From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753195AbcGDGw5 (ORCPT ); Mon, 4 Jul 2016 02:52:57 -0400 Received: from mail-pa0-f49.google.com ([209.85.220.49]:36606 "EHLO mail-pa0-f49.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750928AbcGDGw4 (ORCPT ); Mon, 4 Jul 2016 02:52:56 -0400 Date: Mon, 4 Jul 2016 15:58:15 +0900 From: AKASHI Takahiro To: Thiago Jung Bauermann Cc: kexec@lists.infradead.org, ebiederm@xmission.com, dyoung@redhat.com, bhe@redhat.com, vgoyal@redhat.com, will.deacon@arm.com, catalin.marinas@arm.com, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linuxppc-dev@lists.ozlabs.org Subject: Re: [RFC] arm64: kexec_file_load support Message-ID: <20160704065814.GO20774@linaro.org> Mail-Followup-To: AKASHI Takahiro , Thiago Jung Bauermann , kexec@lists.infradead.org, ebiederm@xmission.com, dyoung@redhat.com, bhe@redhat.com, vgoyal@redhat.com, will.deacon@arm.com, catalin.marinas@arm.com, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linuxppc-dev@lists.ozlabs.org References: <20160701051111.GL20774@linaro.org> <3300473.zhbeG65qgA@hactar> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-2022-jp Content-Disposition: inline In-Reply-To: <3300473.zhbeG65qgA@hactar> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi, On Fri, Jul 01, 2016 at 12:46:31PM -0300, Thiago Jung Bauermann wrote: > Am Freitag, 01 Juli 2016, 14:11:12 schrieb AKASHI Takahiro: > > I'm not sure whether there is any demand for kexec_file_load > > support on arm64, but anyhow I'm working on this and now > > my early prototype code does work fine. > > It is necessary if you want to support loading only signed kernels, and also > if you want IMA to measure the kernel in its event log. > > > There is, however, one essential issue: > > While arm64 kernel requires a device tree blob to be set up > > correctly at boot time, the current system call API doesn't > > have this parameter. > > int kexec_file_load(int kernel_fd, int initrd_fd, > > unsigned long cmdline_len, const char > > *cmdline_ptr, unsigned long flags); > > > > Should we invent a new system call, like kexec_file_load2, > > and, if so, what kind of interface would be desired? > > I'm facing the same issue on powerpc. What I'm doing is taking the device > tree that was used to boot the current kernel and modifying it as necessary > to pass it to the next kernel. That is exactly what I do. > I agree that it would be better if we could have a system call where a > custom device tree could be passed. One suggestion is: For powerpc, you might be able to use dtbImage instead of Image without changing the kernel interfaces. > > kexec_file_load2(int fds[], int fd_types[], int nr_fds, > unsigned long cmdline_len, const char *cmdline_ptr, > unsigned long flags); You don't want to simply add one more argument, i.e. dtb_fd, don't you. I prefer a slightly-simpler interface: struct kexec_file_fd { enum kexec_file_type; int fd; } int kexec_file_load2(struct kexec_file_fd[], int nr_fds, int flags); Or if you want to keep the compatibility with the existing system call, int kexec_file_load(int kernel_fd, int initrd_fd, unsigned long cmdline_len, const char *cmdline_ptr, unsigned long flags, int struct kexec_file_fd[], int nr_fds); Here SYSCALL_DEFINE7() have to be defined, and I'm not sure that we will not have a problem in adding a system call with more than 6 arguments. > Where fds is an array with nr_fds file descriptors and fd_types is an array > specifying what each fd in fds is. So for example, if fds[i] is the kernel, > then fd_types[i] would have the value KEXEC_FILE_KERNEL_FD. If fds[i] is the > device tree blob, fd_types[i], would have the value KEXEC_FILE_DTB and so > on. That way, the syscall can be extended for an arbitrary number and types > of segments that have to be loaded, just like kexec_load. > > Another option is to have a struct: > > kexec_file_load2(struct kexec_file_params *params, unsigned long params_sz); Wow, we can add any number of new parameters with this interface. Thanks, -Takahiro AKASHI > Where: > > struct