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![Vince Weaver](/assets/img/avatar_default.png)
The 64-bit attr.config value for perf trace events was being copied into an "int" before doing a comparison, meaning the top 32 bits were being truncated. As far as I can tell this didn't cause any errors, but it did mean it was possible to create valid aliases for all the tracepoint ids which I don't think was intended. (For example, 0xffffffff00000018 and 0x18 both enable the same tracepoint). Signed-off-by: Vince Weaver <vincent.weaver@maine.edu> Signed-off-by: Peter Zijlstra <peterz@infradead.org> Link: http://lkml.kernel.org/r/alpine.DEB.2.10.1311151236100.11932@vincent-weaver-1.um.maine.edu Signed-off-by: Ingo Molnar <mingo@kernel.org>
353 lines
8.1 KiB
C
353 lines
8.1 KiB
C
/*
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* trace event based perf event profiling/tracing
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*
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* Copyright (C) 2009 Red Hat Inc, Peter Zijlstra <pzijlstr@redhat.com>
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* Copyright (C) 2009-2010 Frederic Weisbecker <fweisbec@gmail.com>
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*/
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#include <linux/module.h>
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#include <linux/kprobes.h>
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#include "trace.h"
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static char __percpu *perf_trace_buf[PERF_NR_CONTEXTS];
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/*
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* Force it to be aligned to unsigned long to avoid misaligned accesses
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* suprises
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*/
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typedef typeof(unsigned long [PERF_MAX_TRACE_SIZE / sizeof(unsigned long)])
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perf_trace_t;
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/* Count the events in use (per event id, not per instance) */
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static int total_ref_count;
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static int perf_trace_event_perm(struct ftrace_event_call *tp_event,
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struct perf_event *p_event)
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{
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if (tp_event->perf_perm) {
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int ret = tp_event->perf_perm(tp_event, p_event);
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if (ret)
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return ret;
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}
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/* The ftrace function trace is allowed only for root. */
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if (ftrace_event_is_function(tp_event) &&
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perf_paranoid_tracepoint_raw() && !capable(CAP_SYS_ADMIN))
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return -EPERM;
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/* No tracing, just counting, so no obvious leak */
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if (!(p_event->attr.sample_type & PERF_SAMPLE_RAW))
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return 0;
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/* Some events are ok to be traced by non-root users... */
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if (p_event->attach_state == PERF_ATTACH_TASK) {
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if (tp_event->flags & TRACE_EVENT_FL_CAP_ANY)
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return 0;
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}
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/*
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* ...otherwise raw tracepoint data can be a severe data leak,
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* only allow root to have these.
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*/
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if (perf_paranoid_tracepoint_raw() && !capable(CAP_SYS_ADMIN))
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return -EPERM;
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return 0;
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}
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static int perf_trace_event_reg(struct ftrace_event_call *tp_event,
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struct perf_event *p_event)
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{
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struct hlist_head __percpu *list;
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int ret = -ENOMEM;
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int cpu;
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p_event->tp_event = tp_event;
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if (tp_event->perf_refcount++ > 0)
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return 0;
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list = alloc_percpu(struct hlist_head);
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if (!list)
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goto fail;
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for_each_possible_cpu(cpu)
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INIT_HLIST_HEAD(per_cpu_ptr(list, cpu));
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tp_event->perf_events = list;
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if (!total_ref_count) {
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char __percpu *buf;
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int i;
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for (i = 0; i < PERF_NR_CONTEXTS; i++) {
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buf = (char __percpu *)alloc_percpu(perf_trace_t);
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if (!buf)
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goto fail;
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perf_trace_buf[i] = buf;
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}
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}
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ret = tp_event->class->reg(tp_event, TRACE_REG_PERF_REGISTER, NULL);
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if (ret)
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goto fail;
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total_ref_count++;
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return 0;
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fail:
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if (!total_ref_count) {
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int i;
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for (i = 0; i < PERF_NR_CONTEXTS; i++) {
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free_percpu(perf_trace_buf[i]);
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perf_trace_buf[i] = NULL;
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}
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}
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if (!--tp_event->perf_refcount) {
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free_percpu(tp_event->perf_events);
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tp_event->perf_events = NULL;
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}
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return ret;
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}
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static void perf_trace_event_unreg(struct perf_event *p_event)
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{
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struct ftrace_event_call *tp_event = p_event->tp_event;
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int i;
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if (--tp_event->perf_refcount > 0)
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goto out;
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tp_event->class->reg(tp_event, TRACE_REG_PERF_UNREGISTER, NULL);
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/*
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* Ensure our callback won't be called anymore. The buffers
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* will be freed after that.
