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-rw-r--r--lib/extensions/mtpmu/aarch64/mtpmu.S96
1 files changed, 96 insertions, 0 deletions
diff --git a/lib/extensions/mtpmu/aarch64/mtpmu.S b/lib/extensions/mtpmu/aarch64/mtpmu.S
new file mode 100644
index 0000000000..0a1d57b9d5
--- /dev/null
+++ b/lib/extensions/mtpmu/aarch64/mtpmu.S
@@ -0,0 +1,96 @@
+/*
+ * Copyright (c) 2020, Arm Limited. All rights reserved.
+ *
+ * SPDX-License-Identifier: BSD-3-Clause
+ */
+
+#include <arch.h>
+#include <asm_macros.S>
+
+ .global mtpmu_disable
+
+/* -------------------------------------------------------------
+ * The functions in this file are called at entrypoint, before
+ * the CPU has decided whether this is a cold or a warm boot.
+ * Therefore there are no stack yet to rely on for a C function
+ * call.
+ * -------------------------------------------------------------
+ */
+
+/*
+ * bool mtpmu_supported(void)
+ *
+ * Return a boolean indicating whether FEAT_MTPMU is supported or not.
+ *
+ * Trash registers: x0, x1
+ */
+func mtpmu_supported
+ mrs x0, id_aa64dfr0_el1
+ mov_imm x1, ID_AA64DFR0_MTPMU_MASK
+ and x0, x1, x0, LSR #ID_AA64DFR0_MTPMU_SHIFT
+ cmp x0, ID_AA64DFR0_MTPMU_SUPPORTED
+ cset x0, eq
+ ret
+endfunc mtpmu_supported
+
+/*
+ * bool el_implemented(unsigned int el_shift)
+ *
+ * Return a boolean indicating if the specified EL is implemented.
+ * The EL is represented as the bitmask shift on id_aa64pfr0_el1 register.
+ *
+ * Trash registers: x0, x1
+ */
+func el_implemented
+ mrs x1, id_aa64pfr0_el1
+ lsr x1, x1, x0
+ cmp x1, #ID_AA64PFR0_ELX_MASK
+ cset x0, eq
+ ret
+endfunc el_implemented
+
+/*
+ * void mtpmu_disable(void)
+ *
+ * Disable mtpmu feature if supported.
+ *
+ * Trash register: x0, x1, x30
+ */
+func mtpmu_disable
+ mov x10, x30
+ bl mtpmu_supported
+ cbz x0, exit_disable
+
+ /* FEAT_MTMPU Supported */
+ mov_imm x0, ID_AA64PFR0_EL3_SHIFT
+ bl el_implemented
+ cbz x0, 1f
+
+ /* EL3 implemented */
+ mrs x0, mdcr_el3
+ mov_imm x1, MDCR_MTPME_BIT
+ bic x0, x0, x1
+ msr mdcr_el3, x0
+
+ /*
+ * If EL3 is implemented, MDCR_EL2.MTPME is implemented as Res0 and
+ * FEAT_MTPMU is controlled only from EL3, so no need to perform
+ * any operations for EL2.
+ */
+ isb
+exit_disable:
+ ret x10
+1:
+ /* EL3 not implemented */
+ mov_imm x0, ID_AA64PFR0_EL2_SHIFT
+ bl el_implemented
+ cbz x0, exit_disable
+
+ /* EL2 implemented */
+ mrs x0, mdcr_el2
+ mov_imm x1, MDCR_EL2_MTPME
+ bic x0, x0, x1
+ msr mdcr_el2, x0
+ isb
+ ret x10
+endfunc mtpmu_disable