From 121daad8fd1dce63076fa55aaedd5dc3f981b334 Mon Sep 17 00:00:00 2001
From: Peter Korsgaard <jacmet@sunsite.dk>
Date: Thu, 31 May 2012 20:53:08 +1000
Subject: hwrng: atmel-rng - fix race condition leading to repeated bits
Data valid gets cleared by reading the ISR (status register) and NOT from
reading ODATA (data register). A new data word can become available between
checking ISR and reading ODATA, causing us to reuse the same data word next
time atmel_trng_read() gets called, if that happens before the following
data word is ready.
With this fixed, rngtest no longer complains of 'Continous run' errors.
Before:
rngtest -c 1000 < /dev/hwrng
rngtest 3
Copyright (c) 2004 by Henrique de Moraes Holschuh
This is free software; see the source for copying conditions. There is NO warr.
rngtest: starting FIPS tests...
rngtest: bits received from input: 20000032
rngtest: FIPS 140-2 successes: 923
rngtest: FIPS 140-2 failures: 77
rngtest: FIPS 140-2(2001-10-10) Monobit: 0
rngtest: FIPS 140-2(2001-10-10) Poker: 0
rngtest: FIPS 140-2(2001-10-10) Runs: 1
rngtest: FIPS 140-2(2001-10-10) Long run: 0
rngtest: FIPS 140-2(2001-10-10) Continuous run: 76
rngtest: input channel speed: (min=721.402; avg=46003.510; max=49321.338)Kibitss
rngtest: FIPS tests speed: (min=11.442; avg=12.714; max=12.801)Mibits/s
rngtest: Program run time: 1931860 microseconds
After:
rngtest -c 1000 < /dev/hwrng
rngtest 3
Copyright (c) 2004 by Henrique de Moraes Holschuh
This is free software; see the source for copying conditions. There is NO warr.
rngtest: starting FIPS tests...
rngtest: bits received from input: 20000032
rngtest: FIPS 140-2 successes: 1000
rngtest: FIPS 140-2 failures: 0
rngtest: FIPS 140-2(2001-10-10) Monobit: 0
rngtest: FIPS 140-2(2001-10-10) Poker: 0
rngtest: FIPS 140-2(2001-10-10) Runs: 0
rngtest: FIPS 140-2(2001-10-10) Long run: 0
rngtest: FIPS 140-2(2001-10-10) Continuous run: 0
rngtest: input channel speed: (min=777.518; avg=36988.482; max=43115.342)Kibitss
rngtest: FIPS tests speed: (min=11.951; avg=12.715; max=12.887)Mibits/s
rngtest: Program run time: 2035543 microseconds
Cc: stable@vger.kernel.org
Signed-off-by: Peter Korsgaard <jacmet@sunsite.dk>
Reported-by: George Pontis <GPontis@z9.com>
Acked-by: Nicolas Ferre <nicolas.ferre@atmel.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
---
drivers/char/hw_random/atmel-rng.c | 7 +++++++
1 file changed, 7 insertions(+)
(limited to 'drivers/char/hw_random/atmel-rng.c')
diff --git a/drivers/char/hw_random/atmel-rng.c b/drivers/char/hw_random/atmel-rng.c
index f518b99f53f5..6289f0eee24c 100644
--- a/drivers/char/hw_random/atmel-rng.c
+++ b/drivers/char/hw_random/atmel-rng.c
@@ -36,6 +36,13 @@ static int atmel_trng_read(struct hwrng *rng, void *buf, size_t max,
/* data ready? */
if (readl(trng->base + TRNG_ODATA) & 1) {
*data = readl(trng->base + TRNG_ODATA);
+ /*
+ ensure data ready is only set again AFTER the next data
+ word is ready in case it got set between checking ISR
+ and reading ODATA, so we don't risk re-reading the
+ same word
+ */
+ readl(trng->base + TRNG_ISR);
return 4;
} else
return 0;
--
cgit
From c475c06f4bb689d6ad87d7512e036d6dface3160 Mon Sep 17 00:00:00 2001
From: Peter Korsgaard <jacmet@sunsite.dk>
Date: Tue, 12 Jun 2012 08:27:04 +0800
Subject: hwrng: atmel-rng - fix data valid check
Brown paper bag: Data valid is LSB of the ISR (status register), and NOT
of ODATA (current random data word)!
With this, rngtest is a lot happier. Before:
rngtest 3
Copyright (c) 2004 by Henrique de Moraes Holschuh
This is free software; see the source for copying conditions. There is NO warr.
rngtest: starting FIPS tests...
rngtest: bits received from input: 20000032
rngtest: FIPS 140-2 successes: 3
rngtest: FIPS 140-2 failures: 997
rngtest: FIPS 140-2(2001-10-10) Monobit: 604
rngtest: FIPS 140-2(2001-10-10) Poker: 996
rngtest: FIPS 140-2(2001-10-10) Runs: 36
rngtest: FIPS 140-2(2001-10-10) Long run: 0
rngtest: FIPS 140-2(2001-10-10) Continuous run: 117
rngtest: input channel speed: (min=622.371; avg=23682.481; max=28224.350)Kibitss
rngtest: FIPS tests speed: (min=12.361; avg=12.718; max=12.861)Mibits/s
rngtest: Program run time: 2331696 microsecondsx
After:
rngtest 3
Copyright (c) 2004 by Henrique de Moraes Holschuh
This is free software; see the source for copying conditions. There is NO warr.
rngtest: starting FIPS tests...
rngtest: bits received from input: 20000032
rngtest: FIPS 140-2 successes: 999
rngtest: FIPS 140-2 failures: 1
rngtest: FIPS 140-2(2001-10-10) Monobit: 0
rngtest: FIPS 140-2(2001-10-10) Poker: 0
rngtest: FIPS 140-2(2001-10-10) Runs: 1
rngtest: FIPS 140-2(2001-10-10) Long run: 0
rngtest: FIPS 140-2(2001-10-10) Continuous run: 0
rngtest: input channel speed: (min=777.363; avg=43588.270; max=47870.711)Kibitss
rngtest: FIPS tests speed: (min=11.943; avg=12.716; max=12.844)Mibits/s
rngtest: Program run time: 1955282 microseconds
Cc: stable@vger.kernel.org
Signed-off-by: Peter Korsgaard <jacmet@sunsite.dk>
Reported-by: George Pontis <GPontis@z9.com>
Acked-by: Nicolas Ferre <nicolas.ferre@atmel.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
---
drivers/char/hw_random/atmel-rng.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
(limited to 'drivers/char/hw_random/atmel-rng.c')
diff --git a/drivers/char/hw_random/atmel-rng.c b/drivers/char/hw_random/atmel-rng.c
index 6289f0eee24c..731c9046cf7b 100644
--- a/drivers/char/hw_random/atmel-rng.c
+++ b/drivers/char/hw_random/atmel-rng.c
@@ -34,7 +34,7 @@ static int atmel_trng_read(struct hwrng *rng, void *buf, size_t max,
u32 *data = buf;
/* data ready? */
- if (readl(trng->base + TRNG_ODATA) & 1) {
+ if (readl(trng->base + TRNG_ISR) & 1) {
*data = readl(trng->base + TRNG_ODATA);
/*
ensure data ready is only set again AFTER the next data
--
cgit