| From linux-kernel-owner+greg=40kroah.com-S1761718AbYBOT7Z@vger.kernel.org Fri Feb 15 12:00:56 2008 |
| From: Ingo Molnar <mingo@elte.hu> |
| Date: Fri, 15 Feb 2008 20:58:54 +0100 |
| Subject: x86_64: CPA, fix cache attribute inconsistency bug |
| To: stable@kernel.org |
| Cc: linux-kernel@vger.kernel.org, Thomas Gleixner <tglx@linutronix.de>, Andi Kleen <andi@firstfloor.org> |
| Message-ID: <20080215195854.GB15432@elte.hu> |
| Content-Disposition: inline |
| |
| From: Ingo Molnar <mingo@elte.hu> |
| |
| 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-2.6.23.9-85.fc8 |
| 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> |
| |
| --- |
| arch/x86_64/mm/pageattr.c | 2 +- |
| 1 file changed, 1 insertion(+), 1 deletion(-) |
| |
| --- 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 |
| 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, |