Commit 9996508b authored by Ian Molton's avatar Ian Molton Committed by Herbert Xu
Browse files

hwrng: core - Replace u32 in driver API with byte array 



This patch implements a new method by which hw_random hardware drivers
can pass data to the core more efficiently, using a shared buffer.

The old methods have been retained as a compatability layer until all the
drivers have been updated.

Signed-off-by: default avatarIan Molton <ian.molton@collabora.co.uk>
Acked-by: default avatarMatt Mackall <mpm@selenic.com>
Acked-by: default avatarRusty Russell <rusty@rustcorp.com.au>
Signed-off-by: default avatarHerbert Xu <herbert@gondor.apana.org.au>
parent 2f32bfd8

drivers/char/hw_random/core.c

+64 −43
Original line number Diff line number Diff line
@@ -52,7 +52,8 @@ 
static struct hwrng *current_rng;

static LIST_HEAD(rng_list);

static DEFINE_MUTEX(rng_mutex);



static int data_avail;

static u8 rng_buffer[SMP_CACHE_BYTES] __cacheline_aligned;



static inline int hwrng_init(struct hwrng *rng)

{
@@ -67,19 +68,6 @@ static inline void hwrng_cleanup(struct hwrng *rng) 
		rng->cleanup(rng);

}



static inline int hwrng_data_present(struct hwrng *rng, int wait)

{

	if (!rng->data_present)

		return 1;

	return rng->data_present(rng, wait);

}



static inline int hwrng_data_read(struct hwrng *rng, u32 *data)

{

	return rng->data_read(rng, data);

}





static int rng_dev_open(struct inode *inode, struct file *filp)

{

	/* enforce read-only access to this chrdev */
@@ -91,54 +79,87 @@ static int rng_dev_open(struct inode *inode, struct file *filp) 
	return 0;

}



static inline int rng_get_data(struct hwrng *rng, u8 *buffer, size_t size,

			int wait) {

	int present;



	if (rng->read)

		return rng->read(rng, (void *)buffer, size, wait);



	if (rng->data_present)

		present = rng->data_present(rng, wait);

	else

		present = 1;



	if (present)

		return rng->data_read(rng, (u32 *)buffer);



	return 0;

}



static ssize_t rng_dev_read(struct file *filp, char __user *buf,

			    size_t size, loff_t *offp)

{

	u32 data;

	ssize_t ret = 0;

	int err = 0;

	int bytes_read;

	int bytes_read, len;



	while (size) {

		if (mutex_lock_interruptible(&rng_mutex)) {

			err = -ERESTARTSYS;

		if (mutex_lock_interruptible(&rng_mutex))

			goto out;

		}



		if (!current_rng) {

			mutex_unlock(&rng_mutex);

			err = -ENODEV;

			goto out;

			goto out_unlock;

		}



		bytes_read = 0;

		if (hwrng_data_present(current_rng,

				       !(filp->f_flags & O_NONBLOCK)))

			bytes_read = hwrng_data_read(current_rng, &data);

		mutex_unlock(&rng_mutex);



		err = -EAGAIN;

		if (!bytes_read && (filp->f_flags & O_NONBLOCK))

			goto out;

		if (!data_avail) {

			bytes_read = rng_get_data(current_rng, rng_buffer,

				sizeof(rng_buffer),

				!(filp->f_flags & O_NONBLOCK));

			if (bytes_read < 0) {

				err = bytes_read;

			goto out;

				goto out_unlock;

			}

			data_avail = bytes_read;

		}



		if (!data_avail) {

			if (filp->f_flags & O_NONBLOCK) {

				err = -EAGAIN;

				goto out_unlock;

			}

		} else {

			len = data_avail;

			if (len > size)

				len = size;



			data_avail -= len;



			if (copy_to_user(buf + ret, rng_buffer + data_avail,

								len)) {

				err = -EFAULT;

		while (bytes_read && size) {

			if (put_user((u8)data, buf++))

				goto out;

			size--;

			ret++;

			bytes_read--;

			data >>= 8;

				goto out_unlock;

			}



			size -= len;

			ret += len;

		}



		mutex_unlock(&rng_mutex);



		if (need_resched())

			schedule_timeout_interruptible(1);



		if (signal_pending(current)) {

			err = -ERESTARTSYS;

		if (signal_pending(current))

			goto out;

		}

	}

out_unlock:

	mutex_unlock(&rng_mutex);

out:

	return ret ? : err;

}
@@ -280,7 +301,7 @@ int hwrng_register(struct hwrng *rng) 
	struct hwrng *old_rng, *tmp;



	if (rng->name == NULL ||

	    rng->data_read == NULL)

	    (rng->data_read == NULL && rng->read == NULL))

		goto out;



	mutex_lock(&rng_mutex);

include/linux/hw_random.h

+5 −2
Original line number Diff line number Diff line
@@ -22,10 +22,12 @@ 
 * @cleanup:		Cleanup callback (can be NULL).

 * @data_present:	Callback to determine if data is available

 *			on the RNG. If NULL, it is assumed that

 *			there is always data available.

 *			there is always data available.  *OBSOLETE*

 * @data_read:		Read data from the RNG device.

 *			Returns the number of lower random bytes in "data".

 *			Must not be NULL.

 *			Must not be NULL.    *OSOLETE*

 * @read:		New API. drivers can fill up to max bytes of data

 *			into the buffer. The buffer is aligned for any type.

 * @priv:		Private data, for use by the RNG driver.

 */

struct hwrng {
@@ -34,6 +36,7 @@ struct hwrng { 
	void (*cleanup)(struct hwrng *rng);

	int (*data_present)(struct hwrng *rng, int wait);

	int (*data_read)(struct hwrng *rng, u32 *data);

	int (*read)(struct hwrng *rng, void *data, size_t max, bool wait);

	unsigned long priv;



	/* internal. */

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