2022-10-25 01:22:58

by Kirill A. Shutemov

Subject: [PATCHv11 09/16] 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 <[email protected]>
Cc: "David S. Miller" <[email protected]>
Cc: Catalin Marinas <[email protected]>
Cc: Will Deacon <[email protected]>
---
arch/arm64/include/asm/mmu_context.h | 6 ++++++
arch/sparc/include/asm/mmu_context_64.h | 6 ++++++
arch/x86/include/asm/mmu_context.h | 6 ++++++
fs/proc/array.c | 6 ++++++
include/linux/mmu_context.h | 7 +++++++
5 files changed, 31 insertions(+)

diff --git a/arch/arm64/include/asm/mmu_context.h b/arch/arm64/include/asm/mmu_context.h
index d3f8b5df0c1f..81ac12d69795 100644
--- a/arch/arm64/include/asm/mmu_context.h
+++ b/arch/arm64/include/asm/mmu_context.h
@@ -278,6 +278,12 @@ 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 7a8380c63aab..799e797c5cdd 100644
--- 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 5bd3d46685dc..84277547ad28 100644
--- a/arch/x86/include/asm/mmu_context.h
+++ b/arch/x86/include/asm/mmu_context.h
@@ -103,6 +103,12 @@ 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 49283b8103c7..d2a94eafe9a3 100644
--- a/fs/proc/array.c
+++ b/fs/proc/array.c
@@ -428,6 +428,11 @@ 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)
{
@@ -443,6 +448,7 @@ 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 b9b970f7ab45..14b9c1fa05c4 100644
--- 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
--
2.38.0

2022-10-28 14:12:23

by Catalin Marinas

Subject: Re: [PATCHv11 09/16] mm: Expose untagging mask in /proc/$PID/status

On Tue, Oct 25, 2022 at 03:17:15AM +0300, Kirill A. Shutemov wrote:
> diff --git a/arch/arm64/include/asm/mmu_context.h b/arch/arm64/include/asm/mmu_context.h
> index d3f8b5df0c1f..81ac12d69795 100644
> --- a/arch/arm64/include/asm/mmu_context.h
> +++ b/arch/arm64/include/asm/mmu_context.h
> @@ -278,6 +278,12 @@ 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>

For arm64:

Acked-by: Catalin Marinas <[email protected]>