diff options
| -rw-r--r-- | arch/x86/kernel/ds.c | 61 |
1 files changed, 28 insertions, 33 deletions
diff --git a/arch/x86/kernel/ds.c b/arch/x86/kernel/ds.c index dc1e7123ea4..98d271e60e0 100644 --- 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]; |