x86, bts, hw-branch-tracer: add _noirq variants to the debug store interface
The hw-branch-tracer uses debug store functions from an on_each_cpu() context, which is simply wrong since the functions may sleep. Add _noirq variants for most functions, which may be called with interrupts disabled. Separate per-cpu and per-task tracing and allow per-cpu tracing to be controlled from any cpu. Make the hw-branch-tracer use the new debug store interface, synchronize with hotplug cpu event using get/put_online_cpus(), and remove the unnecessary spinlock. Make the ptrace bts and the ds selftest code use the new interface. Defer the ds selftest. Signed-off-by: Markus Metzger <markus.t.metzger@intel.com> Cc: roland@redhat.com Cc: eranian@googlemail.com Cc: oleg@redhat.com Cc: juan.villacis@intel.com Cc: ak@linux.jf.intel.com LKML-Reference: <20090403144555.658136000@intel.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
This commit is contained in:
Markus Metzger
committed by
Ingo Molnar
Ingo Molnar
parent
35bb7600c1
commit
de79f54f53
@ -245,60 +245,50 @@ struct ds_context {
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struct pebs_tracer *pebs_master;
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/* Use count: */
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unsigned long count;
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unsigned long count;
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/* Pointer to the context pointer field: */
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struct ds_context **this;
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/* The traced task; NULL for current cpu: */
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/* The traced task; NULL for cpu tracing: */
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struct task_struct *task;
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/* The traced cpu; only valid if task is NULL: */
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int cpu;
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};
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static DEFINE_PER_CPU(struct ds_context *, system_context_array);
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#define system_context per_cpu(system_context_array, smp_processor_id())
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static DEFINE_PER_CPU(struct ds_context *, cpu_context);
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static inline struct ds_context *ds_get_context(struct task_struct *task)
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static struct ds_context *ds_get_context(struct task_struct *task, int cpu)
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{
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struct ds_context **p_context =
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(task ? &task->thread.ds_ctx : &system_context);
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(task ? &task->thread.ds_ctx : &per_cpu(cpu_context, cpu));
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struct ds_context *context = NULL;
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struct ds_context *new_context = NULL;
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unsigned long irq;
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/*
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* Chances are small that we already have a context.
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*
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* Contexts for per-cpu tracing are allocated using
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* smp_call_function(). We must not sleep.
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*/
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new_context = kzalloc(sizeof(*new_context), GFP_ATOMIC);
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/* Chances are small that we already have a context. */
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new_context = kzalloc(sizeof(*new_context), GFP_KERNEL);
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if (!new_context)
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return NULL;
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spin_lock_irqsave(&ds_lock, irq);
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spin_lock_irq(&ds_lock);
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context = *p_context;
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if (!context) {
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if (likely(!context)) {
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context = new_context;
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context->this = p_context;
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context->task = task;
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context->cpu = cpu;
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context->count = 0;
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if (task)
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set_tsk_thread_flag(task, TIF_DS_AREA_MSR);
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if (!task || (task == current))
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wrmsrl(MSR_IA32_DS_AREA, (unsigned long)context->ds);
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*p_context = context;
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}
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context->count++;
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spin_unlock_irqrestore(&ds_lock, irq);
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spin_unlock_irq(&ds_lock);
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if (context != new_context)
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kfree(new_context);
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@ -306,7 +296,7 @@ static inline struct ds_context *ds_get_context(struct task_struct *task)
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return context;
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}
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static inline void ds_put_context(struct ds_context *context)
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static void ds_put_context(struct ds_context *context)
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{
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struct task_struct *task;
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unsigned long irq;
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@ -328,8 +318,15 @@ static inline void ds_put_context(struct ds_context *context)
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if (task)
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clear_tsk_thread_flag(task, TIF_DS_AREA_MSR);
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if (!task || (task == current))
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wrmsrl(MSR_IA32_DS_AREA, 0);
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/*
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* We leave the (now dangling) pointer to the DS configuration in
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* the DS_AREA msr. This is as good or as bad as replacing it with
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* NULL - the hardware would crash if we enabled tracing.
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*
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* This saves us some problems with having to write an msr on a
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* different cpu while preventing others from doing the same for the
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* next context for that same cpu.
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*/
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spin_unlock_irqrestore(&ds_lock, irq);
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@ -340,6 +337,31 @@ static inline void ds_put_context(struct ds_context *context)
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kfree(context);
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}
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static void ds_install_ds_area(struct ds_context *context)
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{
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unsigned long ds;
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ds = (unsigned long)context->ds;
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/*
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* There is a race between the bts master and the pebs master.
