14 #include <linux/signal.h>
  15 #include <linux/slab.h>
  16 #include <linux/timekeeper_internal.h>
  17 #include <linux/vmalloc.h>
  18 #include <linux/random.h>
  19 
  20 #include <asm/cacheflush.h>
  21 #include <asm/vdso.h>
  22 #include <asm/vdso_datapage.h>
  23 #include <asm/vdso_timer_info.h>
  24 #include <asm/cache_info.h>
  25 extern struct cache_info L1_cache_info[2];
  26 extern char vdso_start[], vdso_end[];
  27 static unsigned long vdso_pages __ro_after_init;
  28 static unsigned long timer_mapping_base;
  29 
  30 struct timer_info_t timer_info = {
  31         .cycle_count_down = true,
  32         .mapping_base = EMPTY_TIMER_MAPPING,
  33         .cycle_count_reg_offset = EMPTY_REG_OFFSET
  34 };
  35 /*
  36  * The vDSO data page.
  37  */
  38 static struct page *no_pages[] = { NULL };
  39 
  40 static union {
  41         struct vdso_data data;
  42         u8 page[PAGE_SIZE];
  43 } vdso_data_store __page_aligned_data;
  44 struct vdso_data *vdso_data = &vdso_data_store.data;
  45 static struct vm_special_mapping vdso_spec[2] __ro_after_init = {
  46         {
  47          .name = "[vvar]",
  48          .pages = no_pages,
  49          },
  50         {
  51          .name = "[vdso]",
  52          },
  53 };
  54 
  55 static void get_timer_node_info(void)
  56 {
  57         timer_mapping_base = timer_info.mapping_base;
  58         vdso_data->cycle_count_offset =
  59                 timer_info.cycle_count_reg_offset;
  60         vdso_data->cycle_count_down =
  61                 timer_info.cycle_count_down;
  62 }
  63 
  64 static int __init vdso_init(void)
  65 {
  66         int i;
  67         struct page **vdso_pagelist;
  68 
  69         if (memcmp(vdso_start, "\177ELF", 4)) {
  70                 pr_err("vDSO is not a valid ELF object!\n");
  71                 return -EINVAL;
  72         }
  73         /* Creat a timer io mapping to get clock cycles counter */
  74         get_timer_node_info();
  75 
  76         vdso_pages = (vdso_end - vdso_start) >> PAGE_SHIFT;
  77         pr_info("vdso: %ld pages (%ld code @ %p, %ld data @ %p)\n",
  78                 vdso_pages + 1, vdso_pages, vdso_start, 1L, vdso_data);
  79 
  80         /* Allocate the vDSO pagelist */
  81         vdso_pagelist = kcalloc(vdso_pages, sizeof(struct page *), GFP_KERNEL);
  82         if (vdso_pagelist == NULL)
  83                 return -ENOMEM;
  84 
  85         for (i = 0; i < vdso_pages; i++)
  86                 vdso_pagelist[i] = virt_to_page(vdso_start + i * PAGE_SIZE);
  87         vdso_spec[1].pages = &vdso_pagelist[0];
  88 
  89         return 0;
  90 }
  91 
  92 arch_initcall(vdso_init);
  93 
  94 unsigned long inline vdso_random_addr(unsigned long vdso_mapping_len)
  95 {
  96         unsigned long start = current->mm->mmap_base, end, offset, addr;
  97         start = PAGE_ALIGN(start);
  98 
  99         /* Round the lowest possible end address up to a PMD boundary. */
 100         end = (start + vdso_mapping_len + PMD_SIZE - 1) & PMD_MASK;
 101         if (end >= TASK_SIZE)
 102                 end = TASK_SIZE;
 103         end -= vdso_mapping_len;
 104 
 105         if (end > start) {
 106                 offset = get_random_int() % (((end - start) >> PAGE_SHIFT) + 1);
 107                 addr = start + (offset << PAGE_SHIFT);
 108         } else {
 109                 addr = start;
 110         }
 111         return addr;
 112 }
 113 
 114 int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp)
 115 {
 116         struct mm_struct *mm = current->mm;
 117         unsigned long vdso_base, vdso_text_len, vdso_mapping_len;
 118         struct vm_area_struct *vma;
 119         unsigned long addr = 0;
 120         pgprot_t prot;
 121         int ret, vvar_page_num = 2;
 122 
 123         vdso_text_len = vdso_pages << PAGE_SHIFT;
 124 
 125         if(timer_mapping_base == EMPTY_VALUE)
 126                 vvar_page_num = 1;
 127         /* Be sure to map the data page */
 128         vdso_mapping_len = vdso_text_len + vvar_page_num * PAGE_SIZE;
 129 #ifdef CONFIG_CPU_CACHE_ALIASING
