[RFCv2 10/10] x86: Expose thread features status in /proc/$PID/arch_status

Kirill A. Shutemov
2022-05-11T02:30:46Z

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

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.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