Update Linux to v5.10.109

Sourced from [1]

[1] https://cdn.kernel.org/pub/linux/kernel/v5.x/linux-5.10.109.tar.xz

Change-Id: I19bca9fc6762d4e63bcf3e4cba88bbe560d9c76c
Signed-off-by: Olivier Deprez <olivier.deprez@arm.com>
diff --git a/arch/powerpc/kernel/rtas.c b/arch/powerpc/kernel/rtas.c
index c1e2e35..cccb32c 100644
--- a/arch/powerpc/kernel/rtas.c
+++ b/arch/powerpc/kernel/rtas.c
@@ -41,6 +41,7 @@
 #include <asm/time.h>
 #include <asm/mmu.h>
 #include <asm/topology.h>
+#include <asm/paca.h>
 
 /* This is here deliberately so it's only used in this file */
 void enter_rtas(unsigned long);
@@ -896,6 +897,57 @@
 
 	return atomic_read(&data.error);
 }
+
+/**
+ * rtas_call_reentrant() - Used for reentrant rtas calls
+ * @token:	Token for desired reentrant RTAS call
+ * @nargs:	Number of Input Parameters
+ * @nret:	Number of Output Parameters
+ * @outputs:	Array of outputs
+ * @...:	Inputs for desired RTAS call
+ *
+ * According to LoPAR documentation, only "ibm,int-on", "ibm,int-off",
+ * "ibm,get-xive" and "ibm,set-xive" are currently reentrant.
+ * Reentrant calls need their own rtas_args buffer, so not using rtas.args, but
+ * PACA one instead.
+ *
+ * Return:	-1 on error,
+ *		First output value of RTAS call if (nret > 0),
+ *		0 otherwise,
+ */
+int rtas_call_reentrant(int token, int nargs, int nret, int *outputs, ...)
+{
+	va_list list;
+	struct rtas_args *args;
+	unsigned long flags;
+	int i, ret = 0;
+
+	if (!rtas.entry || token == RTAS_UNKNOWN_SERVICE)
+		return -1;
+
+	local_irq_save(flags);
+	preempt_disable();
+
+	/* We use the per-cpu (PACA) rtas args buffer */
+	args = local_paca->rtas_args_reentrant;
+
+	va_start(list, outputs);
+	va_rtas_call_unlocked(args, token, nargs, nret, list);
+	va_end(list);
+
+	if (nret > 1 && outputs)
+		for (i = 0; i < nret - 1; ++i)
+			outputs[i] = be32_to_cpu(args->rets[i + 1]);
+
+	if (nret > 0)
+		ret = be32_to_cpu(args->rets[0]);
+
+	local_irq_restore(flags);
+	preempt_enable();
+
+	return ret;
+}
+
 #else /* CONFIG_PPC_PSERIES */
 int rtas_ibm_suspend_me(u64 handle)
 {