From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from e23smtp06.au.ibm.com (e23smtp06.au.ibm.com [202.81.31.148]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (Client CN "e23smtp06.au.ibm.com", Issuer "GeoTrust SSL CA" (not verified)) by ozlabs.org (Postfix) with ESMTPS id 609812C00A4 for ; Mon, 13 May 2013 11:05:02 +1000 (EST) Received: from /spool/local by e23smtp06.au.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Mon, 13 May 2013 10:58:43 +1000 Received: from d23relay04.au.ibm.com (d23relay04.au.ibm.com [9.190.234.120]) by d23dlp02.au.ibm.com (Postfix) with ESMTP id 728652BB0023 for ; Mon, 13 May 2013 11:04:57 +1000 (EST) Received: from d23av03.au.ibm.com (d23av03.au.ibm.com [9.190.234.97]) by d23relay04.au.ibm.com (8.13.8/8.13.8/NCO v10.0) with ESMTP id r4D0p0u720906122 for ; Mon, 13 May 2013 10:51:00 +1000 Received: from d23av03.au.ibm.com (loopback [127.0.0.1]) by d23av03.au.ibm.com (8.14.4/8.13.1/NCO v10.0 AVout) with ESMTP id r4D14v0K020855 for ; Mon, 13 May 2013 11:04:57 +1000 Date: Mon, 13 May 2013 11:04:53 +1000 From: Anton Blanchard To: benh@kernel.crashing.org, paulus@samba.org Subject: [PATCH] powerpc/kexec: Fix kexec when using VMX optimised memcpy Message-ID: <20130513110453.02a2d748@kryten> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Cc: linuxppc-dev@lists.ozlabs.org List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , commit b3f271e86e5a (powerpc: POWER7 optimised memcpy using VMX and enhanced prefetch) uses VMX when it is safe to do so (ie not in interrupt). It also looks at the task struct to decide if we have to save the current tasks' VMX state. kexec calls memcpy() at a point where the task struct may have been overwritten by the new kexec segments. If it has been overwritten then when memcpy -> enable_altivec looks up current->thread.regs->msr we get a cryptic oops or lockup. I also notice we aren't initialising thread_info->cpu, which means smp_processor_id is broken. Fix that too. Signed-off-by: Anton Blanchard Cc: # 3.6+ --- Index: b/arch/powerpc/kernel/machine_kexec_64.c =================================================================== --- a/arch/powerpc/kernel/machine_kexec_64.c +++ b/arch/powerpc/kernel/machine_kexec_64.c @@ -17,6 +17,7 @@ #include #include #include +#include #include #include @@ -335,10 +338,13 @@ void default_machine_kexec(struct kimage pr_debug("kexec: Starting switchover sequence.\n"); /* switch to a staticly allocated stack. Based on irq stack code. + * We setup preempt_count to avoid using VMX in memcpy. * XXX: the task struct will likely be invalid once we do the copy! */ kexec_stack.thread_info.task = current_thread_info()->task; kexec_stack.thread_info.flags = 0; + kexec_stack.thread_info.preempt_count = HARDIRQ_OFFSET; + kexec_stack.thread_info.cpu = current_thread_info()->cpu; /* We need a static PACA, too; copy this CPU's PACA over and switch to * it. Also poison per_cpu_offset to catch anyone using non-static