Re: Tracing another stack

[Sterling Augustine <saugustine@google.com>]

On Fri, Nov 27, 2015 at 10:01 PM, Celelibi <celelibi@gmail.com> wrote:
> Hello,
>
> I use gdb with the gdb-stub of qemu to debug a boot loader. When a
> memory fault occurs, a message is printed with the content of most
> registers and a new stack is created to run the handler that never
> terminates.
>
> Can I tell gdb to examine the stack given the content of the stack
> pointer, stack base and program counter of a stack that is not the
> current one?
>
> I tried setting $rsp and $rip to the values I got from the printed
> message, but it turns out it confuses gdb. The "bt" commands shows the
> right first stack frame, but the next ones are those of the interrupt
> handler.

If you have a reasonably mature gdb-stub, you can use the following commands:

# print a list of all threads known to gdb, with numbers
info threads

# switch to a thread numbered X from the above list
thread X

You can now get the back trace for that particular thread with "bt"

You could also do:

thread apply all backtrace

To get a back trace of every thread.

This may not work with certain immature stubs, but it should work with most.