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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platsmp.c (3391B)

      1// SPDX-License-Identifier: GPL-2.0-only
      2/*
      3 * arch/arm/mach-spear13xx/platsmp.c
      4 *
      5 * based upon linux/arch/arm/mach-realview/platsmp.c
      6 *
      7 * Copyright (C) 2012 ST Microelectronics Ltd.
      8 * Shiraz Hashim <shiraz.linux.kernel@gmail.com>
      9 */
     10
     11#include <linux/delay.h>
     12#include <linux/jiffies.h>
     13#include <linux/io.h>
     14#include <linux/smp.h>
     15#include <asm/cacheflush.h>
     16#include <asm/smp_scu.h>
     17#include "spear.h"
     18#include "generic.h"
     19
     20/* XXX spear_pen_release is cargo culted code - DO NOT COPY XXX */
     21volatile int spear_pen_release = -1;
     22
     23/*
     24 * XXX CARGO CULTED CODE - DO NOT COPY XXX
     25 *
     26 * Write spear_pen_release in a way that is guaranteed to be visible to
     27 * all observers, irrespective of whether they're taking part in coherency
     28 * or not.  This is necessary for the hotplug code to work reliably.
     29 */
     30static void spear_write_pen_release(int val)
     31{
     32	spear_pen_release = val;
     33	smp_wmb();
     34	sync_cache_w(&spear_pen_release);
     35}
     36
     37static DEFINE_SPINLOCK(boot_lock);
     38
     39static void __iomem *scu_base = IOMEM(VA_SCU_BASE);
     40
     41static void spear13xx_secondary_init(unsigned int cpu)
     42{
     43	/*
     44	 * let the primary processor know we're out of the
     45	 * pen, then head off into the C entry point
     46	 */
     47	spear_write_pen_release(-1);
     48
     49	/*
     50	 * Synchronise with the boot thread.
     51	 */
     52	spin_lock(&boot_lock);
     53	spin_unlock(&boot_lock);
     54}
     55
     56static int spear13xx_boot_secondary(unsigned int cpu, struct task_struct *idle)
     57{
     58	unsigned long timeout;
     59
     60	/*
     61	 * set synchronisation state between this boot processor
     62	 * and the secondary one
     63	 */
     64	spin_lock(&boot_lock);
     65
     66	/*
     67	 * The secondary processor is waiting to be released from
     68	 * the holding pen - release it, then wait for it to flag
     69	 * that it has been released by resetting spear_pen_release.
     70	 *
     71	 * Note that "spear_pen_release" is the hardware CPU ID, whereas
     72	 * "cpu" is Linux's internal ID.
     73	 */
     74	spear_write_pen_release(cpu);
     75
     76	timeout = jiffies + (1 * HZ);
     77	while (time_before(jiffies, timeout)) {
     78		smp_rmb();
     79		if (spear_pen_release == -1)
     80			break;
     81
     82		udelay(10);
     83	}
     84
     85	/*
     86	 * now the secondary core is starting up let it run its
     87	 * calibrations, then wait for it to finish
     88	 */
     89	spin_unlock(&boot_lock);
     90
     91	return spear_pen_release != -1 ? -ENOSYS : 0;
     92}
     93
     94/*
     95 * Initialise the CPU possible map early - this describes the CPUs
     96 * which may be present or become present in the system.
     97 */
     98static void __init spear13xx_smp_init_cpus(void)
     99{
    100	unsigned int i, ncores = scu_get_core_count(scu_base);
    101
    102	if (ncores > nr_cpu_ids) {
    103		pr_warn("SMP: %u cores greater than maximum (%u), clipping\n",
    104			ncores, nr_cpu_ids);
    105		ncores = nr_cpu_ids;
    106	}
    107
    108	for (i = 0; i < ncores; i++)
    109		set_cpu_possible(i, true);
    110}
    111
    112static void __init spear13xx_smp_prepare_cpus(unsigned int max_cpus)
    113{
    114
    115	scu_enable(scu_base);
    116
    117	/*
    118	 * Write the address of secondary startup into the system-wide location
    119	 * (presently it is in SRAM). The BootMonitor waits until it receives a
    120	 * soft interrupt, and then the secondary CPU branches to this address.
    121	 */
    122	__raw_writel(__pa_symbol(spear13xx_secondary_startup), SYS_LOCATION);
    123}
    124
    125const struct smp_operations spear13xx_smp_ops __initconst = {
    126       .smp_init_cpus		= spear13xx_smp_init_cpus,
    127       .smp_prepare_cpus	= spear13xx_smp_prepare_cpus,
    128       .smp_secondary_init	= spear13xx_secondary_init,
    129       .smp_boot_secondary	= spear13xx_boot_secondary,
    130#ifdef CONFIG_HOTPLUG_CPU
    131       .cpu_die			= spear13xx_cpu_die,
    132#endif
    133};