linux/arch/mips/kernel/smp.c
Alex Smith 4ace6139bf MIPS: SMP: Don't increment irq_count multiple times for call function IPIs
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>
2015-08-03 09:25:12 +02:00

496 lines
11 KiB
C

/*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version 2
* of the License, or (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
*
* Copyright (C) 2000, 2001 Kanoj Sarcar
* Copyright (C) 2000, 2001 Ralf Baechle
* Copyright (C) 2000, 2001 Silicon Graphics, Inc.
* Copyright (C) 2000, 2001, 2003 Broadcom Corporation
*/
#include <linux/cache.h>
#include <linux/delay.h>
#include <linux/init.h>
#include <linux/interrupt.h>
#include <linux/smp.h>
#include <linux/spinlock.h>
#include <linux/threads.h>
#include <linux/module.h>
#include <linux/time.h>
#include <linux/timex.h>
#include <linux/sched.h>
#include <linux/cpumask.h>
#include <linux/cpu.h>
#include <linux/err.h>
#include <linux/ftrace.h>
#include <linux/atomic.h>
#include <asm/cpu.h>
#include <asm/processor.h>
#include <asm/idle.h>
#include <asm/r4k-timer.h>
#include <asm/mmu_context.h>
#include <asm/time.h>
#include <asm/setup.h>
cpumask_t cpu_callin_map; /* Bitmask of started secondaries */
int __cpu_number_map[NR_CPUS]; /* Map physical to logical */
EXPORT_SYMBOL(__cpu_number_map);
int __cpu_logical_map[NR_CPUS]; /* Map logical to physical */
EXPORT_SYMBOL(__cpu_logical_map);
/* Number of TCs (or siblings in Intel speak) per CPU core */
int smp_num_siblings = 1;
EXPORT_SYMBOL(smp_num_siblings);
/* representing the TCs (or siblings in Intel speak) of each logical CPU */
cpumask_t cpu_sibling_map[NR_CPUS] __read_mostly;
EXPORT_SYMBOL(cpu_sibling_map);
/* representing the core map of multi-core chips of each logical CPU */
cpumask_t cpu_core_map[NR_CPUS] __read_mostly;
EXPORT_SYMBOL(cpu_core_map);
/*
* A logcal cpu mask containing only one VPE per core to
* reduce the number of IPIs on large MT systems.
*/
cpumask_t cpu_foreign_map __read_mostly;
EXPORT_SYMBOL(cpu_foreign_map);
/* representing cpus for which sibling maps can be computed */
static cpumask_t cpu_sibling_setup_map;
/* representing cpus for which core maps can be computed */
static cpumask_t cpu_core_setup_map;
cpumask_t cpu_coherent_mask;
static inline void set_cpu_sibling_map(int cpu)
{
int i;
cpumask_set_cpu(cpu, &cpu_sibling_setup_map);
if (smp_num_siblings > 1) {
for_each_cpu(i, &cpu_sibling_setup_map) {
if (cpu_data[cpu].package == cpu_data[i].package &&
cpu_data[cpu].core == cpu_data[i].core) {
cpumask_set_cpu(i, &cpu_sibling_map[cpu]);
cpumask_set_cpu(cpu, &cpu_sibling_map[i]);
}
}
} else
cpumask_set_cpu(cpu, &cpu_sibling_map[cpu]);
}
static inline void set_cpu_core_map(int cpu)
{
int i;
cpumask_set_cpu(cpu, &cpu_core_setup_map);
for_each_cpu(i, &cpu_core_setup_map) {
if (cpu_data[cpu].package == cpu_data[i].package) {
cpumask_set_cpu(i, &cpu_core_map[cpu]);
cpumask_set_cpu(cpu, &cpu_core_map[i]);
}
}
}
/*
* Calculate a new cpu_foreign_map mask whenever a
* new cpu appears or disappears.
*/
static inline void calculate_cpu_foreign_map(void)
{
int i, k, core_present;
cpumask_t temp_foreign_map;
/* Re-calculate the mask */
for_each_online_cpu(i) {
core_present = 0;
for_each_cpu(k, &temp_foreign_map)
if (cpu_data[i].package == cpu_data[k].package &&
cpu_data[i].core == cpu_data[k].core)
core_present = 1;
if (!core_present)
cpumask_set_cpu(i, &temp_foreign_map);
}
cpumask_copy(&cpu_foreign_map, &temp_foreign_map);
}
struct plat_smp_ops *mp_ops;
EXPORT_SYMBOL(mp_ops);
void register_smp_ops(struct plat_smp_ops *ops)
{
if (mp_ops)
printk(KERN_WARNING "Overriding previously set SMP ops\n");
mp_ops = ops;
}
/*
* First C code run on the secondary CPUs after being started up by
* the master.
