From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from cantor2.suse.de ([195.135.220.15] helo=mx2.suse.de) by merlin.infradead.org with esmtps (Exim 4.76 #1 (Red Hat Linux)) id 1T4w1s-00021V-Bn for kexec@lists.infradead.org; Fri, 24 Aug 2012 15:42:37 +0000 Subject: [PATCHv3 6/9] Fix domain pickled_id computation for xen-3.4+ From: Petr Tesarik Date: Fri, 24 Aug 2012 17:42:32 +0200 MIME-Version: 1.0 Message-Id: <201208241742.33067.ptesarik@suse.cz> 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-bounces@lists.infradead.org Errors-To: kexec-bounces+dwmw2=infradead.org@lists.infradead.org To: kexec@lists.infradead.org Cc: Norbert Trapp Originally, Xen stored the 32-bit address of the domain structure in struct page_info. On x86-64, the physical address was stored, but since all heap objects were allocated in the 1:1 mapping which started at 0xffff830000000000, the end result was the same as if we simply chopped off the high bits (actual implementation in makedumpfile). Then, during the development of Xen-3.4, this logic was changed several times for x86-64: changeset 39517e863cc8 widened the _domain field to 64 bits and stored the virtual address of struct domain instead of physical address changeset beba88f6f90d removed the pickle/unpickle macros changeset 0858f961c77a changed _domain back from unsigned long to u32, *and* stores the MFN of struct domain instead All the above changes went into Xen-3.4, and the relation between a domain address and the contents of the _domain field hasn't changed since then. That means, when the MADDR space was compressed in Xen-4.0, the type of the _domain field was changed to _pdx_t, which was specifically invented to preserve its calculation from the struct domain address. To sum it up: 1. For all Xen versions before Xen-3.4, the _domain field contains the address of struct domain (with high bits chopped for x86-64). 2. For all Xen versions starting with Xen-3.4, the _domain field can be computed from struct domain address as: (addr - DIRECTMAP_VIRT_START) >> PAGE_SHIFT Signed-off-by: Petr Tesarik --- arch/x86_64.c | 26 ++++++++++++++++++++------ 1 file changed, 20 insertions(+), 6 deletions(-) --- a/arch/x86_64.c +++ b/arch/x86_64.c @@ -405,12 +405,26 @@ int get_xen_info_x86_64(void) { int i; - /* - * pickled_id == domain addr for x86_64 - */ - for (i = 0; i < info->num_domain; i++) { - info->domain_list[i].pickled_id = - info->domain_list[i].domain_addr; + if (info->xen_crash_info.com && + (info->xen_crash_info.com->xen_major_version >= 4 || + (info->xen_crash_info.com->xen_major_version == 3 && + info->xen_crash_info.com->xen_minor_version >= 4))) { + /* + * cf. changeset 0858f961c77a + */ + for (i = 0; i < info->num_domain; i++) { + info->domain_list[i].pickled_id = + (info->domain_list[i].domain_addr - + DIRECTMAP_VIRT_START) >> PAGESHIFT(); + } + } else { + /* + * pickled_id == domain addr for x86_64 + */ + for (i = 0; i < info->num_domain; i++) { + info->domain_list[i].pickled_id = + info->domain_list[i].domain_addr; + } } return TRUE; _______________________________________________ kexec mailing list kexec@lists.infradead.org http://lists.infradead.org/mailman/listinfo/kexec