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linux-next/arch/sparc/kernel/sysfs.c
Thomas Gleixner ea875ec94e sparc/sysfs: Replace racy task affinity logic 
The mmustat_enable sysfs file accessor functions must run code on the
target CPU. This is achieved by temporarily setting the affinity of the
calling user space thread to the requested CPU and reset it to the original
affinity afterwards.

That's racy vs. concurrent affinity settings for that thread resulting in
code executing on the wrong CPU and overwriting the new affinity setting.

Replace it by using work_on_cpu() which guarantees to run the code on the
requested CPU.

Protection against CPU hotplug is not required as the open sysfs file
already prevents the removal from the CPU offline callback. Using the
hotplug protected version would actually be wrong because it would deadlock
against a CPU hotplug operation of the CPU associated to the sysfs file in
progress.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: David S. Miller <davem@davemloft.net>
Cc: fenghua.yu@intel.com
Cc: tony.luck@intel.com
Cc: herbert@gondor.apana.org.au
Cc: rjw@rjwysocki.net
Cc: peterz@infradead.org
Cc: benh@kernel.crashing.org
Cc: bigeasy@linutronix.de
Cc: jiangshanlai@gmail.com
Cc: sparclinux@vger.kernel.org
Cc: viresh.kumar@linaro.org
Cc: mpe@ellerman.id.au
Cc: tj@kernel.org
Cc: lenb@kernel.org
Link: http://lkml.kernel.org/r/alpine.DEB.2.20.1704131001270.2408@nanos
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2017-04-15 12:20:54 +02:00

277 lines
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/* sysfs.c: Topology sysfs support code for sparc64.
*
* Copyright (C) 2007 David S. Miller <davem@davemloft.net>
*/
#include <linux/sched.h>
#include <linux/device.h>
#include <linux/cpu.h>
#include <linux/smp.h>
#include <linux/percpu.h>
#include <linux/init.h>
#include <asm/cpudata.h>
#include <asm/hypervisor.h>
#include <asm/spitfire.h>
static DEFINE_PER_CPU(struct hv_mmu_statistics, mmu_stats) __attribute__((aligned(64)));
#define SHOW_MMUSTAT_ULONG(NAME) \
static ssize_t show_##NAME(struct device *dev, \
struct device_attribute *attr, char *buf) \
{ \
struct hv_mmu_statistics *p = &per_cpu(mmu_stats, dev->id); \
return sprintf(buf, "%lu\n", p->NAME); \
} \
static DEVICE_ATTR(NAME, 0444, show_##NAME, NULL)
SHOW_MMUSTAT_ULONG(immu_tsb_hits_ctx0_8k_tte);
SHOW_MMUSTAT_ULONG(immu_tsb_ticks_ctx0_8k_tte);
SHOW_MMUSTAT_ULONG(immu_tsb_hits_ctx0_64k_tte);
SHOW_MMUSTAT_ULONG(immu_tsb_ticks_ctx0_64k_tte);
SHOW_MMUSTAT_ULONG(immu_tsb_hits_ctx0_4mb_tte);
SHOW_MMUSTAT_ULONG(immu_tsb_ticks_ctx0_4mb_tte);
SHOW_MMUSTAT_ULONG(immu_tsb_hits_ctx0_256mb_tte);
SHOW_MMUSTAT_ULONG(immu_tsb_ticks_ctx0_256mb_tte);
SHOW_MMUSTAT_ULONG(immu_tsb_hits_ctxnon0_8k_tte);
SHOW_MMUSTAT_ULONG(immu_tsb_ticks_ctxnon0_8k_tte);
SHOW_MMUSTAT_ULONG(immu_tsb_hits_ctxnon0_64k_tte);
SHOW_MMUSTAT_ULONG(immu_tsb_ticks_ctxnon0_64k_tte);
SHOW_MMUSTAT_ULONG(immu_tsb_hits_ctxnon0_4mb_tte);
SHOW_MMUSTAT_ULONG(immu_tsb_ticks_ctxnon0_4mb_tte);
SHOW_MMUSTAT_ULONG(immu_tsb_hits_ctxnon0_256mb_tte);
SHOW_MMUSTAT_ULONG(immu_tsb_ticks_ctxnon0_256mb_tte);
SHOW_MMUSTAT_ULONG(dmmu_tsb_hits_ctx0_8k_tte);
