From 2c66e24d75d424919c42288b418d2e593fa818b1 Mon Sep 17 00:00:00 2001 From: Sai Praneeth Date: Fri, 16 Oct 2015 16:20:27 -0700 Subject: x86/efi: Fix kernel panic when CONFIG_DEBUG_VIRTUAL is enabled When CONFIG_DEBUG_VIRTUAL is enabled, all accesses to __pa(address) are monitored to see whether address falls in direct mapping or kernel text mapping (see Documentation/x86/x86_64/mm.txt for details), if it does not, the kernel panics. During 1:1 mapping of EFI runtime services we access virtual addresses which are == physical addresses, thus the 1:1 mapping and these addresses do not fall in either of the above two regions and hence when passed as arguments to __pa() kernel panics as reported by Dave Hansen here https://lkml.kernel.org/r/5462999A.7090706@intel.com. So, before calling __pa() virtual addresses should be validated which results in skipping call to split_page_count() and that should be fine because it is used to keep track of everything *but* 1:1 mappings. Signed-off-by: Sai Praneeth Prakhya Reported-by: Dave Hansen Reviewed-by: Borislav Petkov Cc: Ricardo Neri Cc: Glenn P Williamson Cc: Ravi Shankar Signed-off-by: Matt Fleming diff --git a/arch/x86/mm/pageattr.c b/arch/x86/mm/pageattr.c index 727158c..9abe0c9 100644 --- a/arch/x86/mm/pageattr.c +++ b/arch/x86/mm/pageattr.c @@ -648,9 +648,12 @@ __split_large_page(struct cpa_data *cpa, pte_t *kpte, unsigned long address, for (i = 0; i < PTRS_PER_PTE; i++, pfn += pfninc) set_pte(&pbase[i], pfn_pte(pfn, canon_pgprot(ref_prot))); - if (pfn_range_is_mapped(PFN_DOWN(__pa(address)), - PFN_DOWN(__pa(address)) + 1)) - split_page_count(level); + if (virt_addr_valid(address)) { + unsigned long pfn = PFN_DOWN(__pa(address)); + + if (pfn_range_is_mapped(pfn, pfn + 1)) + split_page_count(level); + } /* * Install the new, split up pagetable. -- cgit v0.10.2