proc: Add /proc/<pid>/arch_status

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

2 files changed, 10 insertions, 0 deletions

diff --git a/fs/proc/Kconfig b/fs/proc/Kconfig
index 62ee41b4bbd0..4c3dcb718961 100644
--- a/fs/proc/Kconfig
+++ b/fs/proc/Kconfig
@@ -98,3 +98,7 @@ 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
diff --git a/fs/proc/base.c b/fs/proc/base.c
index 9c8ca6cd3ce4..ec436c61eece 100644
--- a/fs/proc/base.c
+++ b/fs/proc/base.c
@@ -3061,6 +3061,9 @@ static const struct pid_entry tgid_base_stuff[] = {
 #ifdef CONFIG_STACKLEAK_METRICS
         ONE("stack_depth", S_IRUGO, proc_stack_depth),
 #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)
@@ -3449,6 +3452,9 @@ static const struct pid_entry tid_base_stuff[] = {
 #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)