If you are in a situation requiring dumping all registers, are effects on
time handling really very important? Apart from anything else, I'd imagine
this patch will cause the dump-all-diagnostic-keyhandlers key to print
hard-to-read interleaved output as multiple handlers contend for the
console.
-- Keir
On 04/05/2010 16:45, "Jan Beulich" <JBeulich@xxxxxxxxxx> wrote:
> On large systems, dumping state may cause time management to get
> stalled for so long a period that it wouldn't recover. Therefore alter
> the state dumping logic to
> - block each CPU as it prints rather than one CPU for a very long time
> - don't print useless data (e.g. the hypervisor context of the
> interrupt that is used for triggering the printing, but isn't part
> of the context that's actuall interesting.
>
> Signed-off-by: Jan Beulich <jbeulich@xxxxxxxxxx>
>
> --- 2010-05-04.orig/xen/arch/ia64/linux-xen/smp.c 2009-05-27
> 13:54:05.000000000 +0200
> +++ 2010-05-04/xen/arch/ia64/linux-xen/smp.c 2010-05-04 13:22:27.000000000
> +0200
> @@ -189,7 +189,7 @@ handle_IPI (int irq, void *dev_id, struc
> * At this point the structure may be gone unless
> * wait is true.
> */
> - (*func)(info);
> + (*func)(info ?: regs);
>
> /* Notify the sending CPU that the task is done. */
> mb();
> --- 2010-05-04.orig/xen/arch/x86/smp.c 2010-04-22 14:43:25.000000000 +0200
> +++ 2010-05-04/xen/arch/x86/smp.c 2010-05-04 13:22:27.000000000 +0200
> @@ -395,7 +395,7 @@ static void __smp_call_function_interrup
>
> if ( call_data.wait )
> {
> - (*func)(info);
> + (*func)(info ?: get_irq_regs());
> mb();
> atomic_inc(&call_data.finished);
> }
> @@ -403,7 +403,7 @@ static void __smp_call_function_interrup
> {
> mb();
> atomic_inc(&call_data.started);
> - (*func)(info);
> + (*func)(info ?: get_irq_regs());
> }
>
> irq_exit();
> --- 2010-05-04.orig/xen/common/keyhandler.c 2010-05-04 13:21:53.000000000
> +0200
> +++ 2010-05-04/xen/common/keyhandler.c 2010-05-04 13:22:27.000000000 +0200
> @@ -71,20 +71,45 @@ static struct keyhandler show_handlers_k
> .desc = "show this message"
> };
>
> -static void __dump_execstate(void *unused)
> +static cpumask_t dump_execstate_mask;
> +
> +static void __dump_execstate(void *_regs)
> {
> - dump_execution_state();
> - printk("*** Dumping CPU%d guest state: ***\n", smp_processor_id());
> + struct cpu_user_regs *regs = _regs;
> + unsigned int cpu = smp_processor_id();
> +
> + if ( !guest_mode(regs) )
> + {
> + printk("\n*** Dumping CPU%u host state: ***\n", cpu);
> + show_execution_state(regs);
> + }
> if ( is_idle_vcpu(current) )
> - printk("No guest context (CPU is idle).\n");
> + printk("No guest context (CPU%u is idle).\n", cpu);
> else
> + {
> + printk("*** Dumping CPU%u guest state (d%d:v%d): ***\n",
> + smp_processor_id(), current->domain->domain_id,
> + current->vcpu_id);
> show_execution_state(guest_cpu_user_regs());
> + }
> +
> + cpu = cycle_cpu(cpu, dump_execstate_mask);
> + if ( cpu < NR_CPUS )
> + {
> + cpu_clear(cpu, dump_execstate_mask);
> + on_selected_cpus(cpumask_of(cpu), __dump_execstate, NULL, 0);
> + }
> + else
> + {
> + printk("\n");
> +
> + console_end_sync();
> + watchdog_enable();
> + }
> }
>
> static void dump_registers(unsigned char key, struct cpu_user_regs *regs)
> {
> - unsigned int cpu;
> -
> /* We want to get everything out that we possibly can. */
> watchdog_disable();
> console_start_sync();
> @@ -92,21 +117,9 @@ static void dump_registers(unsigned char
> printk("'%c' pressed -> dumping registers\n", key);
>
> /* Get local execution state out immediately, in case we get stuck. */
> - printk("\n*** Dumping CPU%d host state: ***\n", smp_processor_id());
> - __dump_execstate(NULL);
> -
> - for_each_online_cpu ( cpu )
> - {
> - if ( cpu == smp_processor_id() )
> - continue;
> - printk("\n*** Dumping CPU%d host state: ***\n", cpu);
> - on_selected_cpus(cpumask_of(cpu), __dump_execstate, NULL, 1);
> - }
> -
> - printk("\n");
> -
> - console_end_sync();
> - watchdog_enable();
> + cpus_andnot(dump_execstate_mask, cpu_online_map,
> + cpumask_of_cpu(smp_processor_id()));
> + __dump_execstate(regs);
> }
>
> static struct keyhandler dump_registers_keyhandler = {
> --- 2010-05-04.orig/xen/include/asm-ia64/linux-xen/asm/ptrace.h 2010-04-19
> 09:12:58.000000000 +0200
> +++ 2010-05-04/xen/include/asm-ia64/linux-xen/asm/ptrace.h 2010-05-04
> 13:22:27.000000000 +0200
> @@ -280,7 +280,7 @@ struct switch_stack {
> # define ia64_task_regs(t) (((struct pt_regs *) ((char *) (t) +
> IA64_STK_OFFSET)) - 1)
> # define ia64_psr(regs) ((struct ia64_psr *) &(regs)->cr_ipsr)
> #ifdef XEN
> -# define guest_mode(regs) (ia64_psr(regs)->cpl != 0)
> +# define guest_mode(regs) (ia64_psr(regs)->cpl && !ia64_psr(regs)->vm)
> # define guest_kernel_mode(regs) (ia64_psr(regs)->cpl == CONFIG_CPL0_EMUL)
> # define vmx_guest_kernel_mode(regs) (ia64_psr(regs)->cpl == 0)
> # define regs_increment_iip(regs) \
>
>
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