[PATCH v2 0/2] GDB: Support getting current task struct in UML

[PATCH v2 0/2] GDB: Support getting current task struct in UML

[Glenn Washburn]

Added suggestions from Jan.

Glenn

Glenn Washburn (2):
  scripts/gdb: Correct indentation in get_current_task
  scripts/gdb: Support getting current task struct in UML

 scripts/gdb/linux/cpus.py | 24 +++++++++++++++---------
 1 file changed, 15 insertions(+), 9 deletions(-)

Range-diff against v1:
1:  f33ebe524590 ! 1:  c5a916e094d9 scripts/gdb: Correct indentation in get_current_task
    @@ Commit message
     
         There is an extra space in a couple blocks in get_current_task.
         Though python does not care, let's make the spacing consistent.
    +    Also, format better an if expression, removing unneeded parenthesis.
     
      ## scripts/gdb/linux/cpus.py ##
     @@ scripts/gdb/linux/cpus.py: def get_current_task(cpu):
    @@ scripts/gdb/linux/cpus.py: def get_current_task(cpu):
     -             raise gdb.GdbError("Sorry, obtaining the current task is not allowed "
     -                                "while running in userspace(EL0)")
     +        current_task_addr = gdb.parse_and_eval("$SP_EL0")
    -+        if((current_task_addr >> 63) != 0):
    ++        if (current_task_addr >> 63) != 0:
     +            current_task = current_task_addr.cast(task_ptr_type)
     +            return current_task.dereference()
     +        else:
2:  8c3db2291f58 ! 2:  683d10e752cd scripts/gdb: Support getting current task struct in UML
    @@ Commit message
         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, the
    -    symbol "uml_kmalloc" is checked for. If it exists, then do the UML
    -    specific way of getting the current task struct.
    +    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.
     
      ## scripts/gdb/linux/cpus.py ##
     @@ scripts/gdb/linux/cpus.py: def get_current_task(cpu):
    @@ scripts/gdb/linux/cpus.py: def get_current_task(cpu):
          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("uml_kmalloc"):
    ++        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:
    @@ scripts/gdb/linux/cpus.py: def get_current_task(cpu):
     +            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):
    +         if (current_task_addr >> 63) != 0:
-- 
2.30.2


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[PATCH v2 1/2] scripts/gdb: Correct indentation in get_current_task

[Glenn Washburn]

There is an extra space in a couple blocks in get_current_task.
Though python does not care, let's make the spacing consistent.
Also, format better an if expression, removing unneeded parenthesis.

Signed-off-by: Glenn Washburn <development@efficientek.com>
---
 scripts/gdb/linux/cpus.py | 18 +++++++++---------
 1 file changed, 9 insertions(+), 9 deletions(-)

diff --git a/scripts/gdb/linux/cpus.py b/scripts/gdb/linux/cpus.py
index 15fc4626d236..3e02a1866751 100644
--- a/scripts/gdb/linux/cpus.py
+++ b/scripts/gdb/linux/cpus.py
@@ -163,16 +163,16 @@ 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()
+        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("$SP_EL0")
-         if((current_task_addr >> 63) != 0):
-             current_task = current_task_addr.cast(task_ptr_type)
-             return current_task.dereference()
-         else:
-             raise gdb.GdbError("Sorry, obtaining the current task is not allowed "
-                                "while running in userspace(EL0)")
+        current_task_addr = gdb.parse_and_eval("$SP_EL0")
+        if (current_task_addr >> 63) != 0:
+            current_task = current_task_addr.cast(task_ptr_type)
+            return current_task.dereference()
+        else:
+            raise gdb.GdbError("Sorry, obtaining the current task is not allowed "
+                               "while running in userspace(EL0)")
     else:
         raise gdb.GdbError("Sorry, obtaining the current task is not yet "
                            "supported with this arch")
-- 
2.30.2


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[PATCH v2 1/2] scripts/gdb: Correct indentation in get_current_task

[Glenn Washburn]

There is an extra space in a couple blocks in get_current_task.
Though python does not care, let's make the spacing consistent.
Also, format better an if expression, removing unneeded parenthesis.

