407 lines
15 KiB
Markdown
407 lines
15 KiB
Markdown
|
---
|
||
|
|
title: Procedures
|
||
|
|
TARGET DECK: Obsidian::STEM
|
||
|
|
FILE TAGS: x86-64
|
||
|
|
tags:
|
||
|
|
- x86-64
|
||
|
|
---
|
||
|
|
|
||
|
|
## Overview
|
||
|
|
|
||
|
|
The x86-64 stack grows towards lower addresses. When a procedure is invoked, more spack on the top of the stack is allocated for that procedure to make use of. This portion of the stack is called a **frame**. The general shape of the stack looks as follows:
|
||
|
|
|
||
|
|
![[x86-64-stack.png]]
|
||
|
|
|
||
|
|
Note parts of this diagram are omitted when possible. For instance, a stack frame may not exist at all if all arguments to a **leaf procedure** can be passed through registers. A leaf procedure is a function that does not call another function.
|
||
|
|
|
||
|
|
%%ANKII
|
||
|
|
Basic
|
||
|
|
What ADT is used internally in procedure-calling mechanisms?
|
||
|
|
Back: A stack.
|
||
|
|
Reference: Bryant, Randal E., and David O'Hallaron. *Computer Systems: A Programmer's Perspective*. Third edition, Global edition. Always Learning. Pearson, 2016.
|
||
|
|
END%%
|
||
|
|
|
||
|
|
%%ANKII
|
||
|
|
Cloze
|
||
|
|
The x86-64 stack grows towards {lower} addresses.
|
||
|
|
Reference: Bryant, Randal E., and David O'Hallaron. *Computer Systems: A Programmer's Perspective*. Third edition, Global edition. Always Learning. Pearson, 2016.
|
||
|
|
END%%
|
||
|
|
|
||
|
|
%%ANKI
|
||
|
|
Basic
|
||
|
|
What is a frame w.r.t. the x86-64 stack?
|
||
|
|
Back: A region of the stack dedicated to a particular function call.
|
||
|
|
Reference: Bryant, Randal E., and David O'Hallaron. *Computer Systems: A Programmer's Perspective*. Third edition, Global edition. Always Learning. Pearson, 2016.
|
||
|
|
<!--ID: 1728480337611-->
|
||
|
|
END%%
|
||
|
|
|
||
|
|
%%ANKI
|
||
|
|
Basic
|
||
|
|
What instructions are used to store and retrieve from the x86-64 stack?
|
||
|
|
Back: `pushq` and `popq`.
|
||
|
|
Reference: Bryant, Randal E., and David O'Hallaron. *Computer Systems: A Programmer's Perspective*. Third edition, Global edition. Always Learning. Pearson, 2016.
|
||
|
|
<!--ID: 1728480337614-->
|
||
|
|
END%%
|
||
|
|
|
||
|
|
%%ANKI
|
||
|
|
Basic
|
||
|
|
What does the "stack pointer" refer to w.r.t. the x86-64 stack?
|
||
|
|
Back: Register `%rsp`.
|
||
|
|
Reference: Bryant, Randal E., and David O'Hallaron. *Computer Systems: A Programmer's Perspective*. Third edition, Global edition. Always Learning. Pearson, 2016.
|
||
|
|
<!--ID: 1728480337617-->
|
||
|
|
END%%
|
||
|
|
|
||
|
|
%%ANKI
|
||
|
|
Basic
|
||
|
|
How is the stack pointer manipulated to allocate space on the x86-64 stack?
|
||
|
|
Back: By decrementing `%rsp` by an appropriate amount.
|
||
|
|
Reference: Bryant, Randal E., and David O'Hallaron. *Computer Systems: A Programmer's Perspective*. Third edition, Global edition. Always Learning. Pearson, 2016.
|
||
|
|
<!--ID: 1728480337621-->
|
||
|
|
END%%
|
||
|
|
|
||
|
|
%%ANKI
|
||
|
|
Basic
|
||
|
|
How is the stack pointer manipulated to deallocate space on the x86-64 stack?
