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Use backtrace to display all of the stack frames from the current point of execution back to main . With an argument N, backtrace N shows only the N innermost frames and backtrace -N shows only the N outermost. The up , down , and frame n commands allow you to change the selected frame.
Selects a stack frame or displays the currently selected stack frame.
Able to view and traverse the function call stack using the where, up, down and frame commands. In order to debug programs with functions (i.e. most programs), it is helpful to inspect the variables of all functions in the current call stack, i.e. the functions called to get to the current point in the program.
A backtrace is a summary of how your program got where it is. It shows one line per frame, for many frames, starting with the currently executing frame (frame zero), followed by its caller (frame one), and on up the stack.
info frame to show the stack frame info
To read the memory at given addresses you should take a look at x
x/x $esp for hex x/d $esp for signed x/u $esp for unsigned etc. x uses the format syntax, you could also take a look at the current instruction via x/i $eip etc.
Use:
bt - backtrace: show stack functions and argsinfo frame - show stack start/end/args/locals pointers x/100x $sp - show stack memory(gdb) bt
#0 zzz () at zzz.c:96
#1 0xf7d39cba in yyy (arg=arg@entry=0x0) at yyy.c:542
#2 0xf7d3a4f6 in yyyinit () at yyy.c:590
#3 0x0804ac0c in gnninit () at gnn.c:374
#4 main (argc=1, argv=0xffffd5e4) at gnn.c:389
(gdb) info frame
Stack level 0, frame at 0xffeac770:
eip = 0x8049047 in main (goo.c:291); saved eip 0xf7f1fea1
source language c.
Arglist at 0xffeac768, args: argc=1, argv=0xffffd5e4
Locals at 0xffeac768, Previous frame's sp is 0xffeac770
Saved registers:
ebx at 0xffeac75c, ebp at 0xffeac768, esi at 0xffeac760, edi at 0xffeac764, eip at 0xffeac76c
(gdb) x/10x $sp
0xffeac63c: 0xf7d39cba 0xf7d3c0d8 0xf7d3c21b 0x00000001
0xffeac64c: 0xf78d133f 0xffeac6f4 0xf7a14450 0xffeac678
0xffeac65c: 0x00000000 0xf7d3790e
You need to use gdb's memory-display commands. The basic one is x, for examine. There's an example on the linked-to page that uses
gdb> x/4xw $sp
to print "four words (w ) of memory above the stack pointer (here, $sp) in hexadecimal (x)". The quotation is slightly paraphrased.
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