From: glider@google.com
To: catalin.marinas@arm.com, will.deacon@arm.com, mark.rutland@arm.com
Cc: akpm@linux-foundation.org,
Alexander Potapenko <glider@google.com>,
linux-kernel@vger.kernel.org,
linux-arm-kernel@lists.infradead.org, keescook@chromium.org
Subject: [PATCH] arm64: define __alloc_zeroed_user_highpage
Date: Thu, 12 Mar 2020 16:59:20 +0100 [thread overview]
Message-ID: <20200312155920.50067-1-glider@google.com> (raw)
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>
---
arch/arm64/include/asm/page.h | 4 ++++
1 file changed, 4 insertions(+)
diff --git a/arch/arm64/include/asm/page.h b/arch/arm64/include/asm/page.h
index d39ddb258a049..75d6cd23a6790 100644
--- a/arch/arm64/include/asm/page.h
+++ b/arch/arm64/include/asm/page.h
@@ -21,6 +21,10 @@ 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)
--
2.25.1.481.gfbce0eb801-goog
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next reply other threads:[~2020-03-12 15:59 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-03-12 15:59 glider [this message]
2020-03-12 16:49 ` [PATCH] arm64: define __alloc_zeroed_user_highpage Mark Rutland
2020-03-12 19:59 ` Alexander Potapenko
2020-03-13 15:03 ` Catalin Marinas
2020-03-17 18:37 ` Catalin Marinas
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