SHOW_MMUSTAT_ULONG(dmmu_tsb_ticks_ctx0_8k_tte);
SHOW_MMUSTAT_ULONG(dmmu_tsb_hits_ctx0_64k_tte);
SHOW_MMUSTAT_ULONG(dmmu_tsb_ticks_ctx0_64k_tte);
SHOW_MMUSTAT_ULONG(dmmu_tsb_hits_ctx0_4mb_tte);
SHOW_MMUSTAT_ULONG(dmmu_tsb_ticks_ctx0_4mb_tte);
SHOW_MMUSTAT_ULONG(dmmu_tsb_hits_ctx0_256mb_tte);
SHOW_MMUSTAT_ULONG(dmmu_tsb_ticks_ctx0_256mb_tte);
SHOW_MMUSTAT_ULONG(dmmu_tsb_hits_ctxnon0_8k_tte);
SHOW_MMUSTAT_ULONG(dmmu_tsb_ticks_ctxnon0_8k_tte);
SHOW_MMUSTAT_ULONG(dmmu_tsb_hits_ctxnon0_64k_tte);
SHOW_MMUSTAT_ULONG(dmmu_tsb_ticks_ctxnon0_64k_tte);
SHOW_MMUSTAT_ULONG(dmmu_tsb_hits_ctxnon0_4mb_tte);
SHOW_MMUSTAT_ULONG(dmmu_tsb_ticks_ctxnon0_4mb_tte);
SHOW_MMUSTAT_ULONG(dmmu_tsb_hits_ctxnon0_256mb_tte);
SHOW_MMUSTAT_ULONG(dmmu_tsb_ticks_ctxnon0_256mb_tte);
static struct attribute *mmu_stat_attrs[] = {
&dev_attr_immu_tsb_hits_ctx0_8k_tte.attr,
&dev_attr_immu_tsb_ticks_ctx0_8k_tte.attr,
&dev_attr_immu_tsb_hits_ctx0_64k_tte.attr,
&dev_attr_immu_tsb_ticks_ctx0_64k_tte.attr,
&dev_attr_immu_tsb_hits_ctx0_4mb_tte.attr,
&dev_attr_immu_tsb_ticks_ctx0_4mb_tte.attr,
&dev_attr_immu_tsb_hits_ctx0_256mb_tte.attr,
&dev_attr_immu_tsb_ticks_ctx0_256mb_tte.attr,
&dev_attr_immu_tsb_hits_ctxnon0_8k_tte.attr,
&dev_attr_immu_tsb_ticks_ctxnon0_8k_tte.attr,
&dev_attr_immu_tsb_hits_ctxnon0_64k_tte.attr,
&dev_attr_immu_tsb_ticks_ctxnon0_64k_tte.attr,
&dev_attr_immu_tsb_hits_ctxnon0_4mb_tte.attr,
&dev_attr_immu_tsb_ticks_ctxnon0_4mb_tte.attr,
&dev_attr_immu_tsb_hits_ctxnon0_256mb_tte.attr,
&dev_attr_immu_tsb_ticks_ctxnon0_256mb_tte.attr,
&dev_attr_dmmu_tsb_hits_ctx0_8k_tte.attr,
&dev_attr_dmmu_tsb_ticks_ctx0_8k_tte.attr,
&dev_attr_dmmu_tsb_hits_ctx0_64k_tte.attr,
&dev_attr_dmmu_tsb_ticks_ctx0_64k_tte.attr,
&dev_attr_dmmu_tsb_hits_ctx0_4mb_tte.attr,
&dev_attr_dmmu_tsb_ticks_ctx0_4mb_tte.attr,
&dev_attr_dmmu_tsb_hits_ctx0_256mb_tte.attr,
&dev_attr_dmmu_tsb_ticks_ctx0_256mb_tte.attr,
&dev_attr_dmmu_tsb_hits_ctxnon0_8k_tte.attr,
&dev_attr_dmmu_tsb_ticks_ctxnon0_8k_tte.attr,
&dev_attr_dmmu_tsb_hits_ctxnon0_64k_tte.attr,
&dev_attr_dmmu_tsb_ticks_ctxnon0_64k_tte.attr,
&dev_attr_dmmu_tsb_hits_ctxnon0_4mb_tte.attr,
&dev_attr_dmmu_tsb_ticks_ctxnon0_4mb_tte.attr,
&dev_attr_dmmu_tsb_hits_ctxnon0_256mb_tte.attr,
&dev_attr_dmmu_tsb_ticks_ctxnon0_256mb_tte.attr,
NULL,
};
static struct attribute_group mmu_stat_group = {
.attrs = mmu_stat_attrs,
.name = "mmu_stats",
};
static long read_mmustat_enable(void *data __maybe_unused)
{
unsigned long ra = 0;
sun4v_mmustat_info(&ra);
return ra != 0;
}
static long write_mmustat_enable(void *data)
{
unsigned long ra, orig_ra, *val = data;
if (*val)
ra = __pa(&per_cpu(mmu_stats, smp_processor_id()));
else
ra = 0UL;
return sun4v_mmustat_conf(ra, &orig_ra);
}
static ssize_t show_mmustat_enable(struct device *s,
struct device_attribute *attr, char *buf)
{
long val = work_on_cpu(s->id, read_mmustat_enable, NULL);
return sprintf(buf, "%lx\n", val);
}
static ssize_t store_mmustat_enable(struct device *s,
struct device_attribute *attr, const char *buf,
size_t count)
{
unsigned long val;
long err;
int ret;
ret = sscanf(buf, "%lu", &val);
if (ret != 1)
return -EINVAL;
err = work_on_cpu(s->id, write_mmustat_enable, &val);
if (err)
return -EIO;
return count;
}
