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TOMOYO Linux Cross Reference
Linux/arch/mips/kernel/vdso.c

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  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/kernel.h>
 17 #include <linux/mm.h>
 18 #include <linux/random.h>
 19 #include <linux/sched.h>
 20 #include <linux/slab.h>
 21 #include <linux/timekeeper_internal.h>
 22 
 23 #include <asm/abi.h>
 24 #include <asm/mips-cps.h>
 25 #include <asm/page.h>
 26 #include <asm/vdso.h>
 27 
 28 /* Kernel-provided data used by the VDSO. */
 29 static union mips_vdso_data vdso_data __page_aligned_data;
 30 
 31 /*
 32  * Mapping for the VDSO data/GIC pages. The real pages are mapped manually, as
 33  * what we map and where within the area they are mapped is determined at
 34  * runtime.
 35  */
 36 static struct page *no_pages[] = { NULL };
 37 static struct vm_special_mapping vdso_vvar_mapping = {
 38         .name = "[vvar]",
 39         .pages = no_pages,
 40 };
 41 
 42 static void __init init_vdso_image(struct mips_vdso_image *image)
 43 {
 44         unsigned long num_pages, i;
 45         unsigned long data_pfn;
 46 
 47         BUG_ON(!PAGE_ALIGNED(image->data));
 48         BUG_ON(!PAGE_ALIGNED(image->size));
 49 
 50         num_pages = image->size / PAGE_SIZE;
 51 
 52         data_pfn = __phys_to_pfn(__pa_symbol(image->data));
 53         for (i = 0; i < num_pages; i++)
 54                 image->mapping.pages[i] = pfn_to_page(data_pfn + i);
 55 }
 56 
 57 static int __init init_vdso(void)
 58 {
 59         init_vdso_image(&vdso_image);
 60 
 61 #ifdef CONFIG_MIPS32_O32
 62         init_vdso_image(&vdso_image_o32);
 63 #endif
 64 
 65 #ifdef CONFIG_MIPS32_N32
 66         init_vdso_image(&vdso_image_n32);
 67 #endif
 68 
 69         return 0;
 70 }
 71 subsys_initcall(init_vdso);
 72 
 73 void update_vsyscall(struct timekeeper *tk)
 74 {
 75         vdso_data_write_begin(&vdso_data);
 76 
 77         vdso_data.xtime_sec = tk->xtime_sec;
 78         vdso_data.xtime_nsec = tk->tkr_mono.xtime_nsec;
 79         vdso_data.wall_to_mono_sec = tk->wall_to_monotonic.tv_sec;
 80         vdso_data.wall_to_mono_nsec = tk->wall_to_monotonic.tv_nsec;
 81         vdso_data.cs_shift = tk->tkr_mono.shift;
 82 
 83         vdso_data.clock_mode = tk->tkr_mono.clock->archdata.vdso_clock_mode;
 84         if (vdso_data.clock_mode != VDSO_CLOCK_NONE) {
 85                 vdso_data.cs_mult = tk->tkr_mono.mult;
 86                 vdso_data.cs_cycle_last = tk->tkr_mono.cycle_last;
 87                 vdso_data.cs_mask = tk->tkr_mono.mask;
 88         }
 89 
 90         vdso_data_write_end(&vdso_data);
 91 }
 92 
 93 void update_vsyscall_tz(void)
 94 {
 95         if (vdso_data.clock_mode != VDSO_CLOCK_NONE) {
 96                 vdso_data.tz_minuteswest = sys_tz.tz_minuteswest;
 97                 vdso_data.tz_dsttime = sys_tz.tz_dsttime;
 98         }
 99 }
100 
101 static unsigned long vdso_base(void)
102 {
103         unsigned long base;
104 
105         /* Skip the delay slot emulation page */
106         base = STACK_TOP + PAGE_SIZE;
107 
108         if (current->flags & PF_RANDOMIZE) {
109                 base += get_random_int() & (VDSO_RANDOMIZE_SIZE - 1);
110                 base = PAGE_ALIGN(base);
111         }
112 
113         return base;
114 }
115 
116 int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp)
117 {
118         struct mips_vdso_image *image = current->thread.abi->vdso;
119         struct mm_struct *mm = current->mm;
120         unsigned long gic_size, vvar_size, size, base, data_addr, vdso_addr, gic_pfn;
121         struct vm_area_struct *vma;
122         int ret;
123 
124         if (down_write_killable(&mm->mmap_sem))
125                 return -EINTR;
126 
