x86: CPA, fix alias checks
c_p_a() did not discover all aliases correctly. (such as when called
on vmalloc()-ed areas or ioremap()-ed areas)
Push the alias checks to the lower, physical level and consistently
discover all aliases that might exist: the low direct mappings and
the high linear kernel-text mappings (on 64-bit).
Thanks to Andi Kleen for pointing out that this was buggy.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
diff --git a/arch/x86/mm/pageattr.c b/arch/x86/mm/pageattr.c
index 4119379..7b4a172 100644
--- a/arch/x86/mm/pageattr.c
+++ b/arch/x86/mm/pageattr.c
@@ -16,6 +16,7 @@
#include <asm/sections.h>
#include <asm/uaccess.h>
#include <asm/pgalloc.h>
+#include <asm/proto.h>
/*
* The current flushing context - we pass it instead of 5 arguments:
@@ -26,8 +27,23 @@
pgprot_t mask_clr;
int numpages;
int flushtlb;
+ unsigned long pfn;
};
+#ifdef CONFIG_X86_64
+
+static inline unsigned long highmap_start_pfn(void)
+{
+ return __pa(_text) >> PAGE_SHIFT;
+}
+
+static inline unsigned long highmap_end_pfn(void)
+{
+ return __pa(round_up((unsigned long)_end, PMD_SIZE)) >> PAGE_SHIFT;
+}
+
+#endif
+
static inline int
within(unsigned long addr, unsigned long start, unsigned long end)
{
@@ -123,29 +139,14 @@
}
}
-#define HIGH_MAP_START __START_KERNEL_map
-#define HIGH_MAP_END (__START_KERNEL_map + KERNEL_TEXT_SIZE)
-
-
-/*
- * Converts a virtual address to a X86-64 highmap address
- */
-static unsigned long virt_to_highmap(void *address)
-{
-#ifdef CONFIG_X86_64
- return __pa((unsigned long)address) + HIGH_MAP_START - phys_base;
-#else
- return (unsigned long)address;
-#endif
-}
-
/*
* Certain areas of memory on x86 require very specific protection flags,
* for example the BIOS area or kernel text. Callers don't always get this
* right (again, ioremap() on BIOS memory is not uncommon) so this function
* checks and fixes these known static required protection bits.
*/
-static inline pgprot_t static_protections(pgprot_t prot, unsigned long address)
+static inline pgprot_t static_protections(pgprot_t prot, unsigned long address,
+ unsigned long pfn)
{
pgprot_t forbidden = __pgprot(0);
@@ -153,30 +154,23 @@
* The BIOS area between 640k and 1Mb needs to be executable for
* PCI BIOS based config access (CONFIG_PCI_GOBIOS) support.
*/
- if (within(__pa(address), BIOS_BEGIN, BIOS_END))
+ if (within(pfn, BIOS_BEGIN >> PAGE_SHIFT, BIOS_END >> PAGE_SHIFT))
pgprot_val(forbidden) |= _PAGE_NX;
/*
* The kernel text needs to be executable for obvious reasons
- * Does not cover __inittext since that is gone later on
+ * Does not cover __inittext since that is gone later on. On
+ * 64bit we do not enforce !NX on the low mapping
*/
if (within(address, (unsigned long)_text, (unsigned long)_etext))
pgprot_val(forbidden) |= _PAGE_NX;
- /*
- * Do the same for the x86-64 high kernel mapping
- */
- if (within(address, virt_to_highmap(_text), virt_to_highmap(_etext)))
- pgprot_val(forbidden) |= _PAGE_NX;
- /* The .rodata section needs to be read-only */
- if (within(address, (unsigned long)__start_rodata,
- (unsigned long)__end_rodata))
- pgprot_val(forbidden) |= _PAGE_RW;
/*
- * Do the same for the x86-64 high kernel mapping
+ * The .rodata section needs to be read-only. Using the pfn
+ * catches all aliases.
