[coreboot-gerrit] New patch to review for coreboot: 74c4e31 arm64: secmon trampoline for restart

[Patrick Georgi (pgeorgi@google.com)]

Patrick Georgi (pgeorgi at google.com) just uploaded a new patch set to gerrit, which you can find at http://review.coreboot.org/9096

-gerrit

commit 74c4e310fd02f94e593e61f5af3fc6700b82a37b
Author: Aaron Durbin <adurbin at chromium.org>
Date:   Fri Sep 19 15:47:27 2014 -0500

    arm64: secmon trampoline for restart
    
    If an exception is taken that the secmon won't return
    to there needs to be way to reset that cpu's state
    w.r.t. stack usage. Therefore, provide secmon_trampoline
    which will reinitialize the exception stack and SP_EL0
    and start executing with SP_EL0 like the initial state
    of the secmon entry.
    
    BUG=chrome-os-partner:30785
    BRANCH=None
    TEST=Built and booted to kernel. Also tested when is PSCI
         is employed in the kernel.
    
    Change-Id: Ie9f5bbe715dcbcf8b67ea40f9a3a5088ac7aa2ad
    Signed-off-by: Patrick Georgi <pgeorgi at chromium.org>
    Original-Commit-Id: f1f546ee3e9eca93baaa1ae0437351205bf548a5
    Original-Change-Id: Ia3da75e1fa0251c8ea30eb0b0523c8a51c03b917
    Original-Signed-off-by: Aaron Durbin <adurbin at chromium.org>
    Original-Reviewed-on: https://chromium-review.googlesource.com/218922
    Original-Reviewed-by: Furquan Shaikh <furquan at chromium.org>
---
 src/arch/arm64/armv8/secmon/Makefile.inc  |  1 +
 src/arch/arm64/armv8/secmon/secmon.h      | 34 +++++++++++++++++++++
 src/arch/arm64/armv8/secmon/secmon_init.c |  5 +++
 src/arch/arm64/armv8/secmon/trampoline.S  | 51 +++++++++++++++++++++++++++++++
 4 files changed, 91 insertions(+)

diff --git a/src/arch/arm64/armv8/secmon/Makefile.inc b/src/arch/arm64/armv8/secmon/Makefile.inc
index 040f568..03b93ed 100644
--- a/src/arch/arm64/armv8/secmon/Makefile.inc
+++ b/src/arch/arm64/armv8/secmon/Makefile.inc
@@ -33,6 +33,7 @@ secmon-S-ccopts += -I$(src)/arch/arm64/include/armv8/ -include $(src)/include/kc
 
 secmon-y += secmon_init.c
 secmon-y += smc.c
+secmon-y += trampoline.S
 secmon-y += ../exception.c
 secmon-y += ../../cpu.c
 secmon-y += ../../transition_asm.S ../../transition.c
diff --git a/src/arch/arm64/armv8/secmon/secmon.h b/src/arch/arm64/armv8/secmon/secmon.h
new file mode 100644
index 0000000..df57e98
--- /dev/null
+++ b/src/arch/arm64/armv8/secmon/secmon.h
@@ -0,0 +1,34 @@
+/*
+ * This file is part of the coreboot project.
+ *
+ * Copyright 2014 Google Inc
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation; version 2 of
+ * the License.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+ * MA 02110-1301 USA
+ */
+
+#ifndef __SECMON_SECMON_H__
+#define __SECMON_SECMON_H__
+
+/*
+ * The secmon_trampoline() switches mode to EL3t reinitializing the both
+ * EL3t and EL3h stacks.
+ */
+void secmon_trampoline(void *entry, void *arg);
+
+/* Wait for action to take place. */
+void secmon_wait_for_action(void);
+
+#endif /* __SECMON_SECMON_H__ */
diff --git a/src/arch/arm64/armv8/secmon/secmon_init.c b/src/arch/arm64/armv8/secmon/secmon_init.c
index de433bb..6172505 100644
--- a/src/arch/arm64/armv8/secmon/secmon_init.c
+++ b/src/arch/arm64/armv8/secmon/secmon_init.c
@@ -29,6 +29,7 @@
 #include <console/console.h>
 #include <rmodule.h>
 #include <stddef.h>
+#include "secmon.h"
 
 static void cpu_init(int bsp)
 {
@@ -62,7 +63,11 @@ static void secmon_init(struct secmon_params *params, int bsp)
 
 		transition_with_entry(params->entry, params->arg, &exc_state);
 	}
+	secmon_wait_for_action();
+}
 
+void secmon_wait_for_action(void)
+{
 	arch_cpu_wait_for_action();
 }
 
diff --git a/src/arch/arm64/armv8/secmon/trampoline.S b/src/arch/arm64/armv8/secmon/trampoline.S
new file mode 100644
index 0000000..cb6a4e4
--- /dev/null
+++ b/src/arch/arm64/armv8/secmon/trampoline.S
@@ -0,0 +1,51 @@
+/*
+ * This file is part of the coreboot project.
+ *
+ * Copyright 2014 Google Inc.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; version 2 of the License.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+
+#include <arch/asm.h>
+
+/*
+ * Call entry(arg) after reinitializing stack state.
+ * void secmon_trampoline(void *entry, void *arg);
+ */
+ENTRY(secmon_trampoline)
+	mov	x22, x0			/* x22 = function pointer */
+	mov	x23, x1			/* x23 = argument */
+	bl	smp_processor_id	/* x0 = cpu */
+	mov	x24, x0
+
+	/* Set the exception stack for this cpu. */
+	bl	cpu_get_exception_stack
+	msr	SPSel, #1
+	isb
+	mov	sp, x0
+
+	/* Have stack pointer use SP_EL0. */
+	msr	SPSel, #0
+	isb
+
+	/* Set stack for this cpu. */
+	mov	x0, x24		/* x0 = cpu */
+	bl	cpu_get_stack
+	mov	sp, x0
+
+	/* Call the function with specified argument. */
+	mov	x1, x22
+	mov	x0, x23
+	br	x1
+ENDPROC(secmon_trampoline)