From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-qt1-x841.google.com (mail-qt1-x841.google.com [IPv6:2607:f8b0:4864:20::841]) by sourceware.org (Postfix) with ESMTPS id AAFAF385DC0B for ; Thu, 23 Apr 2020 16:35:06 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.3.2 sourceware.org AAFAF385DC0B Received: by mail-qt1-x841.google.com with SMTP id e17so1949074qtp.7 for ; Thu, 23 Apr 2020 09:35:06 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:subject:to:cc:references:from:autocrypt :message-id:date:user-agent:mime-version:in-reply-to :content-language:content-transfer-encoding; bh=di5/akpzayNRtycg1bzbnm2ahcAkOvdOWlyGDaY2mAg=; b=dYYDpH3Vcu62ol1gZDgIVht0VRO6DVvAGqt6287Y6CU7gm81Jd5Qc2kBkiwG9tByT2 wPgidj0XKcXMteW077xmlHNrRvZEgIhPu0RDGqBbZFVtQJvCewwJSFZ+UMUhU7F/2L0p Q/0nWQqJxb45nIx4F18J3P9RzMqHm4sp1PEjBF9BOdnazVgkegJ/rSWDgcjIIKkBRGSf uB1kHHgF+1llYo4OS7DjGIigmR17pJwGDUp7mUb4C2vnmCpEa+55uJB4o5FMqWekXNov hu60db2Wz9fPxv5qtxLeyBut47k/X+u020wmyBNKO1+OwEOwfiSSpyLSEGIi2xLC3Y4D AzeA== X-Gm-Message-State: AGi0PubQUo8OK4ptZS8hYMVgNq271uslijwnPS+K5B9V6CPtIe+hWKpK CKnQlU8Q+DnxfgHgGCINDhOddLjwu/xYtQ== X-Google-Smtp-Source: APiQypKmQ6aywRnKhgEb4FIefkp656osP7+QJ75dg3Dm/Sc5qVz4ayGWE8mKHMSrnQLcXQSmX8a83Q== X-Received: by 2002:aed:3bf7:: with SMTP id s52mr5019632qte.362.1587659706022; Thu, 23 Apr 2020 09:35:06 -0700 (PDT) Received: from [192.168.1.4] ([177.194.48.209]) by smtp.googlemail.com with ESMTPSA id v62sm1875885qkb.85.2020.04.23.09.35.03 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 23 Apr 2020 09:35:05 -0700 (PDT) Subject: Re: [musl] Powerpc Linux 'scv' system call ABI proposal take 2 To: Rich Felker Cc: Nicholas Piggin , libc-alpha@sourceware.org, libc-dev@lists.llvm.org, linuxppc-dev@lists.ozlabs.org, musl@lists.openwall.com References: <20200416183151.GA11469@brightrain.aerifal.cx> <1587344003.daumxvs1kh.astroid@bobo.none> <20200420013412.GZ11469@brightrain.aerifal.cx> <1587348538.l1ioqml73m.astroid@bobo.none> <20200420040926.GA11469@brightrain.aerifal.cx> <1587356128.aslvdnmtbw.astroid@bobo.none> <20200420172715.GC11469@brightrain.aerifal.cx> <1587531042.1qvc287tsc.astroid@bobo.none> <20200423023642.GP11469@brightrain.aerifal.cx> <20200423161841.GU11469@brightrain.aerifal.cx> From: Adhemerval Zanella Autocrypt: addr=adhemerval.zanella@linaro.org; prefer-encrypt=mutual; keydata= xsFNBFcVGkoBEADiQU2x/cBBmAVf5C2d1xgz6zCnlCefbqaflUBw4hB/bEME40QsrVzWZ5Nq 8kxkEczZzAOKkkvv4pRVLlLn/zDtFXhlcvQRJ3yFMGqzBjofucOrmdYkOGo0uCaoJKPT186L NWp53SACXguFJpnw4ODI64ziInzXQs/rUJqrFoVIlrPDmNv/LUv1OVPKz20ETjgfpg8MNwG6 iMizMefCl+RbtXbIEZ3TE/IaDT/jcOirjv96lBKrc/pAL0h/O71Kwbbp43fimW80GhjiaN2y