*/
asmlinkage void start_secondary(void)
{
unsigned int cpu;
cpu_probe();
per_cpu_trap_init(false);
mips_clockevent_init();
mp_ops->init_secondary();
cpu_report();
/*
* XXX parity protection should be folded in here when it's converted
* to an option instead of something based on .cputype
*/
calibrate_delay();
preempt_disable();
cpu = smp_processor_id();
cpu_data[cpu].udelay_val = loops_per_jiffy;
cpumask_set_cpu(cpu, &cpu_coherent_mask);
notify_cpu_starting(cpu);
set_cpu_online(cpu, true);
set_cpu_sibling_map(cpu);
set_cpu_core_map(cpu);
calculate_cpu_foreign_map();
cpumask_set_cpu(cpu, &cpu_callin_map);
synchronise_count_slave(cpu);
/*
* irq will be enabled in ->smp_finish(), enabling it too early
* is dangerous.
*/
WARN_ON_ONCE(!irqs_disabled());
mp_ops->smp_finish();
cpu_startup_entry(CPUHP_ONLINE);
}
static void stop_this_cpu(void *dummy)
{
/*
* Remove this CPU. Be a bit slow here and
* set the bits for every online CPU so we don't miss
* any IPI whilst taking this VPE down.
*/
cpumask_copy(&cpu_foreign_map, cpu_online_mask);
/* Make it visible to every other CPU */
smp_mb();
set_cpu_online(smp_processor_id(), false);
calculate_cpu_foreign_map();
local_irq_disable();
while (1);
}
void smp_send_stop(void)
{
smp_call_function(stop_this_cpu, NULL, 0);
}
void __init smp_cpus_done(unsigned int max_cpus)
{
}
/* called from main before smp_init() */
void __init smp_prepare_cpus(unsigned int max_cpus)
{
init_new_context(current, &init_mm);
current_thread_info()->cpu = 0;
mp_ops->prepare_cpus(max_cpus);
set_cpu_sibling_map(0);
set_cpu_core_map(0);
calculate_cpu_foreign_map();
#ifndef CONFIG_HOTPLUG_CPU
init_cpu_present(cpu_possible_mask);
#endif
cpumask_copy(&cpu_coherent_mask, cpu_possible_mask);
}
/* preload SMP state for boot cpu */
void smp_prepare_boot_cpu(void)
{
set_cpu_possible(0, true);
set_cpu_online(0, true);
cpumask_set_cpu(0, &cpu_callin_map);
}
int __cpu_up(unsigned int cpu, struct task_struct *tidle)
{
mp_ops->boot_secondary(cpu, tidle);
/*
* Trust is futile. We should really have timeouts ...
*/
while (!cpumask_test_cpu(cpu, &cpu_callin_map)) {
udelay(100);
schedule();
}
synchronise_count_master(cpu);
return 0;
}
/* Not really SMP stuff ... */
int setup_profiling_timer(unsigned int multiplier)
{
return 0;
}
static void flush_tlb_all_ipi(void *info)
{
local_flush_tlb_all();
}
void flush_tlb_all(void)
{
on_each_cpu(flush_tlb_all_ipi, NULL, 1);
}
static void flush_tlb_mm_ipi(void *mm)
{
local_flush_tlb_mm((struct mm_struct *)mm);
}
/*
* Special Variant of smp_call_function for use by TLB functions:
*
* o No return value
* o collapses to normal function call on UP kernels
* o collapses to normal function call on systems with a single shared
* primary cache.
*/
static inline void smp_on_other_tlbs(void (*func) (void *info), void *info)
{
smp_call_function(func, info, 1);
}
static inline void smp_on_each_tlb(void (*func) (void *info), void *info)
{
preempt_disable();
smp_on_other_tlbs(func, info);
func(info);
preempt_enable();
}
/*
* The following tlb flush calls are invoked when old translations are
* being torn down, or pte attributes are changing. For single threaded
* address spaces, a new context is obtained on the current cpu, and tlb
* context on other cpus are invalidated to force a new context allocation
* at switch_mm time, should the mm ever be used on other cpus. For
* multithreaded address spaces, intercpu interrupts have to be sent.
* Another case where intercpu interrupts are required is when the target
* mm might be active on another cpu (eg debuggers doing the flushes on
* behalf of debugees, kswapd stealing pages from another process etc).
* Kanoj 07/00.
