lists.openwall.net   lists  /  announce  owl-users  owl-dev  john-users  john-dev  passwdqc-users  yescrypt  popa3d-users  /  oss-security  kernel-hardening  musl  sabotage  tlsify  passwords  /  crypt-dev  xvendor  /  Bugtraq  Full-Disclosure  linux-kernel  linux-netdev  linux-ext4  linux-hardening  linux-cve-announce  PHC 
Open Source and information security mailing list archives
 
Hash Suite: Windows password security audit tool. GUI, reports in PDF.
[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Date:	Thu, 6 Mar 2014 17:01:27 -0800
From:	tip-bot for Steven Rostedt <tipbot@...or.com>
To:	linux-tip-commits@...r.kernel.org
Cc:	linux-kernel@...r.kernel.org, hpa@...or.com, mingo@...nel.org,
	brgerst@...il.com, peterz@...radead.org, rostedt@...dmis.org,
	akpm@...ux-foundation.org, srostedt@...hat.com, tglx@...utronix.de,
	hpa@...ux.intel.com
Subject: [tip:x86/threadinfo] x86: Clean up dumpstack_64.c code

Commit-ID:  2223f6f6eeaad6ea0a3acd3f4bc1ae45e8117ddc
Gitweb:     http://git.kernel.org/tip/2223f6f6eeaad6ea0a3acd3f4bc1ae45e8117ddc
Author:     Steven Rostedt <srostedt@...hat.com>
AuthorDate: Thu, 6 Feb 2014 09:41:32 -0500
Committer:  H. Peter Anvin <hpa@...ux.intel.com>
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 <akpm@...ux-foundation.org>
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: Brian Gerst <brgerst@...il.com>
Signed-off-by: Steven Rostedt <rostedt@...dmis.org>
Link: http://lkml.kernel.org/r/20140206144322.086050042@goodmis.org
Signed-off-by: H. Peter Anvin <hpa@...ux.intel.com>
---
 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, "<EOE>");
 			/*
 			 * 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;
 	}
 
 	/*
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/

Powered by blists - more mailing lists