Re: how to continue from a breakpoint in GNU/Hurd

[Yue Lu]

Hi,

Sorry for the late reply.

On Wed, Jul 17, 2013 at 1:25 AM, Luis Machado <lgustavo@codesourcery.com> wrote:

Hi,

On 07/16/2013 02:04 PM, Yue Lu wrote:

Hi,

thanks for you reply.

On Wed, Jul 17, 2013 at 12:44 AM, Luis Machado

Some general thoughts...

Can you make sure the breakpoint has been lifted from the instruction it
replaced? If the breakpoint has been lifted and it is still being hit, then
it sounds like there is some kind of instruction cache problem going on,
where we first need to flush the icache before resuming execution.

If the icache is the problem, then it sounds like something the kernel
itself needs to address.

Luis

I don't know how to flush the icache off-hand, so I used anther way to
bypass this issue. I set the eip to the next instruction's address to
bypass the breakpoint ins. But problem seems doesn't go away.

I don't think the cache invalidation is something the debugger should do. Sounds like something the kernel would do.

When you set the EIP to some other instruction (not the breakpoint one), what do you see when you instruction-step? What does the EIP show after that?

Luis

I don't have do the instruction-step, because I don't know how to step it. Is it must step after continue the inferior at breakpoint?

When I get the exception message, I set the EIP to the next instruction (for instance 0x12345678), after resume it, I call get_thread_state(), and found the EIP is still  0x12345678. The inferior never running anymore.

--

Yue Lu (陆岳)