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 7FE99EB64DD for ; Thu, 22 Jun 2023 20:36:09 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230294AbjFVUgI convert rfc822-to-8bit (ORCPT ); Thu, 22 Jun 2023 16:36:08 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:42780 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229961AbjFVUgG (ORCPT ); Thu, 22 Jun 2023 16:36:06 -0400 Received: from gloria.sntech.de (gloria.sntech.de [185.11.138.130]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id BC07BDC for ; Thu, 22 Jun 2023 13:36:01 -0700 (PDT) Received: from i53875bdf.versanet.de ([83.135.91.223] helo=diego.localnet) by gloria.sntech.de with esmtpsa (TLS1.3) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.94.2) (envelope-from ) id 1qCR1z-00020C-4S; Thu, 22 Jun 2023 22:35:51 +0200 From: Heiko =?ISO-8859-1?Q?St=FCbner?= To: Palmer Dabbelt , Stefan O'Rear Cc: linux-riscv@lists.infradead.org, samuel@sholland.org, guoren@kernel.org, christoph.muellner@vrull.eu, conor.dooley@microchip.com, linux-kernel@vger.kernel.org Subject: Re: [PATCH RFC 2/2] RISC-V: add T-Head vector errata handling Date: Thu, 22 Jun 2023 22:35:50 +0200 Message-ID: <9132027.CDJkKcVGEf@diego> In-Reply-To: <23381fc8-c297-46ed-9e11-a2643e18e4c9@app.fastmail.com> References: <20230228215435.3366914-1-heiko@sntech.de> <1941316.PYKUYFuaPT@diego> <23381fc8-c297-46ed-9e11-a2643e18e4c9@app.fastmail.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8BIT Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Stefan, Am Donnerstag, 22. Juni 2023, 20:58:37 CEST schrieb Stefan O'Rear: > On Thu, Jun 22, 2023, at 1:39 PM, Heiko Stübner wrote: > > Am Dienstag, 13. Juni 2023, 08:35:53 CEST schrieb Stefan O'Rear: > >> vxrm and vxsat are part of fcsr in 0.7.1, so they should already have been > >> handled by __fstate_save and __fstate_restore, and this code is likely to > >> misbehave (saving the new process's vxrm/vxsat in the old process's save area > >> because float state is swapped before vector state in __switch_to). > > > > I'm not sure I follow your description but may be overlooking or have > > misunderstood something. > > > > Somehow I way to often have trouble resolving CSR addresses, but according > > to openSBI, FCSR has the location of 0x3 > > (#define CSR_FCSR 0x003 in include/sbi/riscv_encoding.h) > > > > where CSR_VXSAT and CSR_VXRM are at 0x9 and 0xa respectively. > > (#define CSR_VXSAT 0x9 and #define CSR_VXRM 0xa) > > > > > > And looking at __fstate_save + __fstate_restore the only CSRs accessed seem > > to be CSR_STATUS and FCSR itself. > > > > I definitly won't claim to be right, but don't see the issue yet. > > > > > > Thanks for a hint > > Heiko > > Are you aware of "3.7. Vector Fixed-Point Fields in fcsr" in > riscv-v-spec-0.7.1.pdf? oh wow, thanks a lot for that pointer, now I understand your concern. So in vector-0.7.1 fcsr[10:9] mirrors vxrm and fcsr[8] mirrors vxsat. On a positive note, the T-Head cores seem to not implement the full vector 0.7.1 specification after all, in the documentation I have [0] fcsr[31:8] are declared as "0" and uppermost bits are [7:5] for the "frm" field. So I guess a code comment should suffice to explain :-) Regards Heiko [0] https://github.com/T-head-Semi/openc906/blob/main/doc/%E7%8E%84%E9%93%81C906%E7%94%A8%E6%88%B7%E6%89%8B%E5%86%8C.pdf 16.3.1.3 浮点控制状态寄存器（FCSR） on page 334 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 bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 5FF5DEB64DA for ; Thu, 22 Jun 2023 20:36:09 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:MIME-Version:References:In-Reply-To: Message-ID:Date:Subject:Cc:To:From:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; 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Thu, 22 Jun 2023 22:35:51 +0200 From: Heiko =?ISO-8859-1?Q?St=FCbner?= To: Palmer Dabbelt , Stefan O'Rear Cc: linux-riscv@lists.infradead.org, samuel@sholland.org, guoren@kernel.org, christoph.muellner@vrull.eu, conor.dooley@microchip.com, linux-kernel@vger.kernel.org Subject: Re: [PATCH RFC 2/2] RISC-V: add T-Head vector errata handling Date: Thu, 22 Jun 2023 22:35:50 +0200 Message-ID: <9132027.CDJkKcVGEf@diego> In-Reply-To: <23381fc8-c297-46ed-9e11-a2643e18e4c9@app.fastmail.com> References: <20230228215435.3366914-1-heiko@sntech.de> <1941316.PYKUYFuaPT@diego> <23381fc8-c297-46ed-9e11-a2643e18e4c9@app.fastmail.com> MIME-Version: 1.0 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20230622_133556_729317_FFE207B9 X-CRM114-Status: GOOD ( 19.85 ) X-BeenThere: linux-riscv@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: base64 Sender: "linux-riscv" Errors-To: linux-riscv-bounces+linux-riscv=archiver.kernel.org@lists.infradead.org SGkgU3RlZmFuLAoKQW0gRG9ubmVyc3RhZywgMjIuIEp1bmkgMjAyMywgMjA6NTg6MzcgQ0VTVCBz Y2hyaWViIFN0ZWZhbiBPJ1JlYXI6Cj4gT24gVGh1LCBKdW4gMjIsIDIwMjMsIGF0IDE6MzkgUE0s IEhlaWtvIFN0w7xibmVyIHdyb3RlOgo+ID4gQW0gRGllbnN0YWcsIDEzLiBKdW5pIDIwMjMsIDA4 OjM1OjUzIENFU1Qgc2NocmllYiBTdGVmYW4gTydSZWFyOgo+ID4+IHZ4cm0gYW5kIHZ4c2F0IGFy