From patchwork Wed Jun 24 17:36:01 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Dave Martin X-Patchwork-Id: 11623861 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 057BE13B1 for ; Wed, 24 Jun 2020 17:38:42 +0000 (UTC) Received: from merlin.infradead.org (merlin.infradead.org [205.233.59.134]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id CE41E20738 for ; Wed, 24 Jun 2020 17:38:41 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="Qyq3/HKU" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org CE41E20738 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=arm.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-arm-kernel-bounces+patchwork-linux-arm=patchwork.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=merlin.20170209; h=Sender:Content-Transfer-Encoding: Content-Type:MIME-Version:Cc:List-Subscribe:List-Help:List-Post:List-Archive: List-Unsubscribe:List-Id:References:In-Reply-To:Message-Id:Date:Subject:To: From:Reply-To:Content-ID:Content-Description:Resent-Date:Resent-From: Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=H8rNFXgqftm7i3hXu+4OL2soOzElGbN+v8xk1z1lyWw=; b=Qyq3/HKUiVKjSK7I9zFs8LdkSd hsllT0yq0BhRi16fYfxTr3z8bb+3haEmzut2k5aMTxeD55EMja9zVri+jIa+e4/SLbFZYpJIXAUiq iMKqdGXf4jv4838FdhuwS1oOSxMViOskZy3fzbOVnwWR6EWgc8nA7kTJJe9D/RJyjjSRunHqBq+FU GH2Wckth95BEYaEC7r/xTaaeKxVxY96y/5Mj2zcim+zwv+s1xiBtu5YVW1mYfLvWJ/kmBwetIkBFz rlZZs9Jg+/F0K1n+Ec/M/oqbTJpmkHl6rtgg+48plYCDlMk7DaW/2EjwENLv4PPAGz3pEcP9dvmoh LZn0CqsQ==; Received: from localhost ([::1] helo=merlin.infradead.org) by merlin.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1jo9KP-0004OL-PT; Wed, 24 Jun 2020 17:36:53 +0000 Received: from foss.arm.com ([217.140.110.172]) by merlin.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1jo9KM-0004Mr-FC for linux-arm-kernel@lists.infradead.org; Wed, 24 Jun 2020 17:36:51 +0000 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 2D6931FB; Wed, 24 Jun 2020 10:36:49 -0700 (PDT) Received: from e103592.cambridge.arm.com (usa-sjc-imap-foss1.foss.arm.com [10.121.207.14]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPA id 636FF3F71E; Wed, 24 Jun 2020 10:36:48 -0700 (PDT) From: Dave Martin To: Michael Kerrisk Subject: [PATCH v3 1/2] prctl.2: Add SVE prctls (arm64) Date: Wed, 24 Jun 2020 18:36:01 +0100 Message-Id: <1593020162-9365-2-git-send-email-Dave.Martin@arm.com> X-Mailer: git-send-email 2.1.4 In-Reply-To: <1593020162-9365-1-git-send-email-Dave.Martin@arm.com> References: <1593020162-9365-1-git-send-email-Dave.Martin@arm.com> X-Spam-Note: CRM114 invocation failed X-Spam-Score: -2.3 (--) X-Spam-Report: SpamAssassin version 3.4.4 on merlin.infradead.org summary: Content analysis details: (-2.3 points) pts rule name description ---- ---------------------- -------------------------------------------------- -2.3 RCVD_IN_DNSWL_MED RBL: Sender listed at https://www.dnswl.org/, medium trust [217.140.110.172 listed in list.dnswl.org] 0.0 SPF_HELO_NONE SPF: HELO does not publish an SPF Record -0.0 SPF_PASS SPF: sender matches SPF record X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: linux-arch@vger.kernel.org, linux-man@vger.kernel.org, Will Deacon , linux-arm-kernel@lists.infradead.org, Catalin Marinas MIME-Version: 1.0 Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+patchwork-linux-arm=patchwork.kernel.org@lists.infradead.org Add documentation for the the PR_SVE_SET_VL and PR_SVE_GET_VL prctls added in Linux 4.15 for arm64. Signed-off-by: Dave Martin Cc: Catalin Marinas Cc: Will Deacon --- Since v2: * Clarify that the arg2 enumeration for PR_SVE_SET_VL applies to the bith _other than_ the PR_SVE_VL_LEN_MASK