From: Sai Praneeth <sai.praneeth.prak...@intel.com>
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.7090...@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 <sai.praneeth.prak...@intel.com>
Reported-by: Dave Hansen <dave.han...@intel.com>
Reviewed-by: Borislav Petkov <b...@suse.de>
Cc: Ricardo Neri <ricardo.n...@intel.com>
Cc: Glenn P Williamson <glenn.p.william...@intel.com>
Cc: Ravi Shankar <ravi.v.shan...@intel.com>
Signed-off-by: Matt Fleming <m...@codeblueprint.co.uk>
---
arch/x86/mm/pageattr.c | 9 ++++++---
1 file changed, 6 insertions(+), 3 deletions(-)
diff --git a/arch/x86/mm/pageattr.c b/arch/x86/mm/pageattr.c
index 727158cb3b3c..9abe0c9b1098 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.
--
2.6.0
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majord...@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
