From cc1dc6d039ced64c2f8b8457bf1cccf4ecfc5942 Mon Sep 17 00:00:00 2001
From: Markus Metzger <markus.t.metzger@intel.com>
Date: Tue, 16 Dec 2008 15:51:03 +0100
Subject: x86, bts: remove recursion from get_context
Impact: cleanup
Optimistically allocate a DS context. It is extremely unlikely that
one already existed. This simplifies the code a lot.
Signed-off-by: Markus Metzger <markus.t.metzger@intel.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
---
arch/x86/kernel/ds.c | 58 ++++++++++++++++++++++------------------------------
1 file changed, 25 insertions(+), 33 deletions(-)
(limited to 'arch/x86')
diff --git a/arch/x86/kernel/ds.c b/arch/x86/kernel/ds.c
index dc1e7123ea4e..0dc795951d73 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;
}
--
cgit v1.2.2
From d072c25f531c6513994960401d2c7f059434c0d2 Mon Sep 17 00:00:00 2001
From: Markus Metzger <markus.t.metzger@intel.com>
Date: Tue, 16 Dec 2008 15:53:11 +0100
Subject: x86, bts: correctly report invalid bts records
Impact: change the reporting of empty BTS records
Correctly report a cleared BTS record as invalid. Used to be reported
as branch from 0 to 0.
Signed-off-by: Markus Metzger <markus.t.metzger@intel.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
---
arch/x86/kernel/ds.c | 3 +++
1 file changed, 3 insertions(+)
(limited to 'arch/x86')
diff --git a/arch/x86/kernel/ds.c b/arch/x86/kernel/ds.c
index 0dc795951d73..98d271e60e08 100644
--- a/arch/x86/kernel/ds.c
+++ b/arch/x86/kernel/ds.c
@@ -484,6 +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];
--
cgit v1.2.2