*/
void flush_tlb_mm(struct mm_struct *mm)
{
preempt_disable();
if ((atomic_read(&mm->mm_users) != 1) || (current->mm != mm)) {
smp_on_other_tlbs(flush_tlb_mm_ipi, mm);
} else {
unsigned int cpu;
for_each_online_cpu(cpu) {
if (cpu != smp_processor_id() && cpu_context(cpu, mm))
cpu_context(cpu, mm) = 0;
}
}
local_flush_tlb_mm(mm);
preempt_enable();
}
struct flush_tlb_data {
struct vm_area_struct *vma;
unsigned long addr1;
unsigned long addr2;
};
static void flush_tlb_range_ipi(void *info)
{
struct flush_tlb_data *fd = info;
local_flush_tlb_range(fd->vma, fd->addr1, fd->addr2);
}
void flush_tlb_range(struct vm_area_struct *vma, unsigned long start, unsigned long end)
{
struct mm_struct *mm = vma->vm_mm;
preempt_disable();
if ((atomic_read(&mm->mm_users) != 1) || (current->mm != mm)) {
struct flush_tlb_data fd = {
.vma = vma,
.addr1 = start,
.addr2 = end,
};
smp_on_other_tlbs(flush_tlb_range_ipi, &fd);
} else {
unsigned int cpu;
for_each_online_cpu(cpu) {
if (cpu != smp_processor_id() && cpu_context(cpu, mm))
cpu_context(cpu, mm) = 0;
}
}
local_flush_tlb_range(vma, start, end);
preempt_enable();
}
static void flush_tlb_kernel_range_ipi(void *info)
{
struct flush_tlb_data *fd = info;
local_flush_tlb_kernel_range(fd->addr1, fd->addr2);
}
void flush_tlb_kernel_range(unsigned long start, unsigned long end)
{
struct flush_tlb_data fd = {
.addr1 = start,
.addr2 = end,
};
on_each_cpu(flush_tlb_kernel_range_ipi, &fd, 1);
}
static void flush_tlb_page_ipi(void *info)
{
struct flush_tlb_data *fd = info;
local_flush_tlb_page(fd->vma, fd->addr1);
}
void flush_tlb_page(struct vm_area_struct *vma, unsigned long page)
{
preempt_disable();
if ((atomic_read(&vma->vm_mm->mm_users) != 1) || (current->mm != vma->vm_mm)) {
struct flush_tlb_data fd = {
.vma = vma,
.addr1 = page,
};
smp_on_other_tlbs(flush_tlb_page_ipi, &fd);
} else {
unsigned int cpu;
for_each_online_cpu(cpu) {
if (cpu != smp_processor_id() && cpu_context(cpu, vma->vm_mm))
cpu_context(cpu, vma->vm_mm) = 0;
}
}
local_flush_tlb_page(vma, page);
preempt_enable();
}
static void flush_tlb_one_ipi(void *info)
{
unsigned long vaddr = (unsigned long) info;
local_flush_tlb_one(vaddr);
}
void flush_tlb_one(unsigned long vaddr)
{
smp_on_each_tlb(flush_tlb_one_ipi, (void *) vaddr);
}
EXPORT_SYMBOL(flush_tlb_page);
EXPORT_SYMBOL(flush_tlb_one);
#if defined(CONFIG_KEXEC)
void (*dump_ipi_function_ptr)(void *) = NULL;
void dump_send_ipi(void (*dump_ipi_callback)(void *))
{
int i;
int cpu = smp_processor_id();
dump_ipi_function_ptr = dump_ipi_callback;
smp_mb();
for_each_online_cpu(i)
if (i != cpu)
mp_ops->send_ipi_single(i, SMP_DUMP);
}
EXPORT_SYMBOL(dump_send_ipi);
#endif
#ifdef CONFIG_GENERIC_CLOCKEVENTS_BROADCAST
static DEFINE_PER_CPU(atomic_t, tick_broadcast_count);
static DEFINE_PER_CPU(struct call_single_data, tick_broadcast_csd);
void tick_broadcast(const struct cpumask *mask)
{
atomic_t *count;
struct call_single_data *csd;
int cpu;
for_each_cpu(cpu, mask) {
count = &per_cpu(tick_broadcast_count, cpu);
csd = &per_cpu(tick_broadcast_csd, cpu);
if (atomic_inc_return(count) == 1)
smp_call_function_single_async(cpu, csd);
}
}
static void tick_broadcast_callee(void *info)
{
int cpu = smp_processor_id();
tick_receive_broadcast();
atomic_set(&per_cpu(tick_broadcast_count, cpu), 0);
}
static int __init tick_broadcast_init(void)
{
struct call_single_data *csd;
int cpu;
for (cpu = 0; cpu < NR_CPUS; cpu++) {
csd = &per_cpu(tick_broadcast_csd, cpu);
csd->func = tick_broadcast_callee;
}
return 0;
}
early_initcall(tick_broadcast_init);
#endif /* CONFIG_GENERIC_CLOCKEVENTS_BROADCAST */