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authorMiroslav Benes <mbenes@suse.cz>2020-03-26 12:26:03 +0300
committerJuergen Gross <jgross@suse.com>2020-03-30 18:32:10 +0300
commitc3881eb58d56116c79ac4ee4f40fd15ead124c4b (patch)
tree1cd15be069bf435ff0ed342a019cd23ff2b4b3de /arch/x86/xen/smp_pv.c
parent2f62f36e62daec43aa7b9633ef7f18e042a80bed (diff)
downloadlinux-c3881eb58d56116c79ac4ee4f40fd15ead124c4b.tar.xz
x86/xen: Make the secondary CPU idle tasks reliable
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>
Diffstat (limited to 'arch/x86/xen/smp_pv.c')
-rw-r--r--arch/x86/xen/smp_pv.c3
1 files changed, 2 insertions, 1 deletions
diff --git a/arch/x86/xen/smp_pv.c b/arch/x86/xen/smp_pv.c
index 802ee5bba66c..8fb8a50a28b4 100644
--- a/arch/x86/xen/smp_pv.c
+++ b/arch/x86/xen/smp_pv.c
@@ -53,6 +53,7 @@ static DEFINE_PER_CPU(struct xen_common_irq, xen_irq_work) = { .irq = -1 };
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)
{
@@ -309,7 +310,7 @@ cpu_initialize_context(unsigned int cpu, struct task_struct *idle)
* 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;