Added ability to vmalloc executable memory

Since release 5.8-rc1 the pgprot got removed from __vmalloc
because the only usage was PAGE_KERNEL as argument.
However, this removes the ability to input other arguments
such as 'PAGE_KERNEL_EXEC', which can be used to allocate
memory in which you can execute. For this reason a new
function is introduced called '__vmalloc_exec'.

Signed-off-by: Xander Moerkerken <xander.moerkerken@omron.com>

include/linux/vmalloc.h

@@ -147,6 +147,7 @@ extern void *vzalloc_node(unsigned long size, int node) __alloc_size(1);
 extern void *vmalloc_32(unsigned long size) __alloc_size(1);
 extern void *vmalloc_32_user(unsigned long size) __alloc_size(1);
 extern void *__vmalloc(unsigned long size, gfp_t gfp_mask) __alloc_size(1);
+extern void *__vmalloc_exec(unsigned long size, gfp_t gfp_mask) __alloc_size(1);
 extern void *__vmalloc_node_range(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,

mm/vmalloc.c

@@ -3308,6 +3308,14 @@ void *__vmalloc(unsigned long size, gfp_t gfp_mask)
 }
 EXPORT_SYMBOL(__vmalloc);
 
+
+void *__vmalloc_exec(unsigned long size, gfp_t gfp_mask)
+{
+	return __vmalloc_node_prot(size, 1, gfp_mask, PAGE_KERNEL_EXEC,
+	                          NUMA_NO_NODE, __builtin_return_address(0));
+}
+EXPORT_SYMBOL(__vmalloc_exec);
+
 /**
  * vmalloc - allocate virtually contiguous memory
  * @size:    allocation size