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*
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* The thread/cpu access is synchronized via get/put_cpu() for
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* task tracing and via wrmsr_on_cpu for cpu tracing.
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*
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* If bts and pebs are collected for the same task or same cpu,
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* the same confiuration is written twice.
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*/
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if (context->task) {
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get_cpu();
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if (context->task == current)
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wrmsrl(MSR_IA32_DS_AREA, ds);
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set_tsk_thread_flag(context->task, TIF_DS_AREA_MSR);
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put_cpu();
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} else
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wrmsr_on_cpu(context->cpu, MSR_IA32_DS_AREA,
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(u32)((u64)ds), (u32)((u64)ds >> 32));
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}
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/*
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* Call the tracer's callback on a buffer overflow.
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@ -622,6 +644,7 @@ static void ds_init_ds_trace(struct ds_trace *trace, enum ds_qualifier qual,
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* The value for 'no threshold' is -1, which will set the
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* threshold outside of the buffer, just like we want it.
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*/
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ith *= ds_cfg.sizeof_rec[qual];
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trace->ith = (void *)(buffer + size - ith);
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trace->flags = flags;
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@ -630,7 +653,7 @@ static void ds_init_ds_trace(struct ds_trace *trace, enum ds_qualifier qual,
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static int ds_request(struct ds_tracer *tracer, struct ds_trace *trace,
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enum ds_qualifier qual, struct task_struct *task,
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void *base, size_t size, size_t th, unsigned int flags)
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int cpu, void *base, size_t size, size_t th)
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{
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struct ds_context *context;
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int error;
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@ -643,7 +666,7 @@ static int ds_request(struct ds_tracer *tracer, struct ds_trace *trace,
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if (!base)
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goto out;
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/* We require some space to do alignment adjustments below. */
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/* We need space for alignment adjustments in ds_init_ds_trace(). */
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error = -EINVAL;
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if (size < (DS_ALIGNMENT + ds_cfg.sizeof_rec[qual]))
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goto out;
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@ -660,25 +683,27 @@ static int ds_request(struct ds_tracer *tracer, struct ds_trace *trace,
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tracer->size = size;
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error = -ENOMEM;
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context = ds_get_context(task);
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context = ds_get_context(task, cpu);
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if (!context)
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goto out;
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tracer->context = context;
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ds_init_ds_trace(trace, qual, base, size, th, flags);
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/*
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* Defer any tracer-specific initialization work for the context until
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* context ownership has been clarified.
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*/
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error = 0;
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out:
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return error;
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}
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struct bts_tracer *ds_request_bts(struct task_struct *task,
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void *base, size_t size,
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bts_ovfl_callback_t ovfl, size_t th,
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unsigned int flags)
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static struct bts_tracer *ds_request_bts(struct task_struct *task, int cpu,
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void *base, size_t size,
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bts_ovfl_callback_t ovfl, size_t th,
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unsigned int flags)
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{
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struct bts_tracer *tracer;
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unsigned long irq;
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int error;
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/* Buffer overflow notification is not yet implemented. */
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@ -690,42 +715,46 @@ struct bts_tracer *ds_request_bts(struct task_struct *task,
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if (error < 0)
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goto out;
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/*
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* Per-cpu tracing is typically requested using smp_call_function().
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* We must not sleep.
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*/
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error = -ENOMEM;
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tracer = kzalloc(sizeof(*tracer), GFP_ATOMIC);
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tracer = kzalloc(sizeof(*tracer), GFP_KERNEL);
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if (!tracer)
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goto out_put_tracer;
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tracer->ovfl = ovfl;
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/* Do some more error checking and acquire a tracing context. */
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error = ds_request(&tracer->ds, &tracer->trace.ds,
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ds_bts, task, base, size, th, flags);
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ds_bts, task, cpu, base, size, th);
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if (error < 0)
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goto out_tracer;
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spin_lock_irqsave(&ds_lock, irq);
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/* Claim the bts part of the tracing context we acquired above. */
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spin_lock_irq(&ds_lock);
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error = -EPERM;
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if (tracer->ds.context->bts_master)
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goto out_unlock;
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tracer->ds.context->bts_master = tracer;
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spin_unlock_irqrestore(&ds_lock, irq);
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spin_unlock_irq(&ds_lock);
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/*
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* Now that we own the bts part of the context, let's complete the
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* initialization for that part.
