From mboxrd@z Thu Jan 1 00:00:00 1970 From: Kees Cook Subject: Re: [PATCH 14/29] vmlinux.lds.h: Allow EXCEPTION_TABLE to live in RO_DATA Date: Thu, 10 Oct 2019 09:47:26 -0700 Message-ID: <201910100947.AC066B160@keescook> References: <20190926175602.33098-1-keescook@chromium.org> <20190926175602.33098-15-keescook@chromium.org> <20191010152516.GG7658@zn.tnic> Mime-Version: 1.0 Return-path: DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=chromium.org; s=google; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to; bh=e1YZSnr+tf37urRS0Z3ujXsrRMc5cw+9H7NAi1i2jVA=; b=izpAwLJ1ZfINeJ1IGvzXfqW7v0EVcZgsTyN1EOshDrEdBCIUSqkIleCU5BZWm63bPM eZKMQCfAts2ypPUa2YAeUCHOY9OigZ+1dV2iaRJWF3dFNdzuaPxx+X7j5M9nVPDl6n5z T3tK6luCqjuU0Ibyy5rvMfcc7jZy+Z/gsIufM= Content-Disposition: inline In-Reply-To: <20191010152516.GG7658@zn.tnic> Sender: linux-kernel-owner@vger.kernel.org List-ID: Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: Borislav Petkov Cc: Thomas Gleixner , Rick Edgecombe , Ingo Molnar , "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 On Thu, Oct 10, 2019 at 05:25:16PM +0200, Borislav Petkov wrote: > On Thu, Sep 26, 2019 at 10:55:47AM -0700, Kees Cook wrote: > > Many architectures have an EXCEPTION_TABLE that needs only to be > > read-only. As such, it should live in RO_DATA. This creates a macro to > > identify this case for the architectures that can move EXCEPTION_TABLE > > into RO_DATA. > > > > Signed-off-by: Kees Cook > > --- > > include/asm-generic/vmlinux.lds.h | 12 ++++++++++++ > > 1 file changed, 12 insertions(+) > > > > diff --git a/include/asm-generic/vmlinux.lds.h b/include/asm-generic/vmlinux.lds.h > > index d57a28786bb8..35a6cba39d9f 100644 > > --- a/include/asm-generic/vmlinux.lds.h > > +++ b/include/asm-generic/vmlinux.lds.h > > @@ -69,6 +69,17 @@ > > #define NOTES_HEADERS_RESTORE > > #endif > > > > +/* > > + * Some architectures have non-executable read-only exception tables. > > + * They can be added to the RO_DATA segment by specifying their desired > > + * alignment. > > + */ > > +#ifdef RO_DATA_EXCEPTION_TABLE_ALIGN > > +#define RO_DATA_EXCEPTION_TABLE EXCEPTION_TABLE(RO_DATA_EXCEPTION_TABLE_ALIGN) > > +#else > > +#define RO_DATA_EXCEPTION_TABLE > > +#endif > > + > > /* Align . to a 8 byte boundary equals to maximum function alignment. */ > > #define ALIGN_FUNCTION() . = ALIGN(8) > > > > @@ -508,6 +519,7 @@ > > __stop___modver = .; \ > > } \ > > \ > > + RO_DATA_EXCEPTION_TABLE \ > > NOTES \ > > \ > > . = ALIGN((align)); \ > > -- > > I think you can drop the "DATA" from the names as it is kinda clear > where the exception table lands: > > RO_EXCEPTION_TABLE_ALIGN > RO_EXCEPTION_TABLE > > The "read-only" part is the important one. Excellent point; I was not loving the how long the name was either. :) -- Kees Cook