[{"id":1768469,"web_url":"http://patchwork.ozlabs.org/comment/1768469/","msgid":"<87inglaaqb.fsf@linaro.org>","list_archive_url":null,"date":"2017-09-14T09:30:20","subject":"Re: [PATCH v2 13/28] arm64/sve: Signal handling support","submitter":{"id":39532,"url":"http://patchwork.ozlabs.org/api/people/39532/","name":"Alex Bennée","email":"alex.bennee@linaro.org"},"content":"Dave Martin writes:\n\n> This patch implements support for saving and restoring the SVE\n> registers around signals.\n>\n> A fixed-size header struct sve_context is always included in the\n> signal frame encoding the thread's vector length at the time of\n> signal delivery, optionally followed by a variable-layout structure\n> encoding the SVE registers.\n>\n> Because of the need to preserve backwards compatibility, the FPSIMD\n> view of the SVE registers is always dumped as a struct\n> fpsimd_context in the usual way, in addition to any sve_context.\n>\n> The SVE vector registers are dumped in full, including bits 127:0\n> of each register which alias the corresponding FPSIMD vector\n> registers in the hardware. To avoid any ambiguity about which\n> alias to restore during sigreturn, the kernel always restores bits\n> 127:0 of each SVE vector register from the fpsimd_context in the\n> signal frame (which must be present): userspace needs to take this\n> into account if it wants to modify the SVE vector register contents\n> on return from a signal.\n>\n> FPSR and FPCR, which are used by both FPSIMD and SVE, are not\n> included in sve_context because they are always present in\n> fpsimd_context anyway.\n>\n> For signal delivery, a new helper\n> fpsimd_signal_preserve_current_state() is added to update _both_\n> the FPSIMD and SVE views in the task struct, to make it easier to\n> populate this information into the signal frame. Because of the\n> redundancy between the two views of the state, only one is updated\n> otherwise. In order to avoid racing with a pending discard of the\n> SVE state, this flush is hoisted before the sigframe layout phase,\n> so that the layout and population phases see a consistent view of\n> the thread.\n>\n> Signed-off-by: Dave Martin \n> Cc: Ard Biesheuvel \n> Cc: Alex Bennée \n>\n\nReviewed-by: Alex Bennée \n\n--\nAlex Bennée","headers":{"Return-Path":"","X-Original-To":"incoming-imx@patchwork.ozlabs.org","Delivered-To":"patchwork-incoming-imx@bilbo.ozlabs.org","Authentication-Results":["ozlabs.org;\n\tspf=none (mailfrom) smtp.mailfrom=lists.infradead.org\n\t(client-ip=65.50.211.133; helo=bombadil.infradead.org;\n\tenvelope-from=linux-arm-kernel-bounces+incoming-imx=patchwork.ozlabs.org@lists.infradead.org;\n\treceiver=)","ozlabs.org; dkim=pass (2048-bit key;\n\tunprotected) header.d=lists.infradead.org\n\theader.i=@lists.infradead.org header.b=\"Z8HjZGhs\"; \n\tdkim=fail reason=\"signature verification failed\" (1024-bit key;\n\tunprotected) header.d=linaro.org header.i=@linaro.org\n\theader.b=\"bGxFZzeS\"; 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emacs 25.2.50.3","From":"Alex =?utf-8?q?Benn=C3=A9e?= ","To":"Dave Martin ","Subject":"Re: [PATCH v2 13/28] arm64/sve: Signal handling support","In-reply-to":"<1504198860-12951-14-git-send-email-Dave.Martin@arm.com>","Date":"Thu, 14 Sep 2017 10:30:20 +0100","Message-ID":"<87inglaaqb.fsf@linaro.org>","MIME-Version":"1.0","X-CRM114-Version":"20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 ","X-CRM114-CacheID":"sfid-20170914_023045_780351_408F7ACC ","X-CRM114-Status":"GOOD ( 15.16 )","X-Spam-Score":"-2.7 (--)","X-Spam-Report":"SpamAssassin version 3.4.1 on bombadil.infradead.org summary:\n\tContent analysis details: (-2.7 points)\n\tpts rule name description\n\t---- ----------------------\n\t--------------------------------------------------\n\t-0.7 RCVD_IN_DNSWL_LOW RBL: Sender listed at http://www.dnswl.org/,\n\tlow\n\ttrust [2a00:1450:400c:c09:0:0:0:22c listed in] [list.dnswl.org]\n\t-0.0 SPF_PASS SPF: sender matches SPF record\n\t-1.9 BAYES_00 BODY: Bayes spam probability is 0 to 1%\n\t[score: 0.0000]\n\t-0.1 DKIM_VALID Message has at least one valid DKIM or DK signature\n\t0.1 DKIM_SIGNED Message has a DKIM or DK signature,\n\tnot necessarily valid\n\t-0.1 DKIM_VALID_AU Message has a valid DKIM or DK signature from\n\tauthor's domain","X-BeenThere":"linux-arm-kernel@lists.infradead.org","X-Mailman-Version":"2.1.21","Precedence":"list","List-Unsubscribe":",\n\t","List-Archive":"","List-Post":"","List-Help":"","List-Subscribe":",\n\t","Cc":"linux-arch@vger.kernel.org, libc-alpha@sourceware.org,\n\tArd Biesheuvel ,\n\tSzabolcs Nagy ,\n\tCatalin Marinas ,\n\tWill Deacon , \n\tRichard Sandiford ,\n\tkvmarm@lists.cs.columbia.edu, linux-arm-kernel@lists.infradead.org","Content-Type":"text/plain; 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