x86, bts, hw-branch-tracer: add _noirq variants to the debug store interface
authorMarkus Metzger <markus.t.metzger@intel.com>
Fri, 3 Apr 2009 14:43:40 +0000 (16:43 +0200)
committerIngo Molnar <mingo@elte.hu>
Tue, 7 Apr 2009 11:36:20 +0000 (13:36 +0200)
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>
arch/x86/include/asm/ds.h
arch/x86/kernel/ds.c
arch/x86/kernel/ds_selftest.c
arch/x86/kernel/ptrace.c
kernel/trace/trace_hw_branches.c

index 772f141afb9a1a96e207c111d00723f0b2e457c9..413e127e567d786512e37e95d6668c2f121e1eef 100644 (file)
@@ -15,8 +15,8 @@
  * - buffer allocation (memory accounting)
  *
  *
- * Copyright (C) 2007-2008 Intel Corporation.
- * Markus Metzger <markus.t.metzger@intel.com>, 2007-2008
+ * Copyright (C) 2007-2009 Intel Corporation.
+ * Markus Metzger <markus.t.metzger@intel.com>, 2007-2009
  */
 
 #ifndef _ASM_X86_DS_H
@@ -83,8 +83,10 @@ enum ds_feature {
  * The interrupt threshold is independent from the overflow callback
  * to allow users to use their own overflow interrupt handling mechanism.
  *
- * task: the task to request recording for;
- *       NULL for per-cpu recording on the current cpu
+ * The function might sleep.
+ *
+ * task: the task to request recording for
+ * cpu:  the cpu to request recording for
  * base: the base pointer for the (non-pageable) buffer;
  * size: the size of the provided buffer in bytes
  * ovfl: pointer to a function to be called on buffer overflow;
@@ -93,19 +95,28 @@ enum ds_feature {
  *     -1 if no interrupt threshold is requested.
  * flags: a bit-mask of the above flags
  */
-extern struct bts_tracer *ds_request_bts(struct task_struct *task,
-                                        void *base, size_t size,
-                                        bts_ovfl_callback_t ovfl,
-                                        size_t th, unsigned int flags);
-extern struct pebs_tracer *ds_request_pebs(struct task_struct *task,
-                                          void *base, size_t size,
-                                          pebs_ovfl_callback_t ovfl,
-                                          size_t th, unsigned int flags);
+extern struct bts_tracer *ds_request_bts_task(struct task_struct *task,
+                                             void *base, size_t size,
+                                             bts_ovfl_callback_t ovfl,
+                                             size_t th, unsigned int flags);
+extern struct bts_tracer *ds_request_bts_cpu(int cpu, void *base, size_t size,
+                                            bts_ovfl_callback_t ovfl,
+                                            size_t th, unsigned int flags);
+extern struct pebs_tracer *ds_request_pebs_task(struct task_struct *task,
+                                               void *base, size_t size,
+                                               pebs_ovfl_callback_t ovfl,
+                                               size_t th, unsigned int flags);
+extern struct pebs_tracer *ds_request_pebs_cpu(int cpu,
+                                              void *base, size_t size,
+                                              pebs_ovfl_callback_t ovfl,
+                                              size_t th, unsigned int flags);
 
 /*
  * Release BTS or PEBS resources
  * Suspend and resume BTS or PEBS tracing
  *
+ * Must be called with irq's enabled.
+ *
  * tracer: the tracer handle returned from ds_request_~()
  */
 extern void ds_release_bts(struct bts_tracer *tracer);
@@ -115,6 +126,28 @@ extern void ds_release_pebs(struct pebs_tracer *tracer);
 extern void ds_suspend_pebs(struct pebs_tracer *tracer);
 extern void ds_resume_pebs(struct pebs_tracer *tracer);
 
