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    Subject[PATCH tracing/kprobes v2 2/5] tracing/kprobes: Avoid field name confliction
    Date
    Check whether the argument name is conflict with other field names.

    Changes in v2:
    - Add common_lock_depth to reserved name list.

    Signed-off-by: Masami Hiramatsu <mhiramat@redhat.com>
    Cc: Frederic Weisbecker <fweisbec@gmail.com>
    Cc: Ingo Molnar <mingo@elte.hu>
    Cc: Thomas Gleixner <tglx@linutronix.de>
    Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
    Cc: Steven Rostedt <rostedt@goodmis.org>
    Cc: Mike Galbraith <efault@gmx.de>
    Cc: Paul Mackerras <paulus@samba.org>
    Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
    Cc: Christoph Hellwig <hch@infradead.org>
    Cc: Ananth N Mavinakayanahalli <ananth@in.ibm.com>
    Cc: Jim Keniston <jkenisto@us.ibm.com>
    Cc: Frank Ch. Eigler <fche@redhat.com>
    ---

    kernel/trace/trace_kprobe.c | 65 +++++++++++++++++++++++++++++++++++--------
    1 files changed, 53 insertions(+), 12 deletions(-)

    diff --git a/kernel/trace/trace_kprobe.c b/kernel/trace/trace_kprobe.c
    index f63ead0..eb1fa0f 100644
    --- a/kernel/trace/trace_kprobe.c
    +++ b/kernel/trace/trace_kprobe.c
    @@ -38,6 +38,25 @@
    #define MAX_EVENT_NAME_LEN 64
    #define KPROBE_EVENT_SYSTEM "kprobes"

    +/* Reserved field names */
    +#define FIELD_STRING_IP "ip"
    +#define FIELD_STRING_NARGS "nargs"
    +#define FIELD_STRING_RETIP "ret_ip"
    +#define FIELD_STRING_FUNC "func"
    +
    +const char *reserved_field_names[] = {
    + "common_type",
    + "common_flags",
    + "common_preempt_count",
    + "common_pid",
    + "common_tgid",
    + "common_lock_depth",
    + FIELD_STRING_IP,
    + FIELD_STRING_NARGS,
    + FIELD_STRING_RETIP,
    + FIELD_STRING_FUNC,
    +};
    +
    /* currently, trace_kprobe only supports X86. */

    struct fetch_func {
    @@ -551,6 +570,20 @@ static int parse_probe_arg(char *arg, struct fetch_func *ff, int is_return)
    return ret;
    }

    +/* Return 1 if name is reserved or already used by another argument */
    +static int conflict_field_name(const char *name,
    + struct probe_arg *args, int narg)
    +{
    + int i;
    + for (i = 0; i < ARRAY_SIZE(reserved_field_names); i++)
    + if (!strcmp(reserved_field_names[i], name))
    + return 1;
    + for (i = 0; i < narg; i++)
    + if (!strcmp(args[i].name, name))
    + return 1;
    + return 0;
    +}
    +
    static int create_trace_probe(int argc, char **argv)
    {
    /*
    @@ -652,6 +685,12 @@ static int create_trace_probe(int argc, char **argv)
    *arg++ = '\0';
    else
    arg = argv[i];
    +
    + if (conflict_field_name(argv[i], tp->args, i)) {
    + ret = -EINVAL;
    + goto error;
    + }
    +
    tp->args[i].name = kstrdup(argv[i], GFP_KERNEL);

    /* Parse fetch argument */
    @@ -1054,8 +1093,8 @@ static int kprobe_event_define_fields(struct ftrace_event_call *event_call)
    if (!ret)
    return ret;

    - DEFINE_FIELD(unsigned long, ip, "ip", 0);
    - DEFINE_FIELD(int, nargs, "nargs", 1);
    + DEFINE_FIELD(unsigned long, ip, FIELD_STRING_IP, 0);
    + DEFINE_FIELD(int, nargs, FIELD_STRING_NARGS, 1);
    /* Set argument names as fields */
    for (i = 0; i < tp->nr_args; i++)
    DEFINE_FIELD(unsigned long, args[i], tp->args[i].name, 0);
    @@ -1072,9 +1111,9 @@ static int kretprobe_event_define_fields(struct ftrace_event_call *event_call)
    if (!ret)
    return ret;

    - DEFINE_FIELD(unsigned long, func, "func", 0);
    - DEFINE_FIELD(unsigned long, ret_ip, "ret_ip", 0);
    - DEFINE_FIELD(int, nargs, "nargs", 1);
    + DEFINE_FIELD(unsigned long, func, FIELD_STRING_FUNC, 0);
    + DEFINE_FIELD(unsigned long, ret_ip, FIELD_STRING_RETIP, 0);
    + DEFINE_FIELD(int, nargs, FIELD_STRING_NARGS, 1);
    /* Set argument names as fields */
    for (i = 0; i < tp->nr_args; i++)
    DEFINE_FIELD(unsigned long, args[i], tp->args[i].name, 0);
    @@ -1123,15 +1162,16 @@ static int kprobe_event_show_format(struct ftrace_event_call *call,
    int ret, i;
    struct trace_probe *tp = (struct trace_probe *)call->data;

    - SHOW_FIELD(unsigned long, ip, "ip");
    - SHOW_FIELD(int, nargs, "nargs");
    + SHOW_FIELD(unsigned long, ip, FIELD_STRING_IP);
    + SHOW_FIELD(int, nargs, FIELD_STRING_NARGS);

    /* Show fields */
    for (i = 0; i < tp->nr_args; i++)
    SHOW_FIELD(unsigned long, args[i], tp->args[i].name);
    trace_seq_puts(s, "\n");

    - return __probe_event_show_format(s, tp, "(%lx)", "REC->ip");
    + return __probe_event_show_format(s, tp, "(%lx)",
    + "REC->" FIELD_STRING_IP);
    }

    static int kretprobe_event_show_format(struct ftrace_event_call *call,
    @@ -1141,9 +1181,9 @@ static int kretprobe_event_show_format(struct ftrace_event_call *call,
    int ret, i;
    struct trace_probe *tp = (struct trace_probe *)call->data;

    - SHOW_FIELD(unsigned long, func, "func");
    - SHOW_FIELD(unsigned long, ret_ip, "ret_ip");
    - SHOW_FIELD(int, nargs, "nargs");
    + SHOW_FIELD(unsigned long, func, FIELD_STRING_FUNC);
    + SHOW_FIELD(unsigned long, ret_ip, FIELD_STRING_RETIP);
    + SHOW_FIELD(int, nargs, FIELD_STRING_NARGS);

    /* Show fields */
    for (i = 0; i < tp->nr_args; i++)
    @@ -1151,7 +1191,8 @@ static int kretprobe_event_show_format(struct ftrace_event_call *call,
    trace_seq_puts(s, "\n");

    return __probe_event_show_format(s, tp, "(%lx <- %lx)",
    - "REC->func, REC->ret_ip");
    + "REC->" FIELD_STRING_FUNC
    + ", REC->" FIELD_STRING_RETIP);
    }

    #ifdef CONFIG_EVENT_PROFILE

    --
    Masami Hiramatsu

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

    e-mail: mhiramat@redhat.com


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