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*/
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ds_init_ds_trace(&tracer->trace.ds, ds_bts, base, size, th, flags);
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ds_write_config(tracer->ds.context, &tracer->trace.ds, ds_bts);
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ds_install_ds_area(tracer->ds.context);
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tracer->trace.read = bts_read;
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tracer->trace.write = bts_write;
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ds_write_config(tracer->ds.context, &tracer->trace.ds, ds_bts);
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/* Start tracing. */
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ds_resume_bts(tracer);
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return tracer;
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out_unlock:
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spin_unlock_irqrestore(&ds_lock, irq);
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spin_unlock_irq(&ds_lock);
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ds_put_context(tracer->ds.context);
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out_tracer:
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kfree(tracer);
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@ -735,13 +764,27 @@ struct bts_tracer *ds_request_bts(struct task_struct *task,
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return ERR_PTR(error);
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}
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struct pebs_tracer *ds_request_pebs(struct task_struct *task,
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void *base, size_t size,
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pebs_ovfl_callback_t ovfl, size_t th,
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unsigned int flags)
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struct bts_tracer *ds_request_bts_task(struct task_struct *task,
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void *base, size_t size,
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bts_ovfl_callback_t ovfl,
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size_t th, unsigned int flags)
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{
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return ds_request_bts(task, 0, base, size, ovfl, th, flags);
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}
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struct bts_tracer *ds_request_bts_cpu(int cpu, void *base, size_t size,
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bts_ovfl_callback_t ovfl,
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size_t th, unsigned int flags)
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{
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return ds_request_bts(NULL, cpu, base, size, ovfl, th, flags);
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}
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static struct pebs_tracer *ds_request_pebs(struct task_struct *task, int cpu,
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void *base, size_t size,
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pebs_ovfl_callback_t ovfl, size_t th,
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unsigned int flags)
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{
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struct pebs_tracer *tracer;
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unsigned long irq;
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int error;
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/* Buffer overflow notification is not yet implemented. */
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@ -753,37 +796,43 @@ struct pebs_tracer *ds_request_pebs(struct task_struct *task,
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if (error < 0)
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goto out;
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/*
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* Per-cpu tracing is typically requested using smp_call_function().
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* We must not sleep.
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*/
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error = -ENOMEM;
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tracer = kzalloc(sizeof(*tracer), GFP_ATOMIC);
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tracer = kzalloc(sizeof(*tracer), GFP_KERNEL);
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if (!tracer)
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goto out_put_tracer;
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tracer->ovfl = ovfl;
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/* Do some more error checking and acquire a tracing context. */
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error = ds_request(&tracer->ds, &tracer->trace.ds,
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ds_pebs, task, base, size, th, flags);
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ds_pebs, task, cpu, base, size, th);
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if (error < 0)
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goto out_tracer;
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spin_lock_irqsave(&ds_lock, irq);
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/* Claim the pebs part of the tracing context we acquired above. */
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spin_lock_irq(&ds_lock);
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error = -EPERM;
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if (tracer->ds.context->pebs_master)
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goto out_unlock;
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tracer->ds.context->pebs_master = tracer;
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spin_unlock_irqrestore(&ds_lock, irq);
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spin_unlock_irq(&ds_lock);
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/*
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* Now that we own the pebs part of the context, let's complete the
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* initialization for that part.