127         /* Map delay slot emulation page */
128         base = mmap_region(NULL, STACK_TOP, PAGE_SIZE,
129                            VM_READ|VM_WRITE|VM_EXEC|
130                            VM_MAYREAD|VM_MAYWRITE|VM_MAYEXEC,
131                            0, NULL);
132         if (IS_ERR_VALUE(base)) {
133                 ret = base;
134                 goto out;
135         }
136 
137         /*
138          * Determine total area size. This includes the VDSO data itself, the
139          * data page, and the GIC user page if present. Always create a mapping
140          * for the GIC user area if the GIC is present regardless of whether it
141          * is the current clocksource, in case it comes into use later on. We
142          * only map a page even though the total area is 64K, as we only need
143          * the counter registers at the start.
144          */
145         gic_size = mips_gic_present() ? PAGE_SIZE : 0;
146         vvar_size = gic_size + PAGE_SIZE;
147         size = vvar_size + image->size;
148 
149         /*
150          * Find a region that's large enough for us to perform the
151          * colour-matching alignment below.
152          */
153         if (cpu_has_dc_aliases)
154                 size += shm_align_mask + 1;
155 
156         base = get_unmapped_area(NULL, vdso_base(), size, 0, 0);
157         if (IS_ERR_VALUE(base)) {
158                 ret = base;
159                 goto out;
160         }
161 
162         /*
163          * If we suffer from dcache aliasing, ensure that the VDSO data page
164          * mapping is coloured the same as the kernel's mapping of that memory.
165          * This ensures that when the kernel updates the VDSO data userland
166          * will observe it without requiring cache invalidations.
167          */
168         if (cpu_has_dc_aliases) {
169                 base = __ALIGN_MASK(base, shm_align_mask);
170                 base += ((unsigned long)&vdso_data - gic_size) & shm_align_mask;
171         }
172 
173         data_addr = base + gic_size;
174         vdso_addr = data_addr + PAGE_SIZE;
175 
176         vma = _install_special_mapping(mm, base, vvar_size,
177                                        VM_READ | VM_MAYREAD,
178                                        &vdso_vvar_mapping);
179         if (IS_ERR(vma)) {
180                 ret = PTR_ERR(vma);
181                 goto out;
182         }
183 
184         /* Map GIC user page. */
185         if (gic_size) {
186                 gic_pfn = virt_to_phys(mips_gic_base + MIPS_GIC_USER_OFS) >> PAGE_SHIFT;
187 
188                 ret = io_remap_pfn_range(vma, base, gic_pfn, gic_size,
189                                          pgprot_noncached(PAGE_READONLY));
190                 if (ret)
191                         goto out;
192         }
193 
194         /* Map data page. */
195         ret = remap_pfn_range(vma, data_addr,
196                               virt_to_phys(&vdso_data) >> PAGE_SHIFT,
197                               PAGE_SIZE, PAGE_READONLY);
198         if (ret)
199                 goto out;
200 
201         /* Map VDSO image. */
202         vma = _install_special_mapping(mm, vdso_addr, image->size,
203                                        VM_READ | VM_EXEC |
204                                        VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC,
205                                        &image->mapping);
206         if (IS_ERR(vma)) {
207                 ret = PTR_ERR(vma);
208                 goto out;
209         }
210 
211         mm->context.vdso = (void *)vdso_addr;
212         ret = 0;
213 
214 out:
215         up_write(&mm->mmap_sem);
216         return ret;
217 }
218 

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