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@suse.cz>
Reviewed-by: Juergen Gross <jgross@suse.com>
Signed-off-by: Juergen Gross <jgross@suse.com>
static DEFINE_PER_CPU(struct xen_common_irq, xen_pmu_irq) = { .irq = -1 };
static irqreturn_t xen_irq_work_interrupt(int irq, void *dev_id);
+void asm_cpu_bringup_and_idle(void);
static void cpu_bringup(void)
{
* pointing just below where pt_regs would be if it were a normal
* kernel entry.
*/
- ctxt->user_regs.eip = (unsigned long)cpu_bringup_and_idle;
+ ctxt->user_regs.eip = (unsigned long)asm_cpu_bringup_and_idle;
ctxt->flags = VGCF_IN_KERNEL;
ctxt->user_regs.eflags = 0x1000; /* IOPL_RING1 */
ctxt->user_regs.ds = __USER_DS;
call xen_start_kernel
SYM_CODE_END(startup_xen)
__FINIT
+
+#ifdef CONFIG_XEN_PV_SMP
+.pushsection .text
+SYM_CODE_START(asm_cpu_bringup_and_idle)
+ UNWIND_HINT_EMPTY
+
+ call cpu_bringup_and_idle
+SYM_CODE_END(asm_cpu_bringup_and_idle)
+.popsection
+#endif
#endif
.pushsection .text