+/*
+ * Release BTS or PEBS resources
+ * Suspend and resume BTS or PEBS tracing
+ *
+ * Cpu tracers must call this on the traced cpu.
+ * Task tracers must call ds_release_~_noirq() for themselves.
+ *
+ * May be called with irq's disabled.
+ *
+ * Returns 0 if successful;
+ * -EPERM if the cpu tracer does not trace the current cpu.
+ * -EPERM if the task tracer does not trace itself.
+ *
+ * tracer: the tracer handle returned from ds_request_~()
+ */
+extern int ds_release_bts_noirq(struct bts_tracer *tracer);
+extern int ds_suspend_bts_noirq(struct bts_tracer *tracer);
+extern int ds_resume_bts_noirq(struct bts_tracer *tracer);
+extern int ds_release_pebs_noirq(struct pebs_tracer *tracer);
+extern int ds_suspend_pebs_noirq(struct pebs_tracer *tracer);
+extern int ds_resume_pebs_noirq(struct pebs_tracer *tracer);
+
 
 /*
  * The raw DS buffer state as it is used for BTS and PEBS recording.
index 2071b992c35ce0e7e383a5ed5beb8329c2685fde..21a3852abf6856ee775a3872cd99b54d303cf45b 100644 (file)
@@ -245,60 +245,50 @@ struct ds_context {
        struct pebs_tracer      *pebs_master;
 
        /* Use count: */
-       unsigned long count;
+       unsigned long           count;
 
        /* Pointer to the context pointer field: */
        struct ds_context       **this;
 
-       /* The traced task; NULL for current cpu: */
+       /* The traced task; NULL for cpu tracing: */
        struct task_struct      *task;
-};
 
-static DEFINE_PER_CPU(struct ds_context *, system_context_array);
+       /* The traced cpu; only valid if task is NULL: */
+       int                     cpu;
+};
 
-#define system_context per_cpu(system_context_array, smp_processor_id())
+static DEFINE_PER_CPU(struct ds_context *, cpu_context);
 
 
-static inline struct ds_context *ds_get_context(struct task_struct *task)
+static struct ds_context *ds_get_context(struct task_struct *task, int cpu)
 {
        struct ds_context **p_context =
-               (task ? &task->thread.ds_ctx : &system_context);
+               (task ? &task->thread.ds_ctx : &per_cpu(cpu_context, cpu));
        struct ds_context *context = NULL;
        struct ds_context *new_context = NULL;
-       unsigned long irq;
 
-       /*
-        * Chances are small that we already have a context.
-        *
-        * Contexts for per-cpu tracing are allocated using
-        * smp_call_function(). We must not sleep.
-        */
-       new_context = kzalloc(sizeof(*new_context), GFP_ATOMIC);
+       /* Chances are small that we already have a context. */
+       new_context = kzalloc(sizeof(*new_context), GFP_KERNEL);
        if (!new_context)
                return NULL;
 
-       spin_lock_irqsave(&ds_lock, irq);
+       spin_lock_irq(&ds_lock);
 
        context = *p_context;
-       if (!context) {
+       if (likely(!context)) {
                context = new_context;
 
                context->this = p_context;
                context->task = task;
+               context->cpu = cpu;
                context->count = 0;
 
-               if (task)
-                       set_tsk_thread_flag(task, TIF_DS_AREA_MSR);
-
-               if (!task || (task == current))
-                       wrmsrl(MSR_IA32_DS_AREA, (unsigned long)context->ds);
-
                *p_context = context;
        }
 
        context->count++;
 
-       spin_unlock_irqrestore(&ds_lock, irq);
+       spin_unlock_irq(&ds_lock);
 
        if (context != new_context)
                kfree(new_context);
@@ -306,7 +296,7 @@ static inline struct ds_context *ds_get_context(struct task_struct *task)
        return context;
 }
 
-static inline void ds_put_context(struct ds_context *context)
+static void ds_put_context(struct ds_context *context)
 {
        struct task_struct *task;
        unsigned long irq;
@@ -328,8 +318,15 @@ static inline void ds_put_context(struct ds_context *context)
        if (task)
                clear_tsk_thread_flag(task, TIF_DS_AREA_MSR);
 
-       if (!task || (task == current))
-               wrmsrl(MSR_IA32_DS_AREA, 0);
+       /*
+        * We leave the (now dangling) pointer to the DS configuration in
+        * the DS_AREA msr. This is as good or as bad as replacing it with
+        * NULL - the hardware would crash if we enabled tracing.
+        *
+        * This saves us some problems with having to write an msr on a
+        * different cpu while preventing others from doing the same for the
+        * next context for that same cpu.
+        */
 
        spin_unlock_irqrestore(&ds_lock, irq);
 
