Commit 23c8ef5a authored Mar 12, 2020 by glider@google.com Committed by Alexander Potapenko Mar 30, 2020

FROMLIST: arm64: define __alloc_zeroed_user_highpage



When running the kernel with init_on_alloc=1, calling the default
implementation of __alloc_zeroed_user_highpage() from include/linux/highmem.h
leads to double-initialization of the allocated page (first by the page
allocator, then by clear_user_page().
Calling alloc_page_vma() with __GFP_ZERO, similarly to e.g. x86, seems
to be enough to ensure the user page is zeroed only once.

Signed-off-by: Alexander Potapenko <glider@google.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Bug: 149975351
Link: https://lore.kernel.org/linux-arm-kernel/20200312155920.50067-1-glider@google.com/


Change-Id: I3ff7c3fb082b420491313e0fdd841ce340989d72
Signed-off-by: Alexander Potapenko <glider@google.com>

parent 05cf04f6

arch/arm64/include/asm/page.h

+4 −0

Original line number	Diff line number	Diff line
		@@ -32,6 +32,10 @@ extern void __cpu_copy_user_page(void to, const void from,
		extern void copy_page(void to, const void from);
		extern void clear_page(void *to);

		#define __alloc_zeroed_user_highpage(movableflags, vma, vaddr) \
		alloc_page_vma(GFP_HIGHUSER \| __GFP_ZERO \| movableflags, vma, vaddr)
		#define __HAVE_ARCH_ALLOC_ZEROED_USER_HIGHPAGE

		#define clear_user_page(addr,vaddr,pg) __cpu_clear_user_page(addr, vaddr)
		#define copy_user_page(to,from,vaddr,pg) __cpu_copy_user_page(to, from, vaddr)