linux-kernel - Re: [PATCH 1/2] gdb/scripts: lx-dmesg: Cast log

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Date:   Fri, 23 Jun 2017 18:02:27 +0200
From:   Jan Kiszka <jan.kiszka@...mens.com>
To:     Leonard Crestez <leonard.crestez@....com>,
        Kieran Bingham <kieran@...uared.org.uk>
Cc:     linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/2] gdb/scripts: lx-dmesg: Cast log_buf to void* for addr
 fetch

On 2017-06-23 16:20, Leonard Crestez wrote:
> In some cases it is possible for the str() conversion here to throw
> encoding errors because log_buf might not point to valid ascii. For
> example:
> 
> (gdb) python print str(gdb.parse_and_eval("log_buf"))
> Traceback (most recent call last):
>   File "<string>", line 1, in <module>
> UnicodeEncodeError: 'ascii' codec can't encode character u'\u0303' in
> 	position 24: ordinal not in range(128)
> 
> Avoid this by explicitly casting to (void *) inside the gdb expression.
> 
> Signed-off-by: Leonard Crestez <leonard.crestez@....com>
> ---
>  scripts/gdb/linux/dmesg.py | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/scripts/gdb/linux/dmesg.py b/scripts/gdb/linux/dmesg.py
> index 5afd109..6f8d2b2 100644
> --- a/scripts/gdb/linux/dmesg.py
> +++ b/scripts/gdb/linux/dmesg.py
> @@ -24,7 +24,7 @@ class LxDmesg(gdb.Command):
>  
>      def invoke(self, arg, from_tty):
>          log_buf_addr = int(str(gdb.parse_and_eval(
> -            "'printk.c'::log_buf")).split()[0], 16)
> +            "(void*)'printk.c'::log_buf")).split()[0], 16)

Nit: (void *)

>          log_first_idx = int(gdb.parse_and_eval("'printk.c'::log_first_idx"))
>          log_next_idx = int(gdb.parse_and_eval("'printk.c'::log_next_idx"))
>          log_buf_len = int(gdb.parse_and_eval("'printk.c'::log_buf_len"))
> 

Looks good, makes sense to me.

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

Jan

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