|
||
|
|
Back: By incrementing `%rsp` by an appropriate amount.
|
||
|
|
Reference: Bryant, Randal E., and David O'Hallaron. *Computer Systems: A Programmer's Perspective*. Third edition, Global edition. Always Learning. Pearson, 2016.
|
||
|
|
<!--ID: 1728480337604-->
|
||
|
|
END%%
|
||
|
|
|
||
|
|
%%ANKI
|
||
|
|
Basic
|
||
|
|
Suppose procedure `P` calls `Q`. What data sits at the end of `P`'s frame?
|
||
|
|
Back: A return address.
|
||
|
|
Reference: Bryant, Randal E., and David O'Hallaron. *Computer Systems: A Programmer's Perspective*. Third edition, Global edition. Always Learning. Pearson, 2016.
|
||
|
|
<!--ID: 1728481058927-->
|
||
|
|
END%%
|
||
|
|
|
||
|
|
%%ANKI
|
||
|
|
Cloze
|
||
|
|
A {leaf} procedure is a function that {does not call another function}.
|
||
|
|
Reference: Bryant, Randal E., and David O'Hallaron. *Computer Systems: A Programmer's Perspective*. Third edition, Global edition. Always Learning. Pearson, 2016.
|
||
|
|
<!--ID: 1728481058953-->
|
||
|
|
END%%
|
||
|
|
|
||
|
|
%%ANKI
|
||
|
|
Basic
|
||
|
|
Suppose procedure `P` calls `Q`. The return address belongs to who's frame?
|
||
|
|
Back: `P`
|
||
|
|
Reference: Bryant, Randal E., and David O'Hallaron. *Computer Systems: A Programmer's Perspective*. Third edition, Global edition. Always Learning. Pearson, 2016.
|
||
|
|
<!--ID: 1728481058960-->
|
||
|
|
END%%
|
||
|
|
|
||
|
|
%%ANKI
|
||
|
|
Basic
|
||
|
|
Suppose procedure `P` calls `Q`. Why is the return address considered to be in `P`'s frame?
|
||
|
|
Back: It is state relevant to `P`.
|
||
|
|
Reference: Bryant, Randal E., and David O'Hallaron. *Computer Systems: A Programmer's Perspective*. Third edition, Global edition. Always Learning. Pearson, 2016.
|
||
|
|
<!--ID: 1728481058966-->
|
||
|
|
END%%
|
||
|
|
|
||
|
|
## Control Transfer
|
||
|
|
|
||
|
|
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.
|
||
|
|
|
||
|
|
| Instruction | Operands | Description |
|
||
|
|
| ----------- | ----------- | ---------------- |
|
||
|
|
| `call` | Label | Procedure call |
|
||
|
|
| `call` | \**Operand* | Procedure call |
|
||
|
|
| `ret` | | Return from call |
|
||
|
|
|
||
|
|
%%ANKI
|
||
|
|
Cloze
|
||
|
|
The {`call`} instruction is the counterpart to the {`ret`} instruction.
|
||
|
|
Reference: Bryant, Randal E., and David O'Hallaron. *Computer Systems: A Programmer's Perspective*. Third edition, Global edition. Always Learning. Pearson, 2016.
|
||
|
|
<!--ID: 1728558288130-->
|
||
|
|
END%%
|
||
|
|
|
||
|
|
%%ANKI
|
||
|
|
Basic
|
||
|
|
What two things does the `call` instruction do?
|
||
|
|
Back: It pushes the return address on the stack and updates the PC.
|
||
|
|
Reference: Bryant, Randal E., and David O'Hallaron. *Computer Systems: A Programmer's Perspective*. Third edition, Global edition. Always Learning. Pearson, 2016.
|
||
|
|
<!--ID: 1728558288148-->
|
||
|
|
END%%
|
||
|
|
|
||
|
|
%%ANKI
|
||
|
|
Basic
|
||
|
|
What two things does the `ret` instruction do?
