tracehook: tracehook_expect_breakpoints

This adds tracehook_expect_breakpoints() as a formal hook for the nommu
code to use for its, "Is text-poking likely?" check at mmap time.  This
names the actual semantics the code means to test, and documents it.

Signed-off-by: Roland McGrath <roland@redhat.com>
Cc: Oleg Nesterov <oleg@tv-sign.ru>
Reviewed-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 15 insertions, 0 deletions

diff --git a/include/linux/tracehook.h b/include/linux/tracehook.h
index 6468ca0fe69b..e113e09b0341 100644
--- a/include/linux/tracehook.h
+++ b/include/linux/tracehook.h
@@ -52,6 +52,21 @@
 struct linux_binprm;
 
 /**
+ * tracehook_expect_breakpoints - guess if task memory might be touched
+ * @task:               current task, making a new mapping
+ *
+ * Return nonzero if @task is expected to want breakpoint insertion in
+ * its memory at some point.  A zero return is no guarantee it won't
+ * be done, but this is a hint that it's known to be likely.
+ *
+ * May be called with @task->mm->mmap_sem held for writing.
+ */
+static inline int tracehook_expect_breakpoints(struct task_struct *task)
+{
+        return (task_ptrace(task) & PT_PTRACED) != 0;
+}
+
+/**
  * tracehook_unsafe_exec - check for exec declared unsafe due to tracing
  * @task:               current task doing exec
  *