kexec_file_params { > int version; /* allows struct to be extended in the future */ > int fds[]; > int fd_types[]; > int nr_fds; > unsigned long cmdline_len; > const char *cmdline_ptr; > unsigned long flags; > }; > > This is even more flexible. > > []'s > Thiago Jung Bauermann > IBM Linux Technology Center > From mboxrd@z Thu Jan 1 00:00:00 1970 From: takahiro.akashi@linaro.org (AKASHI Takahiro) Date: Mon, 4 Jul 2016 15:58:15 +0900 Subject: [RFC] arm64: kexec_file_load support In-Reply-To: <3300473.zhbeG65qgA@hactar> References: <20160701051111.GL20774@linaro.org> <3300473.zhbeG65qgA@hactar> Message-ID: <20160704065814.GO20774@linaro.org> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org Hi, On Fri, Jul 01, 2016 at 12:46:31PM -0300, Thiago Jung Bauermann wrote: > Am Freitag, 01 Juli 2016, 14:11:12 schrieb AKASHI Takahiro: > > I'm not sure whether there is any demand for kexec_file_load > > support on arm64, but anyhow I'm working on this and now > > my early prototype code does work fine. > > It is necessary if you want to support loading only signed kernels, and also > if you want IMA to measure the kernel in its event log. > > > There is, however, one essential issue: > > While arm64 kernel requires a device tree blob to be set up > > correctly at boot time, the current system call API doesn't > > have this parameter. > > int kexec_file_load(int kernel_fd, int initrd_fd, > > unsigned long cmdline_len, const char > > *cmdline_ptr, unsigned long flags); > > > > Should we invent a new system call, like kexec_file_load2, > > and, if so, what kind of interface would be desired? > > I'm facing the same issue on powerpc. What I'm doing is taking the device > tree that was used to boot the current kernel and modifying it as necessary > to pass it to the next kernel. That is exactly what I do. > I agree that it would be better if we could have a system call where a > custom device tree could be passed. One suggestion is: For powerpc, you might be able to use dtbImage instead of Image without changing the kernel interfaces. > > kexec_file_load2(int fds[], int fd_types[], int nr_fds, > unsigned long cmdline_len, const char *cmdline_ptr, > unsigned long flags); You don't want to simply add one more argument, i.e. dtb_fd, don't you. I prefer a slightly-simpler interface: struct kexec_file_fd { enum kexec_file_type; int fd; } int kexec_file_load2(struct kexec_file_fd[], int nr_fds, int flags); Or if you want to keep the compatibility with the existing system call, int kexec_file_load(int kernel_fd, int initrd_fd, unsigned long cmdline_len, const char *cmdline_ptr, unsigned long flags, int struct kexec_file_fd[], int nr_fds); Here SYSCALL_DEFINE7() have to be defined, and I'm not sure that we will not have a problem in adding a system call with more than 6 arguments. > Where fds is an array with nr_fds file descriptors and fd_types is an array > specifying what each fd in fds is. So for example, if fds[i] is the kernel, > then fd_types[i] would have the value KEXEC_FILE_KERNEL_FD. If fds[i] is the > device tree blob, fd_types[i], would have the value KEXEC_FILE_DTB and so > on. That way, the syscall can be extended for an arbitrary number and types > of segments that have to be loaded, just like kexec_load. > > Another option is to have a struct: > > kexec_file_load2(struct kexec_file_params *params, unsigned long params_sz); Wow, we can add any number of new parameters with this interface. Thanks, -Takahiro AKASHI > Where: > > struct kexec_file_params { > int version; /* allows struct to be extended in the future */ > int fds[]; > int fd_types[]; > int nr_fds; > unsigned long cmdline_len; > const char *cmdline_ptr; > unsigned long flags; > }; > > This is even more flexible. > > []'s > Thiago Jung Bauermann > IBM Linux Technology Center > From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from mail-pa0-x232.google.com ([2607:f8b0:400e:c03::232]) by bombadil.infradead.org with esmtps (Exim 4.85_2 #1 (Red Hat Linux)) id 1bJxkq-0005aK-M8 for kexec@lists.infradead.org; Mon, 04 Jul 2016 06:53:17 +0000 Received: