[PATCH v5 2/6] 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.

Cc: linux-mm@xxxxxxxxx
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 | 17 +++++++++++++++++
 1 file changed, 17 insertions(+)

diff --git a/include/linux/vmalloc.h b/include/linux/vmalloc.h
index 0221f852a7e1..6c151a0ac02a 100644
--- a/include/linux/vmalloc.h
+++ b/include/linux/vmalloc.h
@@ -249,4 +249,21 @@ 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);
 
+/*
+ * These functions can be optionally implemented by an arch in order to
+ * provide specialized functions for allocating trampoline code.
+ */
+
+#ifdef CONFIG_ARCH_HAS_TEXT_ALLOC
+/*
+ * Allocate memory to be used for trampoline code.
+ */
+void *text_alloc(unsigned long size);
+
+/*
+ * Free memory returned from text_alloc().
+ */
+void text_free(void *region);
+#endif /* CONFIG_ARCH_HAS_TEXT_ALLOC */
+
 #endif /* _LINUX_VMALLOC_H */
-- 
2.25.1