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-rw-r--r--arch/arm64/include/asm/mmu_context.h43
1 files changed, 43 insertions, 0 deletions
diff --git a/arch/arm64/include/asm/mmu_context.h b/arch/arm64/include/asm/mmu_context.h
index 101a42bde728..8ec41e5f56f0 100644
--- a/arch/arm64/include/asm/mmu_context.h
+++ b/arch/arm64/include/asm/mmu_context.h
@@ -64,6 +64,49 @@ static inline void cpu_set_reserved_ttbr0(void)
: "r" (ttbr));
}
+/*
+ * TCR.T0SZ value to use when the ID map is active. Usually equals
+ * TCR_T0SZ(VA_BITS), unless system RAM is positioned very high in
+ * physical memory, in which case it will be smaller.
+ */
+extern u64 idmap_t0sz;
+
+static inline bool __cpu_uses_extended_idmap(void)
+{
+ return (!IS_ENABLED(CONFIG_ARM64_VA_BITS_48) &&
+ unlikely(idmap_t0sz != TCR_T0SZ(VA_BITS)));
+}
+
+static inline void __cpu_set_tcr_t0sz(u64 t0sz)
+{
+ unsigned long tcr;
+
+ if (__cpu_uses_extended_idmap())
+ asm volatile (
+ " mrs %0, tcr_el1 ;"
+ " bfi %0, %1, %2, %3 ;"
+ " msr tcr_el1, %0 ;"
+ " isb"
+ : "=&r" (tcr)
+ : "r"(t0sz), "I"(TCR_T0SZ_OFFSET), "I"(TCR_TxSZ_WIDTH));
+}
+
+/*
+ * Set TCR.T0SZ to the value appropriate for activating the identity map.
+ */
+static inline void cpu_set_idmap_tcr_t0sz(void)
+{
+ __cpu_set_tcr_t0sz(idmap_t0sz);
+}
+
+/*
+ * Set TCR.T0SZ to its default value (based on VA_BITS)
+ */
+static inline void cpu_set_default_tcr_t0sz(void)
+{
+ __cpu_set_tcr_t0sz(TCR_T0SZ(VA_BITS));
+}
+
static inline void switch_new_context(struct mm_struct *mm)
{
unsigned long flags;