x86, bts: add fork and exit handling

[linux-2.6-omap-h63xx.git] / arch / x86 / kernel / ds.c

diff --git a/arch/x86/kernel/ds.c b/arch/x86/kernel/ds.c
index dc1e7123ea4e890d298bac14cb4c20fe63fa8560..da91701a2348cd512531716598453ece7ef8cca6 100644 (file)
--- a/arch/x86/kernel/ds.c
+++ b/arch/x86/kernel/ds.c
@@ -232,53 +232,45 @@ static DEFINE_PER_CPU(struct ds_context *, system_context_array);
 
 #define system_context per_cpu(system_context_array, smp_processor_id())
 
-static struct ds_context *ds_get_context(struct task_struct *task)
+
+static inline struct ds_context *ds_get_context(struct task_struct *task)
 {
        struct ds_context **p_context =
                (task ? &task->thread.ds_ctx : &system_context);
-       struct ds_context *context = *p_context;
+       struct ds_context *context = NULL;
+       struct ds_context *new_context = NULL;
        unsigned long irq;
 
-       if (!context) {
-               context = kzalloc(sizeof(*context), GFP_KERNEL);
-               if (!context)
-                       return NULL;
-
-               spin_lock_irqsave(&ds_lock, irq);
-
-               if (*p_context) {
-                       kfree(context);
+       /* Chances are small that we already have a context. */
+       new_context = kzalloc(sizeof(*new_context), GFP_KERNEL);
+       if (!new_context)
+               return NULL;
 
-                       context = *p_context;
-               } else {
-                       *p_context = context;
+       spin_lock_irqsave(&ds_lock, irq);
 
-                       context->this = p_context;
-                       context->task = task;
+       context = *p_context;
+       if (!context) {
+               context = new_context;
 
-                       if (task)
-                               set_tsk_thread_flag(task, TIF_DS_AREA_MSR);
+               context->this = p_context;
+               context->task = task;
+               context->count = 0;
 
-                       if (!task || (task == current))
-                               wrmsrl(MSR_IA32_DS_AREA,
-                                      (unsigned long)context->ds);
-               }
+               if (task)
+                       set_tsk_thread_flag(task, TIF_DS_AREA_MSR);
 
-               context->count++;
+               if (!task || (task == current))
+                       wrmsrl(MSR_IA32_DS_AREA, (unsigned long)context->ds);
 
-               spin_unlock_irqrestore(&ds_lock, irq);
-       } else {
-               spin_lock_irqsave(&ds_lock, irq);
+               *p_context = context;
+       }
 
-               context = *p_context;
-               if (context)
-                       context->count++;
+       context->count++;
 
-               spin_unlock_irqrestore(&ds_lock, irq);
+       spin_unlock_irqrestore(&ds_lock, irq);
 
-               if (!context)
-                       context = ds_get_context(task);
-       }
+       if (context != new_context)
+               kfree(new_context);
 
        return context;
 }
@@ -492,6 +484,9 @@ static int bts_read(struct bts_tracer *tracer, const void *at,
                out->qualifier = bts_branch;
                out->variant.lbr.from = bts_get(at, bts_from);
                out->variant.lbr.to   = bts_get(at, bts_to);
+
+               if (!out->variant.lbr.from && !out->variant.lbr.to)
+                       out->qualifier = bts_invalid;
        }
 
        return ds_cfg.sizeof_rec[ds_bts];
@@ -1022,3 +1017,14 @@ void ds_switch_to(struct task_struct *prev, struct task_struct *next)
 
        update_debugctlmsr(next->thread.debugctlmsr);
 }
+
+void ds_copy_thread(struct task_struct *tsk, struct task_struct *father)
+{
+       clear_tsk_thread_flag(tsk, TIF_DS_AREA_MSR);
+       tsk->thread.ds_ctx = NULL;
+}
+
+void ds_exit_thread(struct task_struct *tsk)
+{
+       WARN_ON(tsk->thread.ds_ctx);
+}