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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topology.c (4024B)

      1/*
      2 * Populate sysfs with topology information
      3 *
      4 * Written by: Matthew Dobson, IBM Corporation
      5 * Original Code: Paul Dorwin, IBM Corporation, Patrick Mochel, OSDL
      6 *
      7 * Copyright (C) 2002, IBM Corp.
      8 *
      9 * All rights reserved.
     10 *
     11 * This program is free software; you can redistribute it and/or modify
     12 * it under the terms of the GNU General Public License as published by
     13 * the Free Software Foundation; either version 2 of the License, or
     14 * (at your option) any later version.
     15 *
     16 * This program is distributed in the hope that it will be useful, but
     17 * WITHOUT ANY WARRANTY; without even the implied warranty of
     18 * MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, GOOD TITLE or
     19 * NON INFRINGEMENT.  See the GNU General Public License for more
     20 * details.
     21 *
     22 * You should have received a copy of the GNU General Public License
     23 * along with this program; if not, write to the Free Software
     24 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
     25 *
     26 * Send feedback to <colpatch@us.ibm.com>
     27 */
     28#include <linux/interrupt.h>
     29#include <linux/nodemask.h>
     30#include <linux/export.h>
     31#include <linux/mmzone.h>
     32#include <linux/init.h>
     33#include <linux/smp.h>
     34#include <linux/irq.h>
     35#include <asm/io_apic.h>
     36#include <asm/cpu.h>
     37
     38static DEFINE_PER_CPU(struct x86_cpu, cpu_devices);
     39
     40#ifdef CONFIG_HOTPLUG_CPU
     41
     42#ifdef CONFIG_BOOTPARAM_HOTPLUG_CPU0
     43static int cpu0_hotpluggable = 1;
     44#else
     45static int cpu0_hotpluggable;
     46static int __init enable_cpu0_hotplug(char *str)
     47{
     48	cpu0_hotpluggable = 1;
     49	return 1;
     50}
     51
     52__setup("cpu0_hotplug", enable_cpu0_hotplug);
     53#endif
     54
     55#ifdef CONFIG_DEBUG_HOTPLUG_CPU0
     56/*
     57 * This function offlines a CPU as early as possible and allows userspace to
     58 * boot up without the CPU. The CPU can be onlined back by user after boot.
     59 *
     60 * This is only called for debugging CPU offline/online feature.
     61 */
     62int _debug_hotplug_cpu(int cpu, int action)
     63{
     64	int ret;
     65
     66	if (!cpu_is_hotpluggable(cpu))
     67		return -EINVAL;
     68
     69	switch (action) {
     70	case 0:
     71		ret = remove_cpu(cpu);
     72		if (!ret)
     73			pr_info("DEBUG_HOTPLUG_CPU0: CPU %u is now offline\n", cpu);
     74		else
     75			pr_debug("Can't offline CPU%d.\n", cpu);
     76		break;
     77	case 1:
     78		ret = add_cpu(cpu);
     79		if (ret)
     80			pr_debug("Can't online CPU%d.\n", cpu);
     81
     82		break;
     83	default:
     84		ret = -EINVAL;
     85	}
     86
     87	return ret;
     88}
     89
     90static int __init debug_hotplug_cpu(void)
     91{
     92	_debug_hotplug_cpu(0, 0);
     93	return 0;
     94}
     95
     96late_initcall_sync(debug_hotplug_cpu);
     97#endif /* CONFIG_DEBUG_HOTPLUG_CPU0 */
     98
     99int arch_register_cpu(int num)
    100{
    101	struct cpuinfo_x86 *c = &cpu_data(num);
    102
    103	/*
    104	 * Currently CPU0 is only hotpluggable on Intel platforms. Other
    105	 * vendors can add hotplug support later.
    106	 * Xen PV guests don't support CPU0 hotplug at all.
    107	 */
    108	if (c->x86_vendor != X86_VENDOR_INTEL ||
    109	    boot_cpu_has(X86_FEATURE_XENPV))
    110		cpu0_hotpluggable = 0;
    111
    112	/*
    113	 * Two known BSP/CPU0 dependencies: Resume from suspend/hibernate
    114	 * depends on BSP. PIC interrupts depend on BSP.
    115	 *
    116	 * If the BSP dependencies are under control, one can tell kernel to
    117	 * enable BSP hotplug. This basically adds a control file and
    118	 * one can attempt to offline BSP.
    119	 */
    120	if (num == 0 && cpu0_hotpluggable) {
    121		unsigned int irq;
    122		/*
    123		 * We won't take down the boot processor on i386 if some
    124		 * interrupts only are able to be serviced by the BSP in PIC.
    125		 */
    126		for_each_active_irq(irq) {
    127			if (!IO_APIC_IRQ(irq) && irq_has_action(irq)) {
    128				cpu0_hotpluggable = 0;
    129				break;
    130			}
    131		}
    132	}
    133	if (num || cpu0_hotpluggable)
    134		per_cpu(cpu_devices, num).cpu.hotpluggable = 1;
    135
    136	return register_cpu(&per_cpu(cpu_devices, num).cpu, num);
    137}
    138EXPORT_SYMBOL(arch_register_cpu);
    139
    140void arch_unregister_cpu(int num)
    141{
    142	unregister_cpu(&per_cpu(cpu_devices, num).cpu);
    143}
    144EXPORT_SYMBOL(arch_unregister_cpu);
    145#else /* CONFIG_HOTPLUG_CPU */
    146
    147static int __init arch_register_cpu(int num)
    148{
    149	return register_cpu(&per_cpu(cpu_devices, num).cpu, num);
    150}
    151#endif /* CONFIG_HOTPLUG_CPU */
    152
    153static int __init topology_init(void)
    154{
    155	int i;
    156
    157	for_each_present_cpu(i)
    158		arch_register_cpu(i);
    159
    160	return 0;
    161}
    162subsys_initcall(topology_init);