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SubjectRe: [PATCH 1/4] kgdb: x86: Return all segment registers also in 64-bit mode
On 2012-03-16 16:57, Jason Wessel wrote:
> On 03/16/2012 07:17 AM, Jan Kiszka wrote:
>> Even if the content is always 0, gdb expects us to return also ds,
>> es, fs, and gs while in x86-64 mode. Do this to avoid ugly errors on
>> "info registers".
>>
>> Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
>> ---
>> arch/x86/include/asm/kgdb.h | 6 +++++-
>> arch/x86/kernel/kgdb.c | 6 ++++--
>> 2 files changed, 9 insertions(+), 3 deletions(-)
>>
>> diff --git a/arch/x86/include/asm/kgdb.h b/arch/x86/include/asm/kgdb.h
>> index 77e95f5..e857f1a 100644
>> --- a/arch/x86/include/asm/kgdb.h
>> +++ b/arch/x86/include/asm/kgdb.h
>> @@ -64,9 +64,13 @@ enum regnames {
>> GDB_PS, /* 17 */
>> GDB_CS, /* 18 */
>> GDB_SS, /* 19 */
>> + GDB_DS, /* 20 */
>> + GDB_ES, /* 21 */
>> + GDB_FS, /* 22 */
>> + GDB_GS, /* 23 */
>> };
>> #define GDB_ORIG_AX 57
>> -#define DBG_MAX_REG_NUM 20
>> +#define DBG_MAX_REG_NUM 24
>> /* 17 64 bit regs and 3 32 bit regs */
>> #define NUMREGBYTES ((17 * 8) + (3 * 4))
>
> You bumped the register numbers correctly, but you also need to add the correct padding to the NUMREGBYTES or you might not get a large enough memory block for the register struct.
>
> You added 2 32 bit regs, so it should change to:
>
> /* 17 64 bit regs and 5 32 bit regs */
> #define NUMREGBYTES ((17 * 8) + (5 * 4))
>

Oops. Most probably explains the random gs content I saw these days in a
64-bit debugging session.

>
> The rest should be fine. I can test this and add it to the merge queue with the NUMREGBYTES change, unless you disagree.

I don't disagree. :)

Thanks,
Jan

--
Siemens AG, Corporate Technology, CT T DE IT 1
Corporate Competence Center Embedded Linux


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