WGByepnkAVP7FyNarhdDpJhoDmUk9yfwNuIuESaCQtfd3vgKKuo6grcKZ8bHy7IXX1XJj2X/ BgRVhVgMHAnDPFIkXtP+SiarkUaLjGzCz7XkUn4XAGDskBNfbizFqYUQCaL2FdbW3DeZqNIa nSzKAZK7Dm9+0VVSRZXP89w71Y7JUV56xL/PlOE+YKKFdEw+gQjQi0e+DZILAtFjJLoCrkEX w4LluMhYX/X8XP6/C3xW0yOZhvHYyn72sV4yJ1uyc/qz3OY32CRy+bwPzAMAkhdwcORA3JPb kPTlimhQqVgvca8m+MQ/JFZ6D+K7QPyvEv7bQ7M+IzFmTkOCwCJ3xqOD6GjX3aphk8Sr0dq3 4Awlf5xFDAG8dn8Uuutb7naGBd/fEv6t8dfkNyzj6yvc4jpVxwARAQABzUlBZGhlbWVydmFs IFphbmVsbGEgTmV0dG8gKExpbmFybyBWUE4gS2V5KSA8YWRoZW1lcnZhbC56YW5lbGxhQGxp bmFyby5vcmc+wsF3BBMBCAAhBQJXFRpKAhsDBQsJCAcDBRUKCQgLBRYCAwEAAh4BAheAAAoJ EKqx7BSnlIjv0e8P/1YOYoNkvJ+AJcNUaM5a2SA9oAKjSJ/M/EN4Id5Ow41ZJS4lUA0apSXW NjQg3VeVc2RiHab2LIB4MxdJhaWTuzfLkYnBeoy4u6njYcaoSwf3g9dSsvsl3mhtuzm6aXFH /Qsauav77enJh99tI4T+58rp0EuLhDsQbnBic/ukYNv7sQV8dy9KxA54yLnYUFqH6pfH8Lly sTVAMyi5Fg5O5/hVV+Z0Kpr+ZocC1YFJkTsNLAW5EIYSP9ftniqaVsim7MNmodv/zqK0IyDB GLLH1kjhvb5+6ySGlWbMTomt/or/uvMgulz0bRS+LUyOmlfXDdT+t38VPKBBVwFMarNuREU2 69M3a3jdTfScboDd2ck1u7l+QbaGoHZQ8ZNUrzgObltjohiIsazqkgYDQzXIMrD9H19E+8fw kCNUlXxjEgH/Kg8DlpoYJXSJCX0fjMWfXywL6ZXc2xyG/hbl5hvsLNmqDpLpc1CfKcA0BkK+ k8R57fr91mTCppSwwKJYO9T+8J+o4ho/CJnK/jBy1pWKMYJPvvrpdBCWq3MfzVpXYdahRKHI ypk8m4QlRlbOXWJ3TDd/SKNfSSrWgwRSg7XCjSlR7PNzNFXTULLB34sZhjrN6Q8NQZsZnMNs TX8nlGOVrKolnQPjKCLwCyu8PhllU8OwbSMKskcD1PSkG6h3r0AqzsFNBFcVGkoBEACgAdbR Ck+fsfOVwT8zowMiL3l9a2DP3Eeak23ifdZG+8Avb/SImpv0UMSbRfnw/N81IWwlbjkjbGTu oT37iZHLRwYUFmA8fZX0wNDNKQUUTjN6XalJmvhdz9l71H3WnE0wneEM5ahu5V1L1utUWTyh VUwzX1lwJeV3vyrNgI1kYOaeuNVvq7npNR6t6XxEpqPsNc6O77I12XELic2+36YibyqlTJIQ V1SZEbIy26AbC2zH9WqaKyGyQnr/IPbTJ2Lv0dM3RaXoVf+CeK7gB2B+w1hZummD21c1Laua +VIMPCUQ+EM8W9EtX+0iJXxI+wsztLT6vltQcm+5Q7tY+HFUucizJkAOAz98YFucwKefbkTp eKvCfCwiM1bGatZEFFKIlvJ2QNMQNiUrqJBlW9nZp/k7pbG3oStOjvawD9ZbP9e0fnlWJIsj 6c7pX354Yi7kxIk/6gREidHLLqEb/otuwt1aoMPg97iUgDV5mlNef77lWE8vxmlY0FBWIXuZ yv0XYxf1WF6dRizwFFbxvUZzIJp3spAao7jLsQj1DbD2s5+S1BW09A0mI/1DjB6EhNN+4bDB SJCOv/ReK3tFJXuj/HbyDrOdoMt8aIFbe7YFLEExHpSk+HgN05Lg5TyTro8oW7TSMTk+8a5M kzaH4UGXTTBDP/g5cfL3RFPl79ubXwARAQABwsFfBBgBCAAJBQJXFRpKAhsMAAoJEKqx7BSn lIjvI/8P/jg0jl4Tbvg3B5kT6PxJOXHYu9OoyaHLcay6Cd+ZrOd1VQQCbOcgLFbf4Yr+rE9l mYsY67AUgq2QKmVVbn9pjvGsEaz8UmfDnz5epUhDxC6yRRvY4hreMXZhPZ1pbMa6A0a/WOSt AgFj5V6Z4dXGTM/lNManr0HjXxbUYv2WfbNt3/07Db9T+GZkpUotC6iknsTA4rJi6u2ls0W9 1UIvW4o01vb4nZRCj4rni0g6eWoQCGoVDk/xFfy7ZliR5B+3Z3EWRJcQskip/QAHjbLa3pml xAZ484fVxgeESOoaeC9TiBIp0NfH8akWOI0HpBCiBD5xaCTvR7ujUWMvhsX2n881r/hNlR9g fcE6q00qHSPAEgGr1bnFv74/1vbKtjeXLCcRKk3Ulw0bY1OoDxWQr86T2fZGJ/HIZuVVBf3+ gaYJF92GXFynHnea14nFFuFgOni0Mi1zDxYH/8yGGBXvo14KWd8JOW0NJPaCDFJkdS5hu0VY 7vJwKcyHJGxsCLU+Et0mryX8qZwqibJIzu7kUJQdQDljbRPDFd/xmGUFCQiQAncSilYOcxNU EMVCXPAQTteqkvA+gNqSaK1NM9tY0eQ4iJpo+aoX8HAcn4sZzt2pfUB9vQMTBJ2d4+m/qO6+ cFTAceXmIoFsN8+gFN3i8Is3u12u8xGudcBPvpoy4OoG Message-ID: <3fe73604-7c92-e073-cbe7-abb4a8ae7c1a@linaro.org> Date: Thu, 23 Apr 2020 13:35:01 -0300 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.7.0 MIME-Version: 1.0 In-Reply-To: <20200423161841.GU11469@brightrain.aerifal.cx> Content-Type: text/plain; charset=utf-8 Content-Language: en-GB Content-Transfer-Encoding: 7bit X-Spam-Status: No, score=-12.5 required=5.0 tests=BAYES_00, DKIM_SIGNED, DKIM_VALID, DKIM_VALID_AU, DKIM_VALID_EF, KAM_NUMSUBJECT, RCVD_IN_DNSWL_NONE, SPF_HELO_NONE, SPF_PASS, TXREP autolearn=no autolearn_force=no version=3.4.2 X-Spam-Checker-Version: SpamAssassin 3.4.2 (2018-09-13) on server2.sourceware.org X-BeenThere: libc-alpha@sourceware.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Libc-alpha mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 23 Apr 2020 16:35:17 -0000 On 23/04/2020 13:18, Rich Felker wrote: > On Thu, Apr 23, 2020 at 09:13:57AM -0300, Adhemerval Zanella wrote: >> >> >> On 22/04/2020 23:36, Rich Felker wrote: >>> On Wed, Apr 22, 2020 at 04:18:36PM +1000, Nicholas Piggin wrote: >>>> Yeah I had a bit of a play around with musl (which is very nice code I >>>> must say). The powerpc64 syscall asm is missing ctr clobber by the way. >>>> Fortunately adding it doesn't change code generation for me, but it >>>> should be fixed. glibc had the same bug at one point I think (probably >>>> due to syscall ABI documentation not existing -- something now lives in >>>> linux/Documentation/powerpc/syscall64-abi.rst). >>> >>> Do you know anywhere I can read about the ctr issue, possibly the >>> relevant glibc bug report? I'm not particularly familiar with ppc >>> register file (at least I have to refamiliarize myself every time I >>> work on this stuff) so it'd be nice to understand what's >>> potentially-wrong now. >> >> My understanding is the ctr issue only happens for vDSO calls where it >> fallback to a syscall in case an error (invalid argument, etc. and >> assuming if vDSO does not fallback to a syscall it always succeed). >> This makes the vDSO call on powerpc to have same same ABI constraint >> as a syscall, where it clobbers CR0. > > I think you mean "vsyscall", the old thing glibc used where there are > in-userspace implementations of some syscalls with call interfaces > roughly equivalent to a syscall. musl has never used this. It only > uses the actual exported functions from the vdso which have normal > external function call ABI. I wasn't thinking in vsyscall in fact, which afaik it is a x86 thing. The issue is indeed when calling the powerpc provided functions in vDSO, which musl might want to do eventually.