efi_loader: refactor switch to non-secure mode

Refactor the switch from supervisor to hypervisor to a new function called
at the beginning of do_bootefi().

Signed-off-by: Heinrich Schuchardt <xypron.glpk@gmx.de>
Signed-off-by: Alexander Graf <agraf@suse.de>

2 files changed, 57 insertions, 0 deletions

diff --git a/arch/arm/cpu/armv7/Makefile b/arch/arm/cpu/armv7/Makefile
index 4f4647c90a..8c955d0d52 100644
--- a/arch/arm/cpu/armv7/Makefile
+++ b/arch/arm/cpu/armv7/Makefile
@@ -14,6 +14,7 @@ obj-$(CONFIG_SYS_ARM_MPU) += mpu_v7r.o
 
 ifneq ($(CONFIG_SPL_BUILD),y)
 obj-$(CONFIG_EFI_LOADER) += sctlr.o
+obj-$(CONFIG_ARMV7_NONSEC) += exception_level.o
 endif
 
 ifneq ($(CONFIG_SKIP_LOWLEVEL_INIT),y)
diff --git a/arch/arm/cpu/armv7/exception_level.c b/arch/arm/cpu/armv7/exception_level.c
new file mode 100644
index 0000000000..274f03d8bb
--- /dev/null
+++ b/arch/arm/cpu/armv7/exception_level.c
@@ -0,0 +1,56 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Switch to non-secure mode
+ *
+ * Copyright (c) 2018 Heinrich Schuchardt
+ *
+ * This module contains the ARMv7 specific code required for leaving the
+ * secure mode before booting an operating system.
+ */
+
+#include <common.h>
+#include <bootm.h>
+#include <asm/armv7.h>
+#include <asm/secure.h>
+#include <asm/setjmp.h>
+
+/**
+ * entry_non_secure() - entry point when switching to non-secure mode
+ *
+ * When switching to non-secure mode switch_to_non_secure_mode() calls this
+ * function passing a jump buffer. We use this jump buffer to restore the
+ * original stack and register state.
+ *
+ * @non_secure_jmp:	jump buffer for restoring stack and registers
+ */
+static void entry_non_secure(struct jmp_buf_data *non_secure_jmp)
+{
+	dcache_enable();
+	debug("Reached non-secure mode\n");
+
+	/* Restore stack and registers saved in switch_to_non_secure_mode() */
+	longjmp(non_secure_jmp, 1);
+}
+
+/**
+ * switch_to_non_secure_mode() - switch to non-secure mode
+ *
+ * Operating systems may expect to run in non-secure mode. Here we check if
+ * we are running in secure mode and switch to non-secure mode if necessary.
+ */
+void switch_to_non_secure_mode(void)
+{
+	static bool is_nonsec;
+	struct jmp_buf_data non_secure_jmp;
+
+	if (armv7_boot_nonsec() && !is_nonsec) {
+		if (setjmp(&non_secure_jmp))
+			return;
+		dcache_disable();	/* flush cache before switch to HYP */
+		armv7_init_nonsec();
+		is_nonsec = true;
+		secure_ram_addr(_do_nonsec_entry)(entry_non_secure,
+						  (uintptr_t)&non_secure_jmp,
+						  0, 0);
+	}
+}