linux-kernel - [PATCH 19/19] x86/dumpstack: print any pt

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Date:	Thu, 21 Jul 2016 16:21:56 -0500
From:	Josh Poimboeuf <jpoimboe@...hat.com>
To:	Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...nel.org>,
	"H . Peter Anvin" <hpa@...or.com>
Cc:	x86@...nel.org, linux-kernel@...r.kernel.org,
	Andy Lutomirski <luto@...capital.net>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Steven Rostedt <rostedt@...dmis.org>,
	Brian Gerst <brgerst@...il.com>,
	Kees Cook <keescook@...omium.org>,
	Peter Zijlstra <peterz@...radead.org>,
	Frederic Weisbecker <fweisbec@...il.com>,
	Byungchul Park <byungchul.park@....com>
Subject: [PATCH 19/19] x86/dumpstack: print any pt_regs found on the stack

Now that we can find pt_regs registers in the middle of the stack due to
an interrupt or exception, we can print them.  Here's what it looks
like:

   ...
   [<ffffffff8106f7dc>] do_async_page_fault+0x2c/0xa0
   [<ffffffff8189f558>] async_page_fault+0x28/0x30
  RIP: 0010:[<ffffffff814529e2>]  [<ffffffff814529e2>] __clear_user+0x42/0x70
  RSP: 0018:ffff88007876fd38  EFLAGS: 00010202
  RAX: 0000000000000000 RBX: 0000000000000138 RCX: 0000000000000138
  RDX: 0000000000000000 RSI: 0000000000000008 RDI: 000000000061b640
  RBP: ffff88007876fd48 R08: 0000000dc2ced0d0 R09: 0000000000000000
  R10: 0000000000000001 R11: 0000000000000000 R12: 000000000061b640
  R13: 0000000000000000 R14: ffff880078770000 R15: ffff880079947200
   [<ffffffff814529e2>] ? __clear_user+0x42/0x70
   [<ffffffff814529c3>] ? __clear_user+0x23/0x70
   [<ffffffff81452a7b>] clear_user+0x2b/0x40
   ...

Signed-off-by: Josh Poimboeuf <jpoimboe@...hat.com>
---
 arch/x86/kernel/dumpstack.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/arch/x86/kernel/dumpstack.c b/arch/x86/kernel/dumpstack.c
index 0eedb01..4509866 100644
--- a/arch/x86/kernel/dumpstack.c
+++ b/arch/x86/kernel/dumpstack.c
@@ -173,6 +173,14 @@ void show_trace_log_lvl(struct task_struct *task, struct pt_regs *regs,
 			 * printed as unreliable.
 			 */
 			unwind_next_frame(&state);
+
+			/*
+			 * If the previous frame had pt_regs associated with it
+			 * due to an interrupt or exception, print them.
+			 */
+			regs = unwind_get_entry_regs(&state);
+			if (regs)
+				__show_regs(regs, 0);
 		}
 
 		if (str_end)
-- 
2.7.4