*/
- if (within(address, virt_to_highmap(__start_rodata),
- virt_to_highmap(__end_rodata)))
+ if (within(pfn, __pa((unsigned long)__start_rodata) >> PAGE_SHIFT,
+ __pa((unsigned long)__end_rodata) >> PAGE_SHIFT))
pgprot_val(forbidden) |= _PAGE_RW;
prot = __pgprot(pgprot_val(prot) & ~pgprot_val(forbidden));
@@ -253,7 +247,7 @@
try_preserve_large_page(pte_t *kpte, unsigned long address,
struct cpa_data *cpa)
{
- unsigned long nextpage_addr, numpages, pmask, psize, flags, addr;
+ unsigned long nextpage_addr, numpages, pmask, psize, flags, addr, pfn;
pte_t new_pte, old_pte, *tmp;
pgprot_t old_prot, new_prot;
int i, do_split = 1;
@@ -301,7 +295,15 @@
pgprot_val(new_prot) &= ~pgprot_val(cpa->mask_clr);
pgprot_val(new_prot) |= pgprot_val(cpa->mask_set);
- new_prot = static_protections(new_prot, address);
+
+ /*
+ * old_pte points to the large page base address. So we need
+ * to add the offset of the virtual address:
+ */
+ pfn = pte_pfn(old_pte) + ((address & (psize - 1)) >> PAGE_SHIFT);
+ cpa->pfn = pfn;
+
+ new_prot = static_protections(new_prot, address, pfn);
/*
* We need to check the full range, whether
@@ -309,8 +311,9 @@
* the pages in the range we try to preserve:
*/
addr = address + PAGE_SIZE;
- for (i = 1; i < cpa->numpages; i++, addr += PAGE_SIZE) {
- pgprot_t chk_prot = static_protections(new_prot, addr);
+ pfn++;
+ for (i = 1; i < cpa->numpages; i++, addr += PAGE_SIZE, pfn++) {
+ pgprot_t chk_prot = static_protections(new_prot, addr, pfn);
if (pgprot_val(chk_prot) != pgprot_val(new_prot))
goto out_unlock;
@@ -505,46 +508,51 @@
return 0;
}
-static int __change_page_attr(unsigned long address, struct cpa_data *cpa)
+static int __change_page_attr(struct cpa_data *cpa, int primary)
{
+ unsigned long address = cpa->vaddr;
int do_split, err;
unsigned int level;
struct page *kpte_page;
- pte_t *kpte;
+ pte_t *kpte, old_pte;
repeat:
kpte = lookup_address(address, &level);
if (!kpte)
+ return primary ? -EINVAL : 0;
+
+ old_pte = *kpte;
+ if (!pte_val(old_pte)) {
+ if (!primary)
+ return 0;
+ printk(KERN_WARNING "CPA: called for zero pte. "
+ "vaddr = %lx cpa->vaddr = %lx\n", address,
+ cpa->vaddr);
+ WARN_ON(1);
return -EINVAL;
+ }
kpte_page = virt_to_page(kpte);
BUG_ON(PageLRU(kpte_page));
BUG_ON(PageCompound(kpte_page));
if (level == PG_LEVEL_4K) {
- pte_t new_pte, old_pte = *kpte;
+ pte_t new_pte;
pgprot_t new_prot = pte_pgprot(old_pte);
-
- if(!pte_val(old_pte)) {
- printk(KERN_WARNING "CPA: called for zero pte. "
- "vaddr = %lx cpa->vaddr = %lx\n", address,
- cpa->vaddr);
- WARN_ON(1);
- return -EINVAL;
- }
+ unsigned long pfn = pte_pfn(old_pte);
pgprot_val(new_prot) &= ~pgprot_val(cpa->mask_clr);
pgprot_val(new_prot) |= pgprot_val(cpa->mask_set);
- new_prot = static_protections(new_prot, address);
+ new_prot = static_protections(new_prot, address, pfn);
/*
* We need to keep the pfn from the existing PTE,
* after all we're only going to change it's attributes
* not the memory it points to
*/
- new_pte = pfn_pte(pte_pfn(old_pte), canon_pgprot(new_prot));
-
+ new_pte = pfn_pte(pfn, canon_pgprot(new_prot));
+ cpa->pfn = pfn;
/*
* Do we really change anything ?
*/
@@ -581,67 +589,44 @@
return err;
}
-/**
- * change_page_attr_addr - Change page table attributes in linear mapping
- * @address: Virtual address in linear mapping.
