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 lists.ozlabs.org (lists.ozlabs.org [112.213.38.117]) (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 DAE9CC43334 for ; Sat, 18 Jun 2022 08:43:18 +0000 (UTC) Received: from boromir.ozlabs.org (localhost [IPv6:::1]) by lists.ozlabs.org (Postfix) with ESMTP id 4LQ8ZF304Dz3bxt for ; Sat, 18 Jun 2022 18:43:17 +1000 (AEST) Authentication-Results: lists.ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=huawei.com (client-ip=45.249.212.187; helo=szxga01-in.huawei.com; envelope-from=tongtiangen@huawei.com; receiver=) Received: from szxga01-in.huawei.com (szxga01-in.huawei.com [45.249.212.187]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 4LQ8Yh695Fz30Qc for ; Sat, 18 Jun 2022 18:42:44 +1000 (AEST) Received: from dggemv711-chm.china.huawei.com (unknown [172.30.72.55]) by szxga01-in.huawei.com (SkyGuard) with ESMTP id 4LQ8Wd01gMzYXPC; Sat, 18 Jun 2022 16:41:01 +0800 (CST) Received: from kwepemm600017.china.huawei.com (7.193.23.234) by dggemv711-chm.china.huawei.com (10.1.198.66) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2375.24; Sat, 18 Jun 2022 16:42:09 +0800 Received: from [10.174.179.234] (10.174.179.234) by kwepemm600017.china.huawei.com (7.193.23.234) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2375.24; Sat, 18 Jun 2022 16:42:07 +0800 Message-ID: <0da734f3-5743-3df3-3f90-d92e5bd585ce@huawei.com> Date: Sat, 18 Jun 2022 16:42:06 +0800 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:91.0) Gecko/20100101 Thunderbird/91.8.0 Subject: Re: [PATCH -next v5 2/8] arm64: extable: make uaaccess helper use extable type EX_TYPE_UACCESS_ERR_ZERO From: Tong Tiangen To: Mark Rutland References: <20220528065056.1034168-1-tongtiangen@huawei.com> <20220528065056.1034168-3-tongtiangen@huawei.com> <4371a7c9-8766-9fee-2558-e6f43f06ad19@huawei.com> In-Reply-To: <4371a7c9-8766-9fee-2558-e6f43f06ad19@huawei.com> Content-Type: text/plain; charset="UTF-8"; format=flowed Content-Transfer-Encoding: 8bit X-Originating-IP: [10.174.179.234] X-ClientProxiedBy: dggems701-chm.china.huawei.com (10.3.19.178) To kwepemm600017.china.huawei.com (7.193.23.234) X-CFilter-Loop: Reflected X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Kefeng Wang , Dave Hansen , linux-mm@kvack.org, Paul Mackerras , Guohanjun , Will Deacon , "H . Peter Anvin" , x86@kernel.org, Ingo Molnar , Catalin Marinas , Xie XiuQi , Borislav Petkov , Alexander Viro , Thomas Gleixner , linux-arm-kernel@lists.infradead.org, Robin Murphy , linux-kernel@vger.kernel.org, James Morse , Andrew Morton , linuxppc-dev@lists.ozlabs.org Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" 在 2022/6/18 11:26, Tong Tiangen 写道: > > > 在 2022/6/17 16:24, Mark Rutland 写道: >> On Sat, May 28, 2022 at 06:50:50AM +0000, Tong Tiangen wrote: >>> Currnetly, the extable type used by __arch_copy_from/to_user() is >>> EX_TYPE_FIXUP. In fact, It is more clearly to use meaningful >>> EX_TYPE_UACCESS_*. >>> >>> Suggested-by: Mark Rutland >>> Signed-off-by: Tong Tiangen >>> --- >>>   arch/arm64/include/asm/asm-extable.h |  8 ++++++++ >>>   arch/arm64/include/asm/asm-uaccess.h | 12 ++++++------ >>>   2 files changed, 14 insertions(+), 6 deletions(-) >>> >>> diff --git