@@ -340,6 +337,31 @@ static inline void ds_put_context(struct ds_context *context)
        kfree(context);
 }
 
+static void ds_install_ds_area(struct ds_context *context)
+{
+       unsigned long ds;
+
+       ds = (unsigned long)context->ds;
+
+       /*
+        * There is a race between the bts master and the pebs master.
+        *
+        * The thread/cpu access is synchronized via get/put_cpu() for
+        * task tracing and via wrmsr_on_cpu for cpu tracing.
+        *
+        * If bts and pebs are collected for the same task or same cpu,
+        * the same confiuration is written twice.
+        */
+       if (context->task) {
+               get_cpu();
+               if (context->task == current)
+                       wrmsrl(MSR_IA32_DS_AREA, ds);
+               set_tsk_thread_flag(context->task, TIF_DS_AREA_MSR);
+               put_cpu();
+       } else
+               wrmsr_on_cpu(context->cpu, MSR_IA32_DS_AREA,
+                            (u32)((u64)ds), (u32)((u64)ds >> 32));
+}
 
 /*
  * Call the tracer's callback on a buffer overflow.
@@ -622,6 +644,7 @@ static void ds_init_ds_trace(struct ds_trace *trace, enum ds_qualifier qual,
         * The value for 'no threshold' is -1, which will set the
         * threshold outside of the buffer, just like we want it.
         */
+       ith *= ds_cfg.sizeof_rec[qual];
        trace->ith = (void *)(buffer + size - ith);
 
        trace->flags = flags;
@@ -630,7 +653,7 @@ static void ds_init_ds_trace(struct ds_trace *trace, enum ds_qualifier qual,
 
 static int ds_request(struct ds_tracer *tracer, struct ds_trace *trace,
                      enum ds_qualifier qual, struct task_struct *task,
-                     void *base, size_t size, size_t th, unsigned int flags)
+                     int cpu, void *base, size_t size, size_t th)
 {
        struct ds_context *context;
        int error;
@@ -643,7 +666,7 @@ static int ds_request(struct ds_tracer *tracer, struct ds_trace *trace,
        if (!base)
                goto out;
 
-       /* We require some space to do alignment adjustments below. */
+       /* We need space for alignment adjustments in ds_init_ds_trace(). */
        error = -EINVAL;
        if (size < (DS_ALIGNMENT + ds_cfg.sizeof_rec[qual]))
                goto out;
@@ -660,25 +683,27 @@ static int ds_request(struct ds_tracer *tracer, struct ds_trace *trace,
        tracer->size = size;
 
        error = -ENOMEM;
-       context = ds_get_context(task);
+       context = ds_get_context(task, cpu);
        if (!context)
                goto out;
        tracer->context = context;
 
-       ds_init_ds_trace(trace, qual, base, size, th, flags);
+       /*
+        * Defer any tracer-specific initialization work for the context until
+        * context ownership has been clarified.
+        */
 
        error = 0;
  out:
        return error;
 }
 
-struct bts_tracer *ds_request_bts(struct task_struct *task,
-                                 void *base, size_t size,
-                                 bts_ovfl_callback_t ovfl, size_t th,
-                                 unsigned int flags)
+static struct bts_tracer *ds_request_bts(struct task_struct *task, int cpu,
+                                        void *base, size_t size,
+                                        bts_ovfl_callback_t ovfl, size_t th,
+                                        unsigned int flags)
 {
        struct bts_tracer *tracer;
-       unsigned long irq;
        int error;
 
        /* Buffer overflow notification is not yet implemented. */
@@ -690,42 +715,46 @@ struct bts_tracer *ds_request_bts(struct task_struct *task,
        if (error < 0)
                goto out;
 
-       /*
-        * Per-cpu tracing is typically requested using smp_call_function().
-        * We must not sleep.
-        */
        error = -ENOMEM;
-       tracer = kzalloc(sizeof(*tracer), GFP_ATOMIC);
+       tracer = kzalloc(sizeof(*tracer), GFP_KERNEL);
        if (!tracer)
                goto out_put_tracer;
        tracer->ovfl = ovfl;
 
