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
diff --git a/drivers/char/random.c b/drivers/char/random.c
index 7737b5b..7a744d3 100644
--- a/drivers/char/random.c
+++ b/drivers/char/random.c
@@ -640,7 +640,7 @@
*/
void add_device_randomness(const void *buf, unsigned int size)
{
- unsigned long time = get_cycles() ^ jiffies;
+ unsigned long time = random_get_entropy() ^ jiffies;
mix_pool_bytes(&input_pool, buf, size, NULL);
mix_pool_bytes(&input_pool, &time, sizeof(time), NULL);
@@ -677,7 +677,7 @@
goto out;
sample.jiffies = jiffies;
- sample.cycles = get_cycles();
+ sample.cycles = random_get_entropy();
sample.num = num;
mix_pool_bytes(&input_pool, &sample, sizeof(sample), NULL);
@@ -744,7 +744,7 @@
struct fast_pool *fast_pool = &__get_cpu_var(irq_randomness);
struct pt_regs *regs = get_irq_regs();
unsigned long now = jiffies;
- __u32 input[4], cycles = get_cycles();
+ __u32 input[4], cycles = random_get_entropy();
input[0] = cycles ^ jiffies;
input[1] = irq;
@@ -1459,12 +1459,11 @@
static u32 random_int_secret[MD5_MESSAGE_BYTES / 4] ____cacheline_aligned;
-static int __init random_int_secret_init(void)
+int random_int_secret_init(void)
{
get_random_bytes(random_int_secret, sizeof(random_int_secret));
return 0;
}
-late_initcall(random_int_secret_init);
/*
* Get a random word for internal kernel use only. Similar to urandom but
@@ -1483,7 +1482,7 @@
hash = get_cpu_var(get_random_int_hash);
- hash[0] += current->pid + jiffies + get_cycles();
+ hash[0] += current->pid + jiffies + random_get_entropy();
md5_transform(hash, random_int_secret);
ret = hash[0];
put_cpu_var(get_random_int_hash);
diff --git a/include/linux/random.h b/include/linux/random.h
index 3b9377d..6312dd9 100644
--- a/include/linux/random.h
+++ b/include/linux/random.h
@@ -17,6 +17,7 @@
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 dd3edd7..9d3f1a5 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.
diff --git a/init/main.c b/init/main.c
index af310af..63d3e8f 100644
--- a/init/main.c
+++ b/init/main.c
@@ -76,6 +76,7 @@
#include <linux/elevator.h>
#include <linux/sched_clock.h>
#include <linux/context_tracking.h>
+#include <linux/random.h>
#include <asm/io.h>
#include <asm/bugs.h>
@@ -780,6 +781,7 @@
do_ctors();
usermodehelper_enable();
do_initcalls();
+ random_int_secret_init();
}
static void __init do_pre_smp_initcalls(void)
