From: James Bottomley Date: Sun, 26 Mar 2006 09:36:57 +0000 (-0800) Subject: [PATCH] Add API for flushing Anon pages X-Git-Tag: v2.6.17-rc1~656 X-Git-Url: https://err.no/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=03beb07664d768db97bf454ae5c9581cd4737bb4;p=linux-2.6 [PATCH] Add API for flushing Anon pages Currently, get_user_pages() returns fully coherent pages to the kernel for anything other than anonymous pages. This is a problem for things like fuse and the SCSI generic ioctl SG_IO which can potentially wish to do DMA to anonymous pages passed in by users. The fix is to add a new memory management API: flush_anon_page() which is used in get_user_pages() to make anonymous pages coherent. Signed-off-by: James Bottomley Cc: Russell King Cc: "David S. Miller" Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- diff --git a/Documentation/cachetlb.txt b/Documentation/cachetlb.txt index 4ae418889b..1f312a9893 100644 --- a/Documentation/cachetlb.txt +++ b/Documentation/cachetlb.txt @@ -362,6 +362,15 @@ maps this page at its virtual address. likely that you will need to flush the instruction cache for copy_to_user_page(). + void flush_anon_page(struct page *page, unsigned long vmaddr) + When the kernel needs to access the contents of an anonymous + page, it calls this function (currently only + get_user_pages()). Note: flush_dcache_page() deliberately + doesn't work for an anonymous page. The default + implementation is a nop (and should remain so for all coherent + architectures). For incoherent architectures, it should flush + the cache of the page at vmaddr in the current user process. + void flush_icache_range(unsigned long start, unsigned long end) When the kernel stores into addresses that it will execute out of (eg when loading modules), this function is called. diff --git a/include/linux/highmem.h b/include/linux/highmem.h index 6bece9280e..7bd2593dbe 100644 --- a/include/linux/highmem.h +++ b/include/linux/highmem.h @@ -7,6 +7,12 @@ #include +#ifndef ARCH_HAS_FLUSH_ANON_PAGE +static inline void flush_anon_page(struct page *page, unsigned long vmaddr) +{ +} +#endif + #ifdef CONFIG_HIGHMEM #include diff --git a/mm/memory.c b/mm/memory.c index e347e106ca..67686048f0 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -1071,6 +1071,8 @@ int get_user_pages(struct task_struct *tsk, struct mm_struct *mm, } if (pages) { pages[i] = page; + + flush_anon_page(page, start); flush_dcache_page(page); } if (vmas)