The patch titled
random: add a way to get some random bits into the entropy pools early on
has been added to the -mm tree. Its filename is
random-add-a-way-to-get-some-random-bits-into-the-entropy-pools-early-on.patch
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------------------------------------------------------
Subject: random: add a way to get some random bits into the entropy pools early on
From: Arjan van de Ven <arjan@xxxxxxxxxxxxx>
Currently the entropy pool gets seeded on the module_init() level, but
there is at least one consumer of random bits which wants random data at
an earluier time: the oops ID that is printed as part of the oops. As a
result of this, kerneloops.org is seeing a lot of oopses that all share
the same 'random' number; which used to get filed away as "duplicate".
This patch adds a function to the random driver so that various pieces of
the kernel can add random bits (but not entropy!) to the pool, to avoid
this duplicate ID problem.
Signed-off-by: Arjan van de Ven <arjan@xxxxxxxxxxxxxxx>
Cc: Matt Mackall <mpm@xxxxxxxxxxx>
Cc: Theodore Ts'o <tytso@xxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
arch/x86/kernel/apic.c | 7 +++++++
drivers/char/random.c | 29 +++++++++++++++++++++++++++++
include/linux/random.h | 3 +++
kernel/panic.c | 1 +
4 files changed, 40 insertions(+)
diff -puN arch/x86/kernel/apic.c~random-add-a-way-to-get-some-random-bits-into-the-entropy-pools-early-on arch/x86/kernel/apic.c
--- a/arch/x86/kernel/apic.c~random-add-a-way-to-get-some-random-bits-into-the-entropy-pools-early-on
+++ a/arch/x86/kernel/apic.c
@@ -30,6 +30,7 @@
#include <linux/module.h>
#include <linux/dmi.h>
#include <linux/dmar.h>
+#include <linux/random.h>
#include <asm/atomic.h>
#include <asm/smp.h>
@@ -687,6 +688,12 @@ static int __init calibrate_APIC_clock(v
} else
local_irq_enable();
+ /*
+ * by now we have enough time spent that there is some value in
+ * pushing the timestamp to the random pools for early kernel use.
+ */
+ seed_random_pools();
+
if (levt->features & CLOCK_EVT_FEAT_DUMMY) {
pr_warning("APIC timer disabled due to verification failure.\n");
return -1;
diff -puN drivers/char/random.c~random-add-a-way-to-get-some-random-bits-into-the-entropy-pools-early-on drivers/char/random.c
--- a/drivers/char/random.c~random-add-a-way-to-get-some-random-bits-into-the-entropy-pools-early-on
+++ a/drivers/char/random.c
@@ -929,6 +929,35 @@ static int rand_initialize(void)
}
module_init(rand_initialize);
+/*
+ * seed_std_data - seed pool with system timing data
+ *
+ * @r: pool to initialize
+ *
+ * This function mixes some system data into the pool to prepare it for use.
+ * This function can be called really early during boot to at least get some
+ * randomness from the system if random numbers are needed early, for example
+ * as part of the early oops printing.
+ *
+ * No entropy is credited for this seeding.
+ */
+static void seed_std_data(struct entropy_store *r)
+{
+ ktime_t now;
+ unsigned long flags;
+
+ now = ktime_get_real();
+ mix_pool_bytes(r, &now, sizeof(now));
+}
+
+int seed_random_pools(void)
+{
+ seed_std_data(&input_pool);
+ seed_std_data(&blocking_pool);
+ seed_std_data(&nonblocking_pool);
+ return 0;
+}
+
void rand_initialize_irq(int irq)
{
struct timer_rand_state *state;
diff -puN include/linux/random.h~random-add-a-way-to-get-some-random-bits-into-the-entropy-pools-early-on include/linux/random.h
--- a/include/linux/random.h~random-add-a-way-to-get-some-random-bits-into-the-entropy-pools-early-on
+++ a/include/linux/random.h
@@ -72,6 +72,9 @@ unsigned long randomize_range(unsigned l
u32 random32(void);
void srandom32(u32 seed);
+int seed_random_pools(void);
+
+
#endif /* __KERNEL___ */
#endif /* _LINUX_RANDOM_H */
diff -puN kernel/panic.c~random-add-a-way-to-get-some-random-bits-into-the-entropy-pools-early-on kernel/panic.c
--- a/kernel/panic.c~random-add-a-way-to-get-some-random-bits-into-the-entropy-pools-early-on
+++ a/kernel/panic.c
@@ -299,6 +299,7 @@ static u64 oops_id;
static int init_oops_id(void)
{
+ seed_random_pools();
if (!oops_id)
get_random_bytes(&oops_id, sizeof(oops_id));
else
_
Patches currently in -mm which might be from arjan@xxxxxxxxxxxxx are
mm-remove-the-might_sleep-from-lock_page.patch
linux-next.patch
vfs-expand-some-comments-d_path-seq_path.patch
scripts-script-from-kerneloopsorg-to-pretty-print-oops-dumps.patch
jbd-improve-fsync-batching.patch
jbd-improve-fsync-batching-update.patch
random-add-a-way-to-get-some-random-bits-into-the-entropy-pools-early-on.patch
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