diff options
author | Łukasz Stelmach <l.stelmach@samsung.com> | 2017-12-12 17:36:07 +0100 |
---|---|---|
committer | Herbert Xu <herbert@gondor.apana.org.au> | 2017-12-22 19:52:44 +1100 |
commit | 25cf7f06af2264d240c91255bb9c6082d98cc73e (patch) | |
tree | 3aaf008542d30ccde544831bb9f2167910d93be1 /drivers/crypto/exynos-rng.c | |
parent | 99c9acfe594e07085b11cc9c317c9c9961155ee4 (diff) |
crypto: exynos - Introduce mutex to prevent concurrent access to hardware
Hardware operations like reading random numbers and setting a seed need
to be conducted in a single thread. Therefore a mutex is required to
prevent multiple threads (processes) from accessing the hardware at the
same time.
The sequence of mutex_lock() and mutex_unlock() in the exynos_rng_reseed()
function enables switching between different threads waiting for the
driver to generate random numbers for them.
Signed-off-by: Łukasz Stelmach <l.stelmach@samsung.com>
Reviewed-by: Krzysztof Kozlowski <krzk@kernel.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Diffstat (limited to 'drivers/crypto/exynos-rng.c')
-rw-r--r-- | drivers/crypto/exynos-rng.c | 21 |
1 files changed, 21 insertions, 0 deletions
diff --git a/drivers/crypto/exynos-rng.c b/drivers/crypto/exynos-rng.c index 825ed7bfd881..4a06092074b9 100644 --- a/drivers/crypto/exynos-rng.c +++ b/drivers/crypto/exynos-rng.c @@ -22,6 +22,7 @@ #include <linux/err.h> #include <linux/io.h> #include <linux/module.h> +#include <linux/mutex.h> #include <linux/of_device.h> #include <linux/platform_device.h> @@ -79,6 +80,7 @@ struct exynos_rng_dev { enum exynos_prng_type type; void __iomem *mem; struct clk *clk; + struct mutex lock; /* Generated numbers stored for seeding during resume */ u8 seed_save[EXYNOS_RNG_SEED_SIZE]; unsigned int seed_save_len; @@ -191,6 +193,10 @@ static void exynos_rng_reseed(struct exynos_rng_dev *rng) return; exynos_rng_set_seed(rng, seed, read); + + /* Let others do some of their job. */ + mutex_unlock(&rng->lock); + mutex_lock(&rng->lock); } static int exynos_rng_generate(struct crypto_rng *tfm, @@ -206,6 +212,7 @@ static int exynos_rng_generate(struct crypto_rng *tfm, if (ret) return ret; + mutex_lock(&rng->lock); do { ret = exynos_rng_get_random(rng, dst, dlen, &read); if (ret) @@ -216,6 +223,7 @@ static int exynos_rng_generate(struct crypto_rng *tfm, exynos_rng_reseed(rng); } while (dlen > 0); + mutex_unlock(&rng->lock); clk_disable_unprepare(rng->clk); @@ -233,7 +241,9 @@ static int exynos_rng_seed(struct crypto_rng *tfm, const u8 *seed, if (ret) return ret; + mutex_lock(&rng->lock); ret = exynos_rng_set_seed(ctx->rng, seed, slen); + mutex_unlock(&rng->lock); clk_disable_unprepare(rng->clk); @@ -278,6 +288,8 @@ static int exynos_rng_probe(struct platform_device *pdev) rng->type = (enum exynos_prng_type)of_device_get_match_data(&pdev->dev); + mutex_init(&rng->lock); + rng->dev = &pdev->dev; rng->clk = devm_clk_get(&pdev->dev, "secss"); if (IS_ERR(rng->clk)) { @@ -328,9 +340,14 @@ static int __maybe_unused exynos_rng_suspend(struct device *dev) if (ret) return ret; + mutex_lock(&rng->lock); + /* Get new random numbers and store them for seeding on resume. */ exynos_rng_get_random(rng, rng->seed_save, sizeof(rng->seed_save), &(rng->seed_save_len)); + + mutex_unlock(&rng->lock); + dev_dbg(rng->dev, "Stored %u bytes for seeding on system resume\n", rng->seed_save_len); @@ -353,8 +370,12 @@ static int __maybe_unused exynos_rng_resume(struct device *dev) if (ret) return ret; + mutex_lock(&rng->lock); + ret = exynos_rng_set_seed(rng, rng->seed_save, rng->seed_save_len); + mutex_unlock(&rng->lock); + clk_disable_unprepare(rng->clk); return ret; |