mm: Expose untagging mask in /proc/$PID/status

Add a line in /proc/$PID/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@linux.intel.com>
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Tested-by: Alexander Potapenko <glider@google.com>
Link: https://lore.kernel.org/all/20230312112612.31869-10-kirill.shutemov%40linux.intel.com

diff --git a/arch/arm64/include/asm/mmu_context.h b/arch/arm64/include/asm/mmu_context.h
index 72dbd6400549c185edf0c6bc09d096c35bb2ff65..56911691bef05207d88496f665d1df5e7edb66ee 100644 (file)
--- a/arch/arm64/include/asm/mmu_context.h
+++ b/arch/arm64/include/asm/mmu_context.h
@@ -288,6 +288,12 @@ void post_ttbr_update_workaround(void);
 unsigned long arm64_mm_context_get(struct mm_struct *mm);
 void arm64_mm_context_put(struct mm_struct *mm);
 
+#define mm_untag_mask mm_untag_mask
+static inline unsigned long mm_untag_mask(struct mm_struct *mm)
+{
+       return -1UL >> 8;
+}
+
 #include <asm-generic/mmu_context.h>
 
 #endif /* !__ASSEMBLY__ */

diff --git a/arch/sparc/include/asm/mmu_context_64.h b/arch/sparc/include/asm/mmu_context_64.h
index 7a8380c63aab094c49a568883451a6a1e1e591f4..799e797c5cddc10e5793480a1349ba8786e65da2 100644 (file)
--- a/arch/sparc/include/asm/mmu_context_64.h
+++ b/arch/sparc/include/asm/mmu_context_64.h
@@ -185,6 +185,12 @@ static inline void finish_arch_post_lock_switch(void)
        }
 }
 
+#define mm_untag_mask mm_untag_mask
+static inline unsigned long mm_untag_mask(struct mm_struct *mm)
+{
+       return -1UL >> adi_nbits();
+}
+
 #include <asm-generic/mmu_context.h>
 
 #endif /* !(__ASSEMBLY__) */

diff --git a/arch/x86/include/asm/mmu_context.h b/arch/x86/include/asm/mmu_context.h
index eb1387ac40fa9ee7fac6ea51f3cd97c7c6af5439..06eaaf75d57213617022024d43b244efe5747419 100644 (file)
--- a/arch/x86/include/asm/mmu_context.h
+++ b/arch/x86/include/asm/mmu_context.h
@@ -104,6 +104,12 @@ static inline void dup_lam(struct mm_struct *oldmm, struct mm_struct *mm)
        mm->context.untag_mask = oldmm->context.untag_mask;
 }
 
+#define mm_untag_mask mm_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;

diff --git a/fs/proc/array.c b/fs/proc/array.c
index 9b0315d34c58fb3d1780901cd420d02d1d53f269..6daea628bc76587a5c55927d0aea1a1bdb26cf77 100644 (file)
--- a/fs/proc/array.c
+++ b/fs/proc/array.c
@@ -91,6 +91,7 @@
 #include <linux/user_namespace.h>
 #include <linux/fs_struct.h>
 #include <linux/kthread.h>
+#include <linux/mmu_context.h>
 
 #include <asm/processor.h>
 #include "internal.h"
@@ -423,6 +424,11 @@ static inline void task_thp_status(struct seq_file *m, struct mm_struct *mm)
        seq_printf(m, "THP_enabled:\t%d\n", thp_enabled);
 }
 
+static inline void task_untag_mask(struct seq_file *m, struct mm_struct *mm)
+{
+       seq_printf(m, "untag_mask:\t%#lx\n", mm_untag_mask(mm));
+}
+
 int proc_pid_status(struct seq_file *m, struct pid_namespace *ns,
                        struct pid *pid, struct task_struct *task)
 {
@@ -438,6 +444,7 @@ int proc_pid_status(struct seq_file *m, struct pid_namespace *ns,
                task_mem(m, mm);
                task_core_dumping(m, task);
                task_thp_status(m, mm);
+               task_untag_mask(m, mm);
                mmput(mm);
        }
        task_sig(m, task);

diff --git a/include/linux/mmu_context.h b/include/linux/mmu_context.h
index b9b970f7ab45a58bcc79ece84b5479d0d4420f7c..14b9c1fa05c49f27d5843ca415e594c832c7f979 100644 (file)
--- a/include/linux/mmu_context.h
+++ b/include/linux/mmu_context.h
@@ -28,4 +28,11 @@ static inline void leave_mm(int cpu) { }
 # define task_cpu_possible(cpu, p)     cpumask_test_cpu((cpu), task_cpu_possible_mask(p))
 #endif
 
+#ifndef mm_untag_mask
+static inline unsigned long mm_untag_mask(struct mm_struct *mm)
+{
+       return -1UL;
+}
+#endif
+
 #endif