static DEVICE_ATTR(mmustat_enable, 0644, show_mmustat_enable, store_mmustat_enable);
static int mmu_stats_supported;
static int register_mmu_stats(struct device *s)
{
if (!mmu_stats_supported)
return 0;
device_create_file(s, &dev_attr_mmustat_enable);
return sysfs_create_group(&s->kobj, &mmu_stat_group);
}
#ifdef CONFIG_HOTPLUG_CPU
static void unregister_mmu_stats(struct device *s)
{
if (!mmu_stats_supported)
return;
sysfs_remove_group(&s->kobj, &mmu_stat_group);
device_remove_file(s, &dev_attr_mmustat_enable);
}
#endif
#define SHOW_CPUDATA_ULONG_NAME(NAME, MEMBER) \
static ssize_t show_##NAME(struct device *dev, \
struct device_attribute *attr, char *buf) \
{ \
cpuinfo_sparc *c = &cpu_data(dev->id); \
return sprintf(buf, "%lu\n", c->MEMBER); \
}
#define SHOW_CPUDATA_UINT_NAME(NAME, MEMBER) \
static ssize_t show_##NAME(struct device *dev, \
struct device_attribute *attr, char *buf) \
{ \
cpuinfo_sparc *c = &cpu_data(dev->id); \
return sprintf(buf, "%u\n", c->MEMBER); \
}
SHOW_CPUDATA_ULONG_NAME(clock_tick, clock_tick);
SHOW_CPUDATA_UINT_NAME(l1_dcache_size, dcache_size);
SHOW_CPUDATA_UINT_NAME(l1_dcache_line_size, dcache_line_size);
SHOW_CPUDATA_UINT_NAME(l1_icache_size, icache_size);
SHOW_CPUDATA_UINT_NAME(l1_icache_line_size, icache_line_size);
SHOW_CPUDATA_UINT_NAME(l2_cache_size, ecache_size);
SHOW_CPUDATA_UINT_NAME(l2_cache_line_size, ecache_line_size);
static struct device_attribute cpu_core_attrs[] = {
__ATTR(clock_tick, 0444, show_clock_tick, NULL),
__ATTR(l1_dcache_size, 0444, show_l1_dcache_size, NULL),
__ATTR(l1_dcache_line_size, 0444, show_l1_dcache_line_size, NULL),
__ATTR(l1_icache_size, 0444, show_l1_icache_size, NULL),
__ATTR(l1_icache_line_size, 0444, show_l1_icache_line_size, NULL),
__ATTR(l2_cache_size, 0444, show_l2_cache_size, NULL),
__ATTR(l2_cache_line_size, 0444, show_l2_cache_line_size, NULL),
};
static DEFINE_PER_CPU(struct cpu, cpu_devices);
static int register_cpu_online(unsigned int cpu)
{
struct cpu *c = &per_cpu(cpu_devices, cpu);
struct device *s = &c->dev;
int i;
for (i = 0; i < ARRAY_SIZE(cpu_core_attrs); i++)
device_create_file(s, &cpu_core_attrs[i]);
register_mmu_stats(s);
return 0;
}
static int unregister_cpu_online(unsigned int cpu)
{
#ifdef CONFIG_HOTPLUG_CPU
struct cpu *c = &per_cpu(cpu_devices, cpu);
struct device *s = &c->dev;
int i;
unregister_mmu_stats(s);
for (i = 0; i < ARRAY_SIZE(cpu_core_attrs); i++)
device_remove_file(s, &cpu_core_attrs[i]);
#endif
return 0;
}
static void __init check_mmu_stats(void)
{
unsigned long dummy1, err;
if (tlb_type != hypervisor)
return;
err = sun4v_mmustat_info(&dummy1);
if (!err)
mmu_stats_supported = 1;
}
static void register_nodes(void)
{
#ifdef CONFIG_NUMA
int i;
for (i = 0; i < MAX_NUMNODES; i++)
register_one_node(i);
#endif
}
static int __init topology_init(void)
{
int cpu, ret;
register_nodes();
check_mmu_stats();
for_each_possible_cpu(cpu) {
struct cpu *c = &per_cpu(cpu_devices, cpu);
register_cpu(c, cpu);
}
ret = cpuhp_setup_state(CPUHP_AP_ONLINE_DYN, "sparc/topology:online",
register_cpu_online, unregister_cpu_online);
WARN_ON(ret < 0);
return 0;
}
subsys_initcall(topology_init);
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