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| author | Miroslav Benes <mbenes@suse.cz> | 2020-03-26 12:26:03 +0300 |
|---|---|---|
| committer | Juergen Gross <jgross@suse.com> | 2020-03-30 18:32:10 +0300 |
| commit | c3881eb58d56116c79ac4ee4f40fd15ead124c4b (patch) | |
| tree | 1cd15be069bf435ff0ed342a019cd23ff2b4b3de /arch/x86/xen | |
| parent | 2f62f36e62daec43aa7b9633ef7f18e042a80bed (diff) | |
| download | linux-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')
| -rw-r--r-- | arch/x86/xen/smp_pv.c | 3 | ||||
| -rw-r--r-- | arch/x86/xen/xen-head.S | 10 |
2 files changed, 12 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; diff --git a/arch/x86/xen/xen-head.S b/arch/x86/xen/xen-head.S index d63806e1ff7a..7d1c4fcbe8f7 100644 --- a/arch/x86/xen/xen-head.S +++ b/arch/x86/xen/xen-head.S @@ -58,6 +58,16 @@ SYM_CODE_START(startup_xen) 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 |