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https://github.com/AuxXxilium/linux_dsm_epyc7002.git
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4ace6139bf
The majority of SMP platforms handle their IPIs through do_IRQ()
which calls irq_{enter/exit}(). When a call function IPI is received,
smp_call_function_interrupt() is called which also calls
irq_{enter,exit}(), meaning irq_count is raised twice.
When tick broadcasting is used (which is implemented via a call
function IPI), this incorrectly causes all CPU idle time on the core
receiving broadcast ticks to be accounted as time spent servicing
IRQs, as account_process_tick() will account as such if irq_count is
greater than 1. This results in 100% CPU usage being reported on a
core which receives its ticks via broadcast.
This patch removes the SMP smp_call_function_interrupt() wrapper which
calls irq_{enter,exit}(). Platforms which handle their IPIs through
do_IRQ() now call generic_smp_call_function_interrupt() directly to
avoid incrementing irq_count a second time. Platforms which don't
(loongson, sgi-ip27, sibyte) call generic_smp_call_function_interrupt()
wrapped in irq_{enter,exit}().
Signed-off-by: Alex Smith <alex.smith@imgtec.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/10770/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
191 lines
5.2 KiB
C
191 lines
5.2 KiB
C
/*
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* Copyright (C) 2001,2002,2004 Broadcom Corporation
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version 2
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* of the License, or (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
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*/
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#include <linux/init.h>
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#include <linux/delay.h>
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#include <linux/smp.h>
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#include <linux/kernel_stat.h>
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#include <linux/sched.h>
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#include <asm/mmu_context.h>
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#include <asm/io.h>
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#include <asm/fw/cfe/cfe_api.h>
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#include <asm/sibyte/sb1250.h>
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#include <asm/sibyte/bcm1480_regs.h>
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#include <asm/sibyte/bcm1480_int.h>
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/*
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* These are routines for dealing with the bcm1480 smp capabilities
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* independent of board/firmware
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*/
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static void *mailbox_0_set_regs[] = {
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IOADDR(A_BCM1480_IMR_CPU0_BASE + R_BCM1480_IMR_MAILBOX_0_SET_CPU),
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IOADDR(A_BCM1480_IMR_CPU1_BASE + R_BCM1480_IMR_MAILBOX_0_SET_CPU),
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IOADDR(A_BCM1480_IMR_CPU2_BASE + R_BCM1480_IMR_MAILBOX_0_SET_CPU),
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IOADDR(A_BCM1480_IMR_CPU3_BASE + R_BCM1480_IMR_MAILBOX_0_SET_CPU),
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};
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static void *mailbox_0_clear_regs[] = {
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IOADDR(A_BCM1480_IMR_CPU0_BASE + R_BCM1480_IMR_MAILBOX_0_CLR_CPU),
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IOADDR(A_BCM1480_IMR_CPU1_BASE + R_BCM1480_IMR_MAILBOX_0_CLR_CPU),
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IOADDR(A_BCM1480_IMR_CPU2_BASE + R_BCM1480_IMR_MAILBOX_0_CLR_CPU),
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IOADDR(A_BCM1480_IMR_CPU3_BASE + R_BCM1480_IMR_MAILBOX_0_CLR_CPU),
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};
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static void *mailbox_0_regs[] = {
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IOADDR(A_BCM1480_IMR_CPU0_BASE + R_BCM1480_IMR_MAILBOX_0_CPU),
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IOADDR(A_BCM1480_IMR_CPU1_BASE + R_BCM1480_IMR_MAILBOX_0_CPU),
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IOADDR(A_BCM1480_IMR_CPU2_BASE + R_BCM1480_IMR_MAILBOX_0_CPU),
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IOADDR(A_BCM1480_IMR_CPU3_BASE + R_BCM1480_IMR_MAILBOX_0_CPU),
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};
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/*
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* SMP init and finish on secondary CPUs
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*/
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void bcm1480_smp_init(void)
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{
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unsigned int imask = STATUSF_IP4 | STATUSF_IP3 | STATUSF_IP2 |
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STATUSF_IP1 | STATUSF_IP0;
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/* Set interrupt mask, but don't enable */
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change_c0_status(ST0_IM, imask);
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}
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/*
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* These are routines for dealing with the sb1250 smp capabilities
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* independent of board/firmware
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*/
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/*
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* Simple enough; everything is set up, so just poke the appropriate mailbox
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* register, and we should be set
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*/
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static void bcm1480_send_ipi_single(int cpu, unsigned int action)
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{
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__raw_writeq((((u64)action)<< 48), mailbox_0_set_regs[cpu]);
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}
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static void bcm1480_send_ipi_mask(const struct cpumask *mask,
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unsigned int action)
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{
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unsigned int i;
