arch/x86/mm/kmemcheck/shadow.c

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