Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S267985AbUJCPyU (ORCPT ); Sun, 3 Oct 2004 11:54:20 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S267978AbUJCPyU (ORCPT ); Sun, 3 Oct 2004 11:54:20 -0400 Received: from mail.tv-sign.ru ([213.234.233.51]:4298 "EHLO several.ru") by vger.kernel.org with ESMTP id S267985AbUJCPyO (ORCPT ); Sun, 3 Oct 2004 11:54:14 -0400 Message-ID: <41602238.A828A852@tv-sign.ru> Date: Sun, 03 Oct 2004 20:00:56 +0400 From: Oleg Nesterov X-Mailer: Mozilla 4.76 [en] (X11; U; Linux 2.2.20 i686) X-Accept-Language: en MIME-Version: 1.0 To: linux-kernel@vger.kernel.org Cc: Kirill Korotaev , Andrew Morton , Linus Torvalds Subject: [PATCH] alternate stack dump fix. Content-Type: text/plain; charset=koi8-r Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3251 Lines: 111 Hello. Kirill Korotaev wrote: > > This patch fixes incorrect check for stack ptr in > show_trace()->valid_stack_ptr(). When called from hardirq/softirq > show_trace() prints "Stack pointer is garbage, not printing trace" > message instead of call traces. There is another problem in show_trace(). With CONFIG_FRAME_POINTER every call to print_context_stack() will now print entire call chain, switching the stacks transparently, beacause valid_stack_ptr() now accepts ebp in irq stack. Then show trace switch the stack, and calls print_context_stack() again with the same value in ebp, and we have the same dump after printk(" =======================\n"). What do you think about the following patch? Against 2.6.9-rc3. Oleg. Signed-off-by: Oleg Nesterov --- 2.6.9-rc3/arch/i386/kernel/traps.c~ Sun Oct 3 18:45:52 2004 +++ 2.6.9-rc3/arch/i386/kernel/traps.c Sun Oct 3 19:54:07 2004 @@ -107,36 +107,27 @@ int register_die_notifier(struct notifie return err; } -static int valid_stack_ptr(struct task_struct *task, void *p) +static int valid_stack_ptr(struct thread_info *tinfo, void *p) { - if (p <= (void *)task->thread_info) - return 0; - if (kstack_end(p)) - return 0; - return 1; + return p > (void *)tinfo && + p < (void *)tinfo + THREAD_SIZE - 3; } -#ifdef CONFIG_FRAME_POINTER -static void print_context_stack(struct task_struct *task, unsigned long *stack, +static unsigned long print_context_stack(struct thread_info *tinfo, unsigned long *stack, unsigned long ebp) { unsigned long addr; - while (valid_stack_ptr(task, (void *)ebp)) { +#ifdef CONFIG_FRAME_POINTER + while (valid_stack_ptr(tinfo, (void *)ebp)) { addr = *(unsigned long *)(ebp + 4); printk(" [<%08lx>] ", addr); print_symbol("%s", addr); printk("\n"); ebp = *(unsigned long *)ebp; } -} #else -static void print_context_stack(struct task_struct *task, unsigned long *stack, - unsigned long ebp) -{ - unsigned long addr; - - while (!kstack_end(stack)) { + while (valid_stack_ptr(tinfo, stack)) { addr = *stack++; if (__kernel_text_address(addr)) { printk(" [<%08lx>]", addr); @@ -144,9 +135,11 @@ static void print_context_stack(struct t printk("\n"); } } -} #endif + return ebp; +} + void show_trace(struct task_struct *task, unsigned long * stack) { unsigned long ebp; @@ -154,11 +147,6 @@ void show_trace(struct task_struct *task if (!task) task = current; - if (!valid_stack_ptr(task, stack)) { - printk("Stack pointer is garbage, not printing trace\n"); - return; - } - if (task == current) { /* Grab ebp right from our regs */ asm ("movl %%ebp, %0" : "=r" (ebp) : ); @@ -171,7 +159,7 @@ void show_trace(struct task_struct *task struct thread_info *context; context = (struct thread_info *) ((unsigned long)stack & (~(THREAD_SIZE - 1))); - print_context_stack(task, stack, ebp); + ebp = print_context_stack(context, stack, ebp); stack = (unsigned long*)context->previous_esp; if (!stack) break; - 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/