Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932854AbcDYR1G (ORCPT ); Mon, 25 Apr 2016 13:27:06 -0400 Received: from foss.arm.com ([217.140.101.70]:48525 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751696AbcDYR1D (ORCPT ); Mon, 25 Apr 2016 13:27:03 -0400 Date: Mon, 25 Apr 2016 18:26:56 +0100 From: Catalin Marinas To: Yury Norov Cc: arnd@arndb.de, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, linux-arch@vger.kernel.org, linux-s390@vger.kernel.org, pinskia@gmail.com, Prasun.Kapoor@caviumnetworks.com, schwab@suse.de, broonie@kernel.org, linux-doc@vger.kernel.org, heiko.carstens@de.ibm.com, agraf@suse.de, klimov.linux@gmail.com, Andrew Pinski , bamvor.zhangjian@huawei.com, Andrew Pinski , schwidefsky@de.ibm.com, Nathan_Lynch@mentor.com, joseph@codesourcery.com, christoph.muellner@theobroma-systems.com Subject: Re: [PATCH 20/25] arm64:ilp32: add sys_ilp32.c and a separate table (in entry.S) to use it Message-ID: <20160425172656.GI9614@e104818-lin.cambridge.arm.com> References: <1459894127-17698-1-git-send-email-ynorov@caviumnetworks.com> <1459894127-17698-21-git-send-email-ynorov@caviumnetworks.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1459894127-17698-21-git-send-email-ynorov@caviumnetworks.com> User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1337 Lines: 40 On Wed, Apr 06, 2016 at 01:08:42AM +0300, Yury Norov wrote: > --- a/arch/arm64/kernel/entry.S > +++ b/arch/arm64/kernel/entry.S > @@ -715,9 +715,13 @@ ENDPROC(ret_from_fork) > */ > .align 6 > el0_svc: > - adrp stbl, sys_call_table // load syscall table pointer > uxtw scno, w8 // syscall number in w8 > mov sc_nr, #__NR_syscalls > +#ifdef CONFIG_ARM64_ILP32 > + ldr x16, [tsk, #TI_FLAGS] > + tbnz x16, #TIF_32BIT_AARCH64, el0_ilp32_svc // We are using ILP32 > +#endif There is another ldr x16, [tsk, #TI_FLAGS] load further down in the el0_svc_naked block. We should rework these a bit to avoid loading the same location twice unnecessarily. E.g. move the ldr x16 just before el0_svc_naked and branch one line after in case of the ILP32 syscall. > + adrp stbl, sys_call_table // load syscall table pointer > el0_svc_naked: // compat entry point > stp x0, scno, [sp, #S_ORIG_X0] // save the original x0 and syscall number > enable_dbg_and_irq > @@ -737,6 +741,12 @@ ni_sys: > b ret_fast_syscall > ENDPROC(el0_svc) > > +#ifdef CONFIG_ARM64_ILP32 > +el0_ilp32_svc: > + adrp stbl, sys_call_ilp32_table // load syscall table pointer > + b el0_svc_naked > +#endif > + > /* > * This is the really slow path. We're going to be doing context > * switches, and waiting for our parent to respond. -- Catalin