Merge tag 'random_for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tytso/random

Pull /dev/random changes from Ted Ts'o:
 "These patches are designed to enable improvements to /dev/random for
  non-x86 platforms, in particular MIPS and ARM"

* tag 'random_for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tytso/random:
  random: allow architectures to optionally define random_get_entropy()
  random: run random_int_secret_init() run after all late_initcalls

2 files changed, 15 insertions, 0 deletions

diff --git a/include/linux/random.h b/include/linux/random.h
index 3b9377d6b7a5..6312dd9ba449 100644
--- a/include/linux/random.h
+++ b/include/linux/random.h
@@ -17,6 +17,7 @@ extern void add_interrupt_randomness(int irq, int irq_flags);
 extern void get_random_bytes(void *buf, int nbytes);
 extern void get_random_bytes_arch(void *buf, int nbytes);
 void generate_random_uuid(unsigned char uuid_out[16]);
+extern int random_int_secret_init(void);
 
 #ifndef MODULE
 extern const struct file_operations random_fops, urandom_fops;
diff --git a/include/linux/timex.h b/include/linux/timex.h
index dd3edd7dfc94..9d3f1a5b6178 100644
--- a/include/linux/timex.h
+++ b/include/linux/timex.h
@@ -64,6 +64,20 @@
 
 #include <asm/timex.h>
 
+#ifndef random_get_entropy
+/*
+ * The random_get_entropy() function is used by the /dev/random driver
+ * in order to extract entropy via the relative unpredictability of
+ * when an interrupt takes places versus a high speed, fine-grained
+ * timing source or cycle counter.  Since it will be occurred on every
+ * single interrupt, it must have a very low cost/overhead.
+ *
+ * By default we use get_cycles() for this purpose, but individual
+ * architectures may override this in their asm/timex.h header file.
+ */
+#define random_get_entropy()    get_cycles()
+#endif
+
 /*
  * SHIFT_PLL is used as a dampening factor to define how much we
  * adjust the frequency correction for a given offset in PLL mode.