linux-kernel - [PATCH v7 29/31] fs/resctrl: Provide interface to create architecture specific debugfs area

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20250711235341.113933-30-tony.luck@intel.com>
Date: Fri, 11 Jul 2025 16:53:36 -0700
From: Tony Luck <tony.luck@...el.com>
To: Fenghua Yu <fenghuay@...dia.com>,
	Reinette Chatre <reinette.chatre@...el.com>,
	Maciej Wieczor-Retman <maciej.wieczor-retman@...el.com>,
	Peter Newman <peternewman@...gle.com>,
	James Morse <james.morse@....com>,
	Babu Moger <babu.moger@....com>,
	Drew Fustini <dfustini@...libre.com>,
	Dave Martin <Dave.Martin@....com>,
	Anil Keshavamurthy <anil.s.keshavamurthy@...el.com>,
	Chen Yu <yu.c.chen@...el.com>
Cc: x86@...nel.org,
	linux-kernel@...r.kernel.org,
	patches@...ts.linux.dev,
	Tony Luck <tony.luck@...el.com>
Subject: [PATCH v7 29/31] fs/resctrl: Provide interface to create architecture specific debugfs area

Architectures are constrained to just the file interfaces provided by
the file system for each resource. This does not allow for architecture
specific debug interfaces.

Add resctrl_debugfs_mon_info_arch_mkdir() which creates a directory in the
debugfs file system for a resource. Naming follows the layout of the
main resctrl hierarchy:

	/sys/kernel/debug/resctrl/info/{resource}_MON/{arch}

The {arch} last level directory name matches the output of
the user level "uname -m" command.

Architecture code may use this directory for debug information,
or for minor tuning of features. It must not be used for basic
feature enabling as debugfs may not be configured/mounted on
production systems.

Suggested-by: Reinette Chatre <reinette.chatre@...el.com>
Signed-off-by: Tony Luck <tony.luck@...el.com>
---
 include/linux/resctrl.h |  9 +++++++++
 fs/resctrl/rdtgroup.c   | 29 +++++++++++++++++++++++++++++
 2 files changed, 38 insertions(+)

diff --git a/include/linux/resctrl.h b/include/linux/resctrl.h
index 74cd2979549b..ed5085eeee1b 100644
--- a/include/linux/resctrl.h
+++ b/include/linux/resctrl.h
@@ -571,6 +571,15 @@ void resctrl_arch_reset_all_ctrls(struct rdt_resource *r);
 extern unsigned int resctrl_rmid_realloc_threshold;
 extern unsigned int resctrl_rmid_realloc_limit;
 
+/**
+ * resctrl_debugfs_mon_info_arch_mkdir() - Create a debugfs info directory.
+ *					   Removed by resctrl_exit().
+ * @r:	Resource (must be mon_capable).
+ *
+ * Return: dentry pointer on success, or NULL on error.
+ */
+struct dentry *resctrl_debugfs_mon_info_arch_mkdir(struct rdt_resource *r);
+
 int resctrl_init(void);
 void resctrl_exit(void);
 
diff --git a/fs/resctrl/rdtgroup.c b/fs/resctrl/rdtgroup.c
index 9e667d3a93ae..fdd6cf372d6c 100644
--- a/fs/resctrl/rdtgroup.c
+++ b/fs/resctrl/rdtgroup.c
@@ -24,6 +24,7 @@
 #include <linux/sched/task.h>
 #include <linux/slab.h>
 #include <linux/user_namespace.h>
+#include <linux/utsname.h>
 
 #include <uapi/linux/magic.h>
 
@@ -4350,6 +4351,33 @@ int resctrl_init(void)
 	return ret;
 }
 
+static struct dentry *debugfs_resctrl_info;
+
+/*
+ * Create /sys/kernel/debug/resctrl/info/{r->name}_MON/{arch} directory
+ * by request for architecture to use for debugging or minor tuning.
+ * Basic functionality of features must not be controlled by files
+ * added to this directory as debugs may not be configured/mounted
+ * on production systems.
+ */
+struct dentry *resctrl_debugfs_mon_info_arch_mkdir(struct rdt_resource *r)
+{
+	struct dentry *moninfodir;
+	char name[32];
+
+	if (!r->mon_capable)
+		return NULL;
+
+	if (!debugfs_resctrl_info)
+		debugfs_resctrl_info = debugfs_create_dir("info", debugfs_resctrl);
+
+	sprintf(name, "%s_MON", r->name);
+
+	moninfodir = debugfs_create_dir(name, debugfs_resctrl_info);
+
+	return debugfs_create_dir(utsname()->machine, moninfodir);
+}
+
 static bool resctrl_online_domains_exist(void)
 {
 	struct rdt_resource *r;
@@ -4401,6 +4429,7 @@ void resctrl_exit(void)
 
 	debugfs_remove_recursive(debugfs_resctrl);
 	debugfs_resctrl = NULL;
+	debugfs_resctrl_info = NULL;
 	unregister_filesystem(&rdt_fs_type);
 
 	/*
-- 
2.50.0