[CRIU] [RFC 2/5] mm/powerpc: Make VDSO unmap generic

[Christopher Covington]

In order to support unmapping the VDSO on additional architectures, move the
unmap code out from arch/powerpc. Architectures that wish to use the generic
logic must have an unsigned long vdso in mm->context and can opt in by
selecting CONFIG_ARCH_WANT_VDSO_MAP. This allows PowerPC to go back to using
the generic MM hooks, instead of carrying its own.

Signed-off-by: Christopher Covington <cov at codeaurora.org>
---
 arch/powerpc/Kconfig                   |  1 +
 arch/powerpc/include/asm/mmu_context.h | 35 +---------------------------------
 include/asm-generic/mm_hooks.h         |  4 ++++
 3 files changed, 6 insertions(+), 34 deletions(-)

diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
index 7cd32c0..f74320e 100644
--- a/arch/powerpc/Kconfig
+++ b/arch/powerpc/Kconfig
@@ -160,6 +160,7 @@ config PPC
 	select HAVE_ARCH_SECCOMP_FILTER
 	select ARCH_HAS_UBSAN_SANITIZE_ALL
 	select ARCH_SUPPORTS_DEFERRED_STRUCT_PAGE_INIT
+	select ARCH_WANT_VDSO_MAP
 
 config GENERIC_CSUM
 	def_bool CPU_LITTLE_ENDIAN
diff --git a/arch/powerpc/include/asm/mmu_context.h b/arch/powerpc/include/asm/mmu_context.h
index 508b842..3e51842 100644
--- a/arch/powerpc/include/asm/mmu_context.h
+++ b/arch/powerpc/include/asm/mmu_context.h
@@ -8,6 +8,7 @@
 #include <linux/spinlock.h>
 #include <asm/mmu.h>	
 #include <asm/cputable.h>
+#include <asm-generic/mm_hooks.h>
 #include <asm/cputhreads.h>
 
 /*
@@ -126,39 +127,5 @@ static inline void enter_lazy_tlb(struct mm_struct *mm,
 #endif
 }
 
-static inline void arch_dup_mmap(struct mm_struct *oldmm,
-				 struct mm_struct *mm)
-{
-}
-
-static inline void arch_exit_mmap(struct mm_struct *mm)
-{
-}
-
-static inline void arch_unmap(struct mm_struct *mm,
-			      struct vm_area_struct *vma,
-			      unsigned long start, unsigned long end)
-{
-	if (start <= mm->context.vdso && mm->context.vdso < end)
-		mm->context.vdso = 0;
-}
-
-static inline void arch_bprm_mm_init(struct mm_struct *mm,
-				     struct vm_area_struct *vma)
-{
-}
-
-static inline bool arch_vma_access_permitted(struct vm_area_struct *vma,
-		bool write, bool execute, bool foreign)
-{
-	/* by default, allow everything */
-	return true;
-}
-
-static inline bool arch_pte_access_permitted(pte_t pte, bool write)
-{
-	/* by default, allow everything */
-	return true;
-}
 #endif /* __KERNEL__ */
 #endif /* __ASM_POWERPC_MMU_CONTEXT_H */
diff --git a/include/asm-generic/mm_hooks.h b/include/asm-generic/mm_hooks.h
index cc5d9a14..6645116 100644
--- a/include/asm-generic/mm_hooks.h
+++ b/include/asm-generic/mm_hooks.h
@@ -19,6 +19,10 @@ static inline void arch_unmap(struct mm_struct *mm,
 			struct vm_area_struct *vma,
 			unsigned long start, unsigned long end)
 {
+#ifdef CONFIG_ARCH_WANT_VDSO_MAP
+	if (start <= mm->context.vdso && mm->context.vdso < end)
+		mm->context.vdso = 0;
+#endif  /* CONFIG_ARCH_WANT_VDSO_MAP */
 }
 
 static inline void arch_bprm_mm_init(struct mm_struct *mm,
-- 
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