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[198.145.64.163]) by smtp.gmail.com with ESMTPSA id b12sm22351411pga.87.2020.08.18.12.44.49 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 18 Aug 2020 12:44:50 -0700 (PDT) Date: Tue, 18 Aug 2020 12:44:49 -0700 From: Kees Cook To: Christoph Hellwig Cc: Al Viro , Michael Ellerman , x86@kernel.org, linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-arch@vger.kernel.org, linuxppc-dev@lists.ozlabs.org Subject: Re: [PATCH 08/11] x86: make TASK_SIZE_MAX usable from assembly code Message-ID: <202008181244.BBDA7DAB@keescook> References: <20200817073212.830069-1-hch@lst.de> <20200817073212.830069-9-hch@lst.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200817073212.830069-9-hch@lst.de> Sender: linux-arch-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-arch@vger.kernel.org On Mon, Aug 17, 2020 at 09:32:09AM +0200, Christoph Hellwig wrote: > For 64-bit the only hing missing was a strategic _AC, and for 32-bit we typo: thing > need to use __PAGE_OFFSET instead of PAGE_OFFSET in the TASK_SIZE > definition to escape the explicit unsigned long cast. This just works > because __PAGE_OFFSET is defined using _AC itself and thus never needs > the cast anyway. Shouldn't this be folded into the prior patch so there's no bisection problem? -Kees > > Signed-off-by: Christoph Hellwig > --- > arch/x86/include/asm/page_32_types.h | 4 ++-- > arch/x86/include/asm/page_64_types.h | 2 +- > 2 files changed, 3 insertions(+), 3 deletions(-) > > diff --git a/arch/x86/include/asm/page_32_types.h b/arch/x86/include/asm/page_32_types.h > index 26236925fb2c36..f462895a33e452 100644 > --- a/arch/x86/include/asm/page_32_types.h > +++ b/arch/x86/include/asm/page_32_types.h > @@ -44,8 +44,8 @@ > /* > * User space process size: 3GB (default). > */ > -#define IA32_PAGE_OFFSET PAGE_OFFSET > -#define TASK_SIZE PAGE_OFFSET > +#define IA32_PAGE_OFFSET __PAGE_OFFSET > +#define TASK_SIZE __PAGE_OFFSET > #define TASK_SIZE_LOW TASK_SIZE > #define TASK_SIZE_MAX TASK_SIZE > #define DEFAULT_MAP_WINDOW TASK_SIZE > diff --git a/arch/x86/include/asm/page_64_types.h b/arch/x86/include/asm/page_64_types.h > index 996595c9897e0a..838515daf87b36 100644 > --- a/arch/x86/include/asm/page_64_types.h > +++ b/arch/x86/include/asm/page_64_types.h > @@ -76,7 +76,7 @@ > * > * With page table isolation enabled, we map the LDT in ... [stay tuned] > */ > -#define TASK_SIZE_MAX ((1UL << __VIRTUAL_MASK_SHIFT) - PAGE_SIZE) > +#define TASK_SIZE_MAX ((_AC(1,UL) << __VIRTUAL_MASK_SHIFT) - PAGE_SIZE) > > #define DEFAULT_MAP_WINDOW ((1UL << 47) - PAGE_SIZE) > > -- > 2.28.0 > -- Kees Cook