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    Subject[PATCH tracing/kprobes 4/7] tracing/kprobes: Add event profiling support
    Date
    Add *probe_profile_enable/disable for supporting perf tool
    when CONFIG_PROFILE_EVENT=y.

    Signed-off-by: Masami Hiramatsu <mhiramat@redhat.com>
    Cc: Jim Keniston <jkenisto@us.ibm.com>
    Cc: Ananth N Mavinakayanahalli <ananth@in.ibm.com>
    Cc: Andi Kleen <ak@linux.intel.com>
    Cc: Christoph Hellwig <hch@infradead.org>
    Cc: Frank Ch. Eigler <fche@redhat.com>
    Cc: Frederic Weisbecker <fweisbec@gmail.com>
    Cc: H. Peter Anvin <hpa@zytor.com>
    Cc: Ingo Molnar <mingo@elte.hu>
    Cc: Jason Baron <jbaron@redhat.com>
    Cc: K.Prasad <prasad@linux.vnet.ibm.com>
    Cc: Lai Jiangshan <laijs@cn.fujitsu.com>
    Cc: Li Zefan <lizf@cn.fujitsu.com>
    Cc: Peter Zijlstra <peterz@infradead.org>
    Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
    Cc: Steven Rostedt <rostedt@goodmis.org>
    Cc: Tom Zanussi <tzanussi@gmail.com>
    ---

    Documentation/trace/kprobetrace.txt | 4 +
    kernel/trace/trace_kprobe.c | 110 ++++++++++++++++++++++++++++++++++-
    2 files changed, 111 insertions(+), 3 deletions(-)

    diff --git a/Documentation/trace/kprobetrace.txt b/Documentation/trace/kprobetrace.txt
    index db55318..8f882eb 100644
    --- a/Documentation/trace/kprobetrace.txt
    +++ b/Documentation/trace/kprobetrace.txt
    @@ -62,13 +62,15 @@ enabled:
    You can enable/disable the probe by writing 1 or 0 on it.

    format:
    - It shows the format of this probe event. It also shows aliases of arguments
    + This shows the format of this probe event. It also shows aliases of arguments
    which you specified to kprobe_events.

    filter:
    You can write filtering rules of this event. And you can use both of aliase
    names and field names for describing filters.

    +id:
    + This shows the id of this probe event.

    Event Profiling
    ---------------
    diff --git a/kernel/trace/trace_kprobe.c b/kernel/trace/trace_kprobe.c
    index 902a148..21ffb5e 100644
    --- a/kernel/trace/trace_kprobe.c
    +++ b/kernel/trace/trace_kprobe.c
    @@ -28,6 +28,7 @@
    #include <linux/string.h>
    #include <linux/ctype.h>
    #include <linux/ptrace.h>
    +#include <linux/perf_counter.h>

    #include "trace.h"
    #include "trace_output.h"
    @@ -280,6 +281,7 @@ static struct trace_probe *alloc_trace_probe(const char *event,
    } else
    tp->rp.kp.addr = addr;

    + /* Set handler here for checking whether this probe is return or not. */
    if (is_return)
    tp->rp.handler = kretprobe_trace_func;
    else
    @@ -927,10 +929,13 @@ static int probe_event_enable(struct ftrace_event_call *call)
    {
    struct trace_probe *tp = (struct trace_probe *)call->data;

    - if (probe_is_return(tp))
    + if (probe_is_return(tp)) {
    + tp->rp.handler = kretprobe_trace_func;
    return enable_kretprobe(&tp->rp);
    - else
    + } else {
    + tp->rp.kp.pre_handler = kprobe_trace_func;
    return enable_kprobe(&tp->rp.kp);
    + }
    }

    static void probe_event_disable(struct ftrace_event_call *call)
    @@ -1103,6 +1108,101 @@ static int kretprobe_event_show_format(struct ftrace_event_call *call,
    "func, ret_ip");
    }

