From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932492AbbFCOJh (ORCPT ); Wed, 3 Jun 2015 10:09:37 -0400 Received: from mx6.ptsecurity.com ([45.58.112.36]:20052 "EHLO mx6.ptsecurity.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755530AbbFCOJc (ORCPT ); Wed, 3 Jun 2015 10:09:32 -0400 Message-ID: <556F0ACA.6020402@ptsecurity.com> Date: Wed, 3 Jun 2015 17:10:18 +0300 From: Alexander Popov User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.7.0 MIME-Version: 1.0 To: Andrey Ryabinin , Ingo Molnar CC: Thomas Gleixner , Ingo Molnar , "H. Peter Anvin" , Andrey Konovalov , "Andrew Morton" , Kees Cook , "Peter Zijlstra (Intel)" , Andy Lutomirski , Alexander Kuleshov , "Borislav Petkov" , Denys Vlasenko , , Subject: Re: [PATCH v4 1/1] x86_64: fix KASan shadow region page tables References: <1433249837-7096-1-git-send-email-alpopov@ptsecurity.com> <20150603074427.GA1598@gmail.com> <556EBE81.4030408@samsung.com> In-Reply-To: <556EBE81.4030408@samsung.com> Content-Type: text/plain; charset="windows-1252" Content-Transfer-Encoding: 7bit X-ClientProxiedBy: DC1-CAS-02.ptsecurity.ru (10.0.52.115) To DC1-MBX-02.ptsecurity.ru (10.0.52.117) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 03.06.2015 11:44, Andrey Ryabinin wrote: > On 06/03/2015 10:44 AM, Ingo Molnar wrote: >> >> * Alexander Popov wrote: >> >>> #ifdef CONFIG_KASAN >>> void __init kasan_map_early_shadow(pgd_t *pgd); >>> +void __init kasan_early_init(void); >>> void __init kasan_init(void); >>> #else >>> static inline void kasan_map_early_shadow(pgd_t *pgd) { } >>> +static inline void kasan_early_init(void) { } >>> static inline void kasan_init(void) { } >>> #endif >>> >>> diff --git a/arch/x86/kernel/head64.c b/arch/x86/kernel/head64.c >>> index 2b55ee6..e9a84a1 100644 >>> --- a/arch/x86/kernel/head64.c >>> +++ b/arch/x86/kernel/head64.c >>> @@ -161,11 +161,15 @@ asmlinkage __visible void __init x86_64_start_kernel(char * real_mode_data) >>> /* Kill off the identity-map trampoline */ >>> reset_early_page_tables(); >>> >>> - kasan_map_early_shadow(early_level4_pgt); >>> - >>> - /* clear bss before set_intr_gate with early_idt_handler */ >>> + /* >>> + * Clear bss before kasan_early_init and set_intr_gate >>> + * with early_idt_handler >>> + */ >>> clear_bss(); >>> >>> + kasan_early_init(); >>> + kasan_map_early_shadow(early_level4_pgt); >> >> So why isn't kasan_map_early_shadow() called in kasan_early_init()? >> >> High level x86 init code should not be polluted with too many low level details. >> > > Agreed. Eventually, with the patch bellow, we could get rid of the second > kasan_map_early_shadow(init_level4_pgt) call in x86_64_start_kernel(). > Make it static, and call it from kasan_early_init() only. > > ------------------------------------------------------ > From: Andrey Ryabinin > Subject: [PATCH] x86_64: remove not needed clear_page for init_level4_page > > Commit 8170e6bed465 ("x86, 64bit: Use a #PF handler to materialize > early mappings on demand") introduced clear_page(init_level4_pgt); > call in x86_64_start_kernel(). However, this clear_page is useless > because init_level4_page already filled with zeroes in head_64.S > > Commit message in 8170e6bed465 says that this clear_page() was > dropped in v7, but it accidentally reappeared in later versions > of that patchset. > > Signed-off-by: Andrey Ryabinin > --- > arch/x86/kernel/head64.c | 1 - > 1 file changed, 1 deletion(-) > > diff --git a/arch/x86/kernel/head64.c b/arch/x86/kernel/head64.c > index 5a46681..6a6eefd 100644 > --- a/arch/x86/kernel/head64.c > +++ b/arch/x86/kernel/head64.c > @@ -177,7 +177,6 @@ asmlinkage __visible void __init x86_64_start_kernel(char * real_mode_data) > */ > load_ucode_bsp(); > > - clear_page(init_level4_pgt); > /* set init_level4_pgt kernel high mapping*/ > init_level4_pgt[511] = early_level4_pgt[511]; > Hello Ingo and Andrey. Should I make a "patch series" containing Andrey's patch and the 5'th version of my patch or just include changes from Andrey's patch into mine? Best regards, Alexander