+       /* Do some more error checking and acquire a tracing context. */
        error = ds_request(&tracer->ds, &tracer->trace.ds,
-                          ds_bts, task, base, size, th, flags);
+                          ds_bts, task, cpu, base, size, th);
        if (error < 0)
                goto out_tracer;
 
-
-       spin_lock_irqsave(&ds_lock, irq);
+       /* Claim the bts part of the tracing context we acquired above. */
+       spin_lock_irq(&ds_lock);
 
        error = -EPERM;
        if (tracer->ds.context->bts_master)
                goto out_unlock;
        tracer->ds.context->bts_master = tracer;
 
-       spin_unlock_irqrestore(&ds_lock, irq);
+       spin_unlock_irq(&ds_lock);
 
+       /*
+        * Now that we own the bts part of the context, let's complete the
+        * initialization for that part.
+        */
+       ds_init_ds_trace(&tracer->trace.ds, ds_bts, base, size, th, flags);
+       ds_write_config(tracer->ds.context, &tracer->trace.ds, ds_bts);
+       ds_install_ds_area(tracer->ds.context);
 
        tracer->trace.read  = bts_read;
        tracer->trace.write = bts_write;
 
-       ds_write_config(tracer->ds.context, &tracer->trace.ds, ds_bts);
+       /* Start tracing. */
        ds_resume_bts(tracer);
 
        return tracer;
 
  out_unlock:
-       spin_unlock_irqrestore(&ds_lock, irq);
+       spin_unlock_irq(&ds_lock);
        ds_put_context(tracer->ds.context);
  out_tracer:
        kfree(tracer);
@@ -735,13 +764,27 @@ struct bts_tracer *ds_request_bts(struct task_struct *task,
        return ERR_PTR(error);
 }
 
-struct pebs_tracer *ds_request_pebs(struct task_struct *task,
-                                   void *base, size_t size,
-                                   pebs_ovfl_callback_t ovfl, size_t th,
-                                   unsigned int flags)
+struct bts_tracer *ds_request_bts_task(struct task_struct *task,
+                                      void *base, size_t size,
+                                      bts_ovfl_callback_t ovfl,
+                                      size_t th, unsigned int flags)
+{
+       return ds_request_bts(task, 0, base, size, ovfl, th, flags);
+}
+
+struct bts_tracer *ds_request_bts_cpu(int cpu, void *base, size_t size,
+                                     bts_ovfl_callback_t ovfl,
+                                     size_t th, unsigned int flags)
+{
+       return ds_request_bts(NULL, cpu, base, size, ovfl, th, flags);
+}
+
+static struct pebs_tracer *ds_request_pebs(struct task_struct *task, int cpu,
+                                          void *base, size_t size,
+                                          pebs_ovfl_callback_t ovfl, size_t th,
+                                          unsigned int flags)
 {
        struct pebs_tracer *tracer;
-       unsigned long irq;
        int error;
 
        /* Buffer overflow notification is not yet implemented. */
@@ -753,37 +796,43 @@ struct pebs_tracer *ds_request_pebs(struct task_struct *task,
        if (error < 0)
                goto out;
 
-       /*
-        * Per-cpu tracing is typically requested using smp_call_function().
-        * We must not sleep.
-        */
        error = -ENOMEM;
-       tracer = kzalloc(sizeof(*tracer), GFP_ATOMIC);
+       tracer = kzalloc(sizeof(*tracer), GFP_KERNEL);
        if (!tracer)
                goto out_put_tracer;
        tracer->ovfl = ovfl;
 
+       /* Do some more error checking and acquire a tracing context. */
        error = ds_request(&tracer->ds, &tracer->trace.ds,
-                          ds_pebs, task, base, size, th, flags);
+                          ds_pebs, task, cpu, base, size, th);
        if (error < 0)
                goto out_tracer;
 
-       spin_lock_irqsave(&ds_lock, irq);
+       /* Claim the pebs part of the tracing context we acquired above. */
+       spin_lock_irq(&ds_lock);
 
        error = -EPERM;
        if (tracer->ds.context->pebs_master)
                goto out_unlock;
        tracer->ds.context->pebs_master = tracer;
 
-       spin_unlock_irqrestore(&ds_lock, irq);
+       spin_unlock_irq(&ds_lock);
 
