arch/x86/mm/kmemcheck/shadow.c

   1 #include <linux/kmemcheck.h>
   2 #include <linux/module.h>
   3 #include <linux/mm.h>
   4 #include <linux/module.h>
   5
   6 #include <asm/page.h>
   7 #include <asm/pgtable.h>
   8
   9 #include "pte.h"
  10 #include "shadow.h"
  11
  12 /*
  13  * Return the shadow address for the given address. Returns NULL if the
  14  * address is not tracked.
  15  *
  16  * We need to be extremely careful not to follow any invalid pointers,
  17  * because this function can be called for *any* possible address.
  18  */
  19 void *kmemcheck_shadow_lookup(unsigned long address)
  20 {
  21         pte_t *pte;
  22         struct page *page;
  23
  24         if (!virt_addr_valid(address))
  25                 return NULL;
  26
  27         pte = kmemcheck_pte_lookup(address);
  28         if (!pte)
  29                 return NULL;
  30
  31         page = virt_to_page(address);
  32         if (!page->shadow)
  33                 return NULL;
  34         return page->shadow + (address & (PAGE_SIZE - 1));
  35 }
  36
  37 static void mark_shadow(void *address, unsigned int n,
  38         enum kmemcheck_shadow status)
  39 {
  40         unsigned long addr = (unsigned long) address;
  41         unsigned long last_addr = addr + n - 1;
  42         unsigned long page = addr & PAGE_MASK;
  43         unsigned long last_page = last_addr & PAGE_MASK;
  44         unsigned int first_n;
  45         void *shadow;
  46
  47         /* If the memory range crosses a page boundary, stop there. */
  48         if (page == last_page)
  49                 first_n = n;
  50         else
  51                 first_n = page + PAGE_SIZE - addr;
  52
  53         shadow = kmemcheck_shadow_lookup(addr);
  54         if (shadow)
  55                 memset(shadow, status, first_n);
  56
  57         addr += first_n;
  58         n -= first_n;
  59
  60         /* Do full-page memset()s. */
  61         while (n >= PAGE_SIZE) {
  62                 shadow = kmemcheck_shadow_lookup(addr);
  63                 if (shadow)
  64                         memset(shadow, status, PAGE_SIZE);
  65
  66                 addr += PAGE_SIZE;
  67                 n -= PAGE_SIZE;
  68         }
  69
  70         /* Do the remaining page, if any. */
  71         if (n > 0) {
  72                 shadow = kmemcheck_shadow_lookup(addr);
  73                 if (shadow)
  74                         memset(shadow, status, n);
  75         }
  76 }
  77
  78 void kmemcheck_mark_unallocated(void *address, unsigned int n)
  79 {
  80         mark_shadow(address, n, KMEMCHECK_SHADOW_UNALLOCATED);
  81 }
  82
  83 void kmemcheck_mark_uninitialized(void *address, unsigned int n)
  84 {
  85         mark_shadow(address, n, KMEMCHECK_SHADOW_UNINITIALIZED);
  86 }
  87
  88 /*
  89  * Fill the shadow memory of the given address such that the memory at that
  90  * address is marked as being initialized.
  91  */
  92 void kmemcheck_mark_initialized(void *address, unsigned int n)
  93 {
  94         mark_shadow(address, n, KMEMCHECK_SHADOW_INITIALIZED);
  95 }
  96 EXPORT_SYMBOL_GPL(kmemcheck_mark_initialized);
  97
  98 void kmemcheck_mark_freed(void *address, unsigned int n)
  99 {
 100         mark_shadow(address, n, KMEMCHECK_SHADOW_FREED);
 101 }
 102
 103 void kmemcheck_mark_unallocated_pages(struct page *p, unsigned int n)
 104 {
 105         unsigned int i;
 106
 107         for (i = 0; i < n; ++i)
 108                 kmemcheck_mark_unallocated(page_address(&p[i]), PAGE_SIZE);
 109 }
 110
 111 void kmemcheck_mark_uninitialized_pages(struct page *p, unsigned int n)
 112 {
 113         unsigned int i;
 114
 115         for (i = 0; i < n; ++i)
 116                 kmemcheck_mark_uninitialized(page_address(&p[i]), PAGE_SIZE);
 117 }
 118
 119 enum kmemcheck_shadow kmemcheck_shadow_test(void *shadow, unsigned int size)
 120 {
 121         uint8_t *x;
 122         unsigned int i;
 123
 124         x = shadow;
 125
 126 #ifdef CONFIG_KMEMCHECK_PARTIAL_OK
 127         /*
 128          * Make sure _some_ bytes are initialized. Gcc frequently generates
 129          * code to access neighboring bytes.
 130          */
 131         for (i = 0; i < size; ++i) {
 132                 if (x[i] == KMEMCHECK_SHADOW_INITIALIZED)
 133                         return x[i];
 134         }
 135 #else
 136         /* All bytes must be initialized. */
 137         for (i = 0; i < size; ++i) {
 138                 if (x[i] != KMEMCHECK_SHADOW_INITIALIZED)
 139                         return x[i];
 140         }
 141 #endif
 142
 143         return x[0];
 144 }
 145
 146 void kmemcheck_shadow_set(void *shadow, unsigned int size)
 147 {
 148         uint8_t *x;
 149         unsigned int i;
 150
 151         x = shadow;
 152         for (i = 0; i < size; ++i)
 153                 x[i] = KMEMCHECK_SHADOW_INITIALIZED;
 154 }