[for-4.9.y,04/14] random: convert get_random_int/long into get_random_u32/u64

Message ID 1535487205-26280-5-git-send-email-amit.pundir@linaro.org
State New
Headers show
Series
  • Few upstream fixes from OnePlus6's kernel tree
Related show

Commit Message

Amit Pundir Aug. 28, 2018, 8:13 p.m.
From: "Jason A. Donenfeld" <Jason@zx2c4.com>


commit c440408cf6901eeb2c09563397e24a9097907078 upstream.

Many times, when a user wants a random number, he wants a random number
of a guaranteed size. So, thinking of get_random_int and get_random_long
in terms of get_random_u32 and get_random_u64 makes it much easier to
achieve this. It also makes the code simpler.

On 32-bit platforms, get_random_int and get_random_long are both aliased
to get_random_u32. On 64-bit platforms, int->u32 and long->u64.

Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>

Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Theodore Ts'o <tytso@mit.edu>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>

Signed-off-by: Amit Pundir <amit.pundir@linaro.org>

---
 drivers/char/random.c  | 55 +++++++++++++++++++++++++-------------------------
 include/linux/random.h | 17 ++++++++++++++--
 2 files changed, 42 insertions(+), 30 deletions(-)

-- 
2.7.4

Comments

Greg KH Sept. 16, 2018, 1:29 p.m. | #1
On Wed, Aug 29, 2018 at 01:43:15AM +0530, Amit Pundir wrote:
> From: "Jason A. Donenfeld" <Jason@zx2c4.com>

> 

> commit c440408cf6901eeb2c09563397e24a9097907078 upstream.

> 

> Many times, when a user wants a random number, he wants a random number

> of a guaranteed size. So, thinking of get_random_int and get_random_long

> in terms of get_random_u32 and get_random_u64 makes it much easier to

> achieve this. It also makes the code simpler.

> 

> On 32-bit platforms, get_random_int and get_random_long are both aliased

> to get_random_u32. On 64-bit platforms, int->u32 and long->u64.


What bug is this fixing that it needs to be in a stable kernel tree?
The end result is the same before and after this patch, right?

thanks,

greg k-h

Patch

diff --git a/drivers/char/random.c b/drivers/char/random.c
index 81b65d0e7563..464b95a63dc5 100644
--- a/drivers/char/random.c
+++ b/drivers/char/random.c
@@ -2110,8 +2110,8 @@  struct ctl_table random_table[] = {
 
 struct batched_entropy {
 	union {
-		unsigned long entropy_long[CHACHA20_BLOCK_SIZE / sizeof(unsigned long)];
-		unsigned int entropy_int[CHACHA20_BLOCK_SIZE / sizeof(unsigned int)];
+		u64 entropy_u64[CHACHA20_BLOCK_SIZE / sizeof(u64)];
+		u32 entropy_u32[CHACHA20_BLOCK_SIZE / sizeof(u32)];
 	};
 	unsigned int position;
 };
@@ -2121,52 +2121,51 @@  struct batched_entropy {
  * number is either as good as RDRAND or as good as /dev/urandom, with the
  * goal of being quite fast and not depleting entropy.
  */
-static DEFINE_PER_CPU(struct batched_entropy, batched_entropy_long);
-unsigned long get_random_long(void)
+static DEFINE_PER_CPU(struct batched_entropy, batched_entropy_u64);
+u64 get_random_u64(void)
 {
-	unsigned long ret;
+	u64 ret;
 	struct batched_entropy *batch;
 
-	if (arch_get_random_long(&ret))
+#if BITS_PER_LONG == 64
+	if (arch_get_random_long((unsigned long *)&ret))
 		return ret;
+#else
+	if (arch_get_random_long((unsigned long *)&ret) &&
+	    arch_get_random_long((unsigned long *)&ret + 1))
+	    return ret;
+#endif
 
-	batch = &get_cpu_var(batched_entropy_long);
-	if (batch->position % ARRAY_SIZE(batch->entropy_long) == 0) {
-		extract_crng((u8 *)batch->entropy_long);
+	batch = &get_cpu_var(batched_entropy_u64);
+	if (batch->position % ARRAY_SIZE(batch->entropy_u64) == 0) {
+		extract_crng((u8 *)batch->entropy_u64);
 		batch->position = 0;
 	}
-	ret = batch->entropy_long[batch->position++];
-	put_cpu_var(batched_entropy_long);
+	ret = batch->entropy_u64[batch->position++];
+	put_cpu_var(batched_entropy_u64);
 	return ret;
 }
-EXPORT_SYMBOL(get_random_long);
+EXPORT_SYMBOL(get_random_u64);
 
-#if BITS_PER_LONG == 32
-unsigned int get_random_int(void)
-{
-	return get_random_long();
-}
-#else
-static DEFINE_PER_CPU(struct batched_entropy, batched_entropy_int);
-unsigned int get_random_int(void)
+static DEFINE_PER_CPU(struct batched_entropy, batched_entropy_u32);
+u32 get_random_u32(void)
 {
-	unsigned int ret;
+	u32 ret;
 	struct batched_entropy *batch;
 
 	if (arch_get_random_int(&ret))
 		return ret;
 
-	batch = &get_cpu_var(batched_entropy_int);
-	if (batch->position % ARRAY_SIZE(batch->entropy_int) == 0) {
-		extract_crng((u8 *)batch->entropy_int);
+	batch = &get_cpu_var(batched_entropy_u32);
+	if (batch->position % ARRAY_SIZE(batch->entropy_u32) == 0) {
+		extract_crng((u8 *)batch->entropy_u32);
 		batch->position = 0;
 	}
-	ret = batch->entropy_int[batch->position++];
-	put_cpu_var(batched_entropy_int);
+	ret = batch->entropy_u32[batch->position++];
+	put_cpu_var(batched_entropy_u32);
 	return ret;
 }
-#endif
-EXPORT_SYMBOL(get_random_int);
+EXPORT_SYMBOL(get_random_u32);
 
 /**
  * randomize_page - Generate a random, page aligned address
diff --git a/include/linux/random.h b/include/linux/random.h
index 16ab429735a7..ed5c3838780d 100644
--- a/include/linux/random.h
+++ b/include/linux/random.h
@@ -42,8 +42,21 @@  extern void get_random_bytes_arch(void *buf, int nbytes);
 extern const struct file_operations random_fops, urandom_fops;
 #endif
 
-unsigned int get_random_int(void);
-unsigned long get_random_long(void);
+u32 get_random_u32(void);
+u64 get_random_u64(void);
+static inline unsigned int get_random_int(void)
+{
+	return get_random_u32();
+}
+static inline unsigned long get_random_long(void)
+{
+#if BITS_PER_LONG == 64
+	return get_random_u64();
+#else
+	return get_random_u32();
+#endif
+}
+
 unsigned long randomize_page(unsigned long start, unsigned long range);
 
 u32 prandom_u32(void);