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*/
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ds_init_ds_trace(&tracer->trace.ds, ds_pebs, base, size, th, flags);
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ds_write_config(tracer->ds.context, &tracer->trace.ds, ds_pebs);
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ds_install_ds_area(tracer->ds.context);
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/* Start tracing. */
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ds_resume_pebs(tracer);
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return tracer;
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out_unlock:
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spin_unlock_irqrestore(&ds_lock, irq);
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spin_unlock_irq(&ds_lock);
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ds_put_context(tracer->ds.context);
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out_tracer:
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kfree(tracer);
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@ -793,17 +842,27 @@ struct pebs_tracer *ds_request_pebs(struct task_struct *task,
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return ERR_PTR(error);
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}
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void ds_release_bts(struct bts_tracer *tracer)
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struct pebs_tracer *ds_request_pebs_task(struct task_struct *task,
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void *base, size_t size,
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pebs_ovfl_callback_t ovfl,
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size_t th, unsigned int flags)
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{
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return ds_request_pebs(task, 0, base, size, ovfl, th, flags);
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}
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struct pebs_tracer *ds_request_pebs_cpu(int cpu, void *base, size_t size,
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pebs_ovfl_callback_t ovfl,
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size_t th, unsigned int flags)
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{
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return ds_request_pebs(NULL, cpu, base, size, ovfl, th, flags);
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}
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static void ds_free_bts(struct bts_tracer *tracer)
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{
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struct task_struct *task;
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if (!tracer)
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return;
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task = tracer->ds.context->task;
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ds_suspend_bts(tracer);
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WARN_ON_ONCE(tracer->ds.context->bts_master != tracer);
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tracer->ds.context->bts_master = NULL;
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@ -817,9 +876,69 @@ void ds_release_bts(struct bts_tracer *tracer)
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kfree(tracer);
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}
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void ds_release_bts(struct bts_tracer *tracer)
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{
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might_sleep();
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if (!tracer)
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return;
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ds_suspend_bts(tracer);
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ds_free_bts(tracer);
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}
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int ds_release_bts_noirq(struct bts_tracer *tracer)
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{
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struct task_struct *task;
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unsigned long irq;
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int error;
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if (!tracer)
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return 0;
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task = tracer->ds.context->task;
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local_irq_save(irq);
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error = -EPERM;
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if (!task &&
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(tracer->ds.context->cpu != smp_processor_id()))
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goto out;
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error = -EPERM;
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if (task && (task != current))
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goto out;
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ds_suspend_bts_noirq(tracer);
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ds_free_bts(tracer);
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error = 0;
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out:
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local_irq_restore(irq);
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return error;
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}
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static void update_task_debugctlmsr(struct task_struct *task,
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unsigned long debugctlmsr)
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{
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task->thread.debugctlmsr = debugctlmsr;
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get_cpu();
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if (task == current)
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update_debugctlmsr(debugctlmsr);
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if (task->thread.debugctlmsr)
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set_tsk_thread_flag(task, TIF_DEBUGCTLMSR);
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else
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clear_tsk_thread_flag(task, TIF_DEBUGCTLMSR);
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put_cpu();
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}
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void ds_suspend_bts(struct bts_tracer *tracer)
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{
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struct task_struct *task;
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unsigned long debugctlmsr;
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int cpu;
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if (!tracer)
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return;
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@ -827,29 +946,60 @@ void ds_suspend_bts(struct bts_tracer *tracer)
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tracer->flags = 0;
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task = tracer->ds.context->task;
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cpu = tracer->ds.context->cpu;
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if (!task || (task == current))
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update_debugctlmsr(get_debugctlmsr() & ~BTS_CONTROL);
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WARN_ON(!task && irqs_disabled());
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if (task) {
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task->thread.debugctlmsr &= ~BTS_CONTROL;
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debugctlmsr = (task ?
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task->thread.debugctlmsr :
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get_debugctlmsr_on_cpu(cpu));
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debugctlmsr &= ~BTS_CONTROL;
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if (!task->thread.debugctlmsr)
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||||
clear_tsk_thread_flag(task, TIF_DEBUGCTLMSR);
|
||||
}
|
||||
if (task)
|
||||
update_task_debugctlmsr(task, debugctlmsr);
|
||||
else
|
||||
update_debugctlmsr_on_cpu(cpu, debugctlmsr);
|
||||
}
|
||||
|
||||
void ds_resume_bts(struct bts_tracer *tracer)
|
||||
int ds_suspend_bts_noirq(struct bts_tracer *tracer)
|
||||
{
|
||||
struct task_struct *task;
|
||||
unsigned long control;
|
||||
unsigned long debugctlmsr, irq;
|
||||
int cpu, error = 0;
|
||||
|
||||
if (!tracer)
|
||||
return;
|
||||
return 0;
|
||||
|
||||
tracer->flags = tracer->trace.ds.flags;
|
||||
tracer->flags = 0;
|
||||
|
||||
task = tracer->ds.context->task;
|
||||
cpu = tracer->ds.context->cpu;
|
||||
|
||||
local_irq_save(irq);
|
||||
|
||||
error = -EPERM;
|
||||
if (!task && (cpu != smp_processor_id()))
|
||||
goto out;
|
||||
|
||||
debugctlmsr = (task ?
