89 lines
1.5 KiB
Markdown
89 lines
1.5 KiB
Markdown
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---
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title: x86 ASM
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date: 2018-10-15
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---
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# x86 ASM
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## Outline
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* 32 bit System
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## Syntax
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### Intel Syntax (verwendet in Vorlesung)
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* Intel Syntax (Ziel Operant ist immer links)
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* Adressen in `[1234]`
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### AT&T Syntax
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* Ziel Operant ist rechts
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* Register mit `%`
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* Number Literals mit `$`
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## Memory Layout
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* `.bss` global uninitialized variables
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* `.data` global initialized variables
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* heap: dynamic variables
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* `.text`: code (usually read-only)
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* stack: lokale Variablen + procedure activation records
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* heap grows up
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* stack grows down
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### Stack Frame
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* **ESP**: Ende des Stacks
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* **EBP**: Begin des aktuellen Stack Frames
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Enthält:
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* Lokale Variablen
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* Parameter
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* Caller Adresse
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| :---: |
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| <prev frame> |
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| --- |
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| Parameters |
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| :---: |
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| Return address |
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| :---: |
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| prev frame address (alter *EBP*) |
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| :---: |
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| *EBP* -> |
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| Local variables |
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| *ESP* -> |
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| <free memory> |
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| :---: |
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### MOV
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* `mov eax, ebx`: `eax = ebx`
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* `mov edx, [1234]`: `edx = *1234`
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### `PUSH`
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* `push ecx`: Wert von `ecx` auf den Stack, `esp - 4`
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* `pop esi`: `esp + 4`
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### `RET`
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* `pop eip`
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### Subroutinen
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`f(1,2,3)` ->
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```
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push 3
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push 2
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push 1
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call f
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```
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