|
||
|
|
Back: It pops the return address off the stack and updates the PC.
|
||
|
|
Reference: Bryant, Randal E., and David O'Hallaron. *Computer Systems: A Programmer's Perspective*. Third edition, Global edition. Always Learning. Pearson, 2016.
|
||
|
|
<!--ID: 1728558288160-->
|
||
|
|
END%%
|
||
|
|
|
||
|
|
%%ANKI
|
||
|
|
Basic
|
||
|
|
The operand forms of `call` mirror what other instruction class?
|
||
|
|
Back: `JMP`
|
||
|
|
Reference: Bryant, Randal E., and David O'Hallaron. *Computer Systems: A Programmer's Perspective*. Third edition, Global edition. Always Learning. Pearson, 2016.
|
||
|
|
<!--ID: 1728558288165-->
|
||
|
|
END%%
|
||
|
|
|
||
|
|
%%ANKI
|
||
|
|
Basic
|
||
|
|
A `call` instruction pushes what address onto the stack?
|
||
|
|
Back: That of the instruction following the `call` instruction.
|
||
|
|
Reference: Bryant, Randal E., and David O'Hallaron. *Computer Systems: A Programmer's Perspective*. Third edition, Global edition. Always Learning. Pearson, 2016.
|
||
|
|
<!--ID: 1728558288171-->
|
||
|
|
END%%
|
||
|
|
|
||
|
|
%%ANKI
|
||
|
|
Basic
|
||
|
|
What return address is pushed onto the stack after `call` is run?
|
||
|
|
```x86
|
||
|
|
1: ...
|
||
|
|
2: callq .L1
|
||
|
|
3: ...
|
||
|
|
```
|
||
|
|
Back: `3`
|
||
|
|
Reference: Bryant, Randal E., and David O'Hallaron. *Computer Systems: A Programmer's Perspective*. Third edition, Global edition. Always Learning. Pearson, 2016.
|
||
|
|
<!--ID: 1728558288177-->
|
||
|
|
END%%
|
||
|
|
|
||
|
|
%%ANKI
|
||
|
|
Basic
|
||
|
|
What address is the PC updated to after `call` is run?
|
||
|
|
```x86
|
||
|
|
1: ...
|
||
|
|
2: callq .L1
|
||
|
|
3: ...
|
||
|
|
```
|
||
|
|
Back: That corresponding to label `.L1`.
|
||
|
|
Reference: Bryant, Randal E., and David O'Hallaron. *Computer Systems: A Programmer's Perspective*. Third edition, Global edition. Always Learning. Pearson, 2016.
|
||
|
|
<!--ID: 1728558288183-->
|
||
|
|
END%%
|
||
|
|
|
||
|
|
%%ANKI
|
||
|
|
Basic
|
||
|
|
Which register(s) does a `call` instruction update?
|
||
|
|
Back: `%rsp` and `%rip`.
|
||
|
|
Reference: Bryant, Randal E., and David O'Hallaron. *Computer Systems: A Programmer's Perspective*. Third edition, Global edition. Always Learning. Pearson, 2016.
|
||
|
|
<!--ID: 1728559336730-->
|
||
|
|
END%%
|
||
|
|
|
||
|
|
%%ANKI
|
||
|
|
Basic
|
||
|
|
Which register(s) does a `ret` instruction update?
|
||
|
|
Back: `%rsp` and `%rip`.
|
||
|
|
Reference: Bryant, Randal E., and David O'Hallaron. *Computer Systems: A Programmer's Perspective*. Third edition, Global edition. Always Learning. Pearson, 2016.
|
||
|
|
<!--ID: 1728559336760-->
|
||
|
|
END%%
|
||
|
|
|
||
|
|
## Data Transfer
|
||
|
|
|
||
|
|
x86-64 employs 6 registers for passing integral (i.e. integer and pointer) arguments between caller and callee.
