perf events: Clean up pid passing
The kernel perf event creation path shouldn't use find_task_by_vpid() because a vpid exists in a specific namespace. find_task_by_vpid() uses current's pid namespace which isn't always the correct namespace to use for the vpid in all the places perf_event_create_kernel_counter() (and thus find_get_context()) is called. The goal is to clean up pid namespace handling and prevent bugs like: https://bugzilla.kernel.org/show_bug.cgi?id=17281 Instead of using pids switch find_get_context() to use task struct pointers directly. The syscall is responsible for resolving the pid to a task struct. This moves the pid namespace resolution into the syscall much like every other syscall that takes pid parameters. Signed-off-by: Matt Helsley <matthltc@us.ibm.com> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Robin Green <greenrd@greenrd.org> Cc: Prasad <prasad@linux.vnet.ibm.com> Cc: Arnaldo Carvalho de Melo <acme@redhat.com> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Will Deacon <will.deacon@arm.com> Cc: Mahesh Salgaonkar <mahesh@linux.vnet.ibm.com> LKML-Reference: <a134e5e392ab0204961fd1a62c84a222bf5874a9.1284407763.git.matthltc@us.ibm.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
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2ebd4ffb6d
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38a81da220
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@ -96,7 +96,7 @@ static int op_create_counter(int cpu, int event)
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return ret;
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return ret;
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pevent = perf_event_create_kernel_counter(&counter_config[event].attr,
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pevent = perf_event_create_kernel_counter(&counter_config[event].attr,
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cpu, -1,
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cpu, NULL,
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op_overflow_handler);
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op_overflow_handler);
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if (IS_ERR(pevent)) {
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if (IS_ERR(pevent)) {
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@ -902,7 +902,7 @@ extern int perf_event_release_kernel(struct perf_event *event);
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extern struct perf_event *
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extern struct perf_event *
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perf_event_create_kernel_counter(struct perf_event_attr *attr,
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perf_event_create_kernel_counter(struct perf_event_attr *attr,
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int cpu,
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int cpu,
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pid_t pid,
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struct task_struct *task,
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perf_overflow_handler_t callback);
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perf_overflow_handler_t callback);
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extern u64 perf_event_read_value(struct perf_event *event,
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extern u64 perf_event_read_value(struct perf_event *event,
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u64 *enabled, u64 *running);
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u64 *enabled, u64 *running);
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@ -433,8 +433,7 @@ register_user_hw_breakpoint(struct perf_event_attr *attr,
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perf_overflow_handler_t triggered,
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perf_overflow_handler_t triggered,
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struct task_struct *tsk)
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struct task_struct *tsk)
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{
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{
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return perf_event_create_kernel_counter(attr, -1, task_pid_vnr(tsk),
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return perf_event_create_kernel_counter(attr, -1, tsk, triggered);
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triggered);
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}
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}
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EXPORT_SYMBOL_GPL(register_user_hw_breakpoint);
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EXPORT_SYMBOL_GPL(register_user_hw_breakpoint);
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@ -516,7 +515,7 @@ register_wide_hw_breakpoint(struct perf_event_attr *attr,
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get_online_cpus();
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get_online_cpus();
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for_each_online_cpu(cpu) {
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for_each_online_cpu(cpu) {
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pevent = per_cpu_ptr(cpu_events, cpu);
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pevent = per_cpu_ptr(cpu_events, cpu);
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bp = perf_event_create_kernel_counter(attr, cpu, -1, triggered);
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bp = perf_event_create_kernel_counter(attr, cpu, NULL, triggered);
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*pevent = bp;
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*pevent = bp;
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@ -2053,15 +2053,14 @@ errout:
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}
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}
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static struct perf_event_context *
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static struct perf_event_context *
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find_get_context(struct pmu *pmu, pid_t pid, int cpu)
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find_get_context(struct pmu *pmu, struct task_struct *task, int cpu)
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{
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{
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struct perf_event_context *ctx;
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struct perf_event_context *ctx;
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struct perf_cpu_context *cpuctx;
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struct perf_cpu_context *cpuctx;
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struct task_struct *task;
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unsigned long flags;
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unsigned long flags;
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int ctxn, err;
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int ctxn, err;
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if (pid == -1 && cpu != -1) {
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if (!task && cpu != -1) {
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/* Must be root to operate on a CPU event: */
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/* Must be root to operate on a CPU event: */
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if (perf_paranoid_cpu() && !capable(CAP_SYS_ADMIN))
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if (perf_paranoid_cpu() && !capable(CAP_SYS_ADMIN))
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return ERR_PTR(-EACCES);
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return ERR_PTR(-EACCES);
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@ -2084,10 +2083,6 @@ find_get_context(struct pmu *pmu, pid_t pid, int cpu)
