xen/common/random.c


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#include <xen/cache.h>
#include <xen/init.h>
#include <xen/percpu.h>
#include <xen/random.h>
#include <xen/time.h>
#include <asm/random.h>

static DEFINE_PER_CPU(unsigned int, seed);
unsigned int __read_mostly boot_random;

unsigned int get_random(void)
{
    unsigned int next = this_cpu(seed), val = arch_get_random();

    if ( unlikely(!next) )
        next = val ?: NOW();

    if ( !val )
    {
        unsigned int i;

        for ( i = 0; i < sizeof(val) * 8; i += 11 )
        {
            next = next * 1103515245 + 12345;
            val |= ((next >> 16) & 0x7ff) << i;
        }
    }

    this_cpu(seed) = next;

    return val;
}

static int __init cf_check init_boot_random(void)
{
    boot_random = get_random();
    return 0;
}
__initcall(init_boot_random);