--- zzzz-none-000/linux-4.4.271/arch/arm64/kernel/process.c	2021-06-03 06:22:09.000000000 +0000
+++ maple-fsgw-759/linux-4.4.271/arch/arm64/kernel/process.c	2023-12-20 10:37:01.000000000 +0000
@@ -45,6 +45,9 @@
 #include <linux/personality.h>
 #include <linux/notifier.h>
 #include <trace/events/power.h>
+#ifdef CONFIG_THREAD_INFO_IN_TASK
+#include <linux/percpu.h>
+#endif
 
 #include <asm/compat.h>
 #include <asm/cacheflush.h>
@@ -317,6 +320,22 @@
 	: : "r" (tpidr), "r" (tpidrro));
 }
 
+#ifdef CONFIG_THREAD_INFO_IN_TASK
+/*
+ * We store our current task in sp_el0, which is clobbered by userspace. Keep a
+ * shadow copy so that we can restore this upon entry from userspace.
+ *
+ * This is *only* for exception entry from EL0, and is not valid until we
+ * __switch_to() a user task.
+ */
+DEFINE_PER_CPU(struct task_struct *, __entry_task);
+
+static void entry_task_switch(struct task_struct *next)
+{
+	__this_cpu_write(__entry_task, next);
+}
+#endif
+
 /*
  * Thread switching.
  */
@@ -329,6 +348,9 @@
 	tls_thread_switch(next);
 	hw_breakpoint_thread_switch(next);
 	contextidr_thread_switch(next);
+#ifdef CONFIG_THREAD_INFO_IN_TASK
+	entry_task_switch(next);
+#endif
 
 	/*
 	 * Complete any pending TLB or cache maintenance on this CPU in case