a/arch/arm64/include/asm/asm-extable.h >>> b/arch/arm64/include/asm/asm-extable.h >>> index 56ebe183e78b..9c94ac1f082c 100644 >>> --- a/arch/arm64/include/asm/asm-extable.h >>> +++ b/arch/arm64/include/asm/asm-extable.h >>> @@ -28,6 +28,14 @@ >>>       __ASM_EXTABLE_RAW(\insn, \fixup, EX_TYPE_FIXUP, 0) >>>       .endm >>> +/* >>> + * Create an exception table entry for uaccess `insn`, which will >>> branch to `fixup` >>> + * when an unhandled fault is taken. >>> + * ex->data = ~0 means both reg_err and reg_zero is set to wzr(x31). >>> + */ >>> +    .macro          _asm_extable_uaccess, insn, fixup >>> +    __ASM_EXTABLE_RAW(\insn, \fixup, EX_TYPE_UACCESS_ERR_ZERO, ~0) >>> +    .endm >> >> I'm not too keen on using `~0` here, since that also sets other bits >> in the >> data field, and its somewhat opaque. >> >> How painful is it to generate the data fields as with the C version of >> this >> macro, so that we can pass in wzr explciitly for the two sub-fields? >> >> Other than that, this looks good to me. >> >> Thanks, >> Mark. > > ok, will fix next version. > > Thanks, > Tong. I tried to using data filelds as with C version, but here assembly code we can not using operator such as << and |, if we use lsl and orr instructions, the gpr will be occupied. So how about using 0x3ff directly here? it means err register and zero register both set to x31. Thanks, Tong. > >> >>>   /* >>>    * Create an exception table entry for `insn` if `fixup` is >>> provided. Otherwise >>>    * do nothing. >>> diff --git a/arch/arm64/include/asm/asm-uaccess.h >>> b/arch/arm64/include/asm/asm-uaccess.h >>> index 0557af834e03..75b211c98dea 100644 >>> --- a/arch/arm64/include/asm/asm-uaccess.h >>> +++ b/arch/arm64/include/asm/asm-uaccess.h >>> @@ -61,7 +61,7 @@ alternative_else_nop_endif >>>   #define USER(l, x...)                \ >>>   9999:    x;                    \ >>> -    _asm_extable    9999b, l >>> +    _asm_extable_uaccess    9999b, l >>>   /* >>>    * Generate the assembly for LDTR/STTR with exception table entries. >>> @@ -73,8 +73,8 @@ alternative_else_nop_endif >>>   8889:        ldtr    \reg2, [\addr, #8]; >>>           add    \addr, \addr, \post_inc; >>> -        _asm_extable    8888b,\l; >>> -        _asm_extable    8889b,\l; >>> +        _asm_extable_uaccess    8888b, \l; >>> +        _asm_extable_uaccess    8889b, \l; >>>       .endm >>>       .macro user_stp l, reg1, reg2, addr, post_inc >>> @@ -82,14 +82,14 @@ alternative_else_nop_endif >>>   8889:        sttr    \reg2, [\addr, #8]; >>>           add    \addr, \addr, \post_inc; >>> -        _asm_extable    8888b,\l; >>> -        _asm_extable    8889b,\l; >>> +        _asm_extable_uaccess    8888b,\l; >>> +        _asm_extable_uaccess    8889b,\l; >>>       .endm >>>       .macro user_ldst l, inst, reg, addr, post_inc >>>   8888:        \inst        \reg, [\addr]; >>>           add        \addr, \addr, \post_inc; >>> -        _asm_extable    8888b,\l; >>> +        _asm_extable_uaccess    8888b, \l; >>>       .endm >>>   #endif >>> -- >>> 2.25.1 >>> >> . > > _______________________________________________ > linux-arm-kernel mailing list > linux-arm-kernel@lists.infradead.org > http://lists.infradead.org/mailman/listinfo/linux-arm-kernel