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*/
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tracepoint_synchronize_unregister();
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free_percpu(tp_event->perf_events);
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tp_event->perf_events = NULL;
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if (!--total_ref_count) {
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for (i = 0; i < PERF_NR_CONTEXTS; i++) {
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free_percpu(perf_trace_buf[i]);
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perf_trace_buf[i] = NULL;
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}
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}
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out:
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module_put(tp_event->mod);
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}
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static int perf_trace_event_open(struct perf_event *p_event)
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{
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struct ftrace_event_call *tp_event = p_event->tp_event;
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return tp_event->class->reg(tp_event, TRACE_REG_PERF_OPEN, p_event);
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}
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static void perf_trace_event_close(struct perf_event *p_event)
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{
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struct ftrace_event_call *tp_event = p_event->tp_event;
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tp_event->class->reg(tp_event, TRACE_REG_PERF_CLOSE, p_event);
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}
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static int perf_trace_event_init(struct ftrace_event_call *tp_event,
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struct perf_event *p_event)
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{
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int ret;
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ret = perf_trace_event_perm(tp_event, p_event);
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if (ret)
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return ret;
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ret = perf_trace_event_reg(tp_event, p_event);
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if (ret)
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return ret;
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ret = perf_trace_event_open(p_event);
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if (ret) {
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perf_trace_event_unreg(p_event);
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return ret;
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}
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return 0;
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}
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int perf_trace_init(struct perf_event *p_event)
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{
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struct ftrace_event_call *tp_event;
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u64 event_id = p_event->attr.config;
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int ret = -EINVAL;
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mutex_lock(&event_mutex);
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list_for_each_entry(tp_event, &ftrace_events, list) {
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if (tp_event->event.type == event_id &&
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tp_event->class && tp_event->class->reg &&
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try_module_get(tp_event->mod)) {
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ret = perf_trace_event_init(tp_event, p_event);
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if (ret)
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module_put(tp_event->mod);
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break;
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}
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}
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mutex_unlock(&event_mutex);
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return ret;
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}
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void perf_trace_destroy(struct perf_event *p_event)
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{
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mutex_lock(&event_mutex);
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perf_trace_event_close(p_event);
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perf_trace_event_unreg(p_event);
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mutex_unlock(&event_mutex);
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}
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int perf_trace_add(struct perf_event *p_event, int flags)
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{
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struct ftrace_event_call *tp_event = p_event->tp_event;
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struct hlist_head __percpu *pcpu_list;
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struct hlist_head *list;
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pcpu_list = tp_event->perf_events;
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if (WARN_ON_ONCE(!pcpu_list))
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return -EINVAL;
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if (!(flags & PERF_EF_START))
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p_event->hw.state = PERF_HES_STOPPED;
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list = this_cpu_ptr(pcpu_list);
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hlist_add_head_rcu(&p_event->hlist_entry, list);
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return tp_event->class->reg(tp_event, TRACE_REG_PERF_ADD, p_event);
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}
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void perf_trace_del(struct perf_event *p_event, int flags)
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{
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struct ftrace_event_call *tp_event = p_event->tp_event;
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hlist_del_rcu(&p_event->hlist_entry);
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tp_event->class->reg(tp_event, TRACE_REG_PERF_DEL, p_event);
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}
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__kprobes void *perf_trace_buf_prepare(int size, unsigned short type,
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struct pt_regs *regs, int *rctxp)
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{
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struct trace_entry *entry;
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unsigned long flags;
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char *raw_data;