+       /*
+        * Now that we own the pebs part of the context, let's complete the
+        * initialization for that part.
+        */
+       ds_init_ds_trace(&tracer->trace.ds, ds_pebs, base, size, th, flags);
        ds_write_config(tracer->ds.context, &tracer->trace.ds, ds_pebs);
+       ds_install_ds_area(tracer->ds.context);
+
+       /* Start tracing. */
        ds_resume_pebs(tracer);
 
        return tracer;
 
  out_unlock:
-       spin_unlock_irqrestore(&ds_lock, irq);
+       spin_unlock_irq(&ds_lock);
        ds_put_context(tracer->ds.context);
  out_tracer:
        kfree(tracer);
@@ -793,16 +842,26 @@ struct pebs_tracer *ds_request_pebs(struct task_struct *task,
        return ERR_PTR(error);
 }
 
-void ds_release_bts(struct bts_tracer *tracer)
+struct pebs_tracer *ds_request_pebs_task(struct task_struct *task,
+                                        void *base, size_t size,
+                                        pebs_ovfl_callback_t ovfl,
+                                        size_t th, unsigned int flags)
 {
-       struct task_struct *task;
+       return ds_request_pebs(task, 0, base, size, ovfl, th, flags);
+}
 
-       if (!tracer)
-               return;
+struct pebs_tracer *ds_request_pebs_cpu(int cpu, void *base, size_t size,
+                                       pebs_ovfl_callback_t ovfl,
+                                       size_t th, unsigned int flags)
+{
+       return ds_request_pebs(NULL, cpu, base, size, ovfl, th, flags);
+}
 
-       task = tracer->ds.context->task;
+static void ds_free_bts(struct bts_tracer *tracer)
+{
+       struct task_struct *task;
 
-       ds_suspend_bts(tracer);
+       task = tracer->ds.context->task;
 
        WARN_ON_ONCE(tracer->ds.context->bts_master != tracer);
        tracer->ds.context->bts_master = NULL;
@@ -817,9 +876,69 @@ void ds_release_bts(struct bts_tracer *tracer)
        kfree(tracer);
 }
 
+void ds_release_bts(struct bts_tracer *tracer)
+{
+       might_sleep();
+
+       if (!tracer)
+               return;
+
+       ds_suspend_bts(tracer);
+       ds_free_bts(tracer);
+}
+
+int ds_release_bts_noirq(struct bts_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_bts_noirq(tracer);
+       ds_free_bts(tracer);
+
+       error = 0;
+ out:
+       local_irq_restore(irq);
+       return error;
+}
+
+static void update_task_debugctlmsr(struct task_struct *task,
+                                   unsigned long debugctlmsr)
+{
+       task->thread.debugctlmsr = debugctlmsr;
+
+       get_cpu();
+       if (task == current)
+               update_debugctlmsr(debugctlmsr);
+
+       if (task->thread.debugctlmsr)
+               set_tsk_thread_flag(task, TIF_DEBUGCTLMSR);
+       else
+               clear_tsk_thread_flag(task, TIF_DEBUGCTLMSR);
+       put_cpu();
+}
+
 void ds_suspend_bts(struct bts_tracer *tracer)
 {
        struct task_struct *task;
+       unsigned long debugctlmsr;
+       int cpu;
 
        if (!tracer)
                return;
@@ -827,29 +946,60 @@ void ds_suspend_bts(struct bts_tracer *tracer)
        tracer->flags = 0;
 
        task = tracer->ds.context->task;
+       cpu  = tracer->ds.context->cpu;
 
-       if (!task || (task == current))
-               update_debugctlmsr(get_debugctlmsr() & ~BTS_CONTROL);
+       WARN_ON(!task && irqs_disabled());
 
-       if (task) {
-               task->thread.debugctlmsr &= ~BTS_CONTROL;
+       debugctlmsr = (task ?
+                      task->thread.debugctlmsr :
+                      get_debugctlmsr_on_cpu(cpu));
+       debugctlmsr &= ~BTS_CONTROL;
 
-               if (!task->thread.debugctlmsr)
-                       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;
 
+       tracer->flags = tracer->trace.ds.flags;
+
        task = tracer->ds.context->task;
+       cpu  = tracer->ds.context->cpu;
 
