[PATCH v7 3/8] powerpc: detect the trusted boot state of the system

[Nayna Jain <nayna@linux.ibm.com>]

PowerNV systems enables the IMA measurement rules only if the
trusted boot is enabled on the system.

This patch adds the function to detect if the system has trusted
boot enabled.

Signed-off-by: Nayna Jain <nayna@linux.ibm.com>
---
 arch/powerpc/include/asm/secure_boot.h |  6 +++++
 arch/powerpc/kernel/secure_boot.c      | 35 ++++++++++++++++++++++++++
 2 files changed, 41 insertions(+)

diff --git a/arch/powerpc/include/asm/secure_boot.h b/arch/powerpc/include/asm/secure_boot.h
index 23d2ef2f1f7b..ecd08515e301 100644
--- a/arch/powerpc/include/asm/secure_boot.h
+++ b/arch/powerpc/include/asm/secure_boot.h
@@ -12,6 +12,7 @@
 
 bool is_powerpc_os_secureboot_enabled(void);
 struct device_node *get_powerpc_os_sb_node(void);
+bool is_powerpc_trustedboot_enabled(void);
 
 #else
 
@@ -25,5 +26,10 @@ static inline struct device_node *get_powerpc_os_sb_node(void)
 	return NULL;
 }
 
+static inline bool is_powerpc_os_trustedboot_enabled(void)
+{
+	return false;
+}
+
 #endif
 #endif
diff --git a/arch/powerpc/kernel/secure_boot.c b/arch/powerpc/kernel/secure_boot.c
index 0488dbcab6b9..9d5ac1b39e46 100644
--- a/arch/powerpc/kernel/secure_boot.c
+++ b/arch/powerpc/kernel/secure_boot.c
@@ -7,6 +7,27 @@
 #include <linux/of.h>
 #include <asm/secure_boot.h>
 
+static const char * const fwsecureboot_compat[] = {
+	"ibm,secureboot-v1",
+	"ibm,secureboot-v2",
+	NULL,
+};
+
+static struct device_node *get_powerpc_fw_sb_node(void)
+{
+	struct device_node *node;
+	int i;
+
+	for (i = 0; i < ARRAY_SIZE(fwsecureboot_compat); ++i) {
+		node = of_find_compatible_node(NULL, NULL,
+					       fwsecureboot_compat[i]);
+		if (node)
+			return node;
+	}
+
+	return NULL;
+}
+
 struct device_node *get_powerpc_os_sb_node(void)
 {
 	return of_find_compatible_node(NULL, NULL, "ibm,secvar-v1");
@@ -40,3 +61,17 @@ bool is_powerpc_os_secureboot_enabled(void)
 	pr_info("secureboot mode disabled\n");
 	return false;
 }
+
+bool is_powerpc_trustedboot_enabled(void)
+{
+	struct device_node *node;
+
+	node = get_powerpc_fw_sb_node();
+	if (node && (of_find_property(node, "trusted-enabled", NULL))) {
+		pr_info("trustedboot mode enabled\n");
+		return true;
+	}
+
+	pr_info("trustedboot mode disabled\n");
+	return false;
+}
-- 
2.20.1