bits, rather than to all the bits. * Clarify return value semantics for PR_SVE_SET_VL, to highlight that there is no PR_SVE_SET_VL_ONEXEC in the return value and refer to PR_SVE_GET_VL for the rest of the definition. Also clarify when the vector length given in the return value actually takes effect. * Reorder some documentation cross-references to avoid ambiguity about what they apply to. --- man2/prctl.2 | 170 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 170 insertions(+) diff --git a/man2/prctl.2 b/man2/prctl.2 index 88b791b..46ea9d2 100644 --- a/man2/prctl.2 +++ b/man2/prctl.2 @@ -1370,6 +1370,158 @@ call failing with the error .BR ENXIO . For further details, see the kernel source file .IR Documentation/admin\-guide/kernel\-parameters.txt . +.\" prctl PR_SVE_SET_VL +.\" commit 2d2123bc7c7f843aa9db87720de159a049839862 +.\" linux-5.6/Documentation/arm64/sve.rst +.TP +.BR PR_SVE_SET_VL " (since Linux 4.15, only on arm64)" +Configure the thread's SVE vector length, +as specified by +.IR "(int) arg2" . +Arguments +.IR arg3 ", " arg4 " and " arg5 +are ignored. +.IP +The bits of +.I arg2 +corresponding to +.B PR_SVE_VL_LEN_MASK +must be set to the desired vector length in bytes. +This is interpreted as an upper bound: +the kernel will select the greatest available vector length +that does not exceed the value specified. +In particular, specifying +.B SVE_VL_MAX +(defined in +.I ) +for the +.B PR_SVE_VL_LEN_MASK +bits requests the maximum supported vector length. +.IP +In addition, the other bits of +.I arg2 +must be set to one of the following combinations of flags: +.RS +.TP +.B 0 +Perform the change immediately. +At the next +.BR execve (2) +in the thread, +the vector length will be reset to the value configured in +.IR /proc/sys/abi/sve_default_vector_length . +.TP +.B PR_SVE_VL_INHERIT +Perform the change immediately. +Subsequent +.BR execve (2) +calls will preserve the new vector length. +.TP +.B PR_SVE_SET_VL_ONEXEC +Defer the change, so that it is performed at the next +.BR execve (2) +in the thread. +Further +.BR execve (2) +calls will reset the vector length to the value configured in +.IR /proc/sys/abi/sve_default_vector_length . +.TP +.B "PR_SVE_SET_VL_ONEXEC | PR_SVE_VL_INHERIT" +Defer the change, so that it is performed at the next +.BR execve (2) +in the thread. +Further +.BR execve (2) +calls will preserve the new vector length. +.RE +.IP +In all cases, +any previously pending deferred change is canceled. +.IP +The call fails with error +.B EINVAL +if SVE is not supported on the platform, if +.I arg2 +is unrecognized or invalid, or the value in the bits of +.I arg2 +corresponding to +.B PR_SVE_VL_LEN_MASK +is outside the range +.BR SVE_VL_MIN .. SVE_VL_MAX +or is not a multiple of 16. +.IP +On success, +a nonnegative value is returned that describes the +.I selected +configuration. +If +.B PR_SVE_SET_VL_ONEXEC +was included in +.IR arg2 , +then the configuration described by the return value +will take effect at the next +.BR execve (). +Otherwise, the configuration is already in effect when the +.B PR_SVE_SET_VL +call returns. +In either case, the value is encoded in the same way as the return value of +.BR PR_SVE_GET_VL . +Note that there is no explicit flag in the return value +corresponding to +.BR PR_SVE_SET_VL_ONEXEC . +.IP +The configuration (including any pending deferred change) +is inherited across +.BR fork (2) +and +.BR clone (2). +.IP +For more information, see the kernel source file +.I Documentation/arm64/sve.rst +.