android_kernel_oneplus_msm8998/arch/mips/kernel/smp.c
Matt Redfearn 6004eb4d1a MIPS: SMP: Fix deadlock & online race
commit 9e8c399a88f0b87e41a894911475ed2a8f8dff9e upstream.

Commit 6f542ebeaee0 ("MIPS: Fix race on setting and getting
cpu_online_mask") effectively reverted commit 8f46cca1e6c06 ("MIPS: SMP:
Fix possibility of deadlock when bringing CPUs online") and thus has
reinstated the possibility of deadlock.

The commit was based on testing of kernel v4.4, where the CPU hotplug
core code issued a BUG() if the starting CPU is not marked online when
the boot CPU returns from __cpu_up. The commit fixes this race (in
v4.4), but re-introduces the deadlock situation.

As noted in the commit message, upstream differs in this area. Commit
8df3e07e7f21f ("cpu/hotplug: Let upcoming cpu bring itself fully up")
adds a completion event in the CPU hotplug core code, making this race
impossible. However, people were unhappy with relying on the core code
to do the right thing.

To address the issues both commits were trying to fix, add a second
completion event in the MIPS smp hotplug path. It removes the
possibility of a race, since the MIPS smp hotplug code now synchronises
both the boot and secondary CPUs before they return to the hotplug core
code. It also addresses the deadlock by ensuring that the secondary CPU
is not marked online before it's counters are synchronised.

This fix should also be backported to fix the race condition introduced
by the backport of commit 8f46cca1e6c06 ("MIPS: SMP: Fix possibility of
deadlock when bringing CPUs online"), through really that race only
existed before commit 8df3e07e7f21f ("cpu/hotplug: Let upcoming cpu
bring itself fully up").

Signed-off-by: Matt Redfearn <matt.redfearn@imgtec.com>
Fixes: 6f542ebeaee0 ("MIPS: Fix race on setting and getting cpu_online_mask")
CC: Matija Glavinic Pecotic <matija.glavinic-pecotic.ext@nokia.com>
Patchwork: https://patchwork.linux-mips.org/patch/17376/
Signed-off-by: James Hogan <jhogan@kernel.org>
[jhogan@kernel.org: Backported 4.1..4.9]
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2017-11-15 17:13:12 +01:00

510 lines
12 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>
#include <asm/maar.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);
static DECLARE_COMPLETION(cpu_starting);
static DECLARE_COMPLETION(cpu_running);
/*
* 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 */
cpumask_clear(&temp_foreign_map);
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();
maar_init();
/*
* 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);
/* Notify boot CPU that we're starting & ready to sync counters */
complete(&cpu_starting);
synchronise_count_slave(cpu);
/* The CPU is running and counters synchronised, now mark it online */
set_cpu_online(cpu, true);
set_cpu_sibling_map(cpu);
set_cpu_core_map(cpu);
calculate_cpu_foreign_map();
/*
* Notify boot CPU that we're up & online and it can safely return
* from __cpu_up
*/
complete(&cpu_running);
/*
* 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);
}
int __cpu_up(unsigned int cpu, struct task_struct *tidle)
{
mp_ops->boot_secondary(cpu, tidle);
/* Wait for CPU to start and be ready to sync counters */
if (!wait_for_completion_timeout(&cpu_starting,
msecs_to_jiffies(1000))) {
pr_crit("CPU%u: failed to start\n", cpu);
return -EIO;
}
synchronise_count_master(cpu);
/* Wait for CPU to finish startup & mark itself online before return */
wait_for_completion(&cpu_running);
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 */