Signed-off-by: Glenn Washburn <development@efficientek.com>
Reviewed-by: Jan Kiszka <jan.kiszka@siemens.com>
---
 scripts/gdb/linux/cpus.py | 18 +++++++++---------
 1 file changed, 9 insertions(+), 9 deletions(-)

diff --git a/scripts/gdb/linux/cpus.py b/scripts/gdb/linux/cpus.py
index 15fc4626d236..3e02a1866751 100644
--- a/scripts/gdb/linux/cpus.py
+++ b/scripts/gdb/linux/cpus.py
@@ -163,16 +163,16 @@ 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()
+        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("$SP_EL0")
-         if((current_task_addr >> 63) != 0):
-             current_task = current_task_addr.cast(task_ptr_type)
-             return current_task.dereference()
-         else:
-             raise gdb.GdbError("Sorry, obtaining the current task is not allowed "
-                                "while running in userspace(EL0)")
+        current_task_addr = gdb.parse_and_eval("$SP_EL0")
+        if (current_task_addr >> 63) != 0:
+            current_task = current_task_addr.cast(task_ptr_type)
+            return current_task.dereference()
+        else:
+            raise gdb.GdbError("Sorry, obtaining the current task is not allowed "
+                               "while running in userspace(EL0)")
     else:
         raise gdb.GdbError("Sorry, obtaining the current task is not yet "
                            "supported with this arch")
-- 
2.30.2


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[PATCH v2 2/2] scripts/gdb: Support getting current task struct in UML

[Glenn Washburn]

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


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[PATCH v2 2/2] scripts/gdb: Support getting current task struct in UML

[Glenn Washburn]

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


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Re: [PATCH v2 0/2] GDB: Support getting current task struct in UML

[Jan Kiszka]

On 16.02.23 08:37, Glenn Washburn wrote:
> Added suggestions from Jan.
> 
> Glenn
> 
> Glenn Washburn (2):
>   scripts/gdb: Correct indentation in get_current_task
>   scripts/gdb: Support getting current task struct in UML
> 
>  scripts/gdb/linux/cpus.py | 24 +++++++++++++++---------
>  1 file changed, 15 insertions(+), 9 deletions(-)
> 
> Range-diff against v1:
> 1:  f33ebe524590 ! 1:  c5a916e094d9 scripts/gdb: Correct indentation in get_current_task
>     @@ Commit message
>      
>          There is an extra space in a couple blocks in get_current_task.
>          Though python does not care, let's make the spacing consistent.
>     +    Also, format better an if expression, removing unneeded parenthesis.
>      
>       ## scripts/gdb/linux/cpus.py ##
>      @@ scripts/gdb/linux/cpus.py: def get_current_task(cpu):
>     @@ scripts/gdb/linux/cpus.py: def get_current_task(cpu):
>      -             raise gdb.GdbError("Sorry, obtaining the current task is not allowed "
>      -                                "while running in userspace(EL0)")
>      +        current_task_addr = gdb.parse_and_eval("$SP_EL0")
>     -+        if((current_task_addr >> 63) != 0):
>     ++        if (current_task_addr >> 63) != 0:
>      +            current_task = current_task_addr.cast(task_ptr_type)
>      +            return current_task.dereference()
>      +        else:
> 2:  8c3db2291f58 ! 2:  683d10e752cd scripts/gdb: Support getting current task struct in UML
>     @@ Commit message
>          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, the
>     -    symbol "uml_kmalloc" is checked for. If it exists, then do the UML
>     -    specific way of getting the current task struct.
>     +    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.
>      
>       ## scripts/gdb/linux/cpus.py ##
>      @@ scripts/gdb/linux/cpus.py: def get_current_task(cpu):
>     @@ scripts/gdb/linux/cpus.py: def get_current_task(cpu):
>           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("uml_kmalloc"):
>     ++        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:
>     @@ scripts/gdb/linux/cpus.py: def get_current_task(cpu):
>      +            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):
>     +         if (current_task_addr >> 63) != 0:

Reviewed-by: Jan Kiszka <jan.kiszka@siemens.com>

Jan

-- 
Siemens AG, Technology
Competence Center Embedded Linux


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Re: [PATCH v2 0/2] GDB: Support getting current task struct in UML

[Andrew Morton]

On Thu, 16 Feb 2023 08:51:52 +0100 Jan Kiszka <jan.kiszka@siemens.com> wrote:

> On 16.02.23 08:37, Glenn Washburn wrote:
> > Added suggestions from Jan.
> > 
> > Glenn
> > 
> > Glenn Washburn (2):
> >   scripts/gdb: Correct indentation in get_current_task
> >   scripts/gdb: Support getting current task struct in UML
> > 
>
> ...
>
> Reviewed-by: Jan Kiszka <jan.kiszka@siemens.com>
> 

Thanks, but I'm not subscribed to linux-um and my usual
get-it-from-lkml didn't work.