-       ds_suspend_pebs(tracer);
+       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);
index 8c46fbf38c46136f2c8aaca1b0b5573ebb7e1bb3..e5a263c8a14cda4119c8ee9046a2e4e173d343c8 100644 (file)
 
 #include <linux/kernel.h>
 #include <linux/string.h>
+#include <linux/smp.h>
 
 #include <asm/ds.h>
 
 
-#define DS_SELFTEST_BUFFER_SIZE 1021 /* Intentionally chose an odd size. */
+#define BUFFER_SIZE 1021 /* Intentionally chose an odd size. */
 
 
 static int ds_selftest_bts_consistency(const struct bts_trace *trace)
@@ -125,12 +126,12 @@ int ds_selftest_bts(void)
        struct bts_tracer *tracer;
        int error = 0;
        void *top;
-       unsigned char buffer[DS_SELFTEST_BUFFER_SIZE];
+       unsigned char buffer[BUFFER_SIZE];
 
        printk(KERN_INFO "[ds] bts selftest...");
 
-       tracer = ds_request_bts(NULL, buffer, DS_SELFTEST_BUFFER_SIZE,
-                               NULL, (size_t)-1, BTS_KERNEL);
+       tracer = ds_request_bts_cpu(smp_processor_id(), buffer, BUFFER_SIZE,
+                                   NULL, (size_t)-1, BTS_KERNEL);
        if (IS_ERR(tracer)) {
                error = PTR_ERR(tracer);
                tracer = NULL;
index 7c21d1e8cae79915bcf7b130056ad246a2de033c..adbb24322d8f2beb496ff028c0749466fa590ebd 100644 (file)
@@ -800,8 +800,9 @@ static int ptrace_bts_config(struct task_struct *child,
        if (cfg.flags & PTRACE_BTS_O_SCHED)
                flags |= BTS_TIMESTAMPS;
 
-       context->tracer = ds_request_bts(child, context->buffer, context->size,
-                                        NULL, (size_t)-1, flags);
+       context->tracer =
+               ds_request_bts_task(child, context->buffer, context->size,
+                                   NULL, (size_t)-1, flags);
        if (unlikely(IS_ERR(context->tracer))) {
                int error = PTR_ERR(context->tracer);
 
index 8b2109a6c61cc24b2838dfd0b7e7a91b0b1cce35..50565d8cd2ed9f79e937775886020ff91db3ee06 100644 (file)
@@ -4,7 +4,6 @@
  * Copyright (C) 2008-2009 Intel Corporation.
  * Markus Metzger <markus.t.metzger@gmail.com>, 2008-2009
  */
-#include <linux/spinlock.h>
 #include <linux/kallsyms.h>
 #include <linux/debugfs.h>
 #include <linux/ftrace.h>
 
 #define BTS_BUFFER_SIZE (1 << 13)
 
-/*
- * The tracer lock protects the below per-cpu tracer array.
- * It needs to be held to:
- * - start tracing on all cpus
- * - stop tracing on all cpus
- * - start tracing on a single hotplug cpu
- * - stop tracing on a single hotplug cpu
- * - read the trace from all cpus
- * - read the trace from a single cpu
- */
-static DEFINE_SPINLOCK(bts_tracer_lock);
 static DEFINE_PER_CPU(struct bts_tracer *, tracer);
 static DEFINE_PER_CPU(unsigned char[BTS_BUFFER_SIZE], buffer);
 
 #define this_tracer per_cpu(tracer, smp_processor_id())
-#define this_buffer per_cpu(buffer, smp_processor_id())
 
 static int trace_hw_branches_enabled __read_mostly;
 static int trace_hw_branches_suspended __read_mostly;
 static struct trace_array *hw_branch_trace __read_mostly;
 
 
-/*
- * Initialize the tracer for the current cpu.
- * The argument is ignored.
- *
- * pre: bts_tracer_lock must be locked.
- */
-static void bts_trace_init_cpu(void *arg)
+static void bts_trace_init_cpu(int cpu)
 {
-       if (this_tracer)
-               ds_release_bts(this_tracer);
+       per_cpu(tracer, cpu) =
+               ds_request_bts_cpu(cpu, per_cpu(buffer, cpu), BTS_BUFFER_SIZE,
+                                  NULL, (size_t)-1, BTS_KERNEL);
 
