set_rtc_noop, get_rtc_noop are used runtime, therefore need init removed.
Crash was observed on x86 platform where cmos rtc is unused and disabled
via device tree. Function was triggered from ntp: sync_hw_clock, although
CONFIG_RTC_SYSTOHC=n, however sync_cmos_clock doesn't honour that.

  Workqueue: events_power_efficient sync_hw_clock
  RIP: 0010:set_rtc_noop
  Call Trace:
   update_persistent_clock64
   sync_hw_clock

Fix by dropping __init and making set/get_rtc_noop available runtime.

Fixes: c311ed6183f4 ("x86/init: Allow DT configured systems to disable RTC at boot time")
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Matija Glavinic Pecotic <matija.glavinic-pecotic.ext@nokia.com>
---
v4: Update commit subject and message, resend to proper addresses
v3: Update commit message based on Andy's comments (further trim to backtrace, proper tag)
v2: Update commit message based on Andy's comments

 arch/x86/kernel/x86_init.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/x86/kernel/x86_init.c b/arch/x86/kernel/x86_init.c
index ef80d361b463..10622cf2b30f 100644
--- a/arch/x86/kernel/x86_init.c
+++ b/arch/x86/kernel/x86_init.c
@@ -33,8 +33,8 @@ static int __init iommu_init_noop(void) { return 0; }
 static void iommu_shutdown_noop(void) { }
 bool __init bool_x86_init_noop(void) { return false; }
 void x86_op_int_noop(int cpu) { }
-static __init int set_rtc_noop(const struct timespec64 *now) { return -EINVAL; }
-static __init void get_rtc_noop(struct timespec64 *now) { }
+static int set_rtc_noop(const struct timespec64 *now) { return -EINVAL; }
+static void get_rtc_noop(struct timespec64 *now) { }
 
 static __initconst const struct of_device_id of_cmos_match[] = {
 	{ .compatible = "motorola,mc146818" },
-- 
2.30.2

The following commit has been merged into the x86/urgent branch of tip:

Commit-ID:     775d3c514c5b2763a50ab7839026d7561795924d
Gitweb:        https://git.kernel.org/tip/775d3c514c5b2763a50ab7839026d7561795924d
Author:        Matija Glavinic Pecotic <matija.glavinic-pecotic.ext@nokia.com>
AuthorDate:    Thu, 06 Apr 2023 08:26:52 +02:00
Committer:     Thomas Gleixner <tglx@linutronix.de>
CommitterDate: Thu, 13 Apr 2023 14:41:04 +02:00

x86/rtc: Remove __init for runtime functions

set_rtc_noop(), get_rtc_noop() are after booting, therefore their __init
annotation is wrong.

A crash was observed on an x86 platform where CMOS RTC is unused and
disabled via device tree. set_rtc_noop() was invoked from ntp:
sync_hw_clock(), although CONFIG_RTC_SYSTOHC=n, however sync_cmos_clock()
doesn't honour that.

  Workqueue: events_power_efficient sync_hw_clock
  RIP: 0010:set_rtc_noop
  Call Trace:
   update_persistent_clock64
   sync_hw_clock

Fix this by dropping the __init annotation from set/get_rtc_noop().

Fixes: c311ed6183f4 ("x86/init: Allow DT configured systems to disable RTC at boot time")
Signed-off-by: Matija Glavinic Pecotic <matija.glavinic-pecotic.ext@nokia.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Link: https://lore.kernel.org/r/59f7ceb1-446b-1d3d-0bc8-1f0ee94b1e18@nokia.com

---
 arch/x86/kernel/x86_init.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/x86/kernel/x86_init.c b/arch/x86/kernel/x86_init.c
index ef80d36..10622cf 100644
--- a/arch/x86/kernel/x86_init.c
+++ b/arch/x86/kernel/x86_init.c
@@ -33,8 +33,8 @@ static int __init iommu_init_noop(void) { return 0; }
 static void iommu_shutdown_noop(void) { }
 bool __init bool_x86_init_noop(void) { return false; }
 void x86_op_int_noop(int cpu) { }
-static __init int set_rtc_noop(const struct timespec64 *now) { return -EINVAL; }
-static __init void get_rtc_noop(struct timespec64 *now) { }
+static int set_rtc_noop(const struct timespec64 *now) { return -EINVAL; }
+static void get_rtc_noop(struct timespec64 *now) { }
 
 static __initconst const struct of_device_id of_cmos_match[] = {
 	{ .compatible = "motorola,mc146818" },