linux-um.lists.infradead.org archive mirror
 help / color / mirror / Atom feed
From: Glenn Washburn <development@efficientek.com>
To: Jan Kiszka <jan.kiszka@siemens.com>,
	Kieran Bingham <kbingham@kernel.org>
Cc: Glenn Washburn <development@efficientek.com>,
	linux-um <linux-um@lists.infradead.org>,
	Richard Weinberger <richard@nod.at>,
	Johannes Berg <johannes@sipsolutions.net>,
	Anton Ivanov <anton.ivanov@kot-begemot.co.uk>
Subject: [PATCH v2 2/2] scripts/gdb: Support getting current task struct in UML
Date: Thu, 16 Feb 2023 01:37:19 -0600	[thread overview]
Message-ID: <683d10e752cd4852ac62ef3cc3e9a6972a017bdf.1676532759.git.development@efficientek.com> (raw)
In-Reply-To: <cover.1676532759.git.development@efficientek.com>

A running x86 UML kernel reports with architecture "i386:x86-64" as
it is a sub-architecture. However, a difference with bare-metal x86
kernels is in how it manages tasks and the current task struct. To
identify that the inferior is a UML kernel and not bare-metal, check
for the existence of the UML specific symbol "cpu_tasks" which
contains the current task struct.

Signed-off-by: Glenn Washburn <development@efficientek.com>
---
 scripts/gdb/linux/cpus.py | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/scripts/gdb/linux/cpus.py b/scripts/gdb/linux/cpus.py
index 3e02a1866751..4b4ce6464dee 100644
--- a/scripts/gdb/linux/cpus.py
+++ b/scripts/gdb/linux/cpus.py
@@ -163,8 +163,14 @@ def get_current_task(cpu):
     task_ptr_type = task_type.get_type().pointer()
 
     if utils.is_target_arch("x86"):
-        var_ptr = gdb.parse_and_eval("&current_task")
-        return per_cpu(var_ptr, cpu).dereference()
+        if gdb.lookup_global_symbol("cpu_tasks"):
+            # This is a UML kernel, which stores the current task
+            # differently than other x86 sub architectures
+            var_ptr = gdb.parse_and_eval("(struct task_struct *)cpu_tasks[0].task")
+            return var_ptr.dereference()
+        else:
+            var_ptr = gdb.parse_and_eval("&current_task")
+            return per_cpu(var_ptr, cpu).dereference()
     elif utils.is_target_arch("aarch64"):
         current_task_addr = gdb.parse_and_eval("$SP_EL0")
         if (current_task_addr >> 63) != 0:
-- 
2.30.2


_______________________________________________
linux-um mailing list
linux-um@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-um

WARNING: multiple messages have this Message-ID (diff)
From: Glenn Washburn <development@efficientek.com>
To: Jan Kiszka <jan.kiszka@siemens.com>,
	Kieran Bingham <kbingham@kernel.org>
Cc: linux-kernel@vger.kernel.org,
	Andrew Morton <akpm@linux-foundation.org>,
	Glenn Washburn <development@efficientek.com>,
	linux-um <linux-um@lists.infradead.org>,
	Richard Weinberger <richard@nod.at>,
	Johannes Berg <johannes@sipsolutions.net>,
	Anton Ivanov <anton.ivanov@kot-begemot.co.uk>
Subject: [PATCH v2 2/2] scripts/gdb: Support getting current task struct in UML
Date: Fri, 17 Feb 2023 19:11:54 -0600	[thread overview]
Message-ID: <683d10e752cd4852ac62ef3cc3e9a6972a017bdf.1676532759.git.development@efficientek.com> (raw)
Message-ID: <20230218011154.0ct2MVFQVFvujjMF2dXhHMlNzXOCKpe0o3Ooinrk88I@z> (raw)
In-Reply-To: <cover.1676532759.git.development@efficientek.com>

A running x86 UML kernel reports with architecture "i386:x86-64" as
it is a sub-architecture. However, a difference with bare-metal x86
kernels is in how it manages tasks and the current task struct. To
identify that the inferior is a UML kernel and not bare-metal, check
for the existence of the UML specific symbol "cpu_tasks" which
contains the current task struct.

Signed-off-by: Glenn Washburn <development@efficientek.com>
Reviewed-by: Jan Kiszka <jan.kiszka@siemens.com>
---
 scripts/gdb/linux/cpus.py | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/scripts/gdb/linux/cpus.py b/scripts/gdb/linux/cpus.py
index 3e02a1866751..4b4ce6464dee 100644
--- a/scripts/gdb/linux/cpus.py
+++ b/scripts/gdb/linux/cpus.py
@@ -163,8 +163,14 @@ def get_current_task(cpu):
     task_ptr_type = task_type.get_type().pointer()
 
     if utils.is_target_arch("x86"):
-        var_ptr = gdb.parse_and_eval("&current_task")
-        return per_cpu(var_ptr, cpu).dereference()
+        if gdb.lookup_global_symbol("cpu_tasks"):
+            # This is a UML kernel, which stores the current task
+            # differently than other x86 sub architectures
+            var_ptr = gdb.parse_and_eval("(struct task_struct *)cpu_tasks[0].task")
+            return var_ptr.dereference()
+        else:
+            var_ptr = gdb.parse_and_eval("&current_task")
+            return per_cpu(var_ptr, cpu).dereference()
     elif utils.is_target_arch("aarch64"):
         current_task_addr = gdb.parse_and_eval("$SP_EL0")
         if (current_task_addr >> 63) != 0:
-- 
2.30.2


_______________________________________________
linux-um mailing list
linux-um@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-um

  parent reply	other threads:[~2023-02-16  7:37 UTC|newest]

Thread overview: 16+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-02-16  7:37 [PATCH v2 0/2] GDB: Support getting current task struct in UML Glenn Washburn
2023-02-16  7:37 ` [PATCH v2 1/2] scripts/gdb: Correct indentation in get_current_task Glenn Washburn
2023-02-18  1:11   ` Glenn Washburn
2023-02-16  7:37 ` Glenn Washburn [this message]
2023-02-18  1:11   ` [PATCH v2 2/2] scripts/gdb: Support getting current task struct in UML Glenn Washburn
2023-02-16  7:51 ` [PATCH v2 0/2] GDB: " Jan Kiszka
2023-02-16 22:40   ` Andrew Morton
2023-02-16 22:54     ` Richard Weinberger
2023-02-16 23:33       ` Andrew Morton
2023-02-17 10:14         ` Geert Uytterhoeven
2023-02-17 21:56           ` Glenn Washburn
2023-02-17 22:21             ` Andrew Morton
2023-02-18  1:11 ` Glenn Washburn
2023-02-23 21:14 ` Andrew Morton
2023-02-26  6:47   ` Glenn Washburn
2023-02-26 19:35     ` Andrew Morton

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=683d10e752cd4852ac62ef3cc3e9a6972a017bdf.1676532759.git.development@efficientek.com \
    --to=development@efficientek.com \
    --cc=anton.ivanov@kot-begemot.co.uk \
    --cc=jan.kiszka@siemens.com \
    --cc=johannes@sipsolutions.net \
    --cc=kbingham@kernel.org \
    --cc=linux-um@lists.infradead.org \
    --cc=richard@nod.at \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).