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-rw-r--r--include/asm-x86/pgtable-3level.h11
1 files changed, 7 insertions, 4 deletions
diff --git a/include/asm-x86/pgtable-3level.h b/include/asm-x86/pgtable-3level.h
index ed4c6f0e57e..ad71960bca3 100644
--- a/include/asm-x86/pgtable-3level.h
+++ b/include/asm-x86/pgtable-3level.h
@@ -93,17 +93,20 @@ static inline void native_pmd_clear(pmd_t *pmd)
static inline void pud_clear(pud_t *pudp)
{
+ unsigned long pgd;
+
set_pud(pudp, __pud(0));
/*
* Pentium-II erratum A13: in PAE mode we explicitly have to flush
* the TLB via cr3 if the top-level pgd is changed...
*
- * XXX I don't think we need to worry about this here, since
- * when clearing the pud, the calling code needs to flush the
- * tlb anyway. But do it now for safety's sake. - jsgf
+ * Make sure the pud entry we're updating is within the
+ * current pgd to avoid unnecessary TLB flushes.
*/
- write_cr3(read_cr3());
+ pgd = read_cr3();
+ if (__pa(pudp) >= pgd && __pa(pudp) < (pgd + sizeof(pgd_t)*PTRS_PER_PGD))
+ write_cr3(pgd);
}
#define pud_page(pud) \