|
||||
task->thread.debugctlmsr :
|
||||
get_debugctlmsr());
|
||||
debugctlmsr &= ~BTS_CONTROL;
|
||||
|
||||
if (task)
|
||||
update_task_debugctlmsr(task, debugctlmsr);
|
||||
else
|
||||
update_debugctlmsr(debugctlmsr);
|
||||
|
||||
error = 0;
|
||||
out:
|
||||
local_irq_restore(irq);
|
||||
return error;
|
||||
}
|
||||
|
||||
static unsigned long ds_bts_control(struct bts_tracer *tracer)
|
||||
{
|
||||
unsigned long control;
|
||||
|
||||
control = ds_cfg.ctl[dsf_bts];
|
||||
if (!(tracer->trace.ds.flags & BTS_KERNEL))
|
||||
@ -857,25 +1007,77 @@ void ds_resume_bts(struct bts_tracer *tracer)
|
||||
if (!(tracer->trace.ds.flags & BTS_USER))
|
||||
control |= ds_cfg.ctl[dsf_bts_user];
|
||||
|
||||
if (task) {
|
||||
task->thread.debugctlmsr |= control;
|
||||
set_tsk_thread_flag(task, TIF_DEBUGCTLMSR);
|
||||
}
|
||||
|
||||
if (!task || (task == current))
|
||||
update_debugctlmsr(get_debugctlmsr() | control);
|
||||
return control;
|
||||
}
|
||||
|
||||
void ds_release_pebs(struct pebs_tracer *tracer)
|
||||
void ds_resume_bts(struct bts_tracer *tracer)
|
||||
{
|
||||
struct task_struct *task;
|
||||
unsigned long debugctlmsr;
|
||||
int cpu;
|
||||
|
||||
if (!tracer)
|
||||
return;
|
||||
|
||||
task = tracer->ds.context->task;
|
||||
tracer->flags = tracer->trace.ds.flags;
|
||||
|
||||
ds_suspend_pebs(tracer);
|
||||
task = tracer->ds.context->task;
|
||||
cpu = tracer->ds.context->cpu;
|
||||
|
||||
WARN_ON(!task && irqs_disabled());
|
||||
|
||||
debugctlmsr = (task ?
|
||||
task->thread.debugctlmsr :
|
||||
get_debugctlmsr_on_cpu(cpu));
|
||||
debugctlmsr |= ds_bts_control(tracer);
|
||||
|
||||
if (task)
|
||||
update_task_debugctlmsr(task, debugctlmsr);
|
||||
else
|
||||
update_debugctlmsr_on_cpu(cpu, debugctlmsr);
|
||||
}
|
||||
|
||||
int ds_resume_bts_noirq(struct bts_tracer *tracer)
|
||||
{
|
||||
struct task_struct *task;
|
||||
unsigned long debugctlmsr, irq;
|
||||
int cpu, error = 0;
|
||||
|
||||
if (!tracer)
|
||||
return 0;
|
||||
|
||||
tracer->flags = tracer->trace.ds.flags;
|
||||
|
||||
task = tracer->ds.context->task;
|
||||
cpu = tracer->ds.context->cpu;
|
||||
|
||||
local_irq_save(irq);
|
||||
|
||||
error = -EPERM;
|
||||
if (!task && (cpu != smp_processor_id()))
|
||||
goto out;
|
||||
|
||||
debugctlmsr = (task ?
