From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from e06smtp09.uk.ibm.com (e06smtp09.uk.ibm.com [195.75.94.105]) (using TLSv1 with cipher CAMELLIA256-SHA (256/256 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id EEF711A1816 for ; Wed, 20 Jan 2016 21:17:59 +1100 (AEDT) Received: from localhost by e06smtp09.uk.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Wed, 20 Jan 2016 10:17:55 -0000 Received: from b06cxnps4076.portsmouth.uk.ibm.com (d06relay13.portsmouth.uk.ibm.com [9.149.109.198]) by d06dlp02.portsmouth.uk.ibm.com (Postfix) with ESMTP id 24D782190067 for ; Wed, 20 Jan 2016 10:17:42 +0000 (GMT) Received: from d06av01.portsmouth.uk.ibm.com (d06av01.portsmouth.uk.ibm.com [9.149.37.212]) by b06cxnps4076.portsmouth.uk.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id u0KAHshr40763570 for ; Wed, 20 Jan 2016 10:17:54 GMT Received: from d06av01.portsmouth.uk.ibm.com (localhost [127.0.0.1]) by d06av01.portsmouth.uk.ibm.com (8.14.4/8.14.4/NCO v10.0 AVout) with ESMTP id u0KAHrrR008025 for ; Wed, 20 Jan 2016 03:17:53 -0700 Date: Wed, 20 Jan 2016 11:17:51 +0100 From: Heiko Carstens To: Ard Biesheuvel Cc: "linux-kernel@vger.kernel.org" , linux-s390@vger.kernel.org, linuxppc-dev , "x86@kernel.org" , Kees Cook , Andrew Morton , Ingo Molnar , "hpa@zytor.com" , Benjamin Herrenschmidt , mpe@ellerman.id.au, Michal Marek , Rusty Russell Subject: Re: [PATCH 3/4] s390: enable text relative kallsyms for 64-bit targets Message-ID: <20160120101751.GG3395@osiris> References: <1453280738-18721-1-git-send-email-ard.biesheuvel@linaro.org> <1453280738-18721-4-git-send-email-ard.biesheuvel@linaro.org> <20160120094326.GD3395@osiris> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii In-Reply-To: List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , On Wed, Jan 20, 2016 at 11:04:24AM +0100, Ard Biesheuvel wrote: > On 20 January 2016 at 10:43, Heiko Carstens wrote: > > On Wed, Jan 20, 2016 at 10:05:37AM +0100, Ard Biesheuvel wrote: > >> This enables the newly introduced text-relative kallsyms support when > >> building 64-bit targets. This cuts the size of the kallsyms address > >> table in half, reducing the memory footprint of the kernel .rodata > >> section by about 250 KB for a defconfig build. > >> > >> Signed-off-by: Ard Biesheuvel > >> --- > >> > >> diff --git a/arch/s390/Kconfig b/arch/s390/Kconfig > >> index dbeeb3a049f2..588160fd1db0 100644 > >> --- a/arch/s390/Kconfig > >> +++ b/arch/s390/Kconfig > >> @@ -149,6 +149,7 @@ config S390 > >> select HAVE_REGS_AND_STACK_ACCESS_API > >> select HAVE_SYSCALL_TRACEPOINTS > >> select HAVE_VIRT_CPU_ACCOUNTING > >> + select KALLSYMS_TEXT_RELATIVE if 64BIT > > > > Please remove the "if 64BIT" since s390 is always 64BIT in the meantime. > > Tested on s390 and everything seems still to work ;) > > > > Acked-by: Heiko Carstens > > > > Thanks! Did you take a look at /proc/kallsyms, by any chance? It > should look identical with and without these patches Close to identical, since the generated code and offsets change a bit with your new config option enabled and disabled. But only those parts that are linked behind kernel/kallsyms.c. However I did run a couple of ftrace, kprobes tests and enforced call backtraces. Everything still works. So it looks all good.