169 lines
5.5 KiB
Markdown
169 lines
5.5 KiB
Markdown
---
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title: Procedures
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TARGET DECK: Obsidian::STEM
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FILE TAGS: x86-64
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tags:
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- x86-64
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---
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## Overview
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The details of procedures are detailed in [[x86-64/procedures|procedures]]. This file touches on the most relevant instruction classes.
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## CALL and RET
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Like [[conditions#JMP|JMP]] instructions, `call` allows specifying a direct or indirect operand. `call` pushes the address of the instruction following it onto the stack and updates the PC to the operand. `ret` reverts these steps.
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| Instruction | Operands | Description |
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| ----------- | ----------- | ---------------- |
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| `call` | Label | Procedure call |
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| `call` | \**Operand* | Procedure call |
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| `ret` | | Return from call |
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%%ANKI
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Cloze
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The {`call`} instruction is the counterpart to the {`ret`} instruction.
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Reference: Bryant, Randal E., and David O'Hallaron. *Computer Systems: A Programmer's Perspective*. Third edition, Global edition. Always Learning. Pearson, 2016.
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<!--ID: 1728558288130-->
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END%%
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%%ANKI
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Basic
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What two things does the `call` instruction do?
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Back: It pushes the return address on the stack and updates the PC.
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Reference: Bryant, Randal E., and David O'Hallaron. *Computer Systems: A Programmer's Perspective*. Third edition, Global edition. Always Learning. Pearson, 2016.
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<!--ID: 1728558288148-->
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END%%
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%%ANKI
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Basic
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What two things does the `ret` instruction do?
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Back: It pops the return address off the stack and updates the PC.
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Reference: Bryant, Randal E., and David O'Hallaron. *Computer Systems: A Programmer's Perspective*. Third edition, Global edition. Always Learning. Pearson, 2016.
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<!--ID: 1728558288160-->
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END%%
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%%ANKI
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Basic
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How is `ret` equivalently written using a line of assembly?
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Back:
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```asm
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popq %rip
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```
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Reference: Bryant, Randal E., and David O'Hallaron. *Computer Systems: A Programmer's Perspective*. Third edition, Global edition. Always Learning. Pearson, 2016.
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<!--ID: 1731952634162-->
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END%%
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%%ANKI
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Basic
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The operand forms of `call` mirror what other instruction class?
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Back: `JMP`
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Reference: Bryant, Randal E., and David O'Hallaron. *Computer Systems: A Programmer's Perspective*. Third edition, Global edition. Always Learning. Pearson, 2016.
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<!--ID: 1728558288165-->
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END%%
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%%ANKI
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Basic
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A `call` instruction pushes what address onto the stack?
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Back: That of the instruction following the `call` instruction.
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Reference: Bryant, Randal E., and David O'Hallaron. *Computer Systems: A Programmer's Perspective*. Third edition, Global edition. Always Learning. Pearson, 2016.
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<!--ID: 1728558288171-->
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END%%
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%%ANKI
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Basic
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What return address is pushed onto the stack after `call` is run?
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```x86
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1: ...
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2: callq .L1
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3: ...
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```
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Back: The address corresponding to line `3`.
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Reference: Bryant, Randal E., and David O'Hallaron. *Computer Systems: A Programmer's Perspective*. Third edition, Global edition. Always Learning. Pearson, 2016.
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<!--ID: 1728558288177-->
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END%%
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%%ANKI
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Basic
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What address is the PC updated to after `call` is run?
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```x86
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1: ...
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2: callq .L1
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3: ...
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```
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Back: That corresponding to label `.L1`.
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Reference: Bryant, Randal E., and David O'Hallaron. *Computer Systems: A Programmer's Perspective*. Third edition, Global edition. Always Learning. Pearson, 2016.
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<!--ID: 1728558288183-->
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END%%
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%%ANKI
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Basic
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Which register(s) does a `call` instruction update?
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Back: `%rsp` and `%rip`.
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Reference: Bryant, Randal E., and David O'Hallaron. *Computer Systems: A Programmer's Perspective*. Third edition, Global edition. Always Learning. Pearson, 2016.
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<!--ID: 1728559336730-->
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END%%
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%%ANKI
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Basic
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Which register(s) does a `ret` instruction update?
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Back: `%rsp` and `%rip`.
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Reference: Bryant, Randal E., and David O'Hallaron. *Computer Systems: A Programmer's Perspective*. Third edition, Global edition. Always Learning. Pearson, 2016.
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<!--ID: 1728559336760-->
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END%%
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## LEAVE
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`leave` parallels the `ret` instruction. It is equivalent to the following two instructions:
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```asm
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movq %rbp, %rsp
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popq %rbp
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```
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%%ANKI
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Basic
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What two things does the `leave` instruction do?
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Back: Restores the stack pointer and pops off the caller-saved base pointer.
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Reference: Bryant, Randal E., and David O'Hallaron. *Computer Systems: A Programmer's Perspective*. Third edition, Global edition. Always Learning. Pearson, 2016.
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<!--ID: 1731952634163-->
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END%%
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%%ANKI
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Basic
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How is `leave` equivalently written using a pair of instructions?
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Back:
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```asm
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movq %rbp, %rsp
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popq %rbp
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```
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Reference: Bryant, Randal E., and David O'Hallaron. *Computer Systems: A Programmer's Perspective*. Third edition, Global edition. Always Learning. Pearson, 2016.
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<!--ID: 1731952634164-->
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END%%
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%%ANKI
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Basic
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Fixed-sized frames use which of `leave` and/or `ret`?
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Back: Just `ret`.
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Reference: Bryant, Randal E., and David O'Hallaron. *Computer Systems: A Programmer's Perspective*. Third edition, Global edition. Always Learning. Pearson, 2016.
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<!--ID: 1731952715097-->
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END%%
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%%ANKI
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Basic
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Variable-sized frames use which of `leave` and/or `ret`?
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Back: Both.
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Reference: Bryant, Randal E., and David O'Hallaron. *Computer Systems: A Programmer's Perspective*. Third edition, Global edition. Always Learning. Pearson, 2016.
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<!--ID: 1731952715103-->
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END%%
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%%ANKI
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Cloze
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{1:`ret`} is to {2:`%rsp`} whereas {2:`leave`} is to {1:`%rbp`}.
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Reference: Bryant, Randal E., and David O'Hallaron. *Computer Systems: A Programmer's Perspective*. Third edition, Global edition. Always Learning. Pearson, 2016.
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<!--ID: 1731952634165-->
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END%%
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## Bibliography
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* Bryant, Randal E., and David O'Hallaron. *Computer Systems: A Programmer's Perspective*. Third edition, Global edition. Always Learning. Pearson, 2016. |