|
||
|
|
|
||
|
|
| Bits | Arg 1 | Arg2 | Arg3 | Arg4 | Arg5 | Arg6 |
|
||
|
|
| ---- | ------ | ------ | ------ | ------ | ------ | ------ |
|
||
|
|
| 64 | `%rdi` | `%rsi` | `%rdx` | `%rcx` | `%r8` | `%r9` |
|
||
|
|
| 32 | `%edi` | `%esi` | `%edx` | `%ecx` | `%r8d` | `%r9d` |
|
||
|
|
| 16 | `%di` | `%si` | `%dx` | `%cx` | `%r8w` | `%r9w` |
|
||
|
|
| 8 | `%dil` | `%sil` | `%dl` | `%cl` | `%r8b` | `%r9b` |
|
||
|
|
|
||
|
|
%%ANKI
|
||
|
|
Basic
|
||
|
|
How many registers are available for passing integral arguments between procedures?
|
||
|
|
Back: `6`
|
||
|
|
Reference: Bryant, Randal E., and David O'Hallaron. *Computer Systems: A Programmer's Perspective*. Third edition, Global edition. Always Learning. Pearson, 2016.
|
||
|
|
<!--ID: 1728559336766-->
|
||
|
|
END%%
|
||
|
|
|
||
|
|
%%ANKI
|
||
|
|
Basic
|
||
|
|
How many bytes make up the `%rdi` register?
|
||
|
|
Back: $8$
|
||
|
|
Reference: Bryant, Randal E., and David O'Hallaron. *Computer Systems: A Programmer's Perspective*. Third edition, Global edition. Always Learning. Pearson, 2016.
|
||
|
|
<!--ID: 1728559336770-->
|
||
|
|
END%%
|
||
|
|
|
||
|
|
%%ANKI
|
||
|
|
Basic
|
||
|
|
How many bytes make up the `%di` register?
|
||
|
|
Back: $2$
|
||
|
|
Reference: Bryant, Randal E., and David O'Hallaron. *Computer Systems: A Programmer's Perspective*. Third edition, Global edition. Always Learning. Pearson, 2016.
|
||
|
|
<!--ID: 1728559336774-->
|
||
|
|
END%%
|
||
|
|
|
||
|
|
%%ANKI
|
||
|
|
Basic
|
||
|
|
How many bytes make up the `%dil` register?
|
||
|
|
Back: $1$
|
||
|
|
Reference: Bryant, Randal E., and David O'Hallaron. *Computer Systems: A Programmer's Perspective*. Third edition, Global edition. Always Learning. Pearson, 2016.
|
||
|
|
<!--ID: 1728559336779-->
|
||
|
|
END%%
|
||
|
|
|
||
|
|
%%ANKI
|
||
|
|
Basic
|
||
|
|
How many bytes make up the `%edi` register?
|
||
|
|
Back: $4$
|
||
|
|
Reference: Bryant, Randal E., and David O'Hallaron. *Computer Systems: A Programmer's Perspective*. Third edition, Global edition. Always Learning. Pearson, 2016.
|
||
|
|
<!--ID: 1728559336782-->
|
||
|
|
END%%
|
||
|
|
|
||
|
|
%%ANKI
|
||
|
|
Cloze
|
||
|
|
By convention, register {`%rdi`} is used for {the first integral argument}.
|
||
|
|
Reference: Bryant, Randal E., and David O'Hallaron. *Computer Systems: A Programmer's Perspective*. Third edition, Global edition. Always Learning. Pearson, 2016.
|
||
|
|
<!--ID: 1728559336787-->
|
||
|
|
END%%
|
||
|
|
|
||
|
|
%%ANKI
|
||
|
|
Cloze
|
||
|
|
{1:Words} are to {2:`%di`} whereas {2:double words} are to {1:`%edi`}.
