linux-kernel - [RFCv2 10/10] x86: Expose thread features status in /proc/$PID/arch

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Date:   Wed, 11 May 2022 05:27:51 +0300
From:   "Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>
To:     Dave Hansen <dave.hansen@...ux.intel.com>,
        Andy Lutomirski <luto@...nel.org>,
        Peter Zijlstra <peterz@...radead.org>
Cc:     x86@...nel.org, Andrey Ryabinin <aryabinin@...tuozzo.com>,
        Alexander Potapenko <glider@...gle.com>,
        Dmitry Vyukov <dvyukov@...gle.com>,
        "H . J . Lu" <hjl.tools@...il.com>,
        Andi Kleen <ak@...ux.intel.com>,
        Rick Edgecombe <rick.p.edgecombe@...el.com>,
        linux-mm@...ck.org, linux-kernel@...r.kernel.org,
        "Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>
Subject: [RFCv2 10/10] x86: Expose thread features status in /proc/$PID/arch_status

Add two lines in /proc/$PID/arch_status to report enabled and locked
features.

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@...ux.intel.com>
---
 arch/x86/kernel/Makefile     |  2 ++
 arch/x86/kernel/fpu/xstate.c | 47 ---------------------------
 arch/x86/kernel/proc.c       | 63 ++++++++++++++++++++++++++++++++++++
 3 files changed, 65 insertions(+), 47 deletions(-)
 create mode 100644 arch/x86/kernel/proc.c

diff --git a/arch/x86/kernel/Makefile b/arch/x86/kernel/Makefile
index c41ef42adbe8..19dae7a4201b 100644
--- a/arch/x86/kernel/Makefile
+++ b/arch/x86/kernel/Makefile
@@ -149,6 +149,8 @@ obj-$(CONFIG_UNWINDER_GUESS)		+= unwind_guess.o
 
 obj-$(CONFIG_AMD_MEM_ENCRYPT)		+= sev.o
 
+obj-$(CONFIG_PROC_FS)			+= proc.o
+
 ###
 # 64 bit specific files
 ifeq ($(CONFIG_X86_64),y)
diff --git a/arch/x86/kernel/fpu/xstate.c b/arch/x86/kernel/fpu/xstate.c
index 39e1c8626ab9..789a7a1429df 100644
--- a/arch/x86/kernel/fpu/xstate.c
+++ b/arch/x86/kernel/fpu/xstate.c
@@ -10,8 +10,6 @@
 #include <linux/mman.h>
 #include <linux/nospec.h>
 #include <linux/pkeys.h>
-#include <linux/seq_file.h>
-#include <linux/proc_fs.h>
 #include <linux/vmalloc.h>
 
 #include <asm/fpu/api.h>
@@ -1730,48 +1728,3 @@ long fpu_xstate_prctl(struct task_struct *tsk, int option, unsigned long arg2)
 		return -EINVAL;
 	}
 }
-
-#ifdef CONFIG_PROC_PID_ARCH_STATUS
-/*
- * Report the amount of time elapsed in millisecond since last AVX512
- * use in the task.
- */
-static void avx512_status(struct seq_file *m, struct task_struct *task)
-{
-	unsigned long timestamp = READ_ONCE(task->thread.fpu.avx512_timestamp);
-	long delta;
-
-	if (!timestamp) {
-		/*
-		 * Report -1 if no AVX512 usage
-		 */
-		delta = -1;
-	} else {
-		delta = (long)(jiffies - timestamp);
-		/*
-		 * Cap to LONG_MAX if time difference > LONG_MAX
-		 */
-		if (delta < 0)
-			delta = LONG_MAX;
-		delta = jiffies_to_msecs(delta);
-	}
-
-	seq_put_decimal_ll(m, "AVX512_elapsed_ms:\t", delta);
-	seq_putc(m, '\n');
-}
-
-/*
- * Report architecture specific information
- */
-int proc_pid_arch_status(struct seq_file *m, struct pid_namespace *ns,
-			struct pid *pid, struct task_struct *task)
-{
-	/*
-	 * Report AVX512 state if the processor and build option supported.
-	 */
-	if (cpu_feature_enabled(X86_FEATURE_AVX512F))
-		avx512_status(m, task);
-
-	return 0;
-}
-#endif /* CONFIG_PROC_PID_ARCH_STATUS */
diff --git a/arch/x86/kernel/proc.c b/arch/x86/kernel/proc.c
new file mode 100644
index 000000000000..7b2f39031d8a
--- /dev/null
+++ b/arch/x86/kernel/proc.c
@@ -0,0 +1,63 @@
+// SPDX-License-Identifier: GPL-2.0-only
+#include <linux/seq_file.h>
+#include <linux/proc_fs.h>
+#include <uapi/asm/prctl.h>
+
+/*
+ * Report the amount of time elapsed in millisecond since last AVX512
+ * use in the task.
+ */
+static void avx512_status(struct seq_file *m, struct task_struct *task)
+{
+	unsigned long timestamp = READ_ONCE(task->thread.fpu.avx512_timestamp);
+	long delta;
+
+	if (!timestamp) {
+		/*
+		 * Report -1 if no AVX512 usage
+		 */
+		delta = -1;
+	} else {
+		delta = (long)(jiffies - timestamp);
+		/*
+		 * Cap to LONG_MAX if time difference > LONG_MAX
+		 */
+		if (delta < 0)
+			delta = LONG_MAX;
+		delta = jiffies_to_msecs(delta);
+	}
+
+	seq_put_decimal_ll(m, "AVX512_elapsed_ms:\t", delta);
+	seq_putc(m, '\n');
+}
+
+static void dump_features(struct seq_file *m, unsigned long features)
+{
+	if (features & X86_THREAD_LAM_U48)
+		seq_puts(m, "lam_u48 ");
+	if (features & X86_THREAD_LAM_U57)
+		seq_puts(m, "lam_u57 ");
+}
+
+/*
+ * Report architecture specific information
+ */
+int proc_pid_arch_status(struct seq_file *m, struct pid_namespace *ns,
+			struct pid *pid, struct task_struct *task)
+{
+	/*
+	 * Report AVX512 state if the processor and build option supported.
+	 */
+	if (cpu_feature_enabled(X86_FEATURE_AVX512F))
+		avx512_status(m, task);
+
+	seq_puts(m, "Thread_features:\t");
+	dump_features(m, task->thread.features);
+	seq_putc(m, '\n');
+
+	seq_puts(m, "Thread_features_locked:\t");
+	dump_features(m, task->thread.features_locked);
+	seq_putc(m, '\n');
+
+	return 0;
+}
-- 
2.35.1