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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hotplug.c (1952B)

      1// SPDX-License-Identifier: GPL-2.0-only
      2/*
      3 * linux/arch/arm/mach-spear13xx/hotplug.c
      4 *
      5 * Copyright (C) 2012 ST Microelectronics Ltd.
      6 * Deepak Sikri <deepak.sikri@st.com>
      7 *
      8 * based upon linux/arch/arm/mach-realview/hotplug.c
      9 */
     10#include <linux/kernel.h>
     11#include <linux/errno.h>
     12#include <linux/smp.h>
     13#include <asm/cp15.h>
     14#include <asm/smp_plat.h>
     15
     16#include "generic.h"
     17
     18static inline void cpu_enter_lowpower(void)
     19{
     20	unsigned int v;
     21
     22	asm volatile(
     23	"	mcr	p15, 0, %1, c7, c5, 0\n"
     24	"	dsb\n"
     25	/*
     26	 * Turn off coherency
     27	 */
     28	"	mrc	p15, 0, %0, c1, c0, 1\n"
     29	"	bic	%0, %0, #0x20\n"
     30	"	mcr	p15, 0, %0, c1, c0, 1\n"
     31	"	mrc	p15, 0, %0, c1, c0, 0\n"
     32	"	bic	%0, %0, %2\n"
     33	"	mcr	p15, 0, %0, c1, c0, 0\n"
     34	: "=&r" (v)
     35	: "r" (0), "Ir" (CR_C)
     36	: "cc", "memory");
     37}
     38
     39static inline void cpu_leave_lowpower(void)
     40{
     41	unsigned int v;
     42
     43	asm volatile("mrc	p15, 0, %0, c1, c0, 0\n"
     44	"	orr	%0, %0, %1\n"
     45	"	mcr	p15, 0, %0, c1, c0, 0\n"
     46	"	mrc	p15, 0, %0, c1, c0, 1\n"
     47	"	orr	%0, %0, #0x20\n"
     48	"	mcr	p15, 0, %0, c1, c0, 1\n"
     49	: "=&r" (v)
     50	: "Ir" (CR_C)
     51	: "cc");
     52}
     53
     54static inline void spear13xx_do_lowpower(unsigned int cpu, int *spurious)
     55{
     56	for (;;) {
     57		wfi();
     58
     59		if (spear_pen_release == cpu) {
     60			/*
     61			 * OK, proper wakeup, we're done
     62			 */
     63			break;
     64		}
     65
     66		/*
     67		 * Getting here, means that we have come out of WFI without
     68		 * having been woken up - this shouldn't happen
     69		 *
     70		 * Just note it happening - when we're woken, we can report
     71		 * its occurrence.
     72		 */
     73		(*spurious)++;
     74	}
     75}
     76
     77/*
     78 * platform-specific code to shutdown a CPU
     79 *
     80 * Called with IRQs disabled
     81 */
     82void spear13xx_cpu_die(unsigned int cpu)
     83{
     84	int spurious = 0;
     85
     86	/*
     87	 * we're ready for shutdown now, so do it
     88	 */
     89	cpu_enter_lowpower();
     90	spear13xx_do_lowpower(cpu, &spurious);
     91
     92	/*
     93	 * bring this CPU back into the world of cache
     94	 * coherency, and then restore interrupts
     95	 */
     96	cpu_leave_lowpower();
     97
     98	if (spurious)
     99		pr_warn("CPU%u: %u spurious wakeup calls\n", cpu, spurious);
    100}