linux-kernel - [PATCH v6 03/38] mm: Add generic flush_icache

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Message-Id: <20230802151406.3735276-4-willy@infradead.org>
Date:   Wed,  2 Aug 2023 16:13:31 +0100
From:   "Matthew Wilcox (Oracle)" <willy@...radead.org>
To:     Andrew Morton <akpm@...ux-foundation.org>
Cc:     "Matthew Wilcox (Oracle)" <willy@...radead.org>,
        linux-arch@...r.kernel.org, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org, Mike Rapoport <rppt@...nel.org>,
        Anshuman Khandual <anshuman.khandual@....com>
Subject: [PATCH v6 03/38] mm: Add generic flush_icache_pages() and documentation

flush_icache_page() is deprecated but not yet removed, so add
a range version of it.  Change the documentation to refer to
update_mmu_cache_range() instead of update_mmu_cache().

Signed-off-by: Matthew Wilcox (Oracle) <willy@...radead.org>
Acked-by: Mike Rapoport (IBM) <rppt@...nel.org>
Reviewed-by: Anshuman Khandual <anshuman.khandual@....com>
---
 Documentation/core-api/cachetlb.rst | 39 ++++++++++++++++-------------
 include/asm-generic/cacheflush.h    |  5 ++++
 2 files changed, 27 insertions(+), 17 deletions(-)

diff --git a/Documentation/core-api/cachetlb.rst b/Documentation/core-api/cachetlb.rst
index 5c0552e78c58..b645947954fb 100644
--- a/Documentation/core-api/cachetlb.rst
+++ b/Documentation/core-api/cachetlb.rst
@@ -88,13 +88,17 @@ changes occur:
 
 	This is used primarily during fault processing.
 
-5) ``void update_mmu_cache(struct vm_area_struct *vma,
-   unsigned long address, pte_t *ptep)``
+5) ``void update_mmu_cache_range(struct vm_fault *vmf,
+   struct vm_area_struct *vma, unsigned long address, pte_t *ptep,
+   unsigned int nr)``
 
-	At the end of every page fault, this routine is invoked to
-	tell the architecture specific code that a translation
-	now exists at virtual address "address" for address space
-	"vma->vm_mm", in the software page tables.
+	At the end of every page fault, this routine is invoked to tell
+	the architecture specific code that translations now exists
+	in the software page tables for address space "vma->vm_mm"
+	at virtual address "address" for "nr" consecutive pages.
+
+	This routine is also invoked in various other places which pass
+	a NULL "vmf".
 
 	A port may use this information in any way it so chooses.
 	For example, it could use this event to pre-load TLB
@@ -306,17 +310,18 @@ maps this page at its virtual address.
 	private".  The kernel guarantees that, for pagecache pages, it will
 	clear this bit when such a page first enters the pagecache.
 
-	This allows these interfaces to be implemented much more efficiently.
-	It allows one to "defer" (perhaps indefinitely) the actual flush if
-	there are currently no user processes mapping this page.  See sparc64's
-	flush_dcache_page and update_mmu_cache implementations for an example
-	of how to go about doing this.
+	This allows these interfaces to be implemented much more
+	efficiently.  It allows one to "defer" (perhaps indefinitely) the
+	actual flush if there are currently no user processes mapping this
+	page.  See sparc64's flush_dcache_page and update_mmu_cache_range
+	implementations for an example of how to go about doing this.
 
-	The idea is, first at flush_dcache_page() time, if page_file_mapping()
-	returns a mapping, and mapping_mapped on that mapping returns %false,
-	just mark the architecture private page flag bit.  Later, in
-	update_mmu_cache(), a check is made of this flag bit, and if set the
-	flush is done and the flag bit is cleared.
+	The idea is, first at flush_dcache_page() time, if
+	page_file_mapping() returns a mapping, and mapping_mapped on that
+	mapping returns %false, just mark the architecture private page
+	flag bit.  Later, in update_mmu_cache_range(), a check is made
+	of this flag bit, and if set the flush is done and the flag bit
+	is cleared.
 
 	.. important::
 
@@ -369,7 +374,7 @@ maps this page at its virtual address.
   ``void flush_icache_page(struct vm_area_struct *vma, struct page *page)``
 
 	All the functionality of flush_icache_page can be implemented in
-	flush_dcache_page and update_mmu_cache. In the future, the hope
+	flush_dcache_page and update_mmu_cache_range. In the future, the hope
 	is to remove this interface completely.
 
 The final category of APIs is for I/O to deliberately aliased address
diff --git a/include/asm-generic/cacheflush.h b/include/asm-generic/cacheflush.h
index f46258d1a080..09d51a680765 100644
--- a/include/asm-generic/cacheflush.h
+++ b/include/asm-generic/cacheflush.h
@@ -78,6 +78,11 @@ static inline void flush_icache_range(unsigned long start, unsigned long end)
 #endif
 
 #ifndef flush_icache_page
+static inline void flush_icache_pages(struct vm_area_struct *vma,
+				     struct page *page, unsigned int nr)
+{
+}
+
 static inline void flush_icache_page(struct vm_area_struct *vma,
 				     struct page *page)
 {
-- 
2.40.1