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authorIngo Molnar <mingo@elte.hu>2008-02-15 20:58:54 +0100
committerGreg Kroah-Hartman <gregkh@suse.de>2008-02-25 16:14:08 -0800
commitecf5d430a4fd11dcb0212ded41e3f31d66807a93 (patch)
parent8297886712dafa9bd0f641e27ca5352229d2357e (diff)
x86_64: CPA, fix cache attribute inconsistency bug
no upstream git id as the code has been rewritten. fix CPA cache attribute bug in v2.6.23. When phys_base is nonzero (when CONFIG_RELOCATABLE=y) then change_page_attr_addr() miscalculates the secondary alias address by -14 MB (depending on the configured offset). The default 64-bit kernels of Fedora and Ubuntu are affected: $ grep RELOCA /boot/config- CONFIG_RELOCATABLE=y $ grep RELOC /boot/config-2.6.22-14-generic CONFIG_RELOCATABLE=y and probably on many other distros as well. the bug affects all pages in the first 40 MB of physical RAM that are allocated by some subsystem that does ioremap_nocache() on them: if (__pa(address) < KERNEL_TEXT_SIZE) { Hence we might leave page table entries with inconsistent cache attributes around (pages mapped at both UnCacheable and Write-Back), and we can also set the wrong kernel text pages to UnCacheable. the effects of this bug can be random slowdowns and other misbehavior. If for example AGP allocates its aperture pages into the first 40 MB of physical RAM, then the -14 MB bug might mark random kernel texto pages as uncacheable, slowing down a random portion of the 64-bit kernel until the AGP driver is unloaded. Signed-off-by: Ingo Molnar <mingo@elte.hu> Acked-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
1 files changed, 1 insertions, 1 deletions
diff --git a/arch/x86_64/mm/pageattr.c b/arch/x86_64/mm/pageattr.c
index eff3b22a2fb7..7770e1039f30 100644
--- a/arch/x86_64/mm/pageattr.c
+++ b/arch/x86_64/mm/pageattr.c
@@ -207,7 +207,7 @@ int change_page_attr_addr(unsigned long address, int numpages, pgprot_t prot)
if (__pa(address) < KERNEL_TEXT_SIZE) {
unsigned long addr2;
pgprot_t prot2;
- addr2 = __START_KERNEL_map + __pa(address);
+ addr2 = __START_KERNEL_map + __pa(address) - phys_base;
/* Make sure the kernel mappings stay executable */
prot2 = pte_pgprot(pte_mkexec(pfn_pte(0, prot)));
err = __change_page_attr(addr2, pfn, prot2,