CODEWITHSUNDEEP
clinux
J.d.sn
J.d.sn

Reputation: 29

what does __asm__("movl %eax,%esp") return?

here is a little function on a old book:

unsigned long f()
{
   __asm__("movl %eax,%esp");
}

the function explained to get the stack point,but it seems not.It actually gets a 8-bit address much lower than my frame address.I guess it's designed for 32-bit system? Please forgive me if I said something stupid.

Upvotes: 0

Views: 1507

Answers (2)

hexkn1ght
hexkn1ght

Reputation: 63

Actually the code has some mistake

unsigned long f()
{
__asm__("movl %esp,%eax");
}

it provides the stack pointer address

Upvotes: 0

marcolz
marcolz

Reputation: 2970

Indeed, as @James mentioned in the comments, in 64 bit mode, %eax and %esp represent the least significant 32 bits of the 64 bit %rax and %rsp registers.

Upvotes: 2

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