bbapi: Add Compile time check for Linux >= 5.8

Makefile

@@ -12,6 +12,9 @@ SUDO := ${SUDO_${OS}}
 ccflags-y := -DBIOSAPIERR_OFFSET=0
 ccflags-y := -DUNAME_S=\"${OS}\"
 
+# compile test for vmalloc workaround check for Linux >= 5.8
+always-y += compile_test.o
+
 all:
 	make -C $(KDIR) M=$(PWD) modules
 	make -C $(KDIR) M=$(PWD)/button modules

api.c

@@ -192,10 +192,8 @@ static struct kprobe kp = {
 typedef unsigned long (*kallsyms_lookup_name_t)(const char *name);
 kallsyms_lookup_name_t fcn_kallsyms_lookup_name;
 
-typedef void *(*fcn_vmalloc_node_range_t)(unsigned long size, unsigned long align,
-		unsigned long start, unsigned long end, gfp_t gfp_mask,
-		pgprot_t prot, unsigned long vm_flags, int node,
-		const void *caller);
+#include "api_internals.h"
+
 fcn_vmalloc_node_range_t fcn_vmalloc_node_range;
 #endif
 

api_internals.h

@@ -0,0 +1,17 @@
+// SPDX-License-Identifier: MIT
+/**
+    Author:     Bjarne von Horn <vh@igh.de>
+    Copyright (C) 2024 IgH GmbH
+*/
+#ifndef __API_INTERNALS_H
+#define __API_INTERNALS_H
+
+#include <linux/vmalloc.h>
+
+typedef void *(*fcn_vmalloc_node_range_t)(unsigned long size, unsigned long align,
+		unsigned long start, unsigned long end, gfp_t gfp_mask,
+		pgprot_t prot, unsigned long vm_flags, int node,
+		const void *caller);
+
+#endif
+

compile_test.c

@@ -0,0 +1,18 @@
+// SPDX-License-Identifier: MIT
+/**
+    Compile test to ensure __vmalloc_node_range is a symbol and its arguments
+    Author: 	Bjarne von Horn <vh@igh.de>
+    Copyright (C) 2024 IgH GmbH
+*/
+
+#include <linux/version.h>
+
+#if LINUX_VERSION_CODE >= KERNEL_VERSION(5, 8, 0)
+
+#include "api_internals.h"
+#include <linux/vmalloc.h>
+
+
+__attribute__((__used__)) fcn_vmalloc_node_range_t fcn_vmalloc_node_range_test = &__vmalloc_node_range;
+
+#endif