Return address of a recursive program - GDB view

Return address of a recursive program .

Here is a debug showing that the return address in a recursive function call will be same for same line recursive call.

* Saved RIP is the the return pointer .
* RIP is the instruction pointer pointing to the next instruction to be executed.



#include<stdio.h>

int fact(n)
{
        if(n==0)
                return 1;
        else
                return n*fact(n-1);    // return is  0x4004ee
         
}

int main()
{
        int x= fact(5);
printf("   %d     ",x);

}

(gdb) where
#0  fact (n=0) at factorial.c:5
#1  0x00000000004004ee in fact (n=1) at factorial.c:8
#2  0x00000000004004ee in fact (n=2) at factorial.c:8
#3  0x00000000004004ee in fact (n=3) at factorial.c:8
#4  0x00000000004004ee in fact (n=4) at factorial.c:8
#5  0x00000000004004ee in fact (n=5) at factorial.c:8
#6  0x000000000040050b in main () at factorial.c:13


GDB frame info shows return address to be the  "return statement" in fact method . This same for sys stack 1 to 5.


(gdb) info frame 0
Stack frame at 0x7fffffffe180:
 rip = 0x4004cf in fact (factorial.c:5); saved rip 0x4004ee
 called by frame at 0x7fffffffe1a0
 source language c.
 Arglist at 0x7fffffffe170, args: n=0
 Locals at 0x7fffffffe170, Previous frame's sp is 0x7fffffffe180
 Saved registers:
  rbp at 0x7fffffffe170, rip at 0x7fffffffe178

(gdb) info frame 1
Stack frame at 0x7fffffffe1a0:
 rip = 0x4004ee in fact (factorial.c:8); saved rip 0x4004ee
 called by frame at 0x7fffffffe1c0, caller of frame at 0x7fffffffe180
 source language c.
 Arglist at 0x7fffffffe190, args: n=1
 Locals at 0x7fffffffe190, Previous frame's sp is 0x7fffffffe1a0
 Saved registers:
  rbp at 0x7fffffffe190, rip at 0x7fffffffe198

(gdb) info frame 2
Stack frame at 0x7fffffffe1c0:
 rip = 0x4004ee in fact (factorial.c:8); saved rip 0x4004ee
 called by frame at 0x7fffffffe1e0, caller of frame at 0x7fffffffe1a0
 source language c.
 Arglist at 0x7fffffffe1b0, args: n=2
 Locals at 0x7fffffffe1b0, Previous frame's sp is 0x7fffffffe1c0
 Saved registers:
  rbp at 0x7fffffffe1b0, rip at 0x7fffffffe1b8

(gdb) info frame 3
Stack frame at 0x7fffffffe1e0:
 rip = 0x4004ee in fact (factorial.c:8); saved rip 0x4004ee
 called by frame at 0x7fffffffe200, caller of frame at 0x7fffffffe1c0
 source language c.
 Arglist at 0x7fffffffe1d0, args: n=3
 Locals at 0x7fffffffe1d0, Previous frame's sp is 0x7fffffffe1e0
 Saved registers:
  rbp at 0x7fffffffe1d0, rip at 0x7fffffffe1d8

(gdb) info frame 4
Stack frame at 0x7fffffffe200:
 rip = 0x4004ee in fact (factorial.c:8); saved rip 0x4004ee
 called by frame at 0x7fffffffe220, caller of frame at 0x7fffffffe1e0
 source language c.
 Arglist at 0x7fffffffe1f0, args: n=4
 Locals at 0x7fffffffe1f0, Previous frame's sp is 0x7fffffffe200
 Saved registers:
  rbp at 0x7fffffffe1f0, rip at 0x7fffffffe1f8

(gdb) info frame 5
Stack frame at 0x7fffffffe220:
 rip = 0x4004ee in fact (factorial.c:8); saved rip 0x40050b
 called by frame at 0x7fffffffe240, caller of frame at 0x7fffffffe200
 source language c.
 Arglist at 0x7fffffffe210, args: n=5
 Locals at 0x7fffffffe210, Previous frame's sp is 0x7fffffffe220
 Saved registers:
  rbp at 0x7fffffffe210, rip at 0x7fffffffe218

(gdb) info frame 6
Stack frame at 0x7fffffffe240:
 rip = 0x40050b in main (factorial.c:13); saved rip 0x37a941ed5d
 caller of frame at 0x7fffffffe220
 source language c.
 Arglist at 0x7fffffffe230, args:
 Locals at 0x7fffffffe230, Previous frame's sp is 0x7fffffffe240
 Saved registers:
  rbp at 0x7fffffffe230, rip at 0x7fffffffe238