linux-kernel - [PATCH v3 1/3] random: Add support for architectural random hooks

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Date:	Sun, 31 Jul 2011 14:26:54 -0700
From:	"H. Peter Anvin" <hpa@...or.com>
To:	Linus Torvalds <torvalds@...ux-foundation.org>,
	"H. Peter Anvin" <hpa@...or.com>, Ingo Molnar <mingo@...e.hu>,
	Thomas Gleixner <tglx@...utronix.de>,
	Fenghua Yu <fenghua.yu@...el.com>,
	Matt Mackall <mpm@...enic.com>,
	Herbert Xu <herbert@...dor.hengli.com.au>,
	"Theodore Ts'o" <tytso@....edu>, Jeff Garzik <jgarzik@...ox.com>,
	linux-kernel@...r.kernel.org
Cc:	Arjan van de Ven <arjan@...ux.intel.com>,
	"H. Peter Anvin" <hpa@...ux.intel.com>,
	Herbert Xu <herbert@...dor.hengli.com.au>
Subject: [PATCH v3 1/3] random: Add support for architectural random hooks

From: "H. Peter Anvin" <hpa@...or.com>

Add support for architecture-specific hooks into the kernel-directed
random number generator interfaces.  This patchset does not use the
architecture random number generator interfaces for the
userspace-directed interfaces (/dev/random and /dev/urandom), thus
eliminating the need to distinguish between them based on a pool
pointer.

Changes in version 3:
- Moved the hooks from extract_entropy() to get_random_bytes().
- Changes the hooks to inlines.

Signed-off-by: H. Peter Anvin <hpa@...ux.intel.com>
Cc: Fenghua Yu <fenghua.yu@...el.com>
Cc: Matt Mackall <mpm@...enic.com>
Cc: Herbert Xu <herbert@...dor.apana.org.au>
Cc: "Theodore Ts'o" <tytso@....edu>
---
 drivers/char/random.c  |   25 ++++++++++++++++++++++---
 include/linux/random.h |   13 +++++++++++++
 2 files changed, 35 insertions(+), 3 deletions(-)

diff --git a/drivers/char/random.c b/drivers/char/random.c
index d4ddeba..bb58712 100644
--- a/drivers/char/random.c
+++ b/drivers/char/random.c
@@ -932,7 +932,21 @@ static ssize_t extract_entropy_user(struct entropy_store *r, void __user *buf,
  */
 void get_random_bytes(void *buf, int nbytes)
 {
-	extract_entropy(&nonblocking_pool, buf, nbytes, 0, 0);
+	char *p = buf;
+
+	while (nbytes) {
+		unsigned long v;
+		int chunk = min(nbytes, (int)sizeof(unsigned long));
+		
+		if (!arch_get_random_long(&v))
+			break;
+		
+		memcpy(buf, &v, chunk);
+		p += chunk;
+		nbytes -= chunk;
+	}
+
+	extract_entropy(&nonblocking_pool, p, nbytes, 0, 0);
 }
 EXPORT_SYMBOL(get_random_bytes);
 
@@ -1635,8 +1649,13 @@ DEFINE_PER_CPU(__u32 [4], get_random_int_hash);
 unsigned int get_random_int(void)
 {
 	struct keydata *keyptr;
-	__u32 *hash = get_cpu_var(get_random_int_hash);
-	int ret;
+	__u32 *hash;
+	unsigned int ret;
+
+	if (arch_get_random_int(&ret))
+		return ret;
+
+	hash = get_cpu_var(get_random_int_hash);
 
 	keyptr = get_keyptr();
 	hash[0] += current->pid + jiffies + get_cycles();
diff --git a/include/linux/random.h b/include/linux/random.h
index fb7ab9d..079cbba 100644
--- a/include/linux/random.h
+++ b/include/linux/random.h
@@ -102,6 +102,19 @@ static inline void prandom32_seed(struct rnd_state *state, u64 seed)
 	state->s3 = __seed(i, 15);
 }
 
+#ifdef CONFIG_ARCH_RANDOM
+# include <asm/archrandom.h>
+#else
+static inline int arch_get_random_long(unsigned long *v)
+{
+	return 0;
+}
+static inline int arch_get_random_int(unsigned int *v)
+{
+	return 0;
+}
+#endif
+
 #endif /* __KERNEL___ */
 
 #endif /* _LINUX_RANDOM_H */
-- 
1.7.6

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