From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-6.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 615A1C4332B for ; Mon, 23 Mar 2020 20:42:36 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 35BCC2070A for ; Mon, 23 Mar 2020 20:42:36 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726067AbgCWUme convert rfc822-to-8bit (ORCPT ); Mon, 23 Mar 2020 16:42:34 -0400 Received: from poy.remlab.net ([94.23.215.26]:35310 "EHLO ns207790.ip-94-23-215.eu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725844AbgCWUme (ORCPT ); Mon, 23 Mar 2020 16:42:34 -0400 Received: from basile.remlab.net (87-92-31-51.bb.dnainternet.fi [87.92.31.51]) (Authenticated sender: remi) by ns207790.ip-94-23-215.eu (Postfix) with ESMTPSA id 991185FB11; Mon, 23 Mar 2020 21:42:31 +0100 (CET) From: =?ISO-8859-1?Q?R=E9mi?= Denis-Courmont To: Catalin Marinas Cc: Mark Rutland , will@kernel.org, james.morse@arm.com, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 1/3] arm64: clean up trampoline vector loads Date: Mon, 23 Mar 2020 22:42:30 +0200 Message-ID: <2067644.cOvikPKVsA@basile.remlab.net> Organization: Remlab In-Reply-To: <20200323190408.GE4892@mbp> References: <1938400.7m7sAWtiY1@basile.remlab.net> <20200323121437.GC2597@C02TD0UTHF1T.local> <20200323190408.GE4892@mbp> MIME-Version: 1.0 Content-Transfer-Encoding: 8BIT Content-Type: text/plain; charset="UTF-8" Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Le maanantaina 23. maaliskuuta 2020, 21.04.09 EET Catalin Marinas a écrit : > On Mon, Mar 23, 2020 at 12:14:37PM +0000, Mark Rutland wrote: > > On Mon, Mar 23, 2020 at 02:08:53PM +0200, Rémi Denis-Courmont wrote: > > > Le maanantaina 23. maaliskuuta 2020, 14.07.00 EET Mark Rutland a écrit : > > > > On Thu, Mar 19, 2020 at 11:14:05AM +0200, Rémi Denis-Courmont wrote: > > > > > From: Rémi Denis-Courmont > > > > > > > > > > This switches from custom instruction patterns to the regular large > > > > > memory model sequence with ADRP and LDR. In doing so, the ADD > > > > > instruction can be eliminated in the SDEI handler, and the code no > > > > > longer assumes that the trampoline vectors and the vectors address > > > > > both > > > > > start on a page boundary. > > > > > > > > > > Signed-off-by: Rémi Denis-Courmont > > > > > --- > > > > > > > > > > arch/arm64/kernel/entry.S | 9 ++++----- > > > > > 1 file changed, 4 insertions(+), 5 deletions(-) > > > > > > > > > > diff --git a/arch/arm64/kernel/entry.S b/arch/arm64/kernel/entry.S > > > > > index e5d4e30ee242..24f828739696 100644 > > > > > --- a/arch/arm64/kernel/entry.S > > > > > +++ b/arch/arm64/kernel/entry.S > > > > > @@ -805,9 +805,9 @@ alternative_else_nop_endif > > > > > > > > > > 2: > > > > > tramp_map_kernel x30 > > > > > > > > > > #ifdef CONFIG_RANDOMIZE_BASE > > > > > > > > > > - adr x30, tramp_vectors + PAGE_SIZE > > > > > + adrp x30, tramp_vectors + PAGE_SIZE > > > > > > > > > > alternative_insn isb, nop, ARM64_WORKAROUND_QCOM_FALKOR_E1003 > > > > > > > > > > - ldr x30, [x30] > > > > > + ldr x30, [x30, #:lo12:__entry_tramp_data_start] > > > > > > > > I think this is busted for !4K kernels once we reduce the alignment of > > > > __entry_tramp_data_start. > > > > > > > > The ADRP gives us a 64K aligned address (with bits 15:0 clear). The > > > > lo12 > > > > relocation gives us bits 11:0, so we haven't accounted for bits 15:12. > > > > > > IMU, ADRP gives a 4K aligned value, regardless of MMU (TCR) settings. > > > > Sorry, I had erroneously assumed tramp_vectors was page aligned. The > > issue still stands -- we haven't accounted for bits 15:12, as those can > > differ between tramp_vectors and __entry_tramp_data_start. Does that mean that the SDEI code never worked with page size > 4 KiB? > Should we just use adrp on __entry_tramp_data_start? Anyway, the diff > below doesn't solve the issue I'm seeing (only reverting patch 3). AFAIU, the preexisting code uses the manual PAGE_SIZE offset because the offset in the main vmlinux does not match the architected offset inside the fixmap. If so, then using the symbol directly will not work at all. > diff --git a/arch/arm64/kernel/entry.S b/arch/arm64/kernel/entry.S > index ca1340eb46d8..4cc9d1df3985 100644 > --- a/arch/arm64/kernel/entry.S > +++ b/arch/arm64/kernel/entry.S > @@ -810,7 +810,7 @@ alternative_else_nop_endif > 2: > tramp_map_kernel x30 > #ifdef CONFIG_RANDOMIZE_BASE > - adrp x30, tramp_vectors + PAGE_SIZE > + adrp x30, __entry_tramp_data_start > alternative_insn isb, nop, ARM64_WORKAROUND_QCOM_FALKOR_E1003 > ldr x30, [x30, #:lo12:__entry_tramp_data_start] > #else > @@ -964,7 +964,7 @@ SYM_CODE_START(__sdei_asm_entry_trampoline) > 1: str x4, [x1, #(SDEI_EVENT_INTREGS + S_ORIG_ADDR_LIMIT)] > > #ifdef CONFIG_RANDOMIZE_BASE > - adrp x4, tramp_vectors + PAGE_SIZE > + adrp x4, __sdei_asm_trampoline_next_handler > ldr x4, [x4, #:lo12:__sdei_asm_trampoline_next_handler] > #else > ldr x4, =__sdei_asm_handler -- 雷米‧德尼-库尔蒙 http://www.remlab.net/