linux/drivers/base/topology.c
Phil Auld 7ee951acd3 drivers/base: fix userspace break from using bin_attributes for cpumap and cpulist
Using bin_attributes with a 0 size causes fstat and friends to return that
0 size. This breaks userspace code that retrieves the size before reading
the file. Rather than reverting 75bd50fa84 ("drivers/base/node.c: use
bin_attribute to break the size limitation of cpumap ABI") let's put in a
size value at compile time.

For cpulist the maximum size is on the order of
	NR_CPUS * (ceil(log10(NR_CPUS)) + 1)/2

which for 8192 is 20480 (8192 * 5)/2. In order to get near that you'd need
a system with every other CPU on one node. For example: (0,2,4,8, ... ).
To simplify the math and support larger NR_CPUS in the future we are using
(NR_CPUS * 7)/2. We also set it to a min of PAGE_SIZE to retain the older
behavior for smaller NR_CPUS.

The cpumap file the size works out to be NR_CPUS/4 + NR_CPUS/32 - 1
(or NR_CPUS * 9/32 - 1) including the ","s.

Add a set of macros for these values to cpumask.h so they can be used in
multiple places. Apply these to the handful of such files in
drivers/base/topology.c as well as node.c.

As an example, on an 80 cpu 4-node system (NR_CPUS == 8192):

before:

-r--r--r--. 1 root root 0 Jul 12 14:08 system/node/node0/cpulist
-r--r--r--. 1 root root 0 Jul 11 17:25 system/node/node0/cpumap

after:

-r--r--r--. 1 root root 28672 Jul 13 11:32 system/node/node0/cpulist
-r--r--r--. 1 root root  4096 Jul 13 11:31 system/node/node0/cpumap

CONFIG_NR_CPUS = 16384
-r--r--r--. 1 root root 57344 Jul 13 14:03 system/node/node0/cpulist
-r--r--r--. 1 root root  4607 Jul 13 14:02 system/node/node0/cpumap

The actual number of cpus doesn't matter for the reported size since they
are based on NR_CPUS.

Fixes: 75bd50fa84 ("drivers/base/node.c: use bin_attribute to break the size limitation of cpumap ABI")
Fixes: bb9ec13d15 ("topology: use bin_attribute to break the size limitation of cpumap ABI")
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: "Rafael J. Wysocki" <rafael@kernel.org>
Cc: Yury Norov <yury.norov@gmail.com>
Cc: stable@vger.kernel.org
Acked-by: Yury Norov <yury.norov@gmail.com> (for include/linux/cpumask.h)
Signed-off-by: Phil Auld <pauld@redhat.com>
Link: https://lore.kernel.org/r/20220715134924.3466194-1-pauld@redhat.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2022-07-15 17:36:33 +02:00

