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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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