[RFC PATCH 1/7] asm-generic: add generic MMU versions of mmu context functions

Nicholas Piggin
2020-07-10T01:57:14Z

Many of these are no-ops on many architectures, so extend mmu_context.h
to cover MMU and NOMMU, and split the NOMMU bits out to nommu_context.h

Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Remis Lima Baima <remis.developer@googlemail.com>
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
---
arch/microblaze/include/asm/mmu_context.h | 2 +-
arch/sh/include/asm/mmu_context.h | 2 +-
include/asm-generic/mmu_context.h | 57 +++++++++++++++++------
include/asm-generic/nommu_context.h | 19 ++++++++
4 files changed, 64 insertions(+), 16 deletions(-)
create mode 100644 include/asm-generic/nommu_context.h

diff --git a/arch/microblaze/include/asm/mmu_context.h b/arch/microblaze/include/asm/mmu_context.h
index f74f9da07fdc..34004efb3def 100644
--- a/arch/microblaze/include/asm/mmu_context.h
+++ b/arch/microblaze/include/asm/mmu_context.h
@@ -2,5 +2,5 @@
#ifdef CONFIG_MMU
# include <asm/mmu_context_mm.h>
#else
-# include <asm-generic/mmu_context.h>
+# include <asm-generic/nommu_context.h>
#endif
diff --git a/arch/sh/include/asm/mmu_context.h b/arch/sh/include/asm/mmu_context.h
index 48e67d544d53..9470d17c71c2 100644
--- a/arch/sh/include/asm/mmu_context.h
+++ b/arch/sh/include/asm/mmu_context.h
@@ -134,7 +134,7 @@ static inline void switch_mm(struct mm_struct *prev,
#define set_TTB(pgd) do { } while (0)
#define get_TTB() (0)

-#include <asm-generic/mmu_context.h>
+#include <asm-generic/nommu_context.h>

#endif /* CONFIG_MMU */

diff --git a/include/asm-generic/mmu_context.h b/include/asm-generic/mmu_context.h
index 6be9106fb6fb..86cea80a50df 100644
--- a/include/asm-generic/mmu_context.h
+++ b/include/asm-generic/mmu_context.h
@@ -3,44 +3,73 @@
#define __ASM_GENERIC_MMU_CONTEXT_H

/*
- * Generic hooks for NOMMU architectures, which do not need to do
- * anything special here.
+ * Generic hooks to implement no-op functionality.
*/

-#include <asm-generic/mm_hooks.h>
-
struct task_struct;
struct mm_struct;

+/*
+ * enter_lazy_tlb - Called when "tsk" is about to enter lazy TLB mode.
+ *
+ * @mm: the currently active mm context which is becoming lazy
+ * @tsk: task which is entering lazy tlb
+ *
+ * tsk->mm will be NULL
+ */
+#ifndef enter_lazy_tlb
static inline void enter_lazy_tlb(struct mm_struct *mm,
struct task_struct *tsk)
{
}
+#endif

+/**
+ * init_new_context - Initialize context of a new mm_struct.
+ * @tsk: task struct for the mm
+ * @mm: the new mm struct
+ */
+#ifndef init_new_context
static inline int init_new_context(struct task_struct *tsk,
struct mm_struct *mm)
{
return 0;
}
+#endif

+/**
+ * destroy_context - Undo init_new_context when the mm is going away
+ * @mm: old mm struct
+ */
+#ifndef destroy_context
static inline void destroy_context(struct mm_struct *mm)
{
}
+#endif

-static inline void deactivate_mm(struct task_struct *task,
- struct mm_struct *mm)
-{
-}
-
-static inline void switch_mm(struct mm_struct *prev,
- struct mm_struct *next,
- struct task_struct *tsk)
+/**
+ * activate_mm - called after exec switches the current task to a new mm, to switch to it
+ * @prev_mm: previous mm of this task
+ * @next_mm: new mm
+ */
+#ifndef activate_mm
+static inline void activate_mm(struct mm_struct *prev_mm,
+ struct mm_struct *next_mm)
{
+ switch_mm(prev_mm, next_mm, current);
}
+#endif

-static inline void activate_mm(struct mm_struct *prev_mm,
- struct mm_struct *next_mm)
+/**
+ * dectivate_mm - called when an mm is released after exit or exec switches away from it
+ * @tsk: the task
+ * @mm: the old mm
+ */
+#ifndef deactivate_mm
+static inline void deactivate_mm(struct task_struct *tsk,
+ struct mm_struct *mm)
{
}
+#endif

#endif /* __ASM_GENERIC_MMU_CONTEXT_H */
diff --git a/include/asm-generic/nommu_context.h b/include/asm-generic/nommu_context.h
new file mode 100644
index 000000000000..72b8d8b1d81e
--- /dev/null
+++ b/include/asm-generic/nommu_context.h
@@ -0,0 +1,19 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef __ASM_GENERIC_NOMMU_H
+#define __ASM_GENERIC_NOMMU_H
+
+/*
+ * Generic hooks for NOMMU architectures, which do not need to do
+ * anything special here.
+ */
+
+#include <asm-generic/mm_hooks.h>
+#include <asm-generic/mmu_context.h>
+
+static inline void switch_mm(struct mm_struct *prev,
+ struct mm_struct *next,
+ struct task_struct *tsk)
+{
+}
+
+#endif /* __ASM_GENERIC_NOMMU_H */
--
2.23.0