195 lines
5.4 KiB
C

// SPDX-License-Identifier: GPL-2.0+
/*
* driver/base/topology.c - Populate sysfs with cpu topology information
*
* Written by: Zhang Yanmin, Intel Corporation
*
* Copyright (C) 2006, Intel Corp.
*
* All rights reserved.
*/
#include <linux/mm.h>
#include <linux/cpu.h>
#include <linux/module.h>
#include <linux/hardirq.h>
#include <linux/topology.h>
#define define_id_show_func(name, fmt) \
static ssize_t name##_show(struct device *dev, \
struct device_attribute *attr, char *buf) \
{ \
return sysfs_emit(buf, fmt "\n", topology_##name(dev->id)); \
}
#define define_siblings_read_func(name, mask) \
static ssize_t name##_read(struct file *file, struct kobject *kobj, \
struct bin_attribute *attr, char *buf, \
loff_t off, size_t count) \
{ \
struct device *dev = kobj_to_dev(kobj); \
\
return cpumap_print_bitmask_to_buf(buf, topology_##mask(dev->id), \
off, count); \
} \
\
static ssize_t name##_list_read(struct file *file, struct kobject *kobj, \
struct bin_attribute *attr, char *buf, \
loff_t off, size_t count) \
{ \
struct device *dev = kobj_to_dev(kobj); \
\
return cpumap_print_list_to_buf(buf, topology_##mask(dev->id), \
off, count); \
}
define_id_show_func(physical_package_id, "%d");
static DEVICE_ATTR_RO(physical_package_id);
#ifdef TOPOLOGY_DIE_SYSFS
define_id_show_func(die_id, "%d");
static DEVICE_ATTR_RO(die_id);
#endif
#ifdef TOPOLOGY_CLUSTER_SYSFS
define_id_show_func(cluster_id, "%d");
static DEVICE_ATTR_RO(cluster_id);
#endif
define_id_show_func(core_id, "%d");
static DEVICE_ATTR_RO(core_id);
define_id_show_func(ppin, "0x%llx");
static DEVICE_ATTR_ADMIN_RO(ppin);
define_siblings_read_func(thread_siblings, sibling_cpumask);
static BIN_ATTR_RO(thread_siblings, CPUMAP_FILE_MAX_BYTES);
static BIN_ATTR_RO(thread_siblings_list, CPULIST_FILE_MAX_BYTES);
define_siblings_read_func(core_cpus, sibling_cpumask);
static BIN_ATTR_RO(core_cpus, CPUMAP_FILE_MAX_BYTES);
static BIN_ATTR_RO(core_cpus_list, CPULIST_FILE_MAX_BYTES);
define_siblings_read_func(core_siblings, core_cpumask);
static BIN_ATTR_RO(core_siblings, CPUMAP_FILE_MAX_BYTES);
static BIN_ATTR_RO(core_siblings_list, CPULIST_FILE_MAX_BYTES);
#ifdef TOPOLOGY_CLUSTER_SYSFS
define_siblings_read_func(cluster_cpus, cluster_cpumask);
static BIN_ATTR_RO(cluster_cpus, CPUMAP_FILE_MAX_BYTES);
static BIN_ATTR_RO(cluster_cpus_list, CPULIST_FILE_MAX_BYTES);
#endif
#ifdef TOPOLOGY_DIE_SYSFS
define_siblings_read_func(die_cpus, die_cpumask);
static BIN_ATTR_RO(die_cpus, CPUMAP_FILE_MAX_BYTES);
static BIN_ATTR_RO(die_cpus_list, CPULIST_FILE_MAX_BYTES);
#endif
define_siblings_read_func(package_cpus, core_cpumask);
static BIN_ATTR_RO(package_cpus, CPUMAP_FILE_MAX_BYTES);
static BIN_ATTR_RO(package_cpus_list, CPULIST_FILE_MAX_BYTES);
#ifdef TOPOLOGY_BOOK_SYSFS
define_id_show_func(book_id, "%d");
static DEVICE_ATTR_RO(book_id);
define_siblings_read_func(book_siblings, book_cpumask);
static BIN_ATTR_RO(book_siblings, CPUMAP_FILE_MAX_BYTES);
static BIN_ATTR_RO(book_siblings_list, CPULIST_FILE_MAX_BYTES);
#endif
#ifdef TOPOLOGY_DRAWER_SYSFS
define_id_show_func(drawer_id, "%d");
static DEVICE_ATTR_RO(drawer_id);
define_siblings_read_func(drawer_siblings, drawer_cpumask);
static BIN_ATTR_RO(drawer_siblings, CPUMAP_FILE_MAX_BYTES);
static BIN_ATTR_RO(drawer_siblings_list, CPULIST_FILE_MAX_BYTES);
#endif
static struct bin_attribute *bin_attrs[] = {
&bin_attr_core_cpus,
&bin_attr_core_cpus_list,
&bin_attr_thread_siblings,
&bin_attr_thread_siblings_list,
&bin_attr_core_siblings,
&bin_attr_core_siblings_list,
#ifdef TOPOLOGY_CLUSTER_SYSFS
&bin_attr_cluster_cpus,
&bin_attr_cluster_cpus_list,
#endif
#ifdef TOPOLOGY_DIE_SYSFS
&bin_attr_die_cpus,
&bin_attr_die_cpus_list,
#endif
&bin_attr_package_cpus,
&bin_attr_package_cpus_list,
#ifdef TOPOLOGY_BOOK_SYSFS
&bin_attr_book_siblings,
&bin_attr_book_siblings_list,
#endif
#ifdef TOPOLOGY_DRAWER_SYSFS
&bin_attr_drawer_siblings,
&bin_attr_drawer_siblings_list,
#endif
NULL
};
static struct attribute *default_attrs[] = {
&dev_attr_physical_package_id.attr,
#ifdef TOPOLOGY_DIE_SYSFS
&dev_attr_die_id.attr,
#endif
#ifdef TOPOLOGY_CLUSTER_SYSFS
&dev_attr_cluster_id.attr,
#endif
&dev_attr_core_id.attr,
#ifdef TOPOLOGY_BOOK_SYSFS
&dev_attr_book_id.attr,
#endif
#ifdef TOPOLOGY_DRAWER_SYSFS
&dev_attr_drawer_id.attr,
#endif
&dev_attr_ppin.attr,
NULL
};
static umode_t topology_is_visible(struct kobject *kobj,
struct attribute *attr, int unused)
{
if (attr == &dev_attr_ppin.attr && !topology_ppin(kobj_to_dev(kobj)->id))
return 0;
return attr->mode;
}
static const struct attribute_group topology_attr_group = {
.attrs = default_attrs,
.bin_attrs = bin_attrs,
.is_visible = topology_is_visible,
.name = "topology"
};
/* Add/Remove cpu_topology interface for CPU device */
static int topology_add_dev(unsigned int cpu)
{
struct device *dev = get_cpu_device(cpu);
return sysfs_create_group(&dev->kobj, &topology_attr_group);
}
static int topology_remove_dev(unsigned int cpu)
{
struct device *dev = get_cpu_device(cpu);
sysfs_remove_group(&dev->kobj, &topology_attr_group);
return 0;
}
static int __init topology_sysfs_init(void)
{
return cpuhp_setup_state(CPUHP_TOPOLOGY_PREPARE,
"base/topology:prepare", topology_add_dev,
topology_remove_dev);
}
device_initcall(topology_sysfs_init);