Solaris sparc newbie exploit coding misc questions

[ework0 <ework0 () gmail com>]

Hello,

I gather together some misc questions about designing buffer overflows 
PoC's for the solaris sparc architecture:

1. Basically, what is the stack address? how can be the same among 
different process? stack base addr is not related to memory locations? 
How can I get the stack base address? On solaris 10 sparc, running this 
code:

#include <stdio.h>

unsigned long get_sp(void){
       __asm__("or %sp,%sp,%i0");
}


int main()
{
       long i;
       i = get_sp();
       printf("0x%x \n",i);
      
}

Return: 0xffffffff

What's missing?

2. Shellcode on Solaris sparc: In some documentation, it says we always 
should include setreuid() because /bin/sh always check for this, but, i 
have seen some exploit code with a simple /bin/sh execve call.

3. What is exactly the term 'padding' in exploit coding? My english is 
very basic and the translation to my language doesnt help much.

I think that is more than enough, thanks for your kind help to any of 
these questions,