From: Heiko Carstens <hca@linux.ibm.com>
Date: Mon, 11 Sep 2023 19:40:05 +0000 (+0200)
Subject: s390/ctltreg: make initialization of control register save area explicit
X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=d11d5c8c8426a4abdcb2252999f1b57e3aa79e5b;p=linux.git

s390/ctltreg: make initialization of control register save area explicit

Commit e1b9c2749af0 ("s390/smp: ensure global control register contents
are in sync") made the control register save area contained within the
lowcore at absolute address zero a resource which is used when
initializing CPUs. However this is anything but obvious from the code.

Add an ctlreg_init_save_area() function in order to make this explicit.

Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Reviewed-by: Alexander Gordeev <agordeev@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
---

diff --git a/arch/s390/include/asm/ctlreg.h b/arch/s390/include/asm/ctlreg.h
index 57cc610dd9977..1f25601d75a06 100644
--- a/arch/s390/include/asm/ctlreg.h
+++ b/arch/s390/include/asm/ctlreg.h
@@ -110,9 +110,12 @@ static __always_inline void local_ctl_clear_bit(unsigned int cr, unsigned int bi
 	local_ctl_load(cr, &reg);
 }
 
+struct lowcore;
+
 void system_ctlreg_lock(void);
 void system_ctlreg_unlock(void);
 void system_ctl_set_clear_bit(unsigned int cr, unsigned int bit, bool set);
+void system_ctlreg_init_save_area(struct lowcore *lc);
 
 static inline void system_ctl_set_bit(unsigned int cr, unsigned int bit)
 {
diff --git a/arch/s390/kernel/ctlreg.c b/arch/s390/kernel/ctlreg.c
index 14f715bc5f736..7acc408048743 100644
--- a/arch/s390/kernel/ctlreg.c
+++ b/arch/s390/kernel/ctlreg.c
@@ -4,6 +4,7 @@
  */
 
 #include <linux/spinlock.h>
+#include <linux/init.h>
 #include <linux/smp.h>
 #include <asm/abs_lowcore.h>
 #include <asm/ctlreg.h>
@@ -27,6 +28,16 @@ void system_ctlreg_unlock(void)
 	spin_unlock(&system_ctl_lock);
 }
 
+void __init system_ctlreg_init_save_area(struct lowcore *lc)
+{
+	struct lowcore *abs_lc;
+
+	abs_lc = get_abs_lowcore();
+	__local_ctl_store(0, 15, lc->cregs_save_area);
+	__local_ctl_store(0, 15, abs_lc->cregs_save_area);
+	put_abs_lowcore(abs_lc);
+}
+
 struct ctl_bit_parms {
 	unsigned long orval;
 	unsigned long andval;
diff --git a/arch/s390/kernel/setup.c b/arch/s390/kernel/setup.c
index 1c049a65c769f..d399f18d0379e 100644
--- a/arch/s390/kernel/setup.c
+++ b/arch/s390/kernel/setup.c
@@ -449,7 +449,6 @@ static void __init setup_lowcore(void)
 	lc->restart_fn = (unsigned long) do_restart;
 	lc->restart_data = 0;
 	lc->restart_source = -1U;
-	__local_ctl_store(0, 15, lc->cregs_save_area);
 	lc->spinlock_lockval = arch_spin_lockval(0);
 	lc->spinlock_index = 0;
 	arch_spin_lock_setup(0);
@@ -459,6 +458,7 @@ static void __init setup_lowcore(void)
 	lc->kernel_asce = S390_lowcore.kernel_asce;
 	lc->user_asce = S390_lowcore.user_asce;
 
+	system_ctlreg_init_save_area(lc);
 	abs_lc = get_abs_lowcore();
 	abs_lc->restart_stack = lc->restart_stack;
 	abs_lc->restart_fn = lc->restart_fn;
@@ -466,7 +466,6 @@ static void __init setup_lowcore(void)
 	abs_lc->restart_source = lc->restart_source;
 	abs_lc->restart_psw = lc->restart_psw;
 	abs_lc->restart_flags = RESTART_FLAG_CTLREGS;
-	memcpy(abs_lc->cregs_save_area, lc->cregs_save_area, sizeof(abs_lc->cregs_save_area));
 	abs_lc->program_new_psw = lc->program_new_psw;
 	abs_lc->mcesad = lc->mcesad;
 	put_abs_lowcore(abs_lc);