[PATCH v4 3/7] vmalloc: Add text_alloc() and text_free()

[Jarkko Sakkinen]

Introduce functions for allocating memory for dynamic trampolines, such
as kprobes. An arch can promote the availability of these functions with
CONFIG_ARCH_HAS_TEXT_ALLOC. Provide default/fallback implementation
wrapping module_alloc() and module_memfree().

Cc: Andi Kleen <ak@xxxxxxxxxxxxxxx>
Cc: Masami Hiramatsu <mhiramat@xxxxxxxxxx>
Suggested-by: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@xxxxxxxxxxxxxxx>
---
 include/linux/vmalloc.h | 23 +++++++++++++++++++++++
 1 file changed, 23 insertions(+)

diff --git a/include/linux/vmalloc.h b/include/linux/vmalloc.h
index 0221f852a7e1..e981436e30b6 100644
--- a/include/linux/vmalloc.h
+++ b/include/linux/vmalloc.h
@@ -9,6 +9,7 @@
 #include <asm/page.h>		/* pgprot_t */
 #include <linux/rbtree.h>
 #include <linux/overflow.h>
+#include <linux/moduleloader.h>
 
 #include <asm/vmalloc.h>
 
@@ -249,4 +250,26 @@ pcpu_free_vm_areas(struct vm_struct **vms, int nr_vms)
 int register_vmap_purge_notifier(struct notifier_block *nb);
 int unregister_vmap_purge_notifier(struct notifier_block *nb);
 
+#ifdef CONFIG_ARCH_HAS_TEXT_ALLOC
+/*
+ * Allocate memory to be used for dynamic trampoline code.
+ */
+void *text_alloc(unsigned long size);
+
+/*
+ * Free memory returned from text_alloc().
+ */
+void text_free(void *region);
+#else
+static inline void *text_alloc(unsigned long size)
+{
+	return module_alloc(size);
+}
+
+static inline void text_free(void *region)
+{
+	module_memfree(region);
+}
+#endif
+
 #endif /* _LINUX_VMALLOC_H */
-- 
2.25.1