-       this_tracer = ds_request_bts(NULL, this_buffer, BTS_BUFFER_SIZE,
-                                    NULL, (size_t)-1, BTS_KERNEL);
-       if (IS_ERR(this_tracer)) {
-               this_tracer = NULL;
-               return;
-       }
+       if (IS_ERR(per_cpu(tracer, cpu)))
+               per_cpu(tracer, cpu) = NULL;
 }
 
 static int bts_trace_init(struct trace_array *tr)
 {
-       int cpu, avail;
-
-       spin_lock(&bts_tracer_lock);
+       int cpu;
 
        hw_branch_trace = tr;
+       trace_hw_branches_enabled = 0;
 
-       on_each_cpu(bts_trace_init_cpu, NULL, 1);
-
-       /* Check on how many cpus we could enable tracing */
-       avail = 0;
-       for_each_online_cpu(cpu)
-               if (per_cpu(tracer, cpu))
-                       avail++;
+       get_online_cpus();
+       for_each_online_cpu(cpu) {
+               bts_trace_init_cpu(cpu);
 
-       trace_hw_branches_enabled = (avail ? 1 : 0);
+               if (likely(per_cpu(tracer, cpu)))
+                       trace_hw_branches_enabled = 1;
+       }
        trace_hw_branches_suspended = 0;
-
-       spin_unlock(&bts_tracer_lock);
-
+       put_online_cpus();
 
        /* If we could not enable tracing on a single cpu, we fail. */
-       return avail ? 0 : -EOPNOTSUPP;
-}
-
-/*
- * Release the tracer for the current cpu.
- * The argument is ignored.
- *
- * pre: bts_tracer_lock must be locked.
- */
-static void bts_trace_release_cpu(void *arg)
-{
-       if (this_tracer) {
-               ds_release_bts(this_tracer);
-               this_tracer = NULL;
-       }
+       return trace_hw_branches_enabled ? 0 : -EOPNOTSUPP;
 }
 
 static void bts_trace_reset(struct trace_array *tr)
 {
-       spin_lock(&bts_tracer_lock);
+       int cpu;
 
-       on_each_cpu(bts_trace_release_cpu, NULL, 1);
+       get_online_cpus();
+       for_each_online_cpu(cpu) {
+               if (likely(per_cpu(tracer, cpu))) {
+                       ds_release_bts(per_cpu(tracer, cpu));
+                       per_cpu(tracer, cpu) = NULL;
+               }
+       }
        trace_hw_branches_enabled = 0;
        trace_hw_branches_suspended = 0;
-
-       spin_unlock(&bts_tracer_lock);
-}
-
-/*
- * Resume tracing on the current cpu.
- * The argument is ignored.
- *
- * pre: bts_tracer_lock must be locked.
- */
-static void bts_trace_resume_cpu(void *arg)
-{
-       if (this_tracer)
-               ds_resume_bts(this_tracer);
+       put_online_cpus();
 }
 
 static void bts_trace_start(struct trace_array *tr)
 {
-       spin_lock(&bts_tracer_lock);
+       int cpu;
 
-       on_each_cpu(bts_trace_resume_cpu, NULL, 1);
+       get_online_cpus();
+       for_each_online_cpu(cpu)
+               if (likely(per_cpu(tracer, cpu)))
+                       ds_resume_bts(per_cpu(tracer, cpu));
        trace_hw_branches_suspended = 0;
-
-       spin_unlock(&bts_tracer_lock);
-}
-
-/*
- * Suspend tracing on the current cpu.
- * The argument is ignored.
- *
- * pre: bts_tracer_lock must be locked.
- */
-static void bts_trace_suspend_cpu(void *arg)
-{
-       if (this_tracer)
-               ds_suspend_bts(this_tracer);
+       put_online_cpus();
 }
 
 static void bts_trace_stop(struct trace_array *tr)
 {
-       spin_lock(&bts_tracer_lock);
+       int cpu;
 
