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[198.145.64.163]) by smtp.gmail.com with ESMTPSA id x18sm1559678pge.76.2019.10.01.08.48.12 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 01 Oct 2019 08:48:12 -0700 (PDT) Date: Tue, 1 Oct 2019 08:48:11 -0700 From: Kees Cook To: Will Deacon Cc: Thomas Gleixner , Rick Edgecombe , Ingo Molnar , Borislav Petkov , "H. Peter Anvin" , Dave Hansen , Andy Lutomirski , Arnd Bergmann , linux-arch@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, linux-alpha@vger.kernel.org, linux-ia64@vger.kernel.org, linux-s390@vger.kernel.org, linux-c6x-dev@linux-c6x.org, Yoshinori Sato , Michal Simek , linux-parisc@vger.kernel.org, linux-xtensa@linux-xtensa.org, x86@kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 18/29] arm64: Move EXCEPTION_TABLE to RO_DATA segment Message-ID: <201910010846.D0712C1@keescook> References: <20190926175602.33098-1-keescook@chromium.org> <20190926175602.33098-19-keescook@chromium.org> <20191001090355.blnaqlf4rfzucpb2@willie-the-truck> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20191001090355.blnaqlf4rfzucpb2@willie-the-truck> Sender: linux-parisc-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-parisc@vger.kernel.org On Tue, Oct 01, 2019 at 10:03:56AM +0100, Will Deacon wrote: > Hi Kees, > > On Thu, Sep 26, 2019 at 10:55:51AM -0700, Kees Cook wrote: > > The EXCEPTION_TABLE is read-only, so collapse it into RO_DATA. > > > > Signed-off-by: Kees Cook > > --- > > arch/arm64/kernel/vmlinux.lds.S | 6 ++++-- > > 1 file changed, 4 insertions(+), 2 deletions(-) > > > > diff --git a/arch/arm64/kernel/vmlinux.lds.S b/arch/arm64/kernel/vmlinux.lds.S > > index 81d94e371c95..c6ba2eee0ee8 100644 > > --- a/arch/arm64/kernel/vmlinux.lds.S > > +++ b/arch/arm64/kernel/vmlinux.lds.S > > @@ -5,6 +5,8 @@ > > * Written by Martin Mares > > */ > > > > +#define RO_DATA_EXCEPTION_TABLE_ALIGN 8 > > + > > #include > > #include > > #include > > @@ -135,8 +137,8 @@ SECTIONS > > . = ALIGN(SEGMENT_ALIGN); > > _etext = .; /* End of text section */ > > > > - RO_DATA(PAGE_SIZE) /* everything from this point to */ > > - EXCEPTION_TABLE(8) /* __init_begin will be marked RO NX */ > > + /* everything from this point to __init_begin will be marked RO NX */ > > + RO_DATA(PAGE_SIZE) > > > > . = ALIGN(PAGE_SIZE); > > Do you reckon it would be worth merging this last ALIGN directive into the > RO_DATA definition too? Given that we want to map the thing read-only, it > really has to be aligned either side. Actually, taking a closer look, this appears to be redundant: RO_DATA() ends with: . = ALIGN(align) (where "align" is the "PAGE_SIZE" argument to RO_DATA()) > Anyway, that's only a nit, so: > > Acked-by: Will Deacon Thanks! > P.S. Please CC the arm64 maintainers on arm64 patches -- I nearly missed > this one! Okay, I can re-expand my list. I originally had done this but it was getting to be a rather large set of people. :) -- Kees Cook