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for_each_cpu(i, mask)
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bcm1480_send_ipi_single(i, action);
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}
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/*
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* Code to run on secondary just after probing the CPU
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*/
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static void bcm1480_init_secondary(void)
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{
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extern void bcm1480_smp_init(void);
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bcm1480_smp_init();
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}
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/*
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* Do any tidying up before marking online and running the idle
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* loop
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*/
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static void bcm1480_smp_finish(void)
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{
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extern void sb1480_clockevent_init(void);
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sb1480_clockevent_init();
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local_irq_enable();
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}
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/*
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* Setup the PC, SP, and GP of a secondary processor and start it
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* running!
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*/
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static void bcm1480_boot_secondary(int cpu, struct task_struct *idle)
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{
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int retval;
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retval = cfe_cpu_start(cpu_logical_map(cpu), &smp_bootstrap,
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__KSTK_TOS(idle),
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(unsigned long)task_thread_info(idle), 0);
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if (retval != 0)
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printk("cfe_start_cpu(%i) returned %i\n" , cpu, retval);
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}
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/*
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* Use CFE to find out how many CPUs are available, setting up
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* cpu_possible_mask and the logical/physical mappings.
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* XXXKW will the boot CPU ever not be physical 0?
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*
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* Common setup before any secondaries are started
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*/
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static void __init bcm1480_smp_setup(void)
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{
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int i, num;
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init_cpu_possible(cpumask_of(0));
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__cpu_number_map[0] = 0;
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__cpu_logical_map[0] = 0;
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for (i = 1, num = 0; i < NR_CPUS; i++) {
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if (cfe_cpu_stop(i) == 0) {
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set_cpu_possible(i, true);
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__cpu_number_map[i] = ++num;
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__cpu_logical_map[num] = i;
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}
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}
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printk(KERN_INFO "Detected %i available secondary CPU(s)\n", num);
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}
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static void __init bcm1480_prepare_cpus(unsigned int max_cpus)
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{
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}
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struct plat_smp_ops bcm1480_smp_ops = {
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.send_ipi_single = bcm1480_send_ipi_single,
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.send_ipi_mask = bcm1480_send_ipi_mask,
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.init_secondary = bcm1480_init_secondary,
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.smp_finish = bcm1480_smp_finish,
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.boot_secondary = bcm1480_boot_secondary,
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.smp_setup = bcm1480_smp_setup,
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.prepare_cpus = bcm1480_prepare_cpus,
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};
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void bcm1480_mailbox_interrupt(void)
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{
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int cpu = smp_processor_id();
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int irq = K_BCM1480_INT_MBOX_0_0;
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unsigned int action;
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kstat_incr_irq_this_cpu(irq);
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/* Load the mailbox register to figure out what we're supposed to do */
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action = (__raw_readq(mailbox_0_regs[cpu]) >> 48) & 0xffff;
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/* Clear the mailbox to clear the interrupt */
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__raw_writeq(((u64)action)<<48, mailbox_0_clear_regs[cpu]);
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if (action & SMP_RESCHEDULE_YOURSELF)
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scheduler_ipi();
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if (action & SMP_CALL_FUNCTION) {
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irq_enter();
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generic_smp_call_function_interrupt();
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irq_exit();
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}
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}
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