-       on_each_cpu(bts_trace_suspend_cpu, NULL, 1);
+       get_online_cpus();
+       for_each_online_cpu(cpu)
+               if (likely(per_cpu(tracer, cpu)))
+                       ds_suspend_bts(per_cpu(tracer, cpu));
        trace_hw_branches_suspended = 1;
-
-       spin_unlock(&bts_tracer_lock);
+       put_online_cpus();
 }
 
 static int __cpuinit bts_hotcpu_handler(struct notifier_block *nfb,
                                     unsigned long action, void *hcpu)
 {
-       unsigned int cpu = (unsigned long)hcpu;
-
-       spin_lock(&bts_tracer_lock);
-
-       if (!trace_hw_branches_enabled)
-               goto out;
+       int cpu = (long)hcpu;
 
        switch (action) {
        case CPU_ONLINE:
        case CPU_DOWN_FAILED:
-               smp_call_function_single(cpu, bts_trace_init_cpu, NULL, 1);
-
-               if (trace_hw_branches_suspended)
-                       smp_call_function_single(cpu, bts_trace_suspend_cpu,
-                                                NULL, 1);
+               /* The notification is sent with interrupts enabled. */
+               if (trace_hw_branches_enabled) {
+                       bts_trace_init_cpu(cpu);
+
+                       if (trace_hw_branches_suspended &&
+                           likely(per_cpu(tracer, cpu)))
+                               ds_suspend_bts(per_cpu(tracer, cpu));
+               }
                break;
+
        case CPU_DOWN_PREPARE:
-               smp_call_function_single(cpu, bts_trace_release_cpu, NULL, 1);
-               break;
+               /* The notification is sent with interrupts enabled. */
+               if (likely(per_cpu(tracer, cpu))) {
+                       ds_release_bts(per_cpu(tracer, cpu));
+                       per_cpu(tracer, cpu) = NULL;
+               }
        }
 
- out:
-       spin_unlock(&bts_tracer_lock);
        return NOTIFY_DONE;
 }
 
@@ -274,7 +218,7 @@ static void trace_bts_at(const struct bts_trace *trace, void *at)
 /*
  * Collect the trace on the current cpu and write it into the ftrace buffer.
  *
- * pre: bts_tracer_lock must be locked
+ * pre: tracing must be suspended on the current cpu
  */
 static void trace_bts_cpu(void *arg)
 {
@@ -291,10 +235,9 @@ static void trace_bts_cpu(void *arg)
        if (unlikely(!this_tracer))
                return;
 
-       ds_suspend_bts(this_tracer);
        trace = ds_read_bts(this_tracer);
        if (!trace)
-               goto out;
+               return;
 
        for (at = trace->ds.top; (void *)at < trace->ds.end;
             at += trace->ds.size)
@@ -303,18 +246,27 @@ static void trace_bts_cpu(void *arg)
        for (at = trace->ds.begin; (void *)at < trace->ds.top;
             at += trace->ds.size)
                trace_bts_at(trace, at);
-
-out:
-       ds_resume_bts(this_tracer);
 }
 
 static void trace_bts_prepare(struct trace_iterator *iter)
 {
-       spin_lock(&bts_tracer_lock);
+       int cpu;
 
+       get_online_cpus();
+       for_each_online_cpu(cpu)
+               if (likely(per_cpu(tracer, cpu)))
+                       ds_suspend_bts(per_cpu(tracer, cpu));
+       /*
+        * We need to collect the trace on the respective cpu since ftrace
+        * implicitly adds the record for the current cpu.
+        * Once that is more flexible, we could collect the data from any cpu.
+        */
        on_each_cpu(trace_bts_cpu, iter->tr, 1);
 
-       spin_unlock(&bts_tracer_lock);
+       for_each_online_cpu(cpu)
+               if (likely(per_cpu(tracer, cpu)))
+                       ds_resume_bts(per_cpu(tracer, cpu));
+       put_online_cpus();
 }
 
 static void trace_bts_close(struct trace_iterator *iter)
@@ -324,12 +276,11 @@ static void trace_bts_close(struct trace_iterator *iter)
 
 void trace_hw_branch_oops(void)
 {
-       spin_lock(&bts_tracer_lock);
-
-       if (trace_hw_branches_enabled)
+       if (this_tracer) {
+               ds_suspend_bts_noirq(this_tracer);
                trace_bts_cpu(hw_branch_trace);
-
-       spin_unlock(&bts_tracer_lock);
+               ds_resume_bts_noirq(this_tracer);
+       }
 }
 
 struct tracer bts_tracer __read_mostly =