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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 0978FC001E0 for ; Fri, 28 Jul 2023 16:54:52 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234509AbjG1Qyu (ORCPT ); Fri, 28 Jul 2023 12:54:50 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:53818 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233559AbjG1Qy2 (ORCPT ); Fri, 28 Jul 2023 12:54:28 -0400 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id 33B1B469C; Fri, 28 Jul 2023 09:53:31 -0700 (PDT) Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id D4DC82F4; Fri, 28 Jul 2023 09:53:29 -0700 (PDT) Received: from [10.57.0.147] (unknown [10.57.0.147]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id AC61F3F67D; Fri, 28 Jul 2023 09:52:44 -0700 (PDT) Message-ID: <89ce4bc4-00c5-a763-3179-e1d3e9f198b7@arm.com> Date: Fri, 28 Jul 2023 17:52:37 +0100 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.9.0 Subject: Re: [PATCH V13 - RESEND 02/10] arm64/perf: Add BRBE registers and fields Content-Language: en-US To: Will Deacon , Anshuman Khandual Cc: linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, catalin.marinas@arm.com, mark.rutland@arm.com, Mark Brown , Rob Herring , Marc Zyngier , Suzuki Poulose , Peter Zijlstra , Ingo Molnar , Arnaldo Carvalho de Melo , linux-perf-users@vger.kernel.org References: <20230711082455.215983-1-anshuman.khandual@arm.com> <20230711082455.215983-3-anshuman.khandual@arm.com> <20230728162011.GA22050@willie-the-truck> From: James Clark In-Reply-To: <20230728162011.GA22050@willie-the-truck> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 28/07/2023 17:20, Will Deacon wrote: > On Tue, Jul 11, 2023 at 01:54:47PM +0530, Anshuman Khandual wrote: >> This adds BRBE related register definitions and various other related field >> macros there in. These will be used subsequently in a BRBE driver which is >> being added later on. >> >> Cc: Catalin Marinas >> Cc: Will Deacon >> Cc: Marc Zyngier >> Cc: Mark Rutland >> Cc: linux-arm-kernel@lists.infradead.org >> Cc: linux-kernel@vger.kernel.org >> Tested-by: James Clark >> Reviewed-by: Mark Brown >> Signed-off-by: Anshuman Khandual >> --- >> arch/arm64/include/asm/sysreg.h | 103 +++++++++++++++++++++ >> arch/arm64/tools/sysreg | 158 ++++++++++++++++++++++++++++++++ >> 2 files changed, 261 insertions(+) >> >> diff --git a/arch/arm64/include/asm/sysreg.h b/arch/arm64/include/asm/sysreg.h >> index b481935e9314..f95e30c13c8b 100644 >> --- a/arch/arm64/include/asm/sysreg.h >> +++ b/arch/arm64/include/asm/sysreg.h >> @@ -163,6 +163,109 @@ >> #define SYS_DBGDTRTX_EL0 sys_reg(2, 3, 0, 5, 0) >> #define SYS_DBGVCR32_EL2 sys_reg(2, 4, 0, 7, 0) >> >> +#define __SYS_BRBINFO(n) sys_reg(2, 1, 8, ((n) & 0xf), ((((n) & 0x10)) >> 2 + 0)) >> +#define __SYS_BRBSRC(n) sys_reg(2, 1, 8, ((n) & 0xf), ((((n) & 0x10)) >> 2 + 1)) >> +#define __SYS_BRBTGT(n) sys_reg(2, 1, 8, ((n) & 0xf), ((((n) & 0x10)) >> 2 + 2)) > > It's that time on a Friday but... aren't these macros busted? I think you > need brackets before adding the offset, otherwise wouldn't, for example, > target registers 0-15 all access info register 0 and __SYS_BRBTGT(16) would > then start accessing source register 0? > > I'm surprised that the compiler doesn't warn about this, but even more > surprised that you managed to test this. > > Please tell me I'm wrong! > > Will No I think you are right, it is wrong. Luckily there is already an extraneous bracket so you you can fix it by moving one a place down: sys_reg(2, 1, 8, ((n) & 0xf), ((((n) & 0x10) >> 2) + 2)) It's interesting because the test [1] is doing quite a bit and looking at the branch info, and that src and targets match up to function names. I also manually looked at the branch buffers and didn't see anything obviously wrong like things that looked like branch infos in the source or target fields. Will have to take another look to see if it would be possible for the test to catch this. James [1]: https://gitlab.arm.com/linux-arm/linux-jc/-/commit/3a7ddce70c2daadb63fcc511de0a89055ca48b32