 130         vdso_mapping_len += L1_cache_info[DCACHE].aliasing_num - 1;
 131 #endif
 132 
 133         if (down_write_killable(&mm->mmap_sem))
 134                 return -EINTR;
 135 
 136         addr = vdso_random_addr(vdso_mapping_len);
 137         vdso_base = get_unmapped_area(NULL, addr, vdso_mapping_len, 0, 0);
 138         if (IS_ERR_VALUE(vdso_base)) {
 139                 ret = vdso_base;
 140                 goto up_fail;
 141         }
 142 
 143 #ifdef CONFIG_CPU_CACHE_ALIASING
 144         {
 145                 unsigned int aliasing_mask =
 146                     L1_cache_info[DCACHE].aliasing_mask;
 147                 unsigned int page_colour_ofs;
 148                 page_colour_ofs = ((unsigned int)vdso_data & aliasing_mask) -
 149                     (vdso_base & aliasing_mask);
 150                 vdso_base += page_colour_ofs & aliasing_mask;
 151         }
 152 #endif
 153 
 154         vma = _install_special_mapping(mm, vdso_base, vvar_page_num * PAGE_SIZE,
 155                                        VM_READ | VM_MAYREAD, &vdso_spec[0]);
 156         if (IS_ERR(vma)) {
 157                 ret = PTR_ERR(vma);
 158                 goto up_fail;
 159         }
 160 
 161         /*Map vdata to user space */
 162         ret = io_remap_pfn_range(vma, vdso_base,
 163                                  virt_to_phys(vdso_data) >> PAGE_SHIFT,
 164                                  PAGE_SIZE, vma->vm_page_prot);
 165         if (ret)
 166                 goto up_fail;
 167 
 168         /*Map timer to user space */
 169         vdso_base += PAGE_SIZE;
 170         prot = __pgprot(_PAGE_V | _PAGE_M_UR_KR | _PAGE_D |  _PAGE_C_DEV);
 171         ret = io_remap_pfn_range(vma, vdso_base, timer_mapping_base >> PAGE_SHIFT,
 172                                  PAGE_SIZE, prot);
 173         if (ret)
 174                 goto up_fail;
 175 
 176         /*Map vdso to user space */
 177         vdso_base += PAGE_SIZE;
 178         mm->context.vdso = (void *)vdso_base;
 179         vma = _install_special_mapping(mm, vdso_base, vdso_text_len,
 180                                        VM_READ | VM_EXEC |
 181                                        VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC,
 182                                        &vdso_spec[1]);
 183         if (IS_ERR(vma)) {
 184                 ret = PTR_ERR(vma);
 185                 goto up_fail;
 186         }
 187 
 188         up_write(&mm->mmap_sem);
 189         return 0;
 190 
 191 up_fail:
 192         mm->context.vdso = NULL;
 193         up_write(&mm->mmap_sem);
 194         return ret;
 195 }
 196 
 197 static void vdso_write_begin(struct vdso_data *vdata)
 198 {
 199         ++vdso_data->seq_count;
 200         smp_wmb();              /* Pairs with smp_rmb in vdso_read_retry */
 201 }
 202 
 203 static void vdso_write_end(struct vdso_data *vdata)
 204 {
 205         smp_wmb();              /* Pairs with smp_rmb in vdso_read_begin */
 206         ++vdso_data->seq_count;
 207 }
 208 
 209 void update_vsyscall(struct timekeeper *tk)
 210 {
 211         vdso_write_begin(vdso_data);
 212         vdso_data->cs_mask = tk->tkr_mono.mask;
 213         vdso_data->cs_mult = tk->tkr_mono.mult;
 214         vdso_data->cs_shift = tk->tkr_mono.shift;
 215         vdso_data->cs_cycle_last = tk->tkr_mono.cycle_last;
 216         vdso_data->wtm_clock_sec = tk->wall_to_monotonic.tv_sec;
 217         vdso_data->wtm_clock_nsec = tk->wall_to_monotonic.tv_nsec;
 218         vdso_data->xtime_clock_sec = tk->xtime_sec;
 219         vdso_data->xtime_clock_nsec = tk->tkr_mono.xtime_nsec;
 220         vdso_data->xtime_coarse_sec = tk->xtime_sec;
 221         vdso_data->xtime_coarse_nsec = tk->tkr_mono.xtime_nsec >>
 222             tk->tkr_mono.shift;
 223         vdso_data->hrtimer_res = hrtimer_resolution;
 224         vdso_write_end(vdso_data);
 225 }
 226 
 227 void update_vsyscall_tz(void)
 228 {
 229         vdso_data->tz_minuteswest = sys_tz.tz_minuteswest;
 230         vdso_data->tz_dsttime = sys_tz.tz_dsttime;
 231 }