linux/drivers/base/arch_topology.c
Gaku Inami 9de9a44948 Revert "base: arch_topology: fix section mismatch build warnings"
This reverts commit 452562abb5 ("base: arch_topology: fix section
mismatch build warnings"). It causes the notifier call hangs in some
use-cases.

In some cases with using maxcpus, some of cpus are booted first and
then the remaining cpus are booted. As an example, some users who want
to realize fast boot up often use the following procedure.

  1) Define all CPUs on device tree (CA57x4 + CA53x4)
  2) Add "maxcpus=4" in bootargs
  3) Kernel boot up with CA57x4
  4) After kernel boot up, CA53x4 is booted from user

When kernel init was finished, CPUFREQ_POLICY_NOTIFIER was not still
unregisterd. This means that "__init init_cpu_capacity_callback()"
will be called after kernel init sequence. To avoid this problem,
it needs to remove __init{,data} annotations by reverting this commit.

Also, this commit was needed to fix kernel compile issue below.
However, this issue was also fixed by another patch: commit 82d8ba717c
("arch_topology: Fix section miss match warning due to
free_raw_capacity()") in v4.15 as well.
Whereas commit 452562abb5 added all the missing __init annotations,
commit 82d8ba717c removed it from free_raw_capacity().

WARNING: vmlinux.o(.text+0x548f24): Section mismatch in reference
from the function init_cpu_capacity_callback() to the variable
.init.text:$x
The function init_cpu_capacity_callback() references
the variable __init $x.
This is often because init_cpu_capacity_callback lacks a __init
annotation or the annotation of $x is wrong.

Fixes: 82d8ba717c ("arch_topology: Fix section miss match warning due to free_raw_capacity()")
Cc: stable <stable@vger.kernel.org>
Signed-off-by: Gaku Inami <gaku.inami.xh@renesas.com>
Reviewed-by: Dietmar Eggemann <dietmar.eggemann@arm.com>
Tested-by: Dietmar Eggemann <dietmar.eggemann@arm.com>
Acked-by: Sudeep Holla <sudeep.holla@arm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2018-03-15 14:36:20 +01:00

