Re: [Xen-devel] [PATCH v3 2/2] x86/xen: Make the secondary CPU idle tasks reliable

[Jürgen Groß <jgross@xxxxxxxx>]

On 26.03.20 10:26, Miroslav Benes wrote:
> The unwinder reports the secondary CPU idle tasks' stack on XEN PV as
> unreliable, which affects at least live patching.
> cpu_initialize_context() sets up the context of the CPU through
> VCPUOP_initialise hypercall. After it is woken up, the idle task starts
> in cpu_bringup_and_idle() function and its stack starts at the offset
> right below pt_regs. The unwinder correctly detects the end of stack
> there but it is confused by NULL return address in the last frame.
>
> Introduce a wrapper in assembly, which just calls
> cpu_bringup_and_idle(). The return address is thus pushed on the stack
> and the wrapper contains the annotation hint for the unwinder regarding
> the stack state.
>
> Signed-off-by: Miroslav Benes <mbenes@xxxxxxx>
Reviewed-by: Juergen Gross <jgross@xxxxxxxx>


Juergen