    +#ifdef CONFIG_EVENT_PROFILE
    +
    +/* Kprobe profile handler */
    +static __kprobes int kprobe_profile_func(struct kprobe *kp,
    + struct pt_regs *regs)
    +{
    + struct trace_probe *tp = container_of(kp, struct trace_probe, rp.kp);
    + struct ftrace_event_call *call = &tp->call;
    + struct kprobe_trace_entry *entry;
    + int size, i, pc;
    + unsigned long irq_flags;
    +
    + local_save_flags(irq_flags);
    + pc = preempt_count();
    +
    + size = SIZEOF_KPROBE_TRACE_ENTRY(tp->nr_args);
    +
    + do {
    + char raw_data[size];
    + struct trace_entry *ent;
    +
    + *(u64 *)(&raw_data[size - sizeof(u64)]) = 0ULL;
    + entry = (struct kprobe_trace_entry *)raw_data;
    + ent = &entry->ent;
    +
    + tracing_generic_entry_update(ent, irq_flags, pc);
    + ent->type = call->id;
    + entry->nargs = tp->nr_args;
    + entry->ip = (unsigned long)kp->addr;
    + for (i = 0; i < tp->nr_args; i++)
    + entry->args[i] = call_fetch(&tp->args[i], regs);
    + perf_tpcounter_event(call->id, entry->ip, 1, entry, size);
    + } while (0);
    + return 0;
    +}
    +
    +/* Kretprobe profile handler */
    +static __kprobes int kretprobe_profile_func(struct kretprobe_instance *ri,
    + struct pt_regs *regs)
    +{
    + struct trace_probe *tp = container_of(ri->rp, struct trace_probe, rp);
    + struct ftrace_event_call *call = &tp->call;
    + struct kretprobe_trace_entry *entry;
    + int size, i, pc;
    + unsigned long irq_flags;
    +
    + local_save_flags(irq_flags);
    + pc = preempt_count();
    +
    + size = SIZEOF_KRETPROBE_TRACE_ENTRY(tp->nr_args);
    +
    + do {
    + char raw_data[size];
    + struct trace_entry *ent;
    +
    + *(u64 *)(&raw_data[size - sizeof(u64)]) = 0ULL;
    + entry = (struct kretprobe_trace_entry *)raw_data;
    + ent = &entry->ent;
    +
    + tracing_generic_entry_update(ent, irq_flags, pc);
    + ent->type = call->id;
    + entry->nargs = tp->nr_args;
    + entry->func = (unsigned long)tp->rp.kp.addr;
    + entry->ret_ip = (unsigned long)ri->ret_addr;
    + for (i = 0; i < tp->nr_args; i++)
    + entry->args[i] = call_fetch(&tp->args[i], regs);
    + perf_tpcounter_event(call->id, entry->ret_ip, 1, entry, size);
    + } while (0);
    + return 0;
    +}
    +
    +static int probe_profile_enable(struct ftrace_event_call *call)
    +{
    + struct trace_probe *tp = (struct trace_probe *)call->data;
    +
    + if (atomic_inc_return(&call->profile_count))
    + return 0;
    +
    + if (probe_is_return(tp)) {
    + tp->rp.handler = kretprobe_profile_func;
    + return enable_kretprobe(&tp->rp);
    + } else {
    + tp->rp.kp.pre_handler = kprobe_profile_func;
    + return enable_kprobe(&tp->rp.kp);
    + }
    +}
    +
    +static void probe_profile_disable(struct ftrace_event_call *call)
    +{
    + if (atomic_add_negative(-1, &call->profile_count))
    + probe_event_disable(call);
    +}
    +
    +#endif /* CONFIG_EVENT_PROFILE */
    +
    static int register_probe_event(struct trace_probe *tp)
    {
    struct ftrace_event_call *call = &tp->call;
    @@ -1128,6 +1228,12 @@ static int register_probe_event(struct trace_probe *tp)
    call->enabled = 1;
    call->regfunc = probe_event_enable;
    call->unregfunc = probe_event_disable;
    +
    +#ifdef CONFIG_EVENT_PROFILE
    + atomic_set(&call->profile_count, -1);
    + call->profile_enable = probe_profile_enable;
    + call->profile_disable = probe_profile_disable;
    +#endif
    call->data = tp;
    ret = trace_add_event_call(call);
    if (ret) {

    --
    Masami Hiramatsu

    Software Engineer
    Hitachi Computer Products (America), Inc.
    Software Solutions Division

    e-mail: mhiramat@redhat.com


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