Add a line in /proc/$PID/arch_status to report untag_mask. It can be
used to find out LAM status of the process from the outside. It is
useful for debuggers.
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx>
Tested-by: Alexander Potapenko <glider@xxxxxxxxxx>
Acked-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
---
arch/x86/include/asm/mmu_context.h | 10 +++++
arch/x86/kernel/Makefile | 2 +
arch/x86/kernel/fpu/xstate.c | 47 -----------------------
arch/x86/kernel/proc.c | 60 ++++++++++++++++++++++++++++++
4 files changed, 72 insertions(+), 47 deletions(-)
create mode 100644 arch/x86/kernel/proc.c
diff --git a/arch/x86/include/asm/mmu_context.h b/arch/x86/include/asm/mmu_context.h
index 5bd3d46685dc..b0e9ea23758b 100644
--- a/arch/x86/include/asm/mmu_context.h
+++ b/arch/x86/include/asm/mmu_context.h
@@ -103,6 +103,11 @@ static inline void dup_lam(struct mm_struct *oldmm, struct mm_struct *mm)
mm->context.untag_mask = oldmm->context.untag_mask;
}
+static inline unsigned long mm_untag_mask(struct mm_struct *mm)
+{
+ return mm->context.untag_mask;
+}
+
static inline void mm_reset_untag_mask(struct mm_struct *mm)
{
mm->context.untag_mask = -1UL;
@@ -119,6 +124,11 @@ static inline void dup_lam(struct mm_struct *oldmm, struct mm_struct *mm)
{
}
+static inline unsigned long mm_untag_mask(struct mm_struct *mm)
+{
+ return -1UL;
+}
+
static inline void mm_reset_untag_mask(struct mm_struct *mm)
{
}
diff --git a/arch/x86/kernel/Makefile b/arch/x86/kernel/Makefile
index a20a5ebfacd7..fada0e36031b 100644
--- a/arch/x86/kernel/Makefile
+++ b/arch/x86/kernel/Makefile
@@ -139,6 +139,8 @@ obj-$(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 c8340156bfd2..838a6f0627fd 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>
@@ -1745,48 +1743,3 @@ long fpu_xstate_prctl(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..9765b4d05ce4
--- /dev/null
+++ b/arch/x86/kernel/proc.c
@@ -0,0 +1,60 @@
+// SPDX-License-Identifier: GPL-2.0-only
+#include <linux/proc_fs.h>
+#include <linux/sched/mm.h>
+#include <linux/seq_file.h>
+#include <uapi/asm/prctl.h>
+#include <asm/mmu_context.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');
+}
+
+/*
+ * Report architecture specific information
+ */
+int proc_pid_arch_status(struct seq_file *m, struct pid_namespace *ns,
+ struct pid *pid, struct task_struct *task)
+{
+ struct mm_struct *mm;
+ unsigned long untag_mask = -1UL;
+
+ /*
+ * Report AVX512 state if the processor and build option supported.
+ */
+ if (cpu_feature_enabled(X86_FEATURE_AVX512F))
+ avx512_status(m, task);
+
+ mm = get_task_mm(task);
+ if (mm) {
+ untag_mask = mm_untag_mask(task->mm);
+ mmput(mm);
+ }
+
+ seq_printf(m, "untag_mask:\t%#lx\n", untag_mask);
+
+ return 0;
+}
--
2.35.1
