Revision 3af57f78c38131b7a66e2b01e06fdacae01992a3 authored by Heiko Carstens on 17 January 2014, 08:37:15 UTC, committed by David S. Miller on 18 January 2014, 02:54:49 UTC
The s390 bpf jit compiler emits the signed divide instructions "dr" and "d" for unsigned divisions. This can cause problems: the dividend will be zero extended to a 64 bit value and the divisor is the 32 bit signed value as specified A or X accumulator, even though A and X are supposed to be treated as unsigned values. The divide instrunctions will generate an exception if the result cannot be expressed with a 32 bit signed value. This is the case if e.g. the dividend is 0xffffffff and the divisor either 1 or also 0xffffffff (signed: -1). To avoid all these issues simply use unsigned divide instructions. Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com> Signed-off-by: David S. Miller <davem@davemloft.net>
1 parent 75b99db
krng.c
/*
* RNG implementation using standard kernel RNG.
*
* Copyright (c) 2008 Herbert Xu <herbert@gondor.apana.org.au>
*
* This program is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License as published by the
* Free Software Foundation; either version 2 of the License, or (at your
* any later version.
*
*/
#include <crypto/internal/rng.h>
#include <linux/err.h>
#include <linux/init.h>
#include <linux/module.h>
#include <linux/random.h>
static int krng_get_random(struct crypto_rng *tfm, u8 *rdata, unsigned int dlen)
{
get_random_bytes(rdata, dlen);
return 0;
}
static int krng_reset(struct crypto_rng *tfm, u8 *seed, unsigned int slen)
{
return 0;
}
static struct crypto_alg krng_alg = {
.cra_name = "stdrng",
.cra_driver_name = "krng",
.cra_priority = 200,
.cra_flags = CRYPTO_ALG_TYPE_RNG,
.cra_ctxsize = 0,
.cra_type = &crypto_rng_type,
.cra_module = THIS_MODULE,
.cra_u = {
.rng = {
.rng_make_random = krng_get_random,
.rng_reset = krng_reset,
.seedsize = 0,
}
}
};
/* Module initalization */
static int __init krng_mod_init(void)
{
return crypto_register_alg(&krng_alg);
}
static void __exit krng_mod_fini(void)
{
crypto_unregister_alg(&krng_alg);
return;
}
module_init(krng_mod_init);
module_exit(krng_mod_fini);
MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("Kernel Random Number Generator");
MODULE_ALIAS("stdrng");
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