shinys000114/linux
1
0
Fork 0
mirror of https://github.com/hardkernel/linux.git synced 2026-06-08 03:40:35 +09:00
Code Issues Packages Projects Releases Wiki Activity

x86/xen: Make the secondary CPU idle tasks reliable

Browse Source 
commit c3881eb58d upstream.

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>
Signed-off-by: Markus Boehme <markubo@amazon.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Miroslav Benes
2020-03-26 10:26:03 +01:00
committed by Greg Kroah-Hartman
parent 0d3817cb4e
commit 05df3bdbc2
2 changed files with 12 additions and 1 deletions
Download Patch File Download Diff File Expand all files Collapse all files

3
arch/x86/xen/smp_pv.c
View File

@@ -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)
{
@@ -310,7 +311,7 @@ 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;

10
arch/x86/xen/xen-head.S
View File

@@ -58,6 +58,16 @@ ENTRY(startup_xen)
call xen_start_kernel
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