Could we please have a resend, with a cc to linux-kernel?

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Re: [PATCH v2 0/2] GDB: Support getting current task struct in UML

[Richard Weinberger]

----- Ursprüngliche Mail -----
> Von: "Andrew Morton" <akpm@linux-foundation.org>
> Thanks, but I'm not subscribed to linux-um and my usual
> get-it-from-lkml didn't work.
> 
> Could we please have a resend, with a cc to linux-kernel?

You can also get the patches in mbox format from:
https://patchwork.ozlabs.org/project/linux-um/list/?series=342212

Thanks,
//richard

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Re: [PATCH v2 0/2] GDB: Support getting current task struct in UML

[Andrew Morton]

On Thu, 16 Feb 2023 23:54:38 +0100 (CET) Richard Weinberger <richard@nod.at> wrote:

> ----- Ursprüngliche Mail -----
> > Von: "Andrew Morton" <akpm@linux-foundation.org>
> > Thanks, but I'm not subscribed to linux-um and my usual
> > get-it-from-lkml didn't work.
> > 
> > Could we please have a resend, with a cc to linux-kernel?
> 
> You can also get the patches in mbox format from:
> https://patchwork.ozlabs.org/project/linux-um/list/?series=342212

Thanks, but..

- Can't do reply-to-all if I have comments
- Can't collect people's followup acks and review comments
- No Link tag

etc.

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Re: [PATCH v2 0/2] GDB: Support getting current task struct in UML

[Geert Uytterhoeven]

Hi Andrew,

On Fri, Feb 17, 2023 at 12:33 AM Andrew Morton
<akpm@linux-foundation.org> wrote:
> On Thu, 16 Feb 2023 23:54:38 +0100 (CET) Richard Weinberger <richard@nod.at> wrote:
> > ----- Ursprüngliche Mail -----
> > > Von: "Andrew Morton" <akpm@linux-foundation.org>
> > > Thanks, but I'm not subscribed to linux-um and my usual
> > > get-it-from-lkml didn't work.
> > >
> > > Could we please have a resend, with a cc to linux-kernel?
> >
> > You can also get the patches in mbox format from:
> > https://patchwork.ozlabs.org/project/linux-um/list/?series=342212

And from there, you can get the Message-IDs, and use lore:
https://lore.kernel.org/r/683d10e752cd4852ac62ef3cc3e9a6972a017bdf.1676532759.git.development@efficientek.com
or b4:
b4 mbox 683d10e752cd4852ac62ef3cc3e9a6972a017bdf.1676532759.git.development@efficientek.com
b4 am 683d10e752cd4852ac62ef3cc3e9a6972a017bdf.1676532759.git.development@efficientek.com

> Thanks, but..
>
> - Can't do reply-to-all if I have comments
> - Can't collect people's followup acks and review comments
> - No Link tag

Gr{oetje,eeting}s,

                        Geert

-- 
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds

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Re: [PATCH v2 0/2] GDB: Support getting current task struct in UML

[Glenn Washburn]

On Fri, 17 Feb 2023 11:14:01 +0100
Geert Uytterhoeven <geert@linux-m68k.org> wrote:

> Hi Andrew,
> 
> On Fri, Feb 17, 2023 at 12:33 AM Andrew Morton
> <akpm@linux-foundation.org> wrote:
> > On Thu, 16 Feb 2023 23:54:38 +0100 (CET) Richard Weinberger
> > <richard@nod.at> wrote:
> > > ----- Ursprüngliche Mail -----
> > > > Von: "Andrew Morton" <akpm@linux-foundation.org>
> > > > Thanks, but I'm not subscribed to linux-um and my usual
> > > > get-it-from-lkml didn't work.
> > > >
> > > > Could we please have a resend, with a cc to linux-kernel?
> > >
> > > You can also get the patches in mbox format from:
> > > https://patchwork.ozlabs.org/project/linux-um/list/?series=342212
> 
> And from there, you can get the Message-IDs, and use lore:
> https://lore.kernel.org/r/683d10e752cd4852ac62ef3cc3e9a6972a017bdf.1676532759.git.development@efficientek.com
> or b4:
> b4 mbox
> 683d10e752cd4852ac62ef3cc3e9a6972a017bdf.1676532759.git.development@efficientek.com
> b4 am
> 683d10e752cd4852ac62ef3cc3e9a6972a017bdf.1676532759.git.development@efficientek.com
> 
> > Thanks, but..
> >
> > - Can't do reply-to-all if I have comments
> > - Can't collect people's followup acks and review comments
> > - No Link tag

Ok, so do I need to resend after all? And anther point in need of
clarification, regardless of subsystem or area of source, when sending
patches, should I always cc to linux-kernel?

Glenn

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Re: [PATCH v2 0/2] GDB: Support getting current task struct in UML

[Andrew Morton]

On Fri, 17 Feb 2023 15:56:43 -0600 Glenn Washburn <development@efficientek.com> wrote:

> On Fri, 17 Feb 2023 11:14:01 +0100
> Geert Uytterhoeven <geert@linux-m68k.org> wrote:
> 
> > Hi Andrew,
> > 
> > On Fri, Feb 17, 2023 at 12:33 AM Andrew Morton
> > <akpm@linux-foundation.org> wrote:
> > > On Thu, 16 Feb 2023 23:54:38 +0100 (CET) Richard Weinberger
> > > <richard@nod.at> wrote:
> > > > ----- Ursprüngliche Mail -----
> > > > > Von: "Andrew Morton" <akpm@linux-foundation.org>
> > > > > Thanks, but I'm not subscribed to linux-um and my usual
> > > > > get-it-from-lkml didn't work.
> > > > >
> > > > > Could we please have a resend, with a cc to linux-kernel?
> > > >
> > > > You can also get the patches in mbox format from:
> > > > https://patchwork.ozlabs.org/project/linux-um/list/?series=342212
> > 
> > And from there, you can get the Message-IDs, and use lore:
> > https://lore.kernel.org/r/683d10e752cd4852ac62ef3cc3e9a6972a017bdf.1676532759.git.development@efficientek.com
> > or b4:
> > b4 mbox
> > 683d10e752cd4852ac62ef3cc3e9a6972a017bdf.1676532759.git.development@efficientek.com
> > b4 am
> > 683d10e752cd4852ac62ef3cc3e9a6972a017bdf.1676532759.git.development@efficientek.com
> > 
> > > Thanks, but..
> > >
> > > - Can't do reply-to-all if I have comments
> > > - Can't collect people's followup acks and review comments
> > > - No Link tag
> 
> Ok, so do I need to resend after all?

Yes please.  Call it v2, add any acks and reviewed-bys.

> And anther point in need of
> clarification, regardless of subsystem or area of source, when sending
> patches, should I always cc to linux-kernel?

I think it's best.  That's pretty much the only purpose lkml serves now :(


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[PATCH v2 0/2] GDB: Support getting current task struct in UML

[Glenn Washburn]

Added suggestions from Jan.

Glenn

Glenn Washburn (2):
  scripts/gdb: Correct indentation in get_current_task
  scripts/gdb: Support getting current task struct in UML

 scripts/gdb/linux/cpus.py | 24 +++++++++++++++---------
 1 file changed, 15 insertions(+), 9 deletions(-)

Range-diff against v1:
1:  f33ebe524590 ! 1:  c5a916e094d9 scripts/gdb: Correct indentation in get_current_task
    @@ Commit message
     
         There is an extra space in a couple blocks in get_current_task.
         Though python does not care, let's make the spacing consistent.
    +    Also, format better an if expression, removing unneeded parenthesis.
     