\"commit b693d0b372afb39432e1c49ad7b3454855bc6bed +(or +.I Documentation/arm64/sve.txt +before Linux 5.3). +.IP +.B Warning: +Because the compiler or run-time environment +may be using SVE, using this call without the +.B PR_SVE_SET_VL_ONEXEC +flag may crash the calling process. +The conditions for using it safely are complex and system-dependent. +Don't use it unless you really know what you are doing. +.\" prctl PR_SVE_GET_VL +.TP +.BR PR_SVE_GET_VL " (since Linux 4.15, only on arm64)" +Get the thread's current SVE vector length configuration. +.IP +Arguments +.IR arg2 ", " arg3 ", " arg4 " and " arg5 +are ignored. +.IP +Providing that the kernel and platform support SVE +this operation always succeeds, +returning a nonnegative value that describes the +.I current +configuration. +The bits corresponding to +.B PR_SVE_VL_LEN_MASK +contain the currently configured vector length in bytes. +The bit corresponding to +.B PR_SVE_VL_INHERIT +indicates whether the vector length will be inherited +across +.BR execve (2). +.IP +Note that there is no way to determine whether there is +a pending vector length change that has not yet taken effect. +.IP +For more information, see the kernel source file +.I Documentation/arm64/sve.rst +.\"commit b693d0b372afb39432e1c49ad7b3454855bc6bed +(or +.I Documentation/arm64/sve.txt +before Linux 5.3). .\" .\" prctl PR_TASK_PERF_EVENTS_DISABLE .TP @@ -1613,6 +1765,8 @@ On success, .BR PR_GET_NO_NEW_PRIVS , .BR PR_GET_SECUREBITS , .BR PR_GET_SPECULATION_CTRL , +.BR PR_SVE_GET_VL , +.BR PR_SVE_SET_VL , .BR PR_GET_THP_DISABLE , .BR PR_GET_TIMING , .BR PR_GET_TIMERSLACK , @@ -1904,6 +2058,22 @@ See the description of .B PR_PAC_RESET_KEYS above for details. .TP +.B EINVAL +.I option +is +.B PR_SVE_SET_VL +and the arguments are invalid or unsupported, +or SVE is not available on this platform. +See the description of +.B PR_SVE_SET_VL +above for details. +.TP +.B EINVAL +.I option +is +.B PR_SVE_GET_VL +and SVE is not available on this platform. +.TP .B ENODEV .I option was From patchwork Wed Jun 24 17:36:02 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Dave Martin X-Patchwork-Id: 11623863 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 1D33F1392 for ; Wed, 24 Jun 2020 17:38:48 +0000 (UTC) Received: from merlin.infradead.org (merlin.infradead.org [205.233.59.134]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id E535E20738 for ; Wed, 24 Jun 2020 17:38:47 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="qZCZtRaM" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org E535E20738 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=arm.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-arm-kernel-bounces+patchwork-linux-arm=patchwork.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=merlin.20170209; h=Sender:Content-Transfer-Encoding: Content-Type:MIME-Version:Cc:List-Subscribe:List-Help:List-Post:List-Archive: List-Unsubscribe:List-Id:References:In-Reply-To:Message-Id:Date:Subject:To: From:Reply-To:Content-ID:Content-Description:Resent-Date:Resent-From: Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=/nlWoY/AYsnwIF9pPZil++pgoTk6JZ7pj9gjUmEw/X0=; b=qZCZtRaM8tII4CeSakaICiAlt+ w0tvo4UA+G+aVAk6fZ7fxswq514UKh6+y4U2FI3uN9dA9+HTxy2Scu7MP5CPKIVNrk+/QLv2bISZQ O6KCf9vhwsXtG1MXX6lGPq7d0zxjk/WSUF3nihn6Pzne+gwByREhvqx7Ef2KINKxOo/hTulqD6Env lS6Kk1Ux2h4r6z4beW27tXsnC6xlDJnSDZWXVcRuQDkE8WCf9Ou0BixXD0yzvNVsSi2c+67CgjWCk jDgVZ3zbvz44d33m3PnSKWWG0hOteoAqPkqqVFnVAqWegGxrsxIdZn+FgTXjg0PoMUZqkbxDgm8Xw MYy6iE8w==; Received: from localhost ([::1] helo=merlin.infradead.org) by merlin.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1jo9KS-0004Pb-DE; Wed, 24 Jun 2020 17:36:56 +0000 Received: from foss.arm.com ([217.140.110.172]) by merlin.