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

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Date:   Thu, 23 Feb 2023 13:14:02 -0800
From:   Andrew Morton <akpm@...ux-foundation.org>
To:     Glenn Washburn <development@...icientek.com>
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 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:

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")