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I had to track down a segv in some JNI code recently from a core file ... not sure if there is an easier way to do this, here's what I came up with:

Program crashes with segv indicating the error occurs in the following routine:
Java_com_sun_zfsGet+0x18d

I  use the solaris 'dis' command to disassemble the jni library:

# dis /usr/lib/libtest.so
    Java_com_sun__zfsGet+0x184: 83 c4 10           addl   $0x10,%esp
    Java_com_sun__zfsGet+0x187: 83 ec 08           subl   $0x8,%esp
    Java_com_sun__zfsGet+0x18a: 8b 45 08           movl   0x8(%ebp),%eax
    Java_com_sun__zfsGet+0x18d: 8b 00              movl   (%eax),%eax
    Java_com_sun__zfsGet+0x18f: 68 01 00 00 00     pushl  $0x1
    Java_com_sun__zfsGet+0x194: ff 75 08           pushl  0x8(%ebp)

But it's not obvious to which line of C code this segv corresponds ...

I decided to use nanosleep() to place markers in the code, and recompile. For example:

  struct timespec ns;
  ns.tv_sec = 0;
  ns.tv_nsec = 1;
  nanosleep(&ns,(struct timespec *)NULL);

  /* a bit of code */

  ns.tv_nsec = 2;
  nanosleep(&ns,(struct timespec *)NULL);

  /* more code */

  ns.tv_nsec = 3;
  nanosleep(&ns,(struct timespec *)NULL); 

  /* etc, etc */


Now when I recompile, I have an identifiable marker in the disassembled code that I use to match up with my source code.
The new 'dis' output now contains:

  movl   $0x1,-0xc(%ebp) /* This is the value of ns.tv_nsec */
  subl   $0x8,%esp
  pushl  $0x0
  leal   -0x10(%ebp),%eax
  pushl  %eax
  call   -0x4    <Java_com_sun_zfsGet+0x1e>

    for each call to nanosleep().

    By incrementing the number of nsec by one with each call, I can now easily track down the bug in my code.

    With this instrumentation, I see that a segv occurring at Java_com_sun__zfsGet+0x18d corresponds to the
    code following my nanosleep() marker with an ns.tv_nsec value of 6.


Java_com_sun_zfsGet+0x16f: c7 45 f4 06 00 00  movl   $0x6,-0xc(%ebp)
Java_com_sun_zfsGet+0x176: 83 ec 08           subl   $0x8,%esp
Java_com_sun_zfsGet+0x179: 6a 00              pushl  $0x0
Java_com_sun_zfsGet+0x17b: 8d 45 f0           leal   -0x10(%ebp),%eax
Java_com_sun_zfsGet+0x17e: 50                 pushl  %eax
Java_com_sun_zfsGet+0x17f: e8 fc ff ff ff     call   -0x4    <Java_com_sun_zfsGet+0x180>
Java_com_sun_zfsGet+0x184: 83 c4 10           addl   $0x10,%esp
Java_com_sun_zfsGet+0x187: 83 ec 08           subl   $0x8,%esp
Java_com_sun_zfsGet+0x18a: 8b 45 08           movl   0x8(%ebp),%eax
Java_com_sun_zfsGet+0x18d: 8b 00              movl   (%eax),%eax