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1jo9KM-0004Mt-FD for linux-arm-kernel@lists.infradead.org; Wed, 24 Jun 2020 17:36:51 +0000 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 1020D31B; Wed, 24 Jun 2020 10:36:50 -0700 (PDT) Received: from e103592.cambridge.arm.com (usa-sjc-imap-foss1.foss.arm.com [10.121.207.14]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPA id 60E443F71E; Wed, 24 Jun 2020 10:36:49 -0700 (PDT) From: Dave Martin To: Michael Kerrisk Subject: [PATCH v3 2/2] prctl.2: Add tagged address ABI control prctls (arm64) Date: Wed, 24 Jun 2020 18:36:02 +0100 Message-Id: <1593020162-9365-3-git-send-email-Dave.Martin@arm.com> X-Mailer: git-send-email 2.1.4 In-Reply-To: <1593020162-9365-1-git-send-email-Dave.Martin@arm.com> References: <1593020162-9365-1-git-send-email-Dave.Martin@arm.com> X-Spam-Note: CRM114 invocation failed X-Spam-Score: -2.3 (--) X-Spam-Report: SpamAssassin version 3.4.4 on merlin.infradead.org summary: Content analysis details: (-2.3 points) pts rule name description ---- ---------------------- -------------------------------------------------- -2.3 RCVD_IN_DNSWL_MED RBL: Sender listed at https://www.dnswl.org/, medium trust [217.140.110.172 listed in list.dnswl.org] 0.0 SPF_HELO_NONE SPF: HELO does not publish an SPF Record -0.0 SPF_PASS SPF: sender matches SPF record X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: linux-arch@vger.kernel.org, linux-man@vger.kernel.org, Vincenzo Frascino , linux-arm-kernel@lists.infradead.org MIME-Version: 1.0 Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+patchwork-linux-arm=patchwork.kernel.org@lists.infradead.org Add documentation for the the PR_SET_TAGGED_ADDR_CTRL and PR_GET_TAGGED_ADDR_CTRL prctls added in Linux 5.4 for arm64. Signed-off-by: Dave Martin Reviewed-by: Catalin Marinas Cc: Vincenzo Frascino --- Kept Catalin's Reviewed-by, since the changes are pretty minor. Changes since v2: * Clarified type of PR_SET_TAGGED_ADDR_CTRL arg2. * Added Linux commit where enforecement of zeroing reserved args was added for PR_SET_TAGGED_ADDR_CTRL. * Added explicit text regarding how to disable the tagged-address ABI globally through sysctl. * Rearrange the tagged argument syscall exclusion list so that shmdt() isn't called out specially. The reader probably doesn't care about this history here. * Minor rewordings. --- man2/prctl.2 | 161 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 161 insertions(+) diff --git a/man2/prctl.2 b/man2/prctl.2 index 46ea9d2..cf92f3b 100644 --- a/man2/prctl.2 +++ b/man2/prctl.2 @@ -1522,6 +1522,148 @@ For more information, see the kernel source file (or .I Documentation/arm64/sve.txt before Linux 5.3). +.\" prctl PR_SET_TAGGED_ADDR_CTRL +.\" commit 63f0c60379650d82250f22e4cf4137ef3dc4f43d +.TP +.BR PR_SET_TAGGED_ADDR_CTRL " (since Linux 5.4, only on arm64)" +Controls support for passing tagged userspace addresses to the kernel +(i.e., addresses where bits 56\(em63 are not all zero). +.IP +The level of support is selected by +.IR "arg2" , +which can be one of the following: +.RS +.TP +.B 0 +Addresses that are passed +for the purpose of being dereferenced by the kernel +must be untagged. +.TP +.B PR_TAGGED_ADDR_ENABLE +Addresses that are passed +for the purpose of being dereferenced by the kernel +may be tagged, with the exceptions summarized below. +.RE +.IP +The remaining arguments +.IR arg3 ", " arg4 " and " arg5 +must all be zero. +.\" Enforcement added in +.