Runtime validate the VCLOCK_MODE in clocksource::archdata and disable
VCLOCK if invalid, which disables the VDSO but keeps the system running.

Signed-off-by: Thomas Gleixner <t...@linutronix.de>
---
 arch/x86/Kconfig       |    1 +
 arch/x86/kernel/time.c |   16 ++++++++++++++++
 2 files changed, 17 insertions(+)

--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -48,6 +48,7 @@ config X86
        select ACPI_SYSTEM_POWER_STATES_SUPPORT if ACPI
        select ANON_INODES
        select ARCH_CLOCKSOURCE_DATA
+       select ARCH_CLOCKSOURCE_INIT
        select ARCH_DISCARD_MEMBLOCK
        select ARCH_HAS_ACPI_TABLE_UPGRADE      if ACPI
        select ARCH_HAS_DEBUG_VIRTUAL
--- a/arch/x86/kernel/time.c
+++ b/arch/x86/kernel/time.c
@@ -10,6 +10,7 @@
  *
  */
 
+#include <linux/clocksource.h>
 #include <linux/clockchips.h>
 #include <linux/interrupt.h>
 #include <linux/irq.h>
@@ -105,3 +106,18 @@ void __init time_init(void)
 {
        late_time_init = x86_late_time_init;
 }
+
+/*
+ * Sanity check the vdso related archdata content.
+ */
+void clocksource_arch_init(struct clocksource *cs)
+{
+       if (cs->archdata.vclock_mode == VCLOCK_NONE)
+               return;
+
+       if (cs->archdata.vclock_mode >= VCLOCK_MAX) {
+               pr_warn("clocksource %s registered with invalid vclock_mode %d. 
Disabling vclock.\n",
+                       cs->name, cs->archdata.vclock_mode);
+               cs->archdata.vclock_mode = VCLOCK_NONE;
+       }
+}


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