From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753093AbaCGBCH (ORCPT ); Thu, 6 Mar 2014 20:02:07 -0500 Received: from terminus.zytor.com ([198.137.202.10]:53409 "EHLO terminus.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753046AbaCGBCC (ORCPT ); Thu, 6 Mar 2014 20:02:02 -0500 Date: Thu, 6 Mar 2014 17:01:27 -0800 From: tip-bot for Steven Rostedt Message-ID: Cc: linux-kernel@vger.kernel.org, hpa@zytor.com, mingo@kernel.org, brgerst@gmail.com, peterz@infradead.org, rostedt@goodmis.org, akpm@linux-foundation.org, srostedt@redhat.com, tglx@linutronix.de, hpa@linux.intel.com Reply-To: mingo@kernel.org, hpa@zytor.com, linux-kernel@vger.kernel.org, brgerst@gmail.com, peterz@infradead.org, rostedt@goodmis.org, akpm@linux-foundation.org, srostedt@redhat.com, tglx@linutronix.de, hpa@linux.intel.com In-Reply-To: <20140206144322.086050042@goodmis.org> References: <20110806012354.684598995@goodmis.org> <20140206144322.086050042@goodmis.org> To: linux-tip-commits@vger.kernel.org Subject: [tip:x86/threadinfo] x86: Clean up dumpstack_64.c code Git-Commit-ID: 2223f6f6eeaad6ea0a3acd3f4bc1ae45e8117ddc X-Mailer: tip-git-log-daemon Robot-ID: Robot-Unsubscribe: Contact to get blacklisted from these emails MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Content-Type: text/plain; charset=UTF-8 Content-Disposition: inline Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Commit-ID: 2223f6f6eeaad6ea0a3acd3f4bc1ae45e8117ddc Gitweb: http://git.kernel.org/tip/2223f6f6eeaad6ea0a3acd3f4bc1ae45e8117ddc Author: Steven Rostedt AuthorDate: Thu, 6 Feb 2014 09:41:32 -0500 Committer: H. Peter Anvin CommitDate: Thu, 6 Mar 2014 16:56:55 -0800 x86: Clean up dumpstack_64.c code The dump_trace() function in dumpstack_64.c is hard to follow. The test for exception stack is processed differently than the test for irq stack, and the normal stack is outside completely. By restructuring this code to have all the stacks determined by a single function that returns an enum of the following: STACK_IS_NORMAL STACK_IS_EXCEPTION STACK_IS_IRQ STACK_IS_UNKNOWN and has the logic of each within a switch statement. This should make the code much easier to read and understand. Link: http://lkml.kernel.org/r/20110806012354.684598995@goodmis.org Cc: Andrew Morton Cc: Peter Zijlstra Cc: Brian Gerst Signed-off-by: Steven Rostedt Link: http://lkml.kernel.org/r/20140206144322.086050042@goodmis.org Signed-off-by: H. Peter Anvin --- arch/x86/kernel/dumpstack_64.c | 117 +++++++++++++++++++++++++++++------------ 1 file changed, 83 insertions(+), 34 deletions(-) diff --git a/arch/x86/kernel/dumpstack_64.c b/arch/x86/kernel/dumpstack_64.c index addb207..346b1df 100644 --- a/arch/x86/kernel/dumpstack_64.c +++ b/arch/x86/kernel/dumpstack_64.c @@ -104,6 +104,45 @@ in_irq_stack(unsigned long *stack, unsigned long *irq_stack, return (stack >= irq_stack && stack < irq_stack_end); } +static const unsigned long irq_stack_size = + (IRQ_STACK_SIZE - 64) / sizeof(unsigned long); + +enum stack_type { + STACK_IS_UNKNOWN, + STACK_IS_NORMAL, + STACK_IS_EXCEPTION, + STACK_IS_IRQ, +}; + +static enum stack_type +analyze_stack(int cpu, struct task_struct *task, + unsigned long *stack, unsigned long **stack_end, char **id) +{ + unsigned long *irq_stack; + unsigned long addr; + unsigned used = 0; + + addr = ((unsigned long)stack & (~(THREAD_SIZE - 1))); + if ((unsigned long)task_stack_page(task) == addr) + return STACK_IS_NORMAL; + + *stack_end = in_exception_stack(cpu, (unsigned long)stack, + &used, id); + if (*stack_end) + return STACK_IS_EXCEPTION; + + *stack_end = (unsigned long *)per_cpu(irq_stack_ptr, cpu); + if (!