\" commit 3e91ec89f527b9870fe42dcbdb74fd389d123a95 +.IP +On success, the mode specified in +.I arg2 +is set for the calling thread and the the return value is 0. +If the arguments are invalid, +the mode specified in +.I arg2 +is unrecognized, +or if this feature is unsupported by the kernel +or disabled via +.IR /proc/sys/abi/tagged_addr_disabled , +the call fails with +.BR EINVAL . +.IP +In particular, if +.BR prctl ( PR_SET_TAGGED_ADDR_CTRL , +0, 0, 0, 0) +fails with +.B EINVAL +then all addresses passed to the kernel must be untagged. +.IP +Irrespective of which mode is set, +addresses passed to certain interfaces +must always be untagged: +.RS +.IP \(em +.BR brk (2), +.BR mmap (2), +.BR shmat (2), +.BR shmdt (2), +and the +.I new_address +argument of +.BR mremap (2). +.IP +(Prior to Linux 5.6 these accepted tagged addresses, +but the behaviour may not be what you expect. +Don't rely on it.) +.IP \(em +\(oqpolymorphic\(cq interfaces +that accept pointers to arbitrary types cast to a +.I void * +or other generic type, specifically +.BR prctl (2), +.BR ioctl (2), +and in general +.BR setsockopt (2) +(only certain specific +.BR setsockopt (2) +options allow tagged addresses). +.RE +.IP +This list of exclusions may shrink +when moving from one kernel version to a later kernel version. +While the kernel may make some guarantees +for backwards compatibility reasons, +for the purposes of new software +the effect of passing tagged addresses to these interfaces +is unspecified. +.IP +The mode set by this call is inherited across +.BR fork (2) +and +.BR clone (2). +The mode is reset by +.BR execve (2) +to 0 +(i.e., tagged addresses not permitted in the user/kernel ABI). +.IP +For more information, see the kernel source file +.IR Documentation/arm64/tagged\-address\-abi.rst . +.IP +.B Warning: +This call is primarily intended for use by the run-time environment. +A successful +.B PR_SET_TAGGED_ADDR_CTRL +call elsewhere may crash the calling process. +The conditions for using it safely are complex and system-dependent; +Don't use it unless you know what you are doing. +.\" prctl PR_GET_TAGGED_ADDR_CTRL +.\" commit 63f0c60379650d82250f22e4cf4137ef3dc4f43d +.TP +.BR PR_GET_TAGGED_ADDR_CTRL " (since Linux 5.4, only on arm64)" +Returns the current tagged address mode +for the calling thread. +.IP +Arguments +.IR arg2 ", " arg3 ", " arg4 " and " arg5 +must all be zero. +.IP +If the arguments are invalid +or this feature is disabled or unsupported by the kernel, +the call fails with +.BR EINVAL . +In particular, if +.BR prctl ( PR_GET_TAGGED_ADDR_CTRL , +0, 0, 0, 0) +fails with +.BR EINVAL , +then this feature is definitely either unsupported, +or disabled via +.IR /proc/sys/abi/tagged_addr_disabled . +In this case, +all addresses passed to the kernel must be untagged. +.IP +Otherwise, the call returns a nonnegative value +describing the current tagged address mode, +encoded in the same way as the +.I arg2 +argument of +.BR PR_SET_TAGGED_ADDR_CTRL . +.IP +For more information, see the kernel source file +.IR Documentation/arm64/tagged\-address\-abi.rst . .\" .\" prctl PR_TASK_PERF_EVENTS_DISABLE .TP @@ -1767,6 +1909,7 @@ On success, .BR PR_GET_SPECULATION_CTRL , .BR PR_SVE_GET_VL , .BR PR_SVE_SET_VL , +.BR PR_GET_TAGGED_ADDR_CTRL , .BR PR_GET_THP_DISABLE , .BR PR_GET_TIMING , .BR PR_GET_TIMERSLACK , @@ -2074,6 +2217,24 @@ is .B PR_SVE_GET_VL and SVE is not available on this platform. .TP +.B EINVAL +.I option +is +.BR PR_SET_TAGGED_ADDR_CTRL +and the arguments are invalid or unsupported. +See the description of +.B PR_SET_TAGGED_ADDR_CTRL +above for details. +.TP +.B EINVAL +.I option +is +.BR PR_GET_TAGGED_ADDR_CTRL +and the arguments are invalid or unsupported. +See the description of +.B PR_GET_TAGGED_ADDR_CTRL +above for details. +.TP .B ENODEV .I option was