by mail-pa0-x232.google.com with SMTP id bz2so56531838pad.1 for ; Sun, 03 Jul 2016 23:52:55 -0700 (PDT) Date: Mon, 4 Jul 2016 15:58:15 +0900 From: AKASHI Takahiro Subject: Re: [RFC] arm64: kexec_file_load support Message-ID: <20160704065814.GO20774@linaro.org> References: <20160701051111.GL20774@linaro.org> <3300473.zhbeG65qgA@hactar> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <3300473.zhbeG65qgA@hactar> List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "kexec" Errors-To: kexec-bounces+dwmw2=infradead.org@lists.infradead.org To: Thiago Jung Bauermann Cc: linux-arm-kernel@lists.infradead.org, bhe@redhat.com, kexec@lists.infradead.org, linuxppc-dev@lists.ozlabs.org, will.deacon@arm.com, linux-kernel@vger.kernel.org, ebiederm@xmission.com, catalin.marinas@arm.com, dyoung@redhat.com, vgoyal@redhat.com Hi, On Fri, Jul 01, 2016 at 12:46:31PM -0300, Thiago Jung Bauermann wrote: > Am Freitag, 01 Juli 2016, 14:11:12 schrieb AKASHI Takahiro: > > I'm not sure whether there is any demand for kexec_file_load > > support on arm64, but anyhow I'm working on this and now > > my early prototype code does work fine. > > It is necessary if you want to support loading only signed kernels, and also > if you want IMA to measure the kernel in its event log. > > > There is, however, one essential issue: > > While arm64 kernel requires a device tree blob to be set up > > correctly at boot time, the current system call API doesn't > > have this parameter. > > int kexec_file_load(int kernel_fd, int initrd_fd, > > unsigned long cmdline_len, const char > > *cmdline_ptr, unsigned long flags); > > > > Should we invent a new system call, like kexec_file_load2, > > and, if so, what kind of interface would be desired? > > I'm facing the same issue on powerpc. What I'm doing is taking the device > tree that was used to boot the current kernel and modifying it as necessary > to pass it to the next kernel. That is exactly what I do. > I agree that it would be better if we could have a system call where a > custom device tree could be passed. One suggestion is: For powerpc, you might be able to use dtbImage instead of Image without changing the kernel interfaces. > > kexec_file_load2(int fds[], int fd_types[], int nr_fds, > unsigned long cmdline_len, const char *cmdline_ptr, > unsigned long flags); You don't want to simply add one more argument, i.e. dtb_fd, don't you. I prefer a slightly-simpler interface: struct kexec_file_fd { enum kexec_file_type; int fd; } int kexec_file_load2(struct kexec_file_fd[], int nr_fds, int flags); Or if you want to keep the compatibility with the existing system call, int kexec_file_load(int kernel_fd, int initrd_fd, unsigned long cmdline_len, const char *cmdline_ptr, unsigned long flags, int struct kexec_file_fd[], int nr_fds); Here SYSCALL_DEFINE7() have to be defined, and I'm not sure that we will not have a problem in adding a system call with more than 6 arguments. > Where fds is an array with nr_fds file descriptors and fd_types is an array > specifying what each fd in fds is. So for example, if fds[i] is the kernel, > then fd_types[i] would have the value KEXEC_FILE_KERNEL_FD. If fds[i] is the > device tree blob, fd_types[i], would have the value KEXEC_FILE_DTB and so > on. That way, the syscall can be extended for an arbitrary number and types > of segments that have to be loaded, just like kexec_load. > > Another option is to have a struct: > > kexec_file_load2(struct kexec_file_params *params, unsigned long params_sz); Wow, we can add any number of new parameters with this interface. Thanks, -Takahiro AKASHI > Where: > > struct kexec_file_params { > int version; /* allows struct to be extended in the future */ > int fds[]; > int fd_types[]; > int nr_fds; > unsigned long cmdline_len; > const char *cmdline_ptr; > unsigned long flags; > }; > > This is even more flexible. > > []'s > Thiago Jung Bauermann > IBM Linux Technology Center > _______________________________________________ kexec mailing list kexec@lists.infradead.org http://lists.infradead.org/mailman/listinfo/kexec