- * @prot: New page table attribute (PAGE_*)
- *
- * Change page attributes of a page in the direct mapping. This is a variant
- * of change_page_attr() that also works on memory holes that do not have
- * mem_map entry (pfn_valid() is false).
- *
- * See change_page_attr() documentation for more details.
- *
- * Modules and drivers should use the set_memory_* APIs instead.
- */
-static int change_page_attr_addr(struct cpa_data *cpa)
+static int __change_page_attr_set_clr(struct cpa_data *cpa, int checkalias);
+
+static int cpa_process_alias(struct cpa_data *cpa)
{
- int err;
- unsigned long address = cpa->vaddr;
+ struct cpa_data alias_cpa;
+ int ret;
+
+ if (cpa->pfn > max_pfn_mapped)
+ return 0;
+
+ alias_cpa = *cpa;
+ alias_cpa.vaddr = (unsigned long) __va(cpa->pfn << PAGE_SHIFT);
+
+ ret = __change_page_attr_set_clr(&alias_cpa, 0);
#ifdef CONFIG_X86_64
- unsigned long phys_addr = __pa(address);
-
- /*
- * If we are inside the high mapped kernel range, then we
- * fixup the low mapping first. __va() returns the virtual
- * address in the linear mapping:
- */
- if (within(address, HIGH_MAP_START, HIGH_MAP_END))
- address = (unsigned long) __va(phys_addr);
-#endif
-
- err = __change_page_attr(address, cpa);
- if (err)
- return err;
-
-#ifdef CONFIG_X86_64
+ if (ret)
+ return ret;
/*
* If the physical address is inside the kernel map, we need
* to touch the high mapped kernel as well:
*/
- if (within(phys_addr, 0, KERNEL_TEXT_SIZE)) {
- /*
- * Calc the high mapping address. See __phys_addr()
- * for the non obvious details.
- *
- * Note that NX and other required permissions are
- * checked in static_protections().
- */
- address = phys_addr + HIGH_MAP_START - phys_base;
+ if (!within(cpa->pfn, highmap_start_pfn(), highmap_end_pfn()))
+ return 0;
- /*
- * Our high aliases are imprecise, because we check
- * everything between 0 and KERNEL_TEXT_SIZE, so do
- * not propagate lookup failures back to users:
- */
- __change_page_attr(address, cpa);
- }
+ alias_cpa = *cpa;
+ alias_cpa.vaddr =
+ (cpa->pfn << PAGE_SHIFT) + __START_KERNEL_map - phys_base;
+
+ /*
+ * The high mapping range is imprecise, so ignore the return value.
+ */
+ __change_page_attr_set_clr(&alias_cpa, 0);
#endif
- return err;
+ return ret;
}
-static int __change_page_attr_set_clr(struct cpa_data *cpa)
+static int __change_page_attr_set_clr(struct cpa_data *cpa, int checkalias)
{
int ret, numpages = cpa->numpages;
@@ -651,10 +636,17 @@
* preservation check.
*/
cpa->numpages = numpages;
- ret = change_page_attr_addr(cpa);
+
+ ret = __change_page_attr(cpa, checkalias);
if (ret)
return ret;
+ if (checkalias) {
+ ret = cpa_process_alias(cpa);
+ if (ret)
+ return ret;
+ }
+
/*
* Adjust the number of pages with the result of the
* CPA operation. Either a large page has been
@@ -703,7 +695,7 @@
cpa.mask_clr = mask_clr;
cpa.flushtlb = 0;
- ret = __change_page_attr_set_clr(&cpa);
+ ret = __change_page_attr_set_clr(&cpa, 1);
/*
* Check whether we really changed something:
@@ -841,7 +833,7 @@
.mask_set = __pgprot(_PAGE_PRESENT | _PAGE_RW),
.mask_clr = __pgprot(0)};
- return __change_page_attr_set_clr(&cpa);
+ return __change_page_attr_set_clr(&cpa, 1);
}
static int __set_pages_np(struct page *page, int numpages)
@@ -851,7 +843,7 @@
.mask_set = __pgprot(0),
.mask_clr = __pgprot(_PAGE_PRESENT | _PAGE_RW)};
- return __change_page_attr_set_clr(&cpa);
+ return __change_page_attr_set_clr(&cpa, 1);
}
void kernel_map_pages(struct page *page, int numpages, int enable)