|
||||
task->thread.debugctlmsr :
|
||||
get_debugctlmsr());
|
||||
debugctlmsr |= ds_bts_control(tracer);
|
||||
|
||||
if (task)
|
||||
update_task_debugctlmsr(task, debugctlmsr);
|
||||
else
|
||||
update_debugctlmsr(debugctlmsr);
|
||||
|
||||
error = 0;
|
||||
out:
|
||||
local_irq_restore(irq);
|
||||
return error;
|
||||
}
|
||||
|
||||
static void ds_free_pebs(struct pebs_tracer *tracer)
|
||||
{
|
||||
struct task_struct *task;
|
||||
|
||||
task = tracer->ds.context->task;
|
||||
|
||||
WARN_ON_ONCE(tracer->ds.context->pebs_master != tracer);
|
||||
tracer->ds.context->pebs_master = NULL;
|
||||
@ -886,16 +1088,68 @@ void ds_release_pebs(struct pebs_tracer *tracer)
|
||||
kfree(tracer);
|
||||
}
|
||||
|
||||
void ds_release_pebs(struct pebs_tracer *tracer)
|
||||
{
|
||||
might_sleep();
|
||||
|
||||
if (!tracer)
|
||||
return;
|
||||
|
||||
ds_suspend_pebs(tracer);
|
||||
ds_free_pebs(tracer);
|
||||
}
|
||||
|
||||
int ds_release_pebs_noirq(struct pebs_tracer *tracer)
|
||||
{
|
||||
struct task_struct *task;
|
||||
unsigned long irq;
|
||||
int error;
|
||||
|
||||
if (!tracer)
|
||||
return 0;
|
||||
|
||||
task = tracer->ds.context->task;
|
||||
|
||||
local_irq_save(irq);
|
||||
|
||||
error = -EPERM;
|
||||
if (!task &&
|
||||
(tracer->ds.context->cpu != smp_processor_id()))
|
||||
goto out;
|
||||
|
||||
error = -EPERM;
|
||||
if (task && (task != current))
|
||||
goto out;
|
||||
|
||||
ds_suspend_pebs_noirq(tracer);
|
||||
ds_free_pebs(tracer);
|
||||
|
||||
error = 0;
|
||||
out:
|
||||
local_irq_restore(irq);
|
||||
return error;
|
||||
}
|
||||
|
||||
void ds_suspend_pebs(struct pebs_tracer *tracer)
|
||||
{
|
||||
|
||||
}
|
||||
|
||||
int ds_suspend_pebs_noirq(struct pebs_tracer *tracer)
|
||||
{
|
||||
return 0;
|
||||
}
|
||||
|
||||
void ds_resume_pebs(struct pebs_tracer *tracer)
|
||||
{
|
||||
|
||||
}
|
||||
|
||||
int ds_resume_pebs_noirq(struct pebs_tracer *tracer)
|
||||
{
|
||||
return 0;
|
||||
}
|
||||
|
||||
const struct bts_trace *ds_read_bts(struct bts_tracer *tracer)
|
||||
{
|
||||
if (!tracer)
|
||||
@ -1004,26 +1258,6 @@ ds_configure(const struct ds_configuration *cfg,
|
||||
printk(KERN_INFO "[ds] pebs not available\n");
|
||||
}
|
||||
|
||||
if (ds_cfg.sizeof_rec[ds_bts]) {
|
||||
int error;
|
||||
|
||||
error = ds_selftest_bts();
|
||||
if (error) {
|
||||
WARN(1, "[ds] selftest failed. disabling bts.\n");
|
||||
ds_cfg.sizeof_rec[ds_bts] = 0;
|
||||
}
|
||||
}
|
||||
|
||||
if (ds_cfg.sizeof_rec[ds_pebs]) {
|
||||
int error;
|
||||
|
||||
error = ds_selftest_pebs();
|
||||
if (error) {
|
||||
WARN(1, "[ds] selftest failed. disabling pebs.\n");
|
||||
ds_cfg.sizeof_rec[ds_pebs] = 0;
|
||||
}
|
||||
}
|
||||
|
||||
printk(KERN_INFO "[ds] sizes: address: %u bit, ",
|
||||
8 * ds_cfg.sizeof_ptr_field);
|
||||
printk("bts/pebs record: %u/%u bytes\n",
|
||||
@ -1127,3 +1361,29 @@ void ds_copy_thread(struct task_struct *tsk, struct task_struct *father)
|
||||
void ds_exit_thread(struct task_struct *tsk)
|
||||
{
|
||||
}
|
||||
|
||||
static __init int ds_selftest(void)
|
||||
{
|
||||
if (ds_cfg.sizeof_rec[ds_bts]) {
|
||||
int error;
|
||||
|
||||
error = ds_selftest_bts();
|
||||
if (error) {
|
||||
WARN(1, "[ds] selftest failed. disabling bts.\n");
|
||||
ds_cfg.sizeof_rec[ds_bts] = 0;
|
||||
}
|
||||
}
|
||||
|
||||
if (ds_cfg.sizeof_rec[ds_pebs]) {
|
||||
int error;
|
||||
|
||||
error = ds_selftest_pebs();
|
||||
if (error) {
|
||||
WARN(1, "[ds] selftest failed. disabling pebs.\n");
|
||||
ds_cfg.sizeof_rec[ds_pebs] = 0;
|
||||
}
|
||||
}
|
||||
|
||||
return 0;
|
||||
}
|
||||
device_initcall(ds_selftest);
|
||||
|
||||
Reference in New Issue
Block a user