linux-kernel - Re: [PATCH] scripts/gdb/linux/symbols.py: address changes to module_sect

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Message-ID: <7d00d9cb-6860-446c-9eb2-a908c9f7b15c@siemens.com>
Date: Fri, 21 Feb 2025 17:52:37 +0100
From: Jan Kiszka <jan.kiszka@...mens.com>
To: Antonio Quartulli <antonio@...delbit.com>, kbingham@...nel.org
Cc: linux-kernel@...r.kernel.org, Thomas Weißschuh
 <linux@...ssschuh.net>
Subject: Re: [PATCH] scripts/gdb/linux/symbols.py: address changes to
 module_sect_attrs

On 21.02.25 14:03, Antonio Quartulli wrote:
> When loading symbols from kernel modules we used to iterate
> from 0 to module_sect_attrs::nsections, in order to
> retrieve their name and address.
> 
> However module_sect_attrs::nsections has been removed from
> the struct by a previous commit.
> 
> Re-arrange the iteration by accessing all items in
> module_sect_attrs::grp::bin_attrs[] until NULL is found
> (it's a NULL terminated array).
> 
> At the same time the symbol address cannot be extracted
> from module_sect_attrs::attrs[]::address anymore because
> it has also been deleted. Fetch it from
> module_sect_attrs::grp::bin_attrs[]::private as described
> in 4b2c11e4aaf7.
> 
> Fixes: d8959b947a8d ("module: sysfs: Drop member 'module_sect_attrs::nsections'")
> Fixes: 4b2c11e4aaf7 ("module: sysfs: Drop member 'module_sect_attr::address'")
> Cc: Thomas Weißschuh <linux@...ssschuh.net>
> Signed-off-by: Antonio Quartulli <antonio@...delbit.com>
> ---
>  scripts/gdb/linux/symbols.py | 13 +++++++++----
>  1 file changed, 9 insertions(+), 4 deletions(-)
> 
> diff --git a/scripts/gdb/linux/symbols.py b/scripts/gdb/linux/symbols.py
> index f6c1b063775a..610a3dd3c7b4 100644
> --- a/scripts/gdb/linux/symbols.py
> +++ b/scripts/gdb/linux/symbols.py
> @@ -15,6 +15,7 @@ import gdb
>  import os
>  import re
>  
> +from itertools import count
>  from linux import modules, utils, constants
>  
>  
> @@ -95,10 +96,14 @@ lx-symbols command."""
>          except gdb.error:
>              return str(module_addr)
>  
> -        attrs = sect_attrs['attrs']
> -        section_name_to_address = {
> -            attrs[n]['battr']['attr']['name'].string(): attrs[n]['address']
> -            for n in range(int(sect_attrs['nsections']))}
> +        section_name_to_address = {}
> +        for i in count():
> +            # this is a NULL terminated array
> +            if sect_attrs['grp']['bin_attrs'][i] == 0x0:
> +                break
> +
> +            attr = sect_attrs['grp']['bin_attrs'][i].dereference()
> +            section_name_to_address[attr['attr']['name']] = attr['private']

You dropped that .string() from the name - I don't remember the details
anymore but we have it all around when picking up strings from C
structures. Was there a particular reason to do that?

>  
>          textaddr = section_name_to_address.get(".text", module_addr)
>          args = []

Thanks for picking up this task so quickly!

Jan

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