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int pc;
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BUILD_BUG_ON(PERF_MAX_TRACE_SIZE % sizeof(unsigned long));
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if (WARN_ONCE(size > PERF_MAX_TRACE_SIZE,
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"perf buffer not large enough"))
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return NULL;
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pc = preempt_count();
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*rctxp = perf_swevent_get_recursion_context();
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if (*rctxp < 0)
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return NULL;
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raw_data = this_cpu_ptr(perf_trace_buf[*rctxp]);
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/* zero the dead bytes from align to not leak stack to user */
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memset(&raw_data[size - sizeof(u64)], 0, sizeof(u64));
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entry = (struct trace_entry *)raw_data;
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local_save_flags(flags);
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tracing_generic_entry_update(entry, flags, pc);
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entry->type = type;
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return raw_data;
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}
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EXPORT_SYMBOL_GPL(perf_trace_buf_prepare);
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#ifdef CONFIG_FUNCTION_TRACER
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static void
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perf_ftrace_function_call(unsigned long ip, unsigned long parent_ip,
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struct ftrace_ops *ops, struct pt_regs *pt_regs)
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{
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struct ftrace_entry *entry;
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struct hlist_head *head;
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struct pt_regs regs;
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int rctx;
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head = this_cpu_ptr(event_function.perf_events);
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if (hlist_empty(head))
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return;
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#define ENTRY_SIZE (ALIGN(sizeof(struct ftrace_entry) + sizeof(u32), \
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sizeof(u64)) - sizeof(u32))
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BUILD_BUG_ON(ENTRY_SIZE > PERF_MAX_TRACE_SIZE);
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perf_fetch_caller_regs(®s);
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entry = perf_trace_buf_prepare(ENTRY_SIZE, TRACE_FN, NULL, &rctx);
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if (!entry)
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return;
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entry->ip = ip;
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entry->parent_ip = parent_ip;
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perf_trace_buf_submit(entry, ENTRY_SIZE, rctx, 0,
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1, ®s, head, NULL);
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#undef ENTRY_SIZE
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}
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static int perf_ftrace_function_register(struct perf_event *event)
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{
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struct ftrace_ops *ops = &event->ftrace_ops;
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ops->flags |= FTRACE_OPS_FL_CONTROL;
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ops->func = perf_ftrace_function_call;
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return register_ftrace_function(ops);
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}
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static int perf_ftrace_function_unregister(struct perf_event *event)
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{
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struct ftrace_ops *ops = &event->ftrace_ops;
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int ret = unregister_ftrace_function(ops);
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ftrace_free_filter(ops);
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return ret;
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}
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static void perf_ftrace_function_enable(struct perf_event *event)
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{
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ftrace_function_local_enable(&event->ftrace_ops);
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}
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static void perf_ftrace_function_disable(struct perf_event *event)
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{
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ftrace_function_local_disable(&event->ftrace_ops);
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}
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int perf_ftrace_event_register(struct ftrace_event_call *call,
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enum trace_reg type, void *data)
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{
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switch (type) {
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case TRACE_REG_REGISTER:
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case TRACE_REG_UNREGISTER:
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break;
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case TRACE_REG_PERF_REGISTER:
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case TRACE_REG_PERF_UNREGISTER:
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return 0;
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case TRACE_REG_PERF_OPEN:
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return perf_ftrace_function_register(data);
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case TRACE_REG_PERF_CLOSE:
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return perf_ftrace_function_unregister(data);
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case TRACE_REG_PERF_ADD:
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perf_ftrace_function_enable(data);
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return 0;
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case TRACE_REG_PERF_DEL:
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perf_ftrace_function_disable(data);
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return 0;
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}
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return -EINVAL;
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}
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#endif /* CONFIG_FUNCTION_TRACER */
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