Hello.
Jason Wessel wrote:
>>> This patch fixes some corner cases where KGDB will silently hang or
>>> kill the system, if a user accidentally tries to source step into a
>>> spin_unlock() call or source step in on a macro containing
>>> smp_processor_id(). The use of raw_smp_processor_id is desired in
>>> kernel/kgdb.c to fix this particular problem.
>> Hmm, looks like it might fix the issues we also had, and even
>> render the patch which makes KGDB dependent on !DEBUG_PREEMPT (and
>> some others) unneeded...
> Which other parts did you think were not needed? It would be good to
> dump some of that. If this patch doesn't fix the !DEBUG_PREEMPT,
Those were RT specific, IIUC, therefore not submitted...
> perhaps the next one I am sending out about single stepping will fix
> it. If not can you provide me with a test case to see the problem?
Well, for example, with 2.6.18-rt7 kernel, stepping into
smp_processor_id() was blowing away U-Boot (!) on my PPC board (even in
PREEMPT_DESKTOP mode)... On x86, stepping past preempt_disable() caused reboots.
> I had no intention of applying the !DEBUG_PREEMPT patch until I have
> enough information to reproduce the problem or characterization that
> adequately explains why it has no possibility to work. Ideally I would
> like to see the root cause identified so as to craft a solution.
I yet need to check if your patch helps with those issues...
>> Hm, I wonder whether the override will be needed for other
>> architectures...
> Sure the x86_64 arch needs to change too, and the change below should
> address it. I don't know that any other arch has a special rewind that
> is needed.
Perhaps I need to consult the manuals...
> Signed-off-by: Jason Wessel <[EMAIL PROTECTED]>
> Index: linux-2.6.21-standard/arch/x86_64/kernel/kgdb.c
> ===================================================================
> --- linux-2.6.21-standard.orig/arch/x86_64/kernel/kgdb.c
> +++ linux-2.6.21-standard/arch/x86_64/kernel/kgdb.c
> @@ -325,6 +325,14 @@ int kgdb_skipexception(int exception, st
> return 0;
> }
>
> +unsigned long kgdb_arch_pc(int exception, struct pt_regs *regs)
> +{
> + if (exception == 3) {
> + return instruction_pointer(regs) - 1;
> + }
> + return instruction_pointer(regs);
> +}
> +
> struct kgdb_arch arch_kgdb_ops = {
> .gdb_bpt_instr = {0xcc},
> .flags = KGDB_HW_BREAKPOINT,
WBR, Sergei
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