MIPS: Make set_pte() SMP safe.

[pandora-kernel.git] / arch / mips / include / asm / pgtable.h

diff --git a/arch/mips/include/asm/pgtable.h b/arch/mips/include/asm/pgtable.h
index b2202a6..95bcedb 100644 (file)
--- a/arch/mips/include/asm/pgtable.h
+++ b/arch/mips/include/asm/pgtable.h
@@ -153,8 +153,39 @@ static inline void set_pte(pte_t *ptep, pte_t pteval)
                 * Make sure the buddy is global too (if it's !none,
                 * it better already be global)
                 */
+#ifdef CONFIG_SMP
+               /*
+                * For SMP, multiple CPUs can race, so we need to do
+                * this atomically.
+                */
+#ifdef CONFIG_64BIT
+#define LL_INSN "lld"
+#define SC_INSN "scd"
+#else /* CONFIG_32BIT */
+#define LL_INSN "ll"
+#define SC_INSN "sc"
+#endif
+               unsigned long page_global = _PAGE_GLOBAL;
+               unsigned long tmp;
+
+               __asm__ __volatile__ (
+                       "       .set    push\n"
+                       "       .set    noreorder\n"
+                       "1:     " LL_INSN "     %[tmp], %[buddy]\n"
+                       "       bnez    %[tmp], 2f\n"
+                       "        or     %[tmp], %[tmp], %[global]\n"
+                       "       " SC_INSN "     %[tmp], %[buddy]\n"
+                       "       beqz    %[tmp], 1b\n"
+                       "        nop\n"
+                       "2:\n"
+                       "       .set pop"
+                       : [buddy] "+m" (buddy->pte),
+                         [tmp] "=&r" (tmp)
+                       : [global] "r" (page_global));
+#else /* !CONFIG_SMP */
                if (pte_none(*buddy))
                        pte_val(*buddy) = pte_val(*buddy) | _PAGE_GLOBAL;
+#endif /* CONFIG_SMP */
        }
 #endif
 }