255 lines
5.8 KiB
C

// SPDX-License-Identifier: GPL-2.0
/*
* Arch specific cpu topology information
*
* Copyright (C) 2016, ARM Ltd.
* Written by: Juri Lelli, ARM Ltd.
*/
#include <linux/acpi.h>
#include <linux/arch_topology.h>
#include <linux/cpu.h>
#include <linux/cpufreq.h>
#include <linux/device.h>
#include <linux/of.h>
#include <linux/slab.h>
#include <linux/string.h>
#include <linux/sched/topology.h>
DEFINE_PER_CPU(unsigned long, freq_scale) = SCHED_CAPACITY_SCALE;
void arch_set_freq_scale(struct cpumask *cpus, unsigned long cur_freq,
unsigned long max_freq)
{
unsigned long scale;
int i;
scale = (cur_freq << SCHED_CAPACITY_SHIFT) / max_freq;
for_each_cpu(i, cpus)
per_cpu(freq_scale, i) = scale;
}
static DEFINE_MUTEX(cpu_scale_mutex);
DEFINE_PER_CPU(unsigned long, cpu_scale) = SCHED_CAPACITY_SCALE;
void topology_set_cpu_scale(unsigned int cpu, unsigned long capacity)
{
per_cpu(cpu_scale, cpu) = capacity;
}
static ssize_t cpu_capacity_show(struct device *dev,
struct device_attribute *attr,
char *buf)
{
struct cpu *cpu = container_of(dev, struct cpu, dev);
return sprintf(buf, "%lu\n", topology_get_cpu_scale(NULL, cpu->dev.id));
}
static ssize_t cpu_capacity_store(struct device *dev,
struct device_attribute *attr,
const char *buf,
size_t count)
{
struct cpu *cpu = container_of(dev, struct cpu, dev);
int this_cpu = cpu->dev.id;
int i;
unsigned long new_capacity;
ssize_t ret;
if (!count)
return 0;
ret = kstrtoul(buf, 0, &new_capacity);
if (ret)
return ret;
if (new_capacity > SCHED_CAPACITY_SCALE)
return -EINVAL;
mutex_lock(&cpu_scale_mutex);
for_each_cpu(i, &cpu_topology[this_cpu].core_sibling)
topology_set_cpu_scale(i, new_capacity);
mutex_unlock(&cpu_scale_mutex);
return count;
}
static DEVICE_ATTR_RW(cpu_capacity);
static int register_cpu_capacity_sysctl(void)
{
int i;
struct device *cpu;
for_each_possible_cpu(i) {
cpu = get_cpu_device(i);
if (!cpu) {
pr_err("%s: too early to get CPU%d device!\n",
__func__, i);
continue;
}
device_create_file(cpu, &dev_attr_cpu_capacity);
}
return 0;
}
subsys_initcall(register_cpu_capacity_sysctl);
static u32 capacity_scale;
static u32 *raw_capacity;
static int free_raw_capacity(void)
{
kfree(raw_capacity);
raw_capacity = NULL;
return 0;
}
void topology_normalize_cpu_scale(void)
{
u64 capacity;
int cpu;
if (!raw_capacity)
return;
pr_debug("cpu_capacity: capacity_scale=%u\n", capacity_scale);
mutex_lock(&cpu_scale_mutex);
for_each_possible_cpu(cpu) {
pr_debug("cpu_capacity: cpu=%d raw_capacity=%u\n",
cpu, raw_capacity[cpu]);
capacity = (raw_capacity[cpu] << SCHED_CAPACITY_SHIFT)
/ capacity_scale;
topology_set_cpu_scale(cpu, capacity);
pr_debug("cpu_capacity: CPU%d cpu_capacity=%lu\n",
cpu, topology_get_cpu_scale(NULL, cpu));
}
mutex_unlock(&cpu_scale_mutex);
}
bool __init topology_parse_cpu_capacity(struct device_node *cpu_node, int cpu)
{
static bool cap_parsing_failed;
int ret;
u32 cpu_capacity;
if (cap_parsing_failed)
return false;
ret = of_property_read_u32(cpu_node, "capacity-dmips-mhz",
&cpu_capacity);
if (!ret) {
if (!raw_capacity) {
raw_capacity = kcalloc(num_possible_cpus(),
sizeof(*raw_capacity),
GFP_KERNEL);
if (!raw_capacity) {
pr_err("cpu_capacity: failed to allocate memory for raw capacities\n");
cap_parsing_failed = true;
return false;
}
}
capacity_scale = max(cpu_capacity, capacity_scale);
raw_capacity[cpu] = cpu_capacity;
pr_debug("cpu_capacity: %pOF cpu_capacity=%u (raw)\n",
cpu_node, raw_capacity[cpu]);
} else {
if (raw_capacity) {
pr_err("cpu_capacity: missing %pOF raw capacity\n",
cpu_node);
pr_err("cpu_capacity: partial information: fallback to 1024 for all CPUs\n");
}
cap_parsing_failed = true;
free_raw_capacity();
}
return !ret;
}
#ifdef CONFIG_CPU_FREQ
static cpumask_var_t cpus_to_visit;
static void parsing_done_workfn(struct work_struct *work);
static DECLARE_WORK(parsing_done_work, parsing_done_workfn);
static int
init_cpu_capacity_callback(struct notifier_block *nb,
unsigned long val,
void *data)
{
struct cpufreq_policy *policy = data;
int cpu;
if (!raw_capacity)
return 0;
if (val != CPUFREQ_NOTIFY)
return 0;
pr_debug("cpu_capacity: init cpu capacity for CPUs [%*pbl] (to_visit=%*pbl)\n",
cpumask_pr_args(policy->related_cpus),
cpumask_pr_args(cpus_to_visit));
cpumask_andnot(cpus_to_visit, cpus_to_visit, policy->related_cpus);
for_each_cpu(cpu, policy->related_cpus) {
raw_capacity[cpu] = topology_get_cpu_scale(NULL, cpu) *
policy->cpuinfo.max_freq / 1000UL;
capacity_scale = max(raw_capacity[cpu], capacity_scale);
}
if (cpumask_empty(cpus_to_visit)) {
topology_normalize_cpu_scale();
free_raw_capacity();
pr_debug("cpu_capacity: parsing done\n");
schedule_work(&parsing_done_work);
}
return 0;
}
static struct notifier_block init_cpu_capacity_notifier = {
.notifier_call = init_cpu_capacity_callback,
};
static int __init register_cpufreq_notifier(void)
{
int ret;
/*
* on ACPI-based systems we need to use the default cpu capacity
* until we have the necessary code to parse the cpu capacity, so
* skip registering cpufreq notifier.
*/
if (!acpi_disabled || !raw_capacity)
return -EINVAL;
if (!alloc_cpumask_var(&cpus_to_visit, GFP_KERNEL)) {
pr_err("cpu_capacity: failed to allocate memory for cpus_to_visit\n");
return -ENOMEM;
}
cpumask_copy(cpus_to_visit, cpu_possible_mask);
ret = cpufreq_register_notifier(&init_cpu_capacity_notifier,
CPUFREQ_POLICY_NOTIFIER);
if (ret)
free_cpumask_var(cpus_to_visit);
return ret;
}
core_initcall(register_cpufreq_notifier);
static void parsing_done_workfn(struct work_struct *work)
{
cpufreq_unregister_notifier(&init_cpu_capacity_notifier,
CPUFREQ_POLICY_NOTIFIER);
free_cpumask_var(cpus_to_visit);
}
#else
core_initcall(free_raw_capacity);
#endif