CODEWITHSUNDEEP
linuxassemblyterminalgdb
duckyPluck
duckyPluck

Reputation: 177

How do I step through an executable file using gdb?

What I'm attempting to do is to record the values stored in registers at each assembly instruction of a function. All I have is just the executable file to work with. I've figured how to get the asm layout but just having a hard time with stepping through that. When I use "b 1" command to set a break point that I could start stepping through from, I get an error "No line 1 in file "../sysdeps/i386/dl-procinfo.c". Here's a screenshot to show the commands I've entered so far:

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Upvotes: 0

Views: 1787

Answers (1)

Waqar
Waqar

Reputation: 9331

Use a function name or a memory address when putting a breakpoint instead or compile without optimizations if you want line numbers.

(gdb) b main // will put a break point at start of function main
(gdb) r      // run

Alternatively, use start command which sets a temporary breakpoint on main() and starts executing.

Use n to move to next instruction and si to step into a function / label.

To display the registers, you can use info regs command or i r. Alternatively, use registers layout, which is much better. To get the value inside a particular register, use print, e.g print $rax.

(gdb) layout regs

Upvotes: 2

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