tracing/kprobe: Check whether the non-suffixed symbol is notrace

Check whether the non-suffixed symbol is notrace, since suffixed
symbols are generated by the compilers for optimization. Based on
these suffixed symbols, notrace check might not work because
some of them are just a partial code of the original function.
(e.g. cold-cache (unlikely) code is separated from original
 function as FUNCTION.cold.XX)

For example, without this fix,
  # echo p device_add.cold.67 > /sys/kernel/debug/tracing/kprobe_events
  sh: write error: Invalid argument

  # cat /sys/kernel/debug/tracing/error_log
  [  135.491035] trace_kprobe: error: Failed to register probe event
    Command: p device_add.cold.67
               ^
  # dmesg | tail -n 1
  [  135.488599] trace_kprobe: Could not probe notrace function device_add.cold.67

With this,
  # echo p device_add.cold.66 > /sys/kernel/debug/tracing/kprobe_events
  # cat /sys/kernel/debug/kprobes/list
  ffffffff81599de9  k  device_add.cold.66+0x0    [DISABLED]

Actually, kprobe blacklist already did similar thing,
see within_kprobe_blacklist().

Link: http://lkml.kernel.org/r/157233790394.6706.18243942030937189679.stgit@devnote2
Fixes: 45408c4f9250 ("tracing: kprobes: Prohibit probing on notrace function")
Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>

diff --git a/kernel/trace/trace_kprobe.c b/kernel/trace/trace_kprobe.c
index 1552a95c743bfbbc70451501cdd3b4763036ede3..7f890262c8a3a4b71c01ac0a9c5f9146ed6a5223 100644 (file)
--- a/kernel/trace/trace_kprobe.c
+++ b/kernel/trace/trace_kprobe.c
@@ -435,11 +435,10 @@ static int disable_trace_kprobe(struct trace_event_call *call,
 
 #if defined(CONFIG_KPROBES_ON_FTRACE) && \
        !defined(CONFIG_KPROBE_EVENTS_ON_NOTRACE)
-static bool within_notrace_func(struct trace_kprobe *tk)
+static bool __within_notrace_func(unsigned long addr)
 {
-       unsigned long offset, size, addr;
+       unsigned long offset, size;
 
-       addr = trace_kprobe_address(tk);
        if (!addr || !kallsyms_lookup_size_offset(addr, &size, &offset))
                return false;
 
@@ -452,6 +451,28 @@ static bool within_notrace_func(struct trace_kprobe *tk)
         */
        return !ftrace_location_range(addr, addr + size - 1);
 }
+
+static bool within_notrace_func(struct trace_kprobe *tk)
+{
+       unsigned long addr = addr = trace_kprobe_address(tk);
+       char symname[KSYM_NAME_LEN], *p;
+
+       if (!__within_notrace_func(addr))
+               return false;
+
+       /* Check if the address is on a suffixed-symbol */
+       if (!lookup_symbol_name(addr, symname)) {
+               p = strchr(symname, '.');
+               if (!p)
+                       return true;
+               *p = '\0';
+               addr = (unsigned long)kprobe_lookup_name(symname, 0);
+               if (addr)
+                       return __within_notrace_func(addr);
+       }
+
+       return true;
+}
 #else
 #define within_notrace_func(tk)        (false)
 #endif