ZSBwYXJ0IG9mIGZjc3IgaW4gMC43LjEsIHNvIHRoZXkgc2hvdWxkIGFscmVhZHkgaGF2ZSBiZWVu Cj4gPj4gaGFuZGxlZCBieSBfX2ZzdGF0ZV9zYXZlIGFuZCBfX2ZzdGF0ZV9yZXN0b3JlLCBhbmQg dGhpcyBjb2RlIGlzIGxpa2VseSB0bwo+ID4+IG1pc2JlaGF2ZSAoc2F2aW5nIHRoZSBuZXcgcHJv Y2VzcydzIHZ4cm0vdnhzYXQgaW4gdGhlIG9sZCBwcm9jZXNzJ3Mgc2F2ZSBhcmVhCj4gPj4gYmVj YXVzZSBmbG9hdCBzdGF0ZSBpcyBzd2FwcGVkIGJlZm9yZSB2ZWN0b3Igc3RhdGUgaW4gX19zd2l0 Y2hfdG8pLgo+ID4KPiA+IEknbSBub3Qgc3VyZSBJIGZvbGxvdyB5b3VyIGRlc2NyaXB0aW9uIGJ1 dCBtYXkgYmUgb3Zlcmxvb2tpbmcgb3IgaGF2ZQo+ID4gbWlzdW5kZXJzdG9vZCBzb21ldGhpbmcu Cj4gPgo+ID4gU29tZWhvdyBJIHdheSB0byBvZnRlbiBoYXZlIHRyb3VibGUgcmVzb2x2aW5nIENT UiBhZGRyZXNzZXMsIGJ1dCBhY2NvcmRpbmcKPiA+IHRvIG9wZW5TQkksIEZDU1IgaGFzIHRoZSBs b2NhdGlvbiBvZiAweDMKPiA+ICgjZGVmaW5lIENTUl9GQ1NSIDB4MDAzIGluIGluY2x1ZGUvc2Jp L3Jpc2N2X2VuY29kaW5nLmgpCj4gPgo+ID4gd2hlcmUgQ1NSX1ZYU0FUIGFuZCBDU1JfVlhSTSBh cmUgYXQgMHg5IGFuZCAweGEgcmVzcGVjdGl2ZWx5Lgo+ID4gKCNkZWZpbmUgQ1NSX1ZYU0FUIDB4 OSBhbmQgICNkZWZpbmUgQ1NSX1ZYUk0gMHhhKQo+ID4KPiA+Cj4gPiBBbmQgbG9va2luZyBhdCBf X2ZzdGF0ZV9zYXZlICsgX19mc3RhdGVfcmVzdG9yZSB0aGUgb25seSBDU1JzIGFjY2Vzc2VkIHNl ZW0KPiA+IHRvIGJlIENTUl9TVEFUVVMgYW5kIEZDU1IgaXRzZWxmLgo+ID4KPiA+IEkgZGVmaW5p dGx5IHdvbid0IGNsYWltIHRvIGJlIHJpZ2h0LCBidXQgZG9uJ3Qgc2VlIHRoZSBpc3N1ZSB5ZXQu Cj4gPgo+ID4KPiA+IFRoYW5rcyBmb3IgYSBoaW50Cj4gPiBIZWlrbwo+IAo+IEFyZSB5b3UgYXdh cmUgb2YgIjMuNy4gVmVjdG9yIEZpeGVkLVBvaW50IEZpZWxkcyBpbiBmY3NyIiBpbgo+IHJpc2N2 LXYtc3BlYy0wLjcuMS5wZGY/CgpvaCB3b3csIHRoYW5rcyBhIGxvdCBmb3IgdGhhdCBwb2ludGVy LCBub3cgSSB1bmRlcnN0YW5kIHlvdXIgY29uY2Vybi4KClNvIGluIHZlY3Rvci0wLjcuMSBmY3Ny WzEwOjldIG1pcnJvcnMgdnhybSBhbmQgZmNzcls4XSBtaXJyb3JzIHZ4c2F0LgoKCk9uIGEgcG9z aXRpdmUgbm90ZSwgdGhlIFQtSGVhZCBjb3JlcyBzZWVtIHRvIG5vdCBpbXBsZW1lbnQgdGhlIGZ1 bGwKdmVjdG9yIDAuNy4xIHNwZWNpZmljYXRpb24gYWZ0ZXIgYWxsLCBpbiB0aGUgZG9jdW1lbnRh dGlvbiBJIGhhdmUgWzBdCmZjc3JbMzE6OF0gYXJlIGRlY2xhcmVkIGFzICIwIiBhbmQgdXBwZXJt b3N0IGJpdHMgYXJlIFs3OjVdIGZvciB0aGUgImZybSIKZmllbGQuCgpTbyBJIGd1ZXNzIGEgY29k ZSBjb21tZW50IHNob3VsZCBzdWZmaWNlIHRvIGV4cGxhaW4gOi0pCgoKUmVnYXJkcwpIZWlrbwoK ClswXSBodHRwczovL2dpdGh1Yi5jb20vVC1oZWFkLVNlbWkvb3BlbmM5MDYvYmxvYi9tYWluL2Rv Yy8lRTclOEUlODQlRTklOTMlODFDOTA2JUU3JTk0JUE4JUU2JTg4JUI3JUU2JTg5JThCJUU1JTg2 JThDLnBkZgoxNi4zLjEuMyDmta7ngrnmjqfliLbnirbmgIHlr4TlrZjlmajvvIhGQ1NS77yJIG9u IHBhZ2UgMzM0CgoKCl9fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19f X19fCmxpbnV4LXJpc2N2IG1haWxpbmcgbGlzdApsaW51eC1yaXNjdkBsaXN0cy5pbmZyYWRlYWQu b3JnCmh0dHA6Ly9saXN0cy5pbmZyYWRlYWQub3JnL21haWxtYW4vbGlzdGluZm8vbGludXgtcmlz Y3YK