Currently, an architecture must either implement all of the mm hooks
itself, or use all of those provided by the asm-generic implementation.
When an architecture only needs to override a single hook, it must copy
the stub implementations from the asm-generic version.

To avoid this repetition, allow each hook to be overridden indiviually,
by placing each under an #ifndef block. As architectures providing their
own hooks can't include this file today, this shouldn't adversely affect
any existing hooks.

Signed-off-by: Mark Rutland <mark.rutl...@arm.com>
Cc: Arnd Bergmann <a...@arndb.de>
Cc: linux-a...@vger.kernel.org
---
 include/asm-generic/mm_hooks.h | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/include/asm-generic/mm_hooks.h b/include/asm-generic/mm_hooks.h
index ea189d88a3cc..34edf0850d49 100644
--- a/include/asm-generic/mm_hooks.h
+++ b/include/asm-generic/mm_hooks.h
@@ -7,30 +7,41 @@
 #ifndef _ASM_GENERIC_MM_HOOKS_H
 #define _ASM_GENERIC_MM_HOOKS_H
 
+#ifndef arch_dup_mmap
 static inline void arch_dup_mmap(struct mm_struct *oldmm,
                                 struct mm_struct *mm)
 {
 }
+#endif
 
+#ifndef arch_exit_mmap
 static inline void arch_exit_mmap(struct mm_struct *mm)
 {
 }
+#endif
 
+#ifndef arch_unmap
 static inline void arch_unmap(struct mm_struct *mm,
                        struct vm_area_struct *vma,
                        unsigned long start, unsigned long end)
 {
 }
+#endif
 
+#ifndef arch_bprm_mm_init
 static inline void arch_bprm_mm_init(struct mm_struct *mm,
                                     struct vm_area_struct *vma)
 {
 }
+#endif
 
+#ifndef arch_vma_access_permitted
 static inline bool arch_vma_access_permitted(struct vm_area_struct *vma,
                bool write, bool execute, bool foreign)
 {
        /* by default, allow everything */
        return true;
 }
+#endif
+
 #endif /* _ASM_GENERIC_MM_HOOKS_H */
-- 
2.11.0

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