Cirrus Logic CS485 Manual do Utilizador descarregar pdf (Página 22)

CS485G Spring 2015 22

(b) parameters

(d) temporary locations (that don’t ﬁt in registers)

6. On the x86, the %epb register points to the start of the frame, and the

%esp register points to the current top of the stack.

7. The stack (for Unix, at least), grows downward.

(a) pushl src subtracts 4 from %esp and writes the operand at the

new address.

(b) popl dest puts (%esp) in the destination and then adds 4 to

%esp.

bel. The return address is the address of the instruction after

the call.

(d) ret pops the return address and then jumps to it.

8. Example:

804854e: e8 3d 06 00 00 call 8048b90 <main>

8048553: 50 pushl %eax

...

8048591: c3 ret

when %esp %eip

before call 0x108 0x804854e

after call 0x104 0x8048b90

before return 0x104 0x8048591

after return 0x108 0x8048553

9. Linux C frame contents, starting at bottom (right after caller’s frame)

(a) return address (placed by call)

(b) old %ebp

(d) parameters for the next call (“argument build”), last parameter

ﬁrst

(e) %esp points to the last parameter.

10. Lecture 13, 2/13/2015

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Cirrus Logic CS485 Manual do Utilizador Página 22