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Commit 0382d978 authored by Dinesh K Garg's avatar Dinesh K Garg
Browse files

msm_rng: Resolve race condition issues 



Resolve race condition between initializing the mutex vs hwrng
register.
Remove the HWRNG FIFO, not required in Software.

Change-Id: I9fa3e5c7e2e9e14feb88a4656dcfab7dec3cbd67
Signed-off-by: default avatarDinesh K Garg <dineshg@codeaurora.org>
parent bb004d0f

drivers/char/hw_random/msm_rng.c

+39 −24
Original line number Diff line number Diff line
@@ -27,6 +27,7 @@ 
#include <linux/qrng.h>

#include <linux/fs.h>

#include <linux/cdev.h>

#include <linux/delay.h>



#include <linux/platform_data/qcom_crypto_device.h>
@@ -115,10 +116,13 @@ int msm_rng_direct_read(struct msm_rng_device *msm_rng_dev, void *data) 
	unsigned long val;

	unsigned long *retdata = data;

	int ret;

	int failed = 0;



	pdev = msm_rng_dev->pdev;

	base = msm_rng_dev->base;



	mutex_lock(&msm_rng_dev->rng_lock);



	if (msm_rng_dev->qrng_perf_client) {

		ret = msm_bus_scale_client_update_request(

				msm_rng_dev->qrng_perf_client, 1);
@@ -129,13 +133,21 @@ int msm_rng_direct_read(struct msm_rng_device *msm_rng_dev, void *data) 
	ret = clk_prepare_enable(msm_rng_dev->prng_clk);

	if (ret) {

		dev_err(&pdev->dev, "failed to enable clock in callback\n");

		return 0;

		goto err;

	}

	/* read random data from h/w */

	do {

		/* check status bit if data is available */

		if (!(readl_relaxed(base + PRNG_STATUS_OFFSET) & 0x00000001))

			break;	/* no data to read so just bail */

		while (!(readl_relaxed(base + PRNG_STATUS_OFFSET)

					& 0x00000001)) {

			if (failed == 10) {

				pr_err("Data not available after retry\n");

				break;

			}

			pr_err("msm_rng:Data not available!\n");

			msleep_interruptible(10);

			failed++;

		}



		/* read FIFO */

		val = readl_relaxed(base + PRNG_DATA_OUT_OFFSET);
@@ -150,17 +162,17 @@ int msm_rng_direct_read(struct msm_rng_device *msm_rng_dev, void *data) 


	/* vote to turn off clock */

	clk_disable_unprepare(msm_rng_dev->prng_clk);



err:

	if (msm_rng_dev->qrng_perf_client) {

		ret = msm_bus_scale_client_update_request(

				msm_rng_dev->qrng_perf_client, 0);

		if (ret)

			pr_err("bus_scale_client_update_req failed!\n");

	}

	mutex_unlock(&msm_rng_dev->rng_lock);



	val = 0L;

	return currsize;



}



static int msm_rng_drbg_read(struct hwrng *rng,
@@ -169,29 +181,25 @@ static int msm_rng_drbg_read(struct hwrng *rng, 
	struct msm_rng_device *msm_rng_dev;

	struct platform_device *pdev;

	void __iomem *base;

	size_t maxsize;

	size_t currsize = 0;

	unsigned long val;

	unsigned long *retdata = data;

	int ret, ret1;

	int failed = 0;



	msm_rng_dev = (struct msm_rng_device *)rng->priv;

	pdev = msm_rng_dev->pdev;

	base = msm_rng_dev->base;





	down(&msm_rng_dev->drbg_sem);



	/* calculate max size bytes to transfer back to caller */

	maxsize = min_t(size_t, MAX_HW_FIFO_SIZE, max);



	/* no room for word data */

	if (maxsize < 4)

	if (max < 4)

		return 0;



	mutex_lock(&msm_rng_dev->rng_lock);



	/* read random data from CTR-AES based DRBG */

	if (FIPS140_DRBG_ENABLED == msm_rng_dev->fips140_drbg_enabled) {

		ret1 = fips_drbg_gen(msm_rng_dev->drbg_ctx, data, maxsize);

		ret1 = fips_drbg_gen(msm_rng_dev->drbg_ctx, data, max);

		if (FIPS140_PRNG_ERR == ret1)

			panic("random number generator generator error.\n");

	} else
@@ -209,14 +217,21 @@ static int msm_rng_drbg_read(struct hwrng *rng, 
	ret = clk_prepare_enable(msm_rng_dev->prng_clk);

	if (ret) {

		dev_err(&pdev->dev, "failed to enable clock in callback\n");

		up(&msm_rng_dev->drbg_sem);

		return 0;

		goto err;

	}

	/* read random data from h/w */

	do {

		/* check status bit if data is available */

		if (!(readl_relaxed(base + PRNG_STATUS_OFFSET) & 0x00000001))

			break;	/* no data to read so just bail */

		while (!(readl_relaxed(base + PRNG_STATUS_OFFSET)

				& 0x00000001)) {

			if (failed == 10) {

				pr_err("Data not available after retry\n");

				break;

			}

			pr_err("msm_rng:Data not available!\n");

			msleep_interruptible(10);

			failed++;

		}



		/* read FIFO */

		val = readl_relaxed(base + PRNG_DATA_OUT_OFFSET);
@@ -229,12 +244,12 @@ static int msm_rng_drbg_read(struct hwrng *rng, 
		currsize += 4;



		/* make sure we stay on 32bit boundary */

		if ((maxsize - currsize) < 4)

		if ((max - currsize) < 4)

			break;

	} while (currsize < maxsize);

	} while (currsize < max);

	/* vote to turn off clock */

	clk_disable_unprepare(msm_rng_dev->prng_clk);



err:

	if (msm_rng_dev->qrng_perf_client) {

		ret = msm_bus_scale_client_update_request(

				msm_rng_dev->qrng_perf_client, 0);
@@ -242,7 +257,7 @@ static int msm_rng_drbg_read(struct hwrng *rng, 
			pr_err("bus_scale_client_update_req failed!\n");

	}



	up(&msm_rng_dev->drbg_sem);

	mutex_unlock(&msm_rng_dev->rng_lock);



	return currsize;

}
@@ -502,6 +517,8 @@ static int msm_rng_probe(struct platform_device *pdev) 
	if (error)

		goto rollback_clk;



	mutex_init(&msm_rng_dev->rng_lock);



	/* register with hwrng framework */

	msm_rng.priv = (unsigned long) msm_rng_dev;

	error = hwrng_register(&msm_rng);
@@ -527,8 +544,6 @@ static int msm_rng_probe(struct platform_device *pdev) 
	}

	cdev_init(&msm_rng_cdev, &msm_rng_fops);



	sema_init(&msm_rng_dev->drbg_sem, 1);



	_first_msm_drbg_init(msm_rng_dev);



	return error;

drivers/char/hw_random/msm_rng.h

+1 −1
Original line number Diff line number Diff line
@@ -31,7 +31,7 @@ struct msm_rng_device { 
	void __iomem *base;

	struct clk *prng_clk;

	uint32_t qrng_perf_client;

	struct  semaphore drbg_sem;

	struct mutex rng_lock;

	struct fips_drbg_ctx_s *drbg_ctx;

	int    fips140_drbg_enabled;

};