      ## scripts/gdb/linux/cpus.py ##
     @@ scripts/gdb/linux/cpus.py: def get_current_task(cpu):
    @@ scripts/gdb/linux/cpus.py: def get_current_task(cpu):
     -             raise gdb.GdbError("Sorry, obtaining the current task is not allowed "
     -                                "while running in userspace(EL0)")
     +        current_task_addr = gdb.parse_and_eval("$SP_EL0")
    -+        if((current_task_addr >> 63) != 0):
    ++        if (current_task_addr >> 63) != 0:
     +            current_task = current_task_addr.cast(task_ptr_type)
     +            return current_task.dereference()
     +        else:
2:  8c3db2291f58 ! 2:  683d10e752cd scripts/gdb: Support getting current task struct in UML
    @@ Commit message
         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, the
    -    symbol "uml_kmalloc" is checked for. If it exists, then do the UML
    -    specific way of getting the current task struct.
    +    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.
     
      ## scripts/gdb/linux/cpus.py ##
     @@ scripts/gdb/linux/cpus.py: def get_current_task(cpu):
    @@ scripts/gdb/linux/cpus.py: def get_current_task(cpu):
          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("uml_kmalloc"):
    ++        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:
    @@ scripts/gdb/linux/cpus.py: def get_current_task(cpu):
     +            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):
    +         if (current_task_addr >> 63) != 0:
-- 
2.30.2


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Re: [PATCH v2 0/2] GDB: Support getting current task struct in UML

[Andrew Morton]

On Fri, 17 Feb 2023 19:11:52 -0600 Glenn Washburn <development@efficientek.com> wrote:

> Added suggestions from Jan.
> 
> Glenn
> 
> Glenn Washburn (2):
>   scripts/gdb: Correct indentation in get_current_task
>   scripts/gdb: Support getting current task struct in UML
> 

For some reason I get a bunch of rejects when applying these on top of
the latest patchpile.  Please check my end result:

def get_current_task(cpu):
    task_ptr_type = task_type.get_type().pointer()

    if utils.is_target_arch("x86"):
        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):
            current_task = current_task_addr.cast(task_ptr_type)
            return current_task.dereference()
        else:
            raise gdb.GdbError("Sorry, obtaining the current task is not allowed "
                                "while running in userspace(EL0)")
    else:
        raise gdb.GdbError("Sorry, obtaining the current task is not yet "
                           "supported with this arch")




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Re: [PATCH v2 0/2] GDB: Support getting current task struct in UML

[Glenn Washburn]

On Thu, 23 Feb 2023 13:14:02 -0800
Andrew Morton <akpm@linux-foundation.org> wrote:

> On Fri, 17 Feb 2023 19:11:52 -0600 Glenn Washburn
> <development@efficientek.com> wrote:
> 
> > Added suggestions from Jan.
> > 
> > Glenn
> > 
> > Glenn Washburn (2):
> >   scripts/gdb: Correct indentation in get_current_task
> >   scripts/gdb: Support getting current task struct in UML
> > 
> 
> For some reason I get a bunch of rejects when applying these on top of
> the latest patchpile.  Please check my end result:

It looks like there was a change from v6.2-rc8 to v6.2 that caused a
conflict.

> 
> def get_current_task(cpu):
>     task_ptr_type = task_type.get_type().pointer()
> 
>     if utils.is_target_arch("x86"):
>         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()

This is missing the return statement in the second patch.

>         else:
>             var_ptr = gdb.parse_and_eval("&current_task")

It looks like "current_task" has now been changed to
"pcpu_hot.current_task" in v6.2.

Would you like me to resent the series rebased onto v6.2?

Glenn

>             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):
>             current_task = current_task_addr.cast(task_ptr_type)
>             return current_task.dereference()
>         else:
>             raise gdb.GdbError("Sorry, obtaining the current task is
> not allowed " "while running in userspace(EL0)")
>     else:
>         raise gdb.GdbError("Sorry, obtaining the current task is not
> yet " "supported with this arch")
> 
> 
> 

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Re: [PATCH v2 0/2] GDB: Support getting current task struct in UML

[Andrew Morton]

On Sun, 26 Feb 2023 00:47:19 -0600 Glenn Washburn <development@efficientek.com> wrote:

> Would you like me to resent the series rebased onto v6.2?

Yes please ;)  Against current linus tip if possible.

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