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

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Message-ID: <20230226004503.1856e58d@crass-HP-ZBook-15-G2>
Date:   Sun, 26 Feb 2023 00:47:19 -0600
From:   Glenn Washburn <development@...icientek.com>
To:     Andrew Morton <akpm@...ux-foundation.org>
Cc:     Jan Kiszka <jan.kiszka@...mens.com>,
        Kieran Bingham <kbingham@...nel.org>,
        linux-kernel@...r.kernel.org,
        linux-um <linux-um@...ts.infradead.org>,
        Richard Weinberger <richard@....at>,
        Johannes Berg <johannes@...solutions.net>,
        Anton Ivanov <anton.ivanov@...-begemot.co.uk>
Subject: Re: [PATCH v2 0/2] GDB: Support getting current task struct in UML

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

> On Fri, 17 Feb 2023 19:11:52 -0600 Glenn Washburn
> <development@...icientek.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")
> 
> 
>