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Peter Anvin" , linuxppc-dev@lists.ozlabs.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, Kefeng Wang , Xie XiuQi , Guohanjun Subject: Re: [PATCH -next v5 2/8] arm64: extable: make uaaccess helper use extable type EX_TYPE_UACCESS_ERR_ZERO Message-ID: References: <20220528065056.1034168-1-tongtiangen@huawei.com> <20220528065056.1034168-3-tongtiangen@huawei.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20220528065056.1034168-3-tongtiangen@huawei.com> ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1655454291; a=rsa-sha256; cv=none; b=0Q+2fIoxtwamRl0JMRlo/BMuIt0tt/jmbId9mOSqcv4YcTC3gUDuh6F4RoLi+KUQdqscb9 cuVAVVhyDskcQeyIknR7QUg+knw/wPw0NWlkK24wMHJA85JVXoDEozATIciihuwRUNDpfA kYHUkUCZk/C4xR0P9SGiFWvgLFAkM9E= ARC-Authentication-Results: i=1; imf03.hostedemail.com; dkim=none; dmarc=pass (policy=none) header.from=arm.com; spf=pass (imf03.hostedemail.com: domain of mark.rutland@arm.com designates 217.140.110.172 as permitted sender) smtp.mailfrom=mark.rutland@arm.com ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1655454291; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=JKX062VcIs1X8o92pCQeoVFp0nV6/y3LfOxrKIZbIoM=; b=UrGTH8GHFe8SK0EpFDXYaGUuy8IX0XIc+rn24NFXYyWY4fLv08rhhHiW4QyZCcLAtiLekO aHRYOO29ocCj3zaUhR4DfPFJ1pWnbe+tT9vcb3z+Cv321Bk3KmM4zQNjAwze0dKoO7hsSG +UIFJIH3uE7nNc/L4mfNz59+zidJmR4= X-Rspamd-Queue-Id: 8105620090 X-Rspam-User: Authentication-Results: imf03.hostedemail.com; dkim=none; dmarc=pass (policy=none) header.from=arm.com; spf=pass (imf03.hostedemail.com: domain of mark.rutland@arm.com designates 217.140.110.172 as permitted sender) smtp.mailfrom=mark.rutland@arm.com X-Rspamd-Server: rspam06 X-Stat-Signature: o6ngfnpiupxiosus6s1xh3nxgmr137zr X-HE-Tag: 1655454291-939045 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: 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. > /* > * 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 >