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Violators will be prosecuted; (version=TLSv1/SSLv3 cipher=AES256-GCM-SHA384 bits=256/256) Fri, 18 Oct 2019 08:09:32 +0100 Received: from d06av25.portsmouth.uk.ibm.com (d06av25.portsmouth.uk.ibm.com [9.149.105.61]) by b06cxnps4076.portsmouth.uk.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id x9I79WVa54657042 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Fri, 18 Oct 2019 07:09:32 GMT Received: from d06av25.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 00C3B11C054; Fri, 18 Oct 2019 07:09:32 +0000 (GMT) Received: from d06av25.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 97BF911C050; Fri, 18 Oct 2019 07:09:31 +0000 (GMT) Received: from ozlabs.au.ibm.com (unknown [9.192.253.14]) by d06av25.portsmouth.uk.ibm.com (Postfix) with ESMTP; Fri, 18 Oct 2019 07:09:31 +0000 (GMT) Received: from [10.61.2.125] (haven.au.ibm.com [9.192.254.114]) (using TLSv1.2 with cipher AES128-SHA (128/128 bits)) (No client certificate requested) by ozlabs.au.ibm.com (Postfix) with ESMTPSA id 74FE2A022E; Fri, 18 Oct 2019 18:09:29 +1100 (AEDT) Subject: Re: [PATCH v3 06/15] powerpc/32: prepare for CONFIG_VMAP_STACK To: Christophe Leroy , Benjamin Herrenschmidt , Paul Mackerras , Michael Ellerman , npiggin@gmail.com, dja@axtens.net Cc: linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, linux-mm@kvack.org References: <7e9771a56539c58dcd8a871c3dfbe7a932e427b0.1568106758.git.christophe.leroy@c-s.fr> From: Andrew Donnellan Date: Fri, 18 Oct 2019 18:09:29 +1100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.9.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-AU Content-Transfer-Encoding: 8bit X-TM-AS-GCONF: 00 x-cbid: 19101807-4275-0000-0000-000003733550 X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 19101807-4276-0000-0000-000038865061 Message-Id: X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:,, definitions=2019-10-18_02:,, signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 priorityscore=1501 malwarescore=0 suspectscore=0 phishscore=0 bulkscore=0 spamscore=0 clxscore=1015 lowpriorityscore=0 mlxscore=0 impostorscore=0 mlxlogscore=685 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1908290000 definitions=main-1910180068 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 18/10/19 5:46 pm, Christophe Leroy wrote: > > > Le 17/10/2019 à 09:36, Andrew Donnellan a écrit : >> On 10/9/19 7:16 pm, Christophe Leroy wrote: >>> +#if defined(CONFIG_VMAP_STACK) && CONFIG_THREAD_SHIFT < PAGE_SHIFT >>> +#define THREAD_SHIFT        PAGE_SHIFT >>> +#else >>>   #define THREAD_SHIFT        CONFIG_THREAD_SHIFT >>> +#endif >>> >>>   #define THREAD_SIZE        (1 << THREAD_SHIFT) >>> >> >> Looking at 64-bit book3s: with 64K pages, this results in a >> THREAD_SIZE that's too large for immediate mode arithmetic operations, >> which is annoying. Hmm. >> > > Which operation are you thinking about ? > > For instance, 'addi' can't be used anymore, but 'addis' can. Right, I didn't look too closely - yes, they're "addi"s. But also DS-form stores: stdu r1,THREAD_SIZE-STACK_FRAME_OVERHEAD(r3) Anyway, this is just the first thing that broke when I wondered whether a ppc64le_defconfig would even build if I just switched on VMAP_STACK, I'll work around it -- Andrew Donnellan OzLabs, ADL Canberra ajd@linux.ibm.com IBM Australia Limited