From: Aubrey Li <aubrey.li@linux.intel.com>
Date: Thu, 6 Jun 2019 09:22:34 +0800
Subject: proc: Add /proc/<pid>/arch_status
Git-commit: 68bc30bb9f33fc8d11e3d110d29e06490896a999
Patch-mainline: v5.3-rc1
References: jsc#SLE-4915

Exposing architecture specific per process information is useful for
various reasons. An example is the AVX512 usage on x86 which is important
for task placement for power/performance optimizations.

Adding this information to the existing /prcc/pid/status file would be the
obvious choise, but it has been agreed on that a explicit arch_status file
is better in separating the generic and architecture specific information.

[ tglx: Massage changelog ]

Signed-off-by: Aubrey Li <aubrey.li@linux.intel.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Andrew Morton <akpm@linux-foundation.org>
Cc: peterz@infradead.org
Cc: hpa@zytor.com
Cc: ak@linux.intel.com
Cc: tim.c.chen@linux.intel.com
Cc: dave.hansen@intel.com
Cc: arjan@linux.intel.com
Cc: adobriyan@gmail.com
Cc: aubrey.li@intel.com
Cc: linux-api@vger.kernel.org
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Tim Chen <tim.c.chen@linux.intel.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Arjan van de Ven <arjan@linux.intel.com>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Cc: Linux API <linux-api@vger.kernel.org>
Link: https://lkml.kernel.org/r/20190606012236.9391-1-aubrey.li@linux.intel.com

Acked-by: Joerg Roedel <jroedel@suse.de>
---
 fs/proc/Kconfig         | 4 ++++
 fs/proc/base.c          | 6 ++++++
 include/linux/proc_fs.h | 9 +++++++++
 3 files changed, 19 insertions(+)

--- a/fs/proc/Kconfig
+++ b/fs/proc/Kconfig
@@ -96,3 +96,7 @@ config PROC_CHILDREN
 
 	  Say Y if you are running any user-space software which takes benefit from
 	  this interface. For example, rkt is such a piece of software.
+
+config PROC_PID_ARCH_STATUS
+	def_bool n
+	depends on PROC_FS
--- a/fs/proc/base.c
+++ b/fs/proc/base.c
@@ -2962,6 +2962,9 @@ static const struct pid_entry tgid_base_
 #ifdef CONFIG_LIVEPATCH
 	ONE("patch_state",  S_IRUSR, proc_pid_patch_state),
 #endif
+#ifdef CONFIG_PROC_PID_ARCH_STATUS
+	ONE("arch_status", S_IRUGO, proc_pid_arch_status),
+#endif
 };
 
 static int proc_tgid_base_readdir(struct file *file, struct dir_context *ctx)
@@ -3347,6 +3350,9 @@ static const struct pid_entry tid_base_s
 #ifdef CONFIG_LIVEPATCH
 	ONE("patch_state",  S_IRUSR, proc_pid_patch_state),
 #endif
+#ifdef CONFIG_PROC_PID_ARCH_STATUS
+	ONE("arch_status", S_IRUGO, proc_pid_arch_status),
+#endif
 };
 
 static int proc_tid_base_readdir(struct file *file, struct dir_context *ctx)
--- a/include/linux/proc_fs.h
+++ b/include/linux/proc_fs.h
@@ -43,6 +43,15 @@ extern void proc_remove(struct proc_dir_
 extern void remove_proc_entry(const char *, struct proc_dir_entry *);
 extern int remove_proc_subtree(const char *, struct proc_dir_entry *);
 
+#ifdef CONFIG_PROC_PID_ARCH_STATUS
+/*
+ * The architecture which selects CONFIG_PROC_PID_ARCH_STATUS must
+ * provide proc_pid_arch_status() definition.
+ */
+int proc_pid_arch_status(struct seq_file *m, struct pid_namespace *ns,
+			struct pid *pid, struct task_struct *task);
+#endif /* CONFIG_PROC_PID_ARCH_STATUS */
+
 #else /* CONFIG_PROC_FS */
 
 static inline void proc_root_init(void)