armv8: Add ARMv8 MPU configuration logic

Armv8r64 is the first Armv8 platform that only has a PMSA at the
current exception level. The architecture supplement for Armv8r64
describes new fields in ID_AA64MMFR0_EL1 which can be used to detect
whether a VMSA or PMSA is present. These fields are RES0 on Armv8a.

Add logic to read these fields and, for the protection of the memory
used by U-Boot, initialize the MPU instead of the MMU during init, then
clear the MPU regions before transition to the next stage.

Provide a default (blank) MPU memory map, which can be overridden by
board configurations.

Signed-off-by: Peter Hoyes <Peter.Hoyes@arm.com>

1 files changed, 61 insertions, 0 deletions

diff --git a/arch/arm/include/asm/armv8/mpu.h b/arch/arm/include/asm/armv8/mpu.h
new file mode 100644
index 0000000000..c6c8828325
--- /dev/null
+++ b/arch/arm/include/asm/armv8/mpu.h
@@ -0,0 +1,61 @@
+/*
+ * SPDX-License-Identifier: GPL-2.0+
+ *
+ * (C) Copyright 2021 Arm Limited
+ */
+
+#ifndef _ASM_ARMV8_MPU_H_
+#define _ASM_ARMV8_MPU_H_
+
+#include <asm/armv8/mmu.h>
+#include <asm/barriers.h>
+#include <linux/stringify.h>
+
+#define PRSELR_EL2		S3_4_c6_c2_1
+#define PRBAR_EL2		S3_4_c6_c8_0
+#define PRLAR_EL2		S3_4_c6_c8_1
+#define MPUIR_EL2		S3_4_c0_c0_4
+
+#define PRBAR_ADDRESS(addr)	((addr) & ~(0x3fULL))
+
+/* Access permissions */
+#define PRBAR_AP(val)		(((val) & 0x3) << 2)
+#define PRBAR_AP_RW_HYP		PRBAR_AP(0x0)
+#define PRBAR_AP_RW_ANY		PRBAR_AP(0x1)
+#define PRBAR_AP_RO_HYP		PRBAR_AP(0x2)
+#define PRBAR_AP_RO_ANY		PRBAR_AP(0x3)
+
+/* Shareability */
+#define PRBAR_SH(val)		(((val) & 0x3) << 4)
+#define PRBAR_NON_SH		PRBAR_SH(0x0)
+#define PRBAR_OUTER_SH		PRBAR_SH(0x2)
+#define PRBAR_INNER_SH		PRBAR_SH(0x3)
+
+/* Memory attribute (MAIR idx) */
+#define PRLAR_ATTRIDX(val)	(((val) & 0x7) << 1)
+#define PRLAR_EN_BIT		(0x1)
+#define PRLAR_ADDRESS(addr)	((addr) & ~(0x3fULL))
+
+#ifndef __ASSEMBLY__
+
+static inline void setup_el2_mpu_region(uint8_t region, uint64_t base, uint64_t limit)
+{
+	asm volatile("msr " __stringify(PRSELR_EL2) ", %0" : : "r" (region));
+	isb();
+	asm volatile("msr " __stringify(PRBAR_EL2) ", %0" : : "r" (base));
+	asm volatile("msr " __stringify(PRLAR_EL2) ", %0" : : "r" (limit));
+	dsb();
+	isb();
+}
+
+#endif
+
+struct mpu_region {
+	u64 start;
+	u64 end;
+	u64 attrs;
+};
+
+extern struct mpu_region *mpu_mem_map;
+
+#endif /* _ASM_ARMV8_MPU_H_ */