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return ctx;
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return ctx;
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}
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}
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task = find_lively_task_by_vpid(pid);
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if (IS_ERR(task))
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return (void*)task;
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err = -EINVAL;
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err = -EINVAL;
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ctxn = pmu->task_ctx_nr;
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ctxn = pmu->task_ctx_nr;
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if (ctxn < 0)
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if (ctxn < 0)
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@ -5527,6 +5522,7 @@ SYSCALL_DEFINE5(perf_event_open,
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struct perf_event_context *ctx;
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struct perf_event_context *ctx;
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struct file *event_file = NULL;
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struct file *event_file = NULL;
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struct file *group_file = NULL;
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struct file *group_file = NULL;
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struct task_struct *task = NULL;
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struct pmu *pmu;
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struct pmu *pmu;
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int event_fd;
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int event_fd;
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int fput_needed = 0;
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int fput_needed = 0;
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@ -5581,10 +5577,13 @@ SYSCALL_DEFINE5(perf_event_open,
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if ((pmu->task_ctx_nr == perf_sw_context) && group_leader)
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if ((pmu->task_ctx_nr == perf_sw_context) && group_leader)
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pmu = group_leader->pmu;
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pmu = group_leader->pmu;
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if (pid != -1)
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task = find_lively_task_by_vpid(pid);
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/*
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/*
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* Get the target context (task or percpu):
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* Get the target context (task or percpu):
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*/
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*/
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ctx = find_get_context(pmu, pid, cpu);
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ctx = find_get_context(pmu, task, cpu);
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if (IS_ERR(ctx)) {
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if (IS_ERR(ctx)) {
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err = PTR_ERR(ctx);
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err = PTR_ERR(ctx);
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goto err_group_fd;
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goto err_group_fd;
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@ -5666,11 +5665,11 @@ err_fd:
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*
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*
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* @attr: attributes of the counter to create
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* @attr: attributes of the counter to create
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* @cpu: cpu in which the counter is bound
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* @cpu: cpu in which the counter is bound
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* @pid: task to profile
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* @task: task to profile (NULL for percpu)
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*/
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*/
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struct perf_event *
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struct perf_event *
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perf_event_create_kernel_counter(struct perf_event_attr *attr, int cpu,
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perf_event_create_kernel_counter(struct perf_event_attr *attr, int cpu,
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pid_t pid,
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struct task_struct *task,
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perf_overflow_handler_t overflow_handler)
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perf_overflow_handler_t overflow_handler)
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{
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{
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struct perf_event_context *ctx;
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struct perf_event_context *ctx;
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@ -5687,7 +5686,7 @@ perf_event_create_kernel_counter(struct perf_event_attr *attr, int cpu,
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goto err;
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goto err;
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}
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}
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ctx = find_get_context(event->pmu, pid, cpu);
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ctx = find_get_context(event->pmu, task, cpu);
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if (IS_ERR(ctx)) {
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if (IS_ERR(ctx)) {
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err = PTR_ERR(ctx);
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err = PTR_ERR(ctx);
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goto err_free;
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goto err_free;
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@ -358,7 +358,7 @@ static int watchdog_nmi_enable(int cpu)
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/* Try to register using hardware perf events */
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/* Try to register using hardware perf events */
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wd_attr = &wd_hw_attr;
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wd_attr = &wd_hw_attr;
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wd_attr->sample_period = hw_nmi_get_sample_period();
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wd_attr->sample_period = hw_nmi_get_sample_period();
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event = perf_event_create_kernel_counter(wd_attr, cpu, -1, watchdog_overflow_callback);
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event = perf_event_create_kernel_counter(wd_attr, cpu, NULL, watchdog_overflow_callback);
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if (!IS_ERR(event)) {
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if (!IS_ERR(event)) {
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printk(KERN_INFO "NMI watchdog enabled, takes one hw-pmu counter.\n");
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printk(KERN_INFO "NMI watchdog enabled, takes one hw-pmu counter.\n");
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goto out_save;
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goto out_save;
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