Add a function pointer hook (arm64_pre_smp_shutdown_hook) that is invoked
from machine_shutdown() before smp_shutdown_nonboot_cpus(). This allows
platform code (e.g., hypervisors) to perform cleanup that must happen
after device_shutdown() but before secondary CPUs go offline.
In the kexec path, the call sequence is:
kernel_kexec()
kernel_restart_prepare()
device_shutdown() // drivers shut down here
migrate_to_reboot_cpu()
cpu_hotplug_enable()
machine_shutdown()
arm64_pre_smp_shutdown_hook() // new: platform cleanup
smp_shutdown_nonboot_cpus() // CPUs go offline
x86 achieves this via machine_ops.shutdown; ARM64 currently has no
equivalent mechanism. Rather than introducing the full machine_ops
structure, add a targeted hook for the shutdown path.
Signed-off-by: Shradha Gupta <[email protected]>
---
arch/arm64/include/asm/system_misc.h | 2 ++
arch/arm64/kernel/process.c | 13 +++++++++++++
2 files changed, 15 insertions(+)
diff --git a/arch/arm64/include/asm/system_misc.h
b/arch/arm64/include/asm/system_misc.h
index d316a804eb38..7c37b9f33e96 100644
--- a/arch/arm64/include/asm/system_misc.h
+++ b/arch/arm64/include/asm/system_misc.h
@@ -28,6 +28,8 @@ void arm64_notify_die(const char *str, struct pt_regs *regs,
struct mm_struct;
extern void __show_regs(struct pt_regs *);
+extern void (*arm64_pre_smp_shutdown_hook)(void);
+
#endif /* __ASSEMBLER__ */
#endif /* __ASM_SYSTEM_MISC_H */
diff --git a/arch/arm64/kernel/process.c b/arch/arm64/kernel/process.c
index 581f80e9b9b7..41c0e9840913 100644
--- a/arch/arm64/kernel/process.c
+++ b/arch/arm64/kernel/process.c
@@ -88,8 +88,21 @@ void __noreturn arch_cpu_idle_dead(void)
* avoid any code or data used by any SW CPU pin loop. The CPU hotplug
* functionality embodied in smpt_shutdown_nonboot_cpus() to achieve this.
*/
+
+/*
+ * Hook for platform code to perform cleanup after device_shutdown()
+ * but before secondary CPUs are offlined. This runs in the kexec path
+ * from kernel_kexec() after device_shutdown() and cpu_hotplug_enable()
+ * have been called, matching the point at which x86 invokes
+ * machine_ops.shutdown.
+ */
+void (*arm64_pre_smp_shutdown_hook)(void);
+
void machine_shutdown(void)
{
+ if (arm64_pre_smp_shutdown_hook)
+ arm64_pre_smp_shutdown_hook();
+
smp_shutdown_nonboot_cpus(reboot_cpu);
}
--
2.43.0
