[PATCH 3/4] mm: Remove arch_unmap()

[Michael Ellerman]

Now that powerpc no longer uses arch_unmap() to handle VDSO unmapping,
there are no meaningful implementions left. Drop support for it
entirely, and update comments which refer to it.

Suggested-by: Linus Torvalds <torvalds at linux-foundation.org>
Signed-off-by: Michael Ellerman <mpe at ellerman.id.au>
---
 arch/powerpc/include/asm/mmu_context.h |  5 -----
 arch/x86/include/asm/mmu_context.h     |  5 -----
 include/asm-generic/mm_hooks.h         | 11 +++--------
 mm/mmap.c                              | 12 +++---------
 4 files changed, 6 insertions(+), 27 deletions(-)

diff --git a/arch/powerpc/include/asm/mmu_context.h b/arch/powerpc/include/asm/mmu_context.h
index 9b8c1555744e..a334a1368848 100644
--- a/arch/powerpc/include/asm/mmu_context.h
+++ b/arch/powerpc/include/asm/mmu_context.h
@@ -260,11 +260,6 @@ static inline void enter_lazy_tlb(struct mm_struct *mm,
 
 extern void arch_exit_mmap(struct mm_struct *mm);
 
-static inline void arch_unmap(struct mm_struct *mm,
-			      unsigned long start, unsigned long end)
-{
-}
-
 #ifdef CONFIG_PPC_MEM_KEYS
 bool arch_vma_access_permitted(struct vm_area_struct *vma, bool write,
 			       bool execute, bool foreign);
diff --git a/arch/x86/include/asm/mmu_context.h b/arch/x86/include/asm/mmu_context.h
index 8dac45a2c7fc..80f2a3187aa6 100644
--- a/arch/x86/include/asm/mmu_context.h
+++ b/arch/x86/include/asm/mmu_context.h
@@ -232,11 +232,6 @@ static inline bool is_64bit_mm(struct mm_struct *mm)
 }
 #endif
 
-static inline void arch_unmap(struct mm_struct *mm, unsigned long start,
-			      unsigned long end)
-{
-}
-
 /*
  * We only want to enforce protection keys on the current process
  * because we effectively have no access to PKRU for other
diff --git a/include/asm-generic/mm_hooks.h b/include/asm-generic/mm_hooks.h
index 4dbb177d1150..6eea3b3c1e65 100644
--- a/include/asm-generic/mm_hooks.h
+++ b/include/asm-generic/mm_hooks.h
@@ -1,8 +1,8 @@
 /* SPDX-License-Identifier: GPL-2.0 */
 /*
- * Define generic no-op hooks for arch_dup_mmap, arch_exit_mmap
- * and arch_unmap to be included in asm-FOO/mmu_context.h for any
- * arch FOO which doesn't need to hook these.
+ * Define generic no-op hooks for arch_dup_mmap and arch_exit_mmap
+ * to be included in asm-FOO/mmu_context.h for any arch FOO which
+ * doesn't need to hook these.
  */
 #ifndef _ASM_GENERIC_MM_HOOKS_H
 #define _ASM_GENERIC_MM_HOOKS_H
@@ -17,11 +17,6 @@ static inline void arch_exit_mmap(struct mm_struct *mm)
 {
 }
 
-static inline void arch_unmap(struct mm_struct *mm,
-			unsigned long start, unsigned long end)
-{
-}
-
 static inline bool arch_vma_access_permitted(struct vm_area_struct *vma,
 		bool write, bool execute, bool foreign)
 {
diff --git a/mm/mmap.c b/mm/mmap.c
index 24bd6aa9155c..adaaf1ef197a 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -2789,7 +2789,7 @@ do_vmi_align_munmap(struct vma_iterator *vmi, struct vm_area_struct *vma,
  *
  * This function takes a @mas that is either pointing to the previous VMA or set
  * to MA_START and sets it up to remove the mapping(s).  The @len will be
- * aligned and any arch_unmap work will be preformed.
+ * aligned.
  *
  * Return: 0 on success and drops the lock if so directed, error and leaves the
  * lock held otherwise.
@@ -2809,16 +2809,12 @@ int do_vmi_munmap(struct vma_iterator *vmi, struct mm_struct *mm,
 		return -EINVAL;
 
 	/*
-	 * Check if memory is sealed before arch_unmap.
-	 * Prevent unmapping a sealed VMA.
+	 * Check if memory is sealed, prevent unmapping a sealed VMA.
 	 * can_modify_mm assumes we have acquired the lock on MM.
 	 */
 	if (unlikely(!can_modify_mm(mm, start, end)))
 		return -EPERM;
 
-	 /* arch_unmap() might do unmaps itself.  */
-	arch_unmap(mm, start, end);
-
 	/* Find the first overlapping VMA */
 	vma = vma_find(vmi, end);
 	if (!vma) {
@@ -3232,14 +3228,12 @@ int do_vma_munmap(struct vma_iterator *vmi, struct vm_area_struct *vma,
 	struct mm_struct *mm = vma->vm_mm;
 
 	/*
-	 * Check if memory is sealed before arch_unmap.
-	 * Prevent unmapping a sealed VMA.
+	 * Check if memory is sealed, prevent unmapping a sealed VMA.
 	 * can_modify_mm assumes we have acquired the lock on MM.
 	 */
 	if (unlikely(!can_modify_mm(mm, start, end)))
 		return -EPERM;
 
-	arch_unmap(mm, start, end);
 	return do_vmi_align_munmap(vmi, vma, mm, start, end, uf, unlock);
 }
 
-- 
2.45.2