linux-kernel - [PATCH] scripts/gdb: fix get_thread

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Date:   Thu, 18 Jan 2018 21:01:59 +0000
From:   Xi Kangjie <imxikangjie@...il.com>
To:     jan.kiszka@...mens.com, kieran@...uared.org.uk
Cc:     linux-kernel@...r.kernel.org, Xi Kangjie <imxikangjie@...il.com>
Subject: [PATCH] scripts/gdb: fix get_thread_info

Since kernel 4.9, the thread_info has been moved into task_struct,
no longer locates at the bottom of kernel stack.

See commits:
- commit c65eacbe290b ("sched/core: Allow putting thread_info into
task_struct")
- commit 15f4eae70d36 ("x86: Move thread_info into task_struct")

Before fix:
(gdb) set $current = $lx_current()
(gdb) p $lx_thread_info($current)
$1 = {flags = 1470918301}
(gdb) p $current.thread_info
$2 = {flags = 2147483648}

After fix:
(gdb) p $lx_thread_info($current)
$1 = {flags = 2147483648}
(gdb) p $current.thread_info
$2 = {flags = 2147483648}

Signed-off-by: Xi Kangjie <imxikangjie@...il.com>
---
 scripts/gdb/linux/tasks.py | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/scripts/gdb/linux/tasks.py b/scripts/gdb/linux/tasks.py
index 1bf949c43b76..f6ab3ccf698f 100644
--- a/scripts/gdb/linux/tasks.py
+++ b/scripts/gdb/linux/tasks.py
@@ -96,6 +96,8 @@ def get_thread_info(task):
         thread_info_addr = task.address + ia64_task_size
         thread_info = thread_info_addr.cast(thread_info_ptr_type)
     else:
+        if task.type.fields()[0].type == thread_info_type.get_type():
+            return task['thread_info']
         thread_info = task['stack'].cast(thread_info_ptr_type)
     return thread_info.dereference()
 
-- 
2.13.2