[PATCH 5/8] arm64: Split soft_restart into two stages

[Geoff Levand]

Remove the call to setup_restart() from within soft_restart(), change
setup_restart() from local to global scope by removing its static attribute,
and add a function prototype for setup_restart() in system_misc.h.

Splitting setup_restart() and soft_restart() into two different operations
allows for the calling routine to call setup_restart(), then perform some
operation with the identity map in enabled, and then call soft_restart() to
disable the MMU and perform the soft reset.  It is expected that the calling
routine will call setup_restart(), then shortly thereafter call soft_restart().

To properly manage the shutdown of spin-table secondary CPUs it is necessary to
transition those CPUs into a state compatible with booting.txt.  The existing
implementation of soft_restart() did not allow for the transition to an
identity mapped spin loop.

Signed-off-by: Geoff Levand <geoff at infradead.org>
---
 arch/arm64/include/asm/system_misc.h | 1 +
 arch/arm64/kernel/process.c          | 4 +---
 2 files changed, 2 insertions(+), 3 deletions(-)

diff --git a/arch/arm64/include/asm/system_misc.h b/arch/arm64/include/asm/system_misc.h
index 7a18fab..15bc824 100644
--- a/arch/arm64/include/asm/system_misc.h
+++ b/arch/arm64/include/asm/system_misc.h
@@ -41,6 +41,7 @@ struct mm_struct;
 extern void show_pte(struct mm_struct *mm, unsigned long addr);
 extern void __show_regs(struct pt_regs *);
 
+void setup_restart(void);
 void soft_restart(unsigned long);
 extern void (*arm_pm_restart)(enum reboot_mode reboot_mode, const char *cmd);
 
diff --git a/arch/arm64/kernel/process.c b/arch/arm64/kernel/process.c
index 6391485..d52c660 100644
--- a/arch/arm64/kernel/process.c
+++ b/arch/arm64/kernel/process.c
@@ -50,7 +50,7 @@
 #include <asm/processor.h>
 #include <asm/stacktrace.h>
 
-static void setup_restart(void)
+void setup_restart(void)
 {
 	/*
 	 * Tell the mm system that we are going to reboot -
@@ -74,8 +74,6 @@ void soft_restart(unsigned long addr)
 	typedef void (*phys_reset_t)(unsigned long);
 	phys_reset_t phys_reset;
 
-	setup_restart();
-
 	/* Switch to the identity mapping */
 	phys_reset = (phys_reset_t)virt_to_phys(cpu_reset);
 	phys_reset(addr);
-- 
1.9.1