From 9996508b3353063f2d6c48c1a28a84543d72d70b Mon Sep 17 00:00:00 2001 From: Ian Molton Date: Tue, 1 Dec 2009 14:47:32 +0800 Subject: [PATCH] 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: Ian Molton Acked-by: Matt Mackall Acked-by: Rusty Russell Signed-off-by: Herbert Xu --- drivers/char/hw_random/core.c | 107 ++++++++++++++++++++-------------- include/linux/hw_random.h | 7 ++- 2 files changed, 69 insertions(+), 45 deletions(-) diff --git a/drivers/char/hw_random/core.c b/drivers/char/hw_random/core.c index fc93e2fc7c7..82367262f3a 100644 --- a/drivers/char/hw_random/core.c +++ b/drivers/char/hw_random/core.c @@ -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) { - err = -ERESTARTSYS; - if (mutex_lock_interruptible(&rng_mutex)) + if (mutex_lock_interruptible(&rng_mutex)) { + err = -ERESTARTSYS; 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 (bytes_read < 0) { - err = bytes_read; - 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_unlock; + } + data_avail = bytes_read; } - err = -EFAULT; - while (bytes_read && size) { - if (put_user((u8)data, buf++)) - goto out; - size--; - ret++; - bytes_read--; - data >>= 8; + 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; + goto out_unlock; + } + + size -= len; + ret += len; } + mutex_unlock(&rng_mutex); + if (need_resched()) schedule_timeout_interruptible(1); - err = -ERESTARTSYS; - if (signal_pending(current)) + + if (signal_pending(current)) { + err = -ERESTARTSYS; 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); diff --git a/include/linux/hw_random.h b/include/linux/hw_random.h index 7244456e7e6..9bede7633f7 100644 --- a/include/linux/hw_random.h +++ b/include/linux/hw_random.h @@ -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. */ -- 2.39.5