[U-Boot] [PATCH v3] ARM: bootm: Allow booting in secure mode on hyp capable systems

[Hans de Goede]

Older Linux kernels will not properly boot in hype mode, add support for a
bootm_boot_mode environment variable, which when set to "sec" will cause
u-boot to boot in secure mode even when build with non-sec (and hyp) support.

Signed-off-by: Hans de Goede <hdegoede at redhat.com>
Acked-by: Marc Zyngier <marc.zyngier at arm.com>
Acked-by: Siarhei Siamashka <siarhei.siamashka at gmail.com>

--
Changes in v2:
-Allow changing the default boot mode to secure through defining
 CONFIG_ARMV7_SEC_BY_DEFAULT, this is useful for archs which have a Kconfig
 option for compatibility with older kernels
Changes in v3:
-Add an else at the end of the #ifdef NONSEC block so that if do_nonsec_entry
 fails we do not end up re-trying in secure mode
---
 arch/arm/lib/bootm.c | 31 ++++++++++++++++++++++++++-----
 1 file changed, 26 insertions(+), 5 deletions(-)

diff --git a/arch/arm/lib/bootm.c b/arch/arm/lib/bootm.c
index 39fe7a1..25b941c 100644
--- a/arch/arm/lib/bootm.c
+++ b/arch/arm/lib/bootm.c
@@ -235,6 +235,26 @@ static void boot_prep_linux(bootm_headers_t *images)
 	}
 }
 
+#if defined(CONFIG_ARMV7_NONSEC) || defined(CONFIG_ARMV7_VIRT)
+static bool boot_nonsec(void)
+{
+	char *s = getenv("bootm_boot_mode");
+#ifdef CONFIG_ARMV7_SEC_BY_DEFAULT
+	bool nonsec = false;
+#else
+	bool nonsec = true;
+#endif
+
+	if (s && !strcmp(s, "sec"))
+		nonsec = false;
+
+	if (s && !strcmp(s, "nonsec"))
+		nonsec = true;
+
+	return nonsec;
+}
+#endif
+
 /* Subcommand: GO */
 static void boot_jump_linux(bootm_headers_t *images, int flag)
 {
@@ -283,12 +303,13 @@ static void boot_jump_linux(bootm_headers_t *images, int flag)
 
 	if (!fake) {
 #if defined(CONFIG_ARMV7_NONSEC) || defined(CONFIG_ARMV7_VIRT)
-		armv7_init_nonsec();
-		secure_ram_addr(_do_nonsec_entry)(kernel_entry,
-						  0, machid, r2);
-#else
-		kernel_entry(0, machid, r2);
+		if (boot_nonsec()) {
+			armv7_init_nonsec();
+			secure_ram_addr(_do_nonsec_entry)(kernel_entry,
+							  0, machid, r2);
+		} else
 #endif
+			kernel_entry(0, machid, r2);
 	}
 #endif
 }
-- 
2.1.0