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Merge branch 'x86-rdrand-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

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* 'x86-rdrand-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86, random: Verify RDRAND functionality and allow it to be disabled
  x86, random: Architectural inlines to get random integers with RDRAND
  random: Add support for architectural random hooks

Fix up trivial conflicts in drivers/char/random.c: the architectural
random hooks touched "get_random_int()" that was simplified to use MD5
and not do the keyptr thing any more (see commit 6e5714eaf7: "net:
Compute protocol sequence numbers and fragment IDs using MD5").
This commit is contained in:
Linus Torvalds 2011-10-28 05:29:07 -07:00
commit 8e6d539e0f
8 changed files with 199 additions and 2 deletions
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5
Documentation/kernel-parameters.txt
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@ -1797,6 +1797,11 @@ bytes respectively. Such letter suffixes can also be entirely omitted.
noresidual [PPC] Don't use residual data on PReP machines.
nordrand [X86] Disable the direct use of the RDRAND
instruction even if it is supported by the
processor. RDRAND is still available to user
space applications.
noresume [SWSUSP] Disables resume and restores original swap
space.

9
arch/x86/Kconfig
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@ -1454,6 +1454,15 @@ config ARCH_USES_PG_UNCACHED
def_bool y
depends on X86_PAT
config ARCH_RANDOM
def_bool y
prompt "x86 architectural random number generator" if EXPERT
---help---
Enable the x86 architectural RDRAND instruction
(Intel Bull Mountain technology) to generate random numbers.
If supported, this is a high bandwidth, cryptographically
secure hardware random number generator.
config EFI
bool "EFI runtime service support"
depends on ACPI

75
arch/x86/include/asm/archrandom.h Normal file
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@ -0,0 +1,75 @@
/*
* This file is part of the Linux kernel.
*
* Copyright (c) 2011, Intel Corporation
* Authors: Fenghua Yu <fenghua.yu@intel.com>,
* H. Peter Anvin <hpa@linux.intel.com>
*
* This program is free software; you can redistribute it and/or modify it
* under the terms and conditions of the GNU General Public License,
* version 2, as published by the Free Software Foundation.
*
* This program is distributed in the hope it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
* more details.
*
* You should have received a copy of the GNU General Public License along with
* this program; if not, write to the Free Software Foundation, Inc.,
* 51 Franklin St - Fifth Floor, Boston, MA 02110-1301 USA.
*
*/
#ifndef ASM_X86_ARCHRANDOM_H
#define ASM_X86_ARCHRANDOM_H
#include <asm/processor.h>
#include <asm/cpufeature.h>
#include <asm/alternative.h>
#include <asm/nops.h>
#define RDRAND_RETRY_LOOPS 10
#define RDRAND_INT ".byte 0x0f,0xc7,0xf0"
#ifdef CONFIG_X86_64
# define RDRAND_LONG ".byte 0x48,0x0f,0xc7,0xf0"
#else
# define RDRAND_LONG RDRAND_INT
#endif
#ifdef CONFIG_ARCH_RANDOM
#define GET_RANDOM(name, type, rdrand, nop) \
static inline int name(type *v) \
{ \
int ok; \
alternative_io("movl $0, %0\n\t" \
nop, \
"\n1: " rdrand "\n\t" \
"jc 2f\n\t" \
"decl %0\n\t" \
"jnz 1b\n\t" \
"2:", \
X86_FEATURE_RDRAND, \
ASM_OUTPUT2("=r" (ok), "=a" (*v)), \
"0" (RDRAND_RETRY_LOOPS)); \
return ok; \
}
#ifdef CONFIG_X86_64
GET_RANDOM(arch_get_random_long, unsigned long, RDRAND_LONG, ASM_NOP5);
GET_RANDOM(arch_get_random_int, unsigned int, RDRAND_INT, ASM_NOP4);
#else
GET_RANDOM(arch_get_random_long, unsigned long, RDRAND_LONG, ASM_NOP3);
GET_RANDOM(arch_get_random_int, unsigned int, RDRAND_INT, ASM_NOP3);
#endif /* CONFIG_X86_64 */
#endif /* CONFIG_ARCH_RANDOM */
extern void x86_init_rdrand(struct cpuinfo_x86 *c);
#endif /* ASM_X86_ARCHRANDOM_H */

