From 3bbda69c48d27474a9e6a90cf4680b295a7efa46 Mon Sep 17 00:00:00 2001
From: "Aneesh Kumar K.V" <aneesh.kumar@linux.ibm.com>
Date: Wed, 7 Jul 2021 18:10:18 -0700
Subject: mm/mremap: allow arch runtime override

Patch series "Speedup mremap on ppc64", v8.

This patchset enables MOVE_PMD/MOVE_PUD support on power.  This requires
the platform to support updating higher-level page tables without updating
page table entries.  This also needs to invalidate the Page Walk Cache on
architecture supporting the same.

This patch (of 3):

Architectures like ppc64 support faster mremap only with radix
translation.  Hence allow a runtime check w.r.t support for fast mremap.

Link: https://lkml.kernel.org/r/20210616045735.374532-1-aneesh.kumar@linux.ibm.com
Link: https://lkml.kernel.org/r/20210616045735.374532-2-aneesh.kumar@linux.ibm.com
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Kalesh Singh <kaleshsingh@google.com>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Joel Fernandes <joel@joelfernandes.org>
Cc: Christophe Leroy <christophe.leroy@csgroup.eu>
Cc: Kirill A. Shutemov <kirill@shutemov.name>
Cc: "Aneesh Kumar K . V" <aneesh.kumar@linux.ibm.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---
 mm/mremap.c | 15 ++++++++++++++-
 1 file changed, 14 insertions(+), 1 deletion(-)

(limited to 'mm/mremap.c')

diff --git a/mm/mremap.c b/mm/mremap.c
index 52369139f1b9..5989d3990020 100644
--- a/mm/mremap.c
+++ b/mm/mremap.c
@@ -25,7 +25,7 @@
 #include <linux/userfaultfd_k.h>
 
 #include <asm/cacheflush.h>
-#include <asm/tlbflush.h>
+#include <asm/tlb.h>
 #include <asm/pgalloc.h>
 
 #include "internal.h"
@@ -210,6 +210,15 @@ static void move_ptes(struct vm_area_struct *vma, pmd_t *old_pmd,
 		drop_rmap_locks(vma);
 }
 
+#ifndef arch_supports_page_table_move
+#define arch_supports_page_table_move arch_supports_page_table_move
+static inline bool arch_supports_page_table_move(void)
+{
+	return IS_ENABLED(CONFIG_HAVE_MOVE_PMD) ||
+		IS_ENABLED(CONFIG_HAVE_MOVE_PUD);
+}
+#endif
+
 #ifdef CONFIG_HAVE_MOVE_PMD
 static bool move_normal_pmd(struct vm_area_struct *vma, unsigned long old_addr,
 		  unsigned long new_addr, pmd_t *old_pmd, pmd_t *new_pmd)
@@ -218,6 +227,8 @@ static bool move_normal_pmd(struct vm_area_struct *vma, unsigned long old_addr,
 	struct mm_struct *mm = vma->vm_mm;
 	pmd_t pmd;
 
+	if (!arch_supports_page_table_move())
+		return false;
 	/*
 	 * The destination pmd shouldn't be established, free_pgtables()
 	 * should have released it.
@@ -284,6 +295,8 @@ static bool move_normal_pud(struct vm_area_struct *vma, unsigned long old_addr,
 	struct mm_struct *mm = vma->vm_mm;
 	pud_t pud;
 
+	if (!arch_supports_page_table_move())
+		return false;
 	/*
 	 * The destination pud shouldn't be established, free_pgtables()
 	 * should have released it.
-- 
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