cachepc-linux

Fork of AMDESE/linux with modifications for CachePC side-channel attack
git clone https://git.sinitax.com/sinitax/cachepc-linux
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rng.c (863B)

      1// SPDX-License-Identifier: GPL-2.0-or-later
      2/*
      3 * Derived from arch/powerpc/platforms/powernv/rng.c, which is:
      4 * Copyright 2013, Michael Ellerman, IBM Corporation.
      5 */
      6
      7#define pr_fmt(fmt)	"microwatt-rng: " fmt
      8
      9#include <linux/kernel.h>
     10#include <linux/smp.h>
     11#include <asm/archrandom.h>
     12#include <asm/cputable.h>
     13#include <asm/machdep.h>
     14#include "microwatt.h"
     15
     16#define DARN_ERR 0xFFFFFFFFFFFFFFFFul
     17
     18static int microwatt_get_random_darn(unsigned long *v)
     19{
     20	unsigned long val;
     21
     22	/* Using DARN with L=1 - 64-bit conditioned random number */
     23	asm volatile(PPC_DARN(%0, 1) : "=r"(val));
     24
     25	if (val == DARN_ERR)
     26		return 0;
     27
     28	*v = val;
     29
     30	return 1;
     31}
     32
     33void __init microwatt_rng_init(void)
     34{
     35	unsigned long val;
     36	int i;
     37
     38	for (i = 0; i < 10; i++) {
     39		if (microwatt_get_random_darn(&val)) {
     40			ppc_md.get_random_seed = microwatt_get_random_darn;
     41			return;
     42		}
     43	}
     44}