1
arch/x86/kernel/cpu/Makefile
View File

@ -15,6 +15,7 @@ CFLAGS_common.o := $(nostackp)
obj-y := intel_cacheinfo.o scattered.o topology.o
obj-y += proc.o capflags.o powerflags.o common.o
obj-y += vmware.o hypervisor.o sched.o mshyperv.o
obj-y += rdrand.o
obj-$(CONFIG_X86_32) += bugs.o
obj-$(CONFIG_X86_64) += bugs_64.o

2
arch/x86/kernel/cpu/common.c
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@ -15,6 +15,7 @@
#include <asm/stackprotector.h>
#include <asm/perf_event.h>
#include <asm/mmu_context.h>
#include <asm/archrandom.h>
#include <asm/hypervisor.h>
#include <asm/processor.h>
#include <asm/sections.h>
@ -860,6 +861,7 @@ static void __cpuinit identify_cpu(struct cpuinfo_x86 *c)
#endif
init_hypervisor(c);
x86_init_rdrand(c);
/*
* Clear/Set all flags overriden by options, need do it

73
arch/x86/kernel/cpu/rdrand.c Normal file
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@ -0,0 +1,73 @@
/*
* This file is part of the Linux kernel.
*
* Copyright (c) 2011, Intel Corporation
* Authors: Fenghua Yu <fenghua.yu@intel.com>,
* H. Peter Anvin <hpa@linux.intel.com>
*
* This program is free software; you can redistribute it and/or modify it
* under the terms and conditions of the GNU General Public License,
* version 2, as published by the Free Software Foundation.
*
* This program is distributed in the hope it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
* more details.
*
* You should have received a copy of the GNU General Public License along with
* this program; if not, write to the Free Software Foundation, Inc.,
* 51 Franklin St - Fifth Floor, Boston, MA 02110-1301 USA.
*
*/
#include <asm/processor.h>
#include <asm/archrandom.h>
#include <asm/sections.h>
static int __init x86_rdrand_setup(char *s)
{
setup_clear_cpu_cap(X86_FEATURE_RDRAND);
return 1;
}
__setup("nordrand", x86_rdrand_setup);
/* We can't use arch_get_random_long() here since alternatives haven't run */
static inline int rdrand_long(unsigned long *v)
{
int ok;
asm volatile("1: " RDRAND_LONG "\n\t"
"jc 2f\n\t"
"decl %0\n\t"
"jnz 1b\n\t"
"2:"
: "=r" (ok), "=a" (*v)
: "0" (RDRAND_RETRY_LOOPS));
return ok;
}
/*
* Force a reseed cycle; we are architecturally guaranteed a reseed
* after no more than 512 128-bit chunks of random data. This also
* acts as a test of the CPU capability.
*/
#define RESEED_LOOP ((512*128)/sizeof(unsigned long))
void __cpuinit x86_init_rdrand(struct cpuinfo_x86 *c)
{
#ifdef CONFIG_ARCH_RANDOM
unsigned long tmp;
int i, count, ok;
if (!cpu_has(c, X86_FEATURE_RDRAND))
return; /* Nothing to do */
for (count = i = 0; i < RESEED_LOOP; i++) {
ok = rdrand_long(&tmp);
if (ok)
count++;
}
if (count != RESEED_LOOP)
clear_cpu_cap(c, X86_FEATURE_RDRAND);
#endif
}

23
drivers/char/random.c
View File

@ -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);
@ -1318,9 +1332,14 @@ late_initcall(random_int_secret_init);
DEFINE_PER_CPU(__u32 [MD5_DIGEST_WORDS], get_random_int_hash);
unsigned int get_random_int(void)
{
__u32 *hash = get_cpu_var(get_random_int_hash);
__u32 *hash;
unsigned int ret;
if (arch_get_random_int(&ret))
return ret;
hash = get_cpu_var(get_random_int_hash);
hash[0] += current->pid + jiffies + get_cycles();
md5_transform(hash, random_int_secret);
ret = hash[0];

13
include/linux/random.h
View File

@ -91,6 +91,19 @@ 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 */