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Merge tag 'random_for_linus' of git://git.kernel.org/pub/scm/linux/ke…

…rnel/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
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2 parents 8273548 + 61875f3 commit f715729ee4cb666f51749f6cd86d06fff1e6e17b @torvalds torvalds committed Oct 10, 2013
Showing with 22 additions and 6 deletions.
  1. +5 −6 drivers/char/random.c
  2. +1 −0 include/linux/random.h
  3. +14 −0 include/linux/timex.h
  4. +2 −0 init/main.c
View
@@ -640,7 +640,7 @@ struct timer_rand_state {
*/
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 @@ static void add_timer_randomness(struct timer_rand_state *state, unsigned num)
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 @@ void add_interrupt_randomness(int irq, int irq_flags)
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 @@ struct ctl_table random_table[] = {
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 @@ unsigned int get_random_int(void)
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);
View
@@ -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;
View
@@ -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.
View
@@ -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 @@ static void __init do_basic_setup(void)
do_ctors();
usermodehelper_enable();
do_initcalls();
+ random_int_secret_init();
}
static void __init do_pre_smp_initcalls(void)

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