Revision 89c38422e072bb453e3045b8f1b962a344c3edea authored by John Garry on 08 November 2018, 10:17:03 UTC, committed by Rob Herring on 08 November 2018, 18:44:34 UTC
Currently the NUMA distance map parsing does not validate the distance table for the distance-matrix rules 1-2 in [1]. However the arch NUMA code may enforce some of these rules, but not all. Such is the case for the arm64 port, which does not enforce the rule that the distance between separates nodes cannot equal LOCAL_DISTANCE. The patch adds the following rules validation: - distance of node to self equals LOCAL_DISTANCE - distance of separate nodes > LOCAL_DISTANCE This change avoids a yet-unresolved crash reported in [2]. A note on dealing with symmetrical distances between nodes: Validating symmetrical distances between nodes is difficult. If it were mandated in the bindings that every distance must be recorded in the table, then it would be easy. However, it isn't. In addition to this, it is also possible to record [b, a] distance only (and not [a, b]). So, when processing the table for [b, a], we cannot assert that current distance of [a, b] != [b, a] as invalid, as [a, b] distance may not be present in the table and current distance would be default at REMOTE_DISTANCE. As such, we maintain the policy that we overwrite distance [a, b] = [b, a] for b > a. This policy is different to kernel ACPI SLIT validation, which allows non-symmetrical distances (ACPI spec SLIT rules allow it). However, the distance debug message is dropped as it may be misleading (for a distance which is later overwritten). Some final notes on semantics: - It is implied that it is the responsibility of the arch NUMA code to reset the NUMA distance map for an error in distance map parsing. - It is the responsibility of the FW NUMA topology parsing (whether OF or ACPI) to enforce NUMA distance rules, and not arch NUMA code. [1] Documents/devicetree/bindings/numa.txt [2] https://www.spinics.net/lists/arm-kernel/msg683304.html Cc: stable@vger.kernel.org # 4.7 Signed-off-by: John Garry <john.garry@huawei.com> Acked-by: Will Deacon <will.deacon@arm.com> Signed-off-by: Rob Herring <robh@kernel.org>
1 parent 6778be4
utsname_sysctl.c
/*
* Copyright (C) 2007
*
* Author: Eric Biederman <ebiederm@xmision.com>
*
* 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, version 2 of the
* License.
*/
#include <linux/export.h>
#include <linux/uts.h>
#include <linux/utsname.h>
#include <linux/sysctl.h>
#include <linux/wait.h>
#include <linux/rwsem.h>
#ifdef CONFIG_PROC_SYSCTL
static void *get_uts(struct ctl_table *table)
{
char *which = table->data;
struct uts_namespace *uts_ns;
uts_ns = current->nsproxy->uts_ns;
which = (which - (char *)&init_uts_ns) + (char *)uts_ns;
return which;
}
/*
* Special case of dostring for the UTS structure. This has locks
* to observe. Should this be in kernel/sys.c ????
*/
static int proc_do_uts_string(struct ctl_table *table, int write,
void __user *buffer, size_t *lenp, loff_t *ppos)
{
struct ctl_table uts_table;
int r;
char tmp_data[__NEW_UTS_LEN + 1];
memcpy(&uts_table, table, sizeof(uts_table));
uts_table.data = tmp_data;
/*
* Buffer the value in tmp_data so that proc_dostring() can be called
* without holding any locks.
* We also need to read the original value in the write==1 case to
* support partial writes.
*/
down_read(&uts_sem);
memcpy(tmp_data, get_uts(table), sizeof(tmp_data));
up_read(&uts_sem);
r = proc_dostring(&uts_table, write, buffer, lenp, ppos);
if (write) {
/*
* Write back the new value.
* Note that, since we dropped uts_sem, the result can
* theoretically be incorrect if there are two parallel writes
* at non-zero offsets to the same sysctl.
*/
down_write(&uts_sem);
memcpy(get_uts(table), tmp_data, sizeof(tmp_data));
up_write(&uts_sem);
proc_sys_poll_notify(table->poll);
}
return r;
}
#else
#define proc_do_uts_string NULL
#endif
static DEFINE_CTL_TABLE_POLL(hostname_poll);
static DEFINE_CTL_TABLE_POLL(domainname_poll);
static struct ctl_table uts_kern_table[] = {
{
.procname = "ostype",
.data = init_uts_ns.name.sysname,
.maxlen = sizeof(init_uts_ns.name.sysname),
.mode = 0444,
.proc_handler = proc_do_uts_string,
},
{
.procname = "osrelease",
.data = init_uts_ns.name.release,
.maxlen = sizeof(init_uts_ns.name.release),
.mode = 0444,
.proc_handler = proc_do_uts_string,
},
{
.procname = "version",
.data = init_uts_ns.name.version,
.maxlen = sizeof(init_uts_ns.name.version),
.mode = 0444,
.proc_handler = proc_do_uts_string,
},
{
.procname = "hostname",
.data = init_uts_ns.name.nodename,
.maxlen = sizeof(init_uts_ns.name.nodename),
.mode = 0644,
.proc_handler = proc_do_uts_string,
.poll = &hostname_poll,
},
{
.procname = "domainname",
.data = init_uts_ns.name.domainname,
.maxlen = sizeof(init_uts_ns.name.domainname),
.mode = 0644,
.proc_handler = proc_do_uts_string,
.poll = &domainname_poll,
},
{}
};
static struct ctl_table uts_root_table[] = {
{
.procname = "kernel",
.mode = 0555,
.child = uts_kern_table,
},
{}
};
#ifdef CONFIG_PROC_SYSCTL
/*
* Notify userspace about a change in a certain entry of uts_kern_table,
* identified by the parameter proc.
*/
void uts_proc_notify(enum uts_proc proc)
{
struct ctl_table *table = &uts_kern_table[proc];
proc_sys_poll_notify(table->poll);
}
#endif
static int __init utsname_sysctl_init(void)
{
register_sysctl_table(uts_root_table);
return 0;
}
device_initcall(utsname_sysctl_init);
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