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hw-breakpoints: Fix task-bound breakpoint slot allocation
Whatever the context nature of a breakpoint, we always perform the following constraint checks before allocating it a slot: - Check the number of pinned breakpoint bound the concerned cpus - Check the max number of task-bound breakpoints that are belonging to a task. - Add both and see if we have a reamining slot for the new breakpoint This is the right thing to do when we are about to register a cpu-only bound breakpoint. But not if we are dealing with a task bound breakpoint. What we want in this case is: - Check the number of pinned breakpoint bound the concerned cpus - Check the number of breakpoints that already belong to the task in which the breakpoint to register is bound to. - Add both This fixes a regression that makes the "firefox -g" command fail to register breakpoints once we deal with a secondary thread. Reported-by: Walt <w41ter@gmail.com> Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com> Cc: Prasad <prasad@linux.vnet.ibm.com>
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@ -83,50 +83,16 @@ static unsigned int max_task_bp_pinned(int cpu)
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return 0;
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}
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/*
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* Report the number of pinned/un-pinned breakpoints we have in
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* a given cpu (cpu > -1) or in all of them (cpu = -1).
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*/
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static void fetch_bp_busy_slots(struct bp_busy_slots *slots, int cpu)
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static int task_bp_pinned(struct task_struct *tsk)
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{
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if (cpu >= 0) {
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slots->pinned = per_cpu(nr_cpu_bp_pinned, cpu);
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slots->pinned += max_task_bp_pinned(cpu);
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slots->flexible = per_cpu(nr_bp_flexible, cpu);
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return;
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}
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for_each_online_cpu(cpu) {
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unsigned int nr;
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nr = per_cpu(nr_cpu_bp_pinned, cpu);
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nr += max_task_bp_pinned(cpu);
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if (nr > slots->pinned)
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slots->pinned = nr;
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nr = per_cpu(nr_bp_flexible, cpu);
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if (nr > slots->flexible)
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slots->flexible = nr;
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}
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}
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/*
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* Add a pinned breakpoint for the given task in our constraint table
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*/
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static void toggle_bp_task_slot(struct task_struct *tsk, int cpu, bool enable)
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{
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int count = 0;
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struct perf_event *bp;
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struct perf_event_context *ctx = tsk->perf_event_ctxp;
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unsigned int *tsk_pinned;
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struct list_head *list;
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struct perf_event *bp;
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unsigned long flags;
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int count = 0;
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if (WARN_ONCE(!ctx, "No perf context for this task"))
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return;
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return 0;
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list = &ctx->event_list;
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@ -143,8 +109,58 @@ static void toggle_bp_task_slot(struct task_struct *tsk, int cpu, bool enable)
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spin_unlock_irqrestore(&ctx->lock, flags);
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if (WARN_ONCE(count < 0, "No breakpoint counter found in the counter list"))
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return count;
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}
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/*
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* Report the number of pinned/un-pinned breakpoints we have in
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* a given cpu (cpu > -1) or in all of them (cpu = -1).
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*/
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static void
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fetch_bp_busy_slots(struct bp_busy_slots *slots, struct perf_event *bp)
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{
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int cpu = bp->cpu;
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struct task_struct *tsk = bp->ctx->task;
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if (cpu >= 0) {
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slots->pinned = per_cpu(nr_cpu_bp_pinned, cpu);
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if (!tsk)
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slots->pinned += max_task_bp_pinned(cpu);
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else
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slots->pinned += task_bp_pinned(tsk);
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slots->flexible = per_cpu(nr_bp_flexible, cpu);
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return;
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}
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for_each_online_cpu(cpu) {
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unsigned int nr;
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nr = per_cpu(nr_cpu_bp_pinned, cpu);
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if (!tsk)
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nr += max_task_bp_pinned(cpu);
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else
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nr += task_bp_pinned(tsk);
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if (nr > slots->pinned)
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slots->pinned = nr;
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nr = per_cpu(nr_bp_flexible, cpu);
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if (nr > slots->flexible)
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slots->flexible = nr;
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}
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}
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/*
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* Add a pinned breakpoint for the given task in our constraint table
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*/
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static void toggle_bp_task_slot(struct task_struct *tsk, int cpu, bool enable)
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{
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unsigned int *tsk_pinned;
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int count = 0;
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count = task_bp_pinned(tsk);
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tsk_pinned = per_cpu(task_bp_pinned, cpu);
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if (enable) {
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@ -233,7 +249,7 @@ int reserve_bp_slot(struct perf_event *bp)
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mutex_lock(&nr_bp_mutex);
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fetch_bp_busy_slots(&slots, bp->cpu);
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fetch_bp_busy_slots(&slots, bp);
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/* Flexible counters need to keep at least one slot */
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if (slots.pinned + (!!slots.flexible) == HBP_NUM) {
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