*stack_end) + return STACK_IS_UNKNOWN; + + irq_stack = *stack_end - irq_stack_size; + + if (in_irq_stack(stack, irq_stack, *stack_end)) + return STACK_IS_IRQ; + + return STACK_IS_UNKNOWN; +} + /* * x86-64 can have up to three kernel stacks: * process stack @@ -116,12 +155,11 @@ void dump_trace(struct task_struct *task, struct pt_regs *regs, const struct stacktrace_ops *ops, void *data) { const unsigned cpu = get_cpu(); - unsigned long *irq_stack_end = - (unsigned long *)per_cpu(irq_stack_ptr, cpu); - unsigned used = 0; struct thread_info *tinfo; - int graph = 0; + unsigned long *irq_stack; unsigned long dummy; + int graph = 0; + int done = 0; if (!task) task = current; @@ -143,49 +181,60 @@ void dump_trace(struct task_struct *task, struct pt_regs *regs, * exceptions */ tinfo = task_thread_info(task); - for (;;) { + while (!done) { + unsigned long *stack_end; + enum stack_type stype; char *id; - unsigned long *estack_end; - estack_end = in_exception_stack(cpu, (unsigned long)stack, - &used, &id); - if (estack_end) { + stype = analyze_stack(cpu, task, stack, &stack_end, &id); + + /* Default finish unless specified to continue */ + done = 1; + + switch (stype) { + + /* Break out early if we are on the thread stack */ + case STACK_IS_NORMAL: + break; + + case STACK_IS_EXCEPTION: + if (ops->stack(data, id) < 0) break; bp = ops->walk_stack(tinfo, stack, bp, ops, - data, estack_end, &graph); + data, stack_end, &graph); ops->stack(data, ""); /* * We link to the next stack via the * second-to-last pointer (index -2 to end) in the * exception stack: */ - stack = (unsigned long *) estack_end[-2]; - continue; - } - if (irq_stack_end) { - unsigned long *irq_stack; - irq_stack = irq_stack_end - - (IRQ_STACK_SIZE - 64) / sizeof(*irq_stack); - - if (in_irq_stack(stack, irq_stack, irq_stack_end)) { - if (ops->stack(data, "IRQ") < 0) - break; - bp = ops->walk_stack(tinfo, stack, bp, - ops, data, irq_stack_end, &graph); - /* - * We link to the next stack (which would be - * the process stack normally) the last - * pointer (index -1 to end) in the IRQ stack: - */ - stack = (unsigned long *) (irq_stack_end[-1]); - irq_stack_end = NULL; - ops->stack(data, "EOI"); - continue; - } + stack = (unsigned long *) stack_end[-2]; + done = 0; + break; + + case STACK_IS_IRQ: + + if (ops->stack(data, "IRQ") < 0) + break; + bp = ops->walk_stack(tinfo, stack, bp, + ops, data, stack_end, &graph); + /* + * We link to the next stack (which would be + * the process stack normally) the last + * pointer (index -1 to end) in the IRQ stack: + */ + stack = (unsigned long *) (stack_end[-1]); + irq_stack = stack_end - irq_stack_size; + ops->stack(data, "EOI"); + done = 0; + break; + + case STACK_IS_UNKNOWN: + ops->stack(data, "UNK"); + break; } - break; } /*