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-rw-r--r--kernel/hw_breakpoint.c78
1 files changed, 41 insertions, 37 deletions
diff --git a/kernel/hw_breakpoint.c b/kernel/hw_breakpoint.c
index 71ed3ce..d71a987 100644
--- a/kernel/hw_breakpoint.c
+++ b/kernel/hw_breakpoint.c
@@ -41,6 +41,7 @@
#include <linux/sched.h>
#include <linux/init.h>
#include <linux/slab.h>
+#include <linux/list.h>
#include <linux/cpu.h>
#include <linux/smp.h>
@@ -62,6 +63,9 @@ static DEFINE_PER_CPU(unsigned int, nr_bp_flexible[TYPE_MAX]);
static int nr_slots[TYPE_MAX];
+/* Keep track of the breakpoints attached to tasks */
+static LIST_HEAD(bp_task_head);
+
static int constraints_initialized;
/* Gather the number of total pinned and un-pinned bp in a cpuset */
@@ -103,33 +107,21 @@ static unsigned int max_task_bp_pinned(int cpu, enum bp_type_idx type)
return 0;
}
-static int task_bp_pinned(struct task_struct *tsk, enum bp_type_idx type)
+/*
+ * Count the number of breakpoints of the same type and same task.
+ * The given event must be not on the list.
+ */
+static int task_bp_pinned(struct perf_event *bp, enum bp_type_idx type)
{
- struct perf_event_context *ctx = tsk->perf_event_ctxp;
- struct list_head *list;
- struct perf_event *bp;
- unsigned long flags;
+ struct perf_event_context *ctx = bp->ctx;
+ struct perf_event *iter;
int count = 0;
- if (WARN_ONCE(!ctx, "No perf context for this task"))
- return 0;
-
- list = &ctx->event_list;
-
- raw_spin_lock_irqsave(&ctx->lock, flags);
-
- /*
- * The current breakpoint counter is not included in the list
- * at the open() callback time
- */
- list_for_each_entry(bp, list, event_entry) {
- if (bp->attr.type == PERF_TYPE_BREAKPOINT)
- if (find_slot_idx(bp) == type)
- count += hw_breakpoint_weight(bp);
+ list_for_each_entry(iter, &bp_task_head, hw.bp_list) {
+ if (iter->ctx == ctx && find_slot_idx(iter) == type)
+ count += hw_breakpoint_weight(iter);
}
- raw_spin_unlock_irqrestore(&ctx->lock, flags);
-
return count;
}
@@ -149,7 +141,7 @@ fetch_bp_busy_slots(struct bp_busy_slots *slots, struct perf_event *bp,
if (!tsk)
slots->pinned += max_task_bp_pinned(cpu, type);
else
- slots->pinned += task_bp_pinned(tsk, type);
+ slots->pinned += task_bp_pinned(bp, type);
slots->flexible = per_cpu(nr_bp_flexible[type], cpu);
return;
@@ -162,7 +154,7 @@ fetch_bp_busy_slots(struct bp_busy_slots *slots, struct perf_event *bp,
if (!tsk)
nr += max_task_bp_pinned(cpu, type);
else
- nr += task_bp_pinned(tsk, type);
+ nr += task_bp_pinned(bp, type);
if (nr > slots->pinned)
slots->pinned = nr;
@@ -188,7 +180,7 @@ fetch_this_slot(struct bp_busy_slots *slots, int weight)
/*
* Add a pinned breakpoint for the given task in our constraint table
*/
-static void toggle_bp_task_slot(struct task_struct *tsk, int cpu, bool enable,
+static void toggle_bp_task_slot(struct perf_event *bp, int cpu, bool enable,
enum bp_type_idx type, int weight)
{
unsigned int *tsk_pinned;
@@ -196,10 +188,11 @@ static void toggle_bp_task_slot(struct task_struct *tsk, int cpu, bool enable,
int old_idx = 0;
int idx = 0;
- old_count = task_bp_pinned(tsk, type);
+ old_count = task_bp_pinned(bp, type);
old_idx = old_count - 1;
idx = old_idx + weight;
+ /* tsk_pinned[n] is the number of tasks having n breakpoints */
tsk_pinned = per_cpu(nr_task_bp_pinned[type], cpu);
if (enable) {
tsk_pinned[idx]++;
@@ -222,23 +215,30 @@ toggle_bp_slot(struct perf_event *bp, bool enable, enum bp_type_idx type,
int cpu = bp->cpu;
struct task_struct *tsk = bp->ctx->task;
+ /* Pinned counter cpu profiling */
+ if (!tsk) {
+
+ if (enable)
+ per_cpu(nr_cpu_bp_pinned[type], bp->cpu) += weight;
+ else
+ per_cpu(nr_cpu_bp_pinned[type], bp->cpu) -= weight;
+ return;
+ }
+
/* Pinned counter task profiling */
- if (tsk) {
- if (cpu >= 0) {
- toggle_bp_task_slot(tsk, cpu, enable, type, weight);
- return;
- }
+ if (!enable)
+ list_del(&bp->hw.bp_list);
+
+ if (cpu >= 0) {
+ toggle_bp_task_slot(bp, cpu, enable, type, weight);
+ } else {
for_each_online_cpu(cpu)
- toggle_bp_task_slot(tsk, cpu, enable, type, weight);
- return;
+ toggle_bp_task_slot(bp, cpu, enable, type, weight);
}
- /* Pinned counter cpu profiling */
if (enable)
- per_cpu(nr_cpu_bp_pinned[type], bp->cpu) += weight;
- else
- per_cpu(nr_cpu_bp_pinned[type], bp->cpu) -= weight;
+ list_add_tail(&bp->hw.bp_list, &bp_task_head);
}
/*
@@ -312,6 +312,10 @@ static int __reserve_bp_slot(struct perf_event *bp)
weight = hw_breakpoint_weight(bp);
fetch_bp_busy_slots(&slots, bp, type);
+ /*
+ * Simulate the addition of this breakpoint to the constraints
+ * and see the result.
+ */
fetch_this_slot(&slots, weight);
/* Flexible counters need to keep at least one slot */
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