Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1762749AbXHUG7g (ORCPT ); Tue, 21 Aug 2007 02:59:36 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1760366AbXHUGzk (ORCPT ); Tue, 21 Aug 2007 02:55:40 -0400 Received: from canuck.infradead.org ([209.217.80.40]:44367 "EHLO canuck.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1761097AbXHUGzj (ORCPT ); Tue, 21 Aug 2007 02:55:39 -0400 Date: Mon, 20 Aug 2007 23:56:05 -0700 From: Greg KH To: linux-kernel@vger.kernel.org, stable@kernel.org, cebbert@redhat.com, patches@x86-64.org Cc: Justin Forbes , Zwane Mwaikambo , "Theodore Ts'o" , Randy Dunlap , Dave Jones , Chuck Wolber , Chris Wedgwood , Michael Krufky , Domenico Andreoli , torvalds@linux-foundation.org, akpm@linux-foundation.org, alan@lxorguk.ukuu.org.uk, Andi Kleen , Greg Kroah-Hartman Subject: [patch 19/20] i386: Fix double fault handler Message-ID: <20070821065605.GT5275@kroah.com> References: <20070821064251.972690753@blue.kroah.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline; filename="i386-fix-double-fault-handler.patch" In-Reply-To: <20070821065210.GA5275@kroah.com> User-Agent: Mutt/1.5.15 (2007-04-06) X-Bad-Reply: References and In-Reply-To but no 'Re:' in Subject. Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3006 Lines: 88 -stable review patch. If anyone has any objections, please let us know. ------------------ From: Chuck Ebbert The new percpu code has apparently broken the doublefault handler when CONFIG_DEBUG_SPINLOCK is set. Doublefault is handled by a hardware task, making the check SPIN_BUG_ON(lock->owner == current, lock, "recursion"); fault because it uses the FS register to access the percpu data for current, and that register is zero in the new TSS. (The trace I saw was on 2.6.20 where it was GS, but it looks like this will still happen with FS on 2.6.22.) Initializing FS in the doublefault_tss should fix it. AK: Also fix broken ptr_ok() and turn printks into KERN_EMERG AK: And add a PANIC prefix to make clear the system will hang AK: (e.g. x86-64 will recover) Signed-off-by: Chuck Ebbert Signed-off-by: Andi Kleen Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman --- arch/i386/kernel/doublefault.c | 13 +++++++------ 1 file changed, 7 insertions(+), 6 deletions(-) --- a/arch/i386/kernel/doublefault.c +++ b/arch/i386/kernel/doublefault.c @@ -13,7 +13,7 @@ static unsigned long doublefault_stack[DOUBLEFAULT_STACKSIZE]; #define STACK_START (unsigned long)(doublefault_stack+DOUBLEFAULT_STACKSIZE) -#define ptr_ok(x) ((x) > PAGE_OFFSET && (x) < PAGE_OFFSET + 0x1000000) +#define ptr_ok(x) ((x) > PAGE_OFFSET && (x) < PAGE_OFFSET + MAXMEM) static void doublefault_fn(void) { @@ -23,23 +23,23 @@ static void doublefault_fn(void) store_gdt(&gdt_desc); gdt = gdt_desc.address; - printk("double fault, gdt at %08lx [%d bytes]\n", gdt, gdt_desc.size); + printk(KERN_EMERG "PANIC: double fault, gdt at %08lx [%d bytes]\n", gdt, gdt_desc.size); if (ptr_ok(gdt)) { gdt += GDT_ENTRY_TSS << 3; tss = *(u16 *)(gdt+2); tss += *(u8 *)(gdt+4) << 16; tss += *(u8 *)(gdt+7) << 24; - printk("double fault, tss at %08lx\n", tss); + printk(KERN_EMERG "double fault, tss at %08lx\n", tss); if (ptr_ok(tss)) { struct i386_hw_tss *t = (struct i386_hw_tss *)tss; - printk("eip = %08lx, esp = %08lx\n", t->eip, t->esp); + printk(KERN_EMERG "eip = %08lx, esp = %08lx\n", t->eip, t->esp); - printk("eax = %08lx, ebx = %08lx, ecx = %08lx, edx = %08lx\n", + printk(KERN_EMERG "eax = %08lx, ebx = %08lx, ecx = %08lx, edx = %08lx\n", t->eax, t->ebx, t->ecx, t->edx); - printk("esi = %08lx, edi = %08lx\n", + printk(KERN_EMERG "esi = %08lx, edi = %08lx\n", t->esi, t->edi); } } @@ -63,6 +63,7 @@ struct tss_struct doublefault_tss __cach .cs = __KERNEL_CS, .ss = __KERNEL_DS, .ds = __USER_DS, + .fs = __KERNEL_PERCPU, .__cr3 = __pa(swapper_pg_dir) } -- - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/