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x86 Assembly Questions

Name: Anonymous 2014-04-26 23:52

$ cat bork.asm

section .data
fuck: dd 0xDEADBEEF

section .text
global _start
_start:
mov dword [fuck],0xABADC0DA

mov eax,1
mov ebx,0
int 0x80


Why doesn't writing to the .data segment segfault? Shouldn't Linux map it to a read-only page?

$ nasm -f elf bork.asm
$ gold -s -o bork-gold bork.asm
$ ld -s -melf_i386 -o bork-ld bork.o
$ du -bh *
432 bork-gold
132 bork.asm
340 bork-ld
608 bork.o


How does such a minimal binary take up 300+ bytes?

Name: Anonymous 2014-05-26 19:41

>>83
Lookup can be O(1), especially with a non-hash table. Bury the fp in a global struct. (But globals! Functions are global symbols too, deal with it.)

>>85
O(10) is still O(1). You're going to have to switch to cyclomatic complexity if you want to whine about large multipliers.

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