|
||
|
|
Reference: Bryant, Randal E., and David O'Hallaron. *Computer Systems: A Programmer's Perspective*. Third edition, Global edition. Always Learning. Pearson, 2016.
|
||
|
|
<!--ID: 1728559336792-->
|
||
|
|
END%%
|
||
|
|
|
||
|
|
%%ANKI
|
||
|
|
Cloze
|
||
|
|
{1:Bytes} are to {2:`%dil`} whereas {2:quad words} are to {1:`%rdi`}.
|
||
|
|
Reference: Bryant, Randal E., and David O'Hallaron. *Computer Systems: A Programmer's Perspective*. Third edition, Global edition. Always Learning. Pearson, 2016.
|
||
|
|
<!--ID: 1728559336797-->
|
||
|
|
END%%
|
||
|
|
|
||
|
|
%%ANKI
|
||
|
|
Basic
|
||
|
|
How do you access the low-order 2 bytes of `%rdi`?
|
||
|
|
Back: By using `%di`.
|
||
|
|
Reference: Bryant, Randal E., and David O'Hallaron. *Computer Systems: A Programmer's Perspective*. Third edition, Global edition. Always Learning. Pearson, 2016.
|
||
|
|
<!--ID: 1728559336802-->
|
||
|
|
END%%
|
||
|
|
|
||
|
|
%%ANKI
|
||
|
|
Basic
|
||
|
|
How do you access the low-order 4 bytes of `%rdi`?
|
||
|
|
Back: By using `%edi`.
|
||
|
|
Reference: Bryant, Randal E., and David O'Hallaron. *Computer Systems: A Programmer's Perspective*. Third edition, Global edition. Always Learning. Pearson, 2016.
|
||
|
|
<!--ID: 1728559336808-->
|
||
|
|
END%%
|
||
|
|
|
||
|
|
%%ANKI
|
||
|
|
Basic
|
||
|
|
How do you access the low-order byte of `%rdi`?
|
||
|
|
Back: By using `%dil`.
|
||
|
|
Reference: Bryant, Randal E., and David O'Hallaron. *Computer Systems: A Programmer's Perspective*. Third edition, Global edition. Always Learning. Pearson, 2016.
|
||
|
|
<!--ID: 1728559336813-->
|
||
|
|
END%%
|
||
|
|
|
||
|
|
%%ANKI
|
||
|
|
Basic
|
||
|
|
Which register should the first integral argument of a procedure be placed in?
|
||
|
|
Back: `%rdi`
|
||
|
|
Reference: Bryant, Randal E., and David O'Hallaron. *Computer Systems: A Programmer's Perspective*. Third edition, Global edition. Always Learning. Pearson, 2016.
|
||
|
|
<!--ID: 1728559336817-->
|
||
|
|
END%%
|
||
|
|
|
||
|
|
%%ANKI
|
||
|
|
Basic
|
||
|
|
From smallest to largest, list the four "first integral argument" registers.
|
||
|
|
Back: `%dil`, `%di`, `%edi`, and `%rdi`.
|
||
|
|
Reference: Bryant, Randal E., and David O'Hallaron. *Computer Systems: A Programmer's Perspective*. Third edition, Global edition. Always Learning. Pearson, 2016.
|
||
|
|
<!--ID: 1728559336823-->
|
||
|
|
END%%
|
||
|
|
|
||
|
|
%%ANKI
|
||
|
|
Basic
|
||
|
|
How many bytes make up the `%rsi` register?
|
||
|
|
Back: $8$
|
||
|
|
Reference: Bryant, Randal E., and David O'Hallaron. *Computer Systems: A Programmer's Perspective*. Third edition, Global edition. Always Learning. Pearson, 2016.
|
||
|
|
<!--ID: 1728559336829-->
|
||
|
|
END%%
|
||
|
|
|
||
|
|
%%ANKI
|
||
|
|
Basic
|
||
|
|
How many bytes make up the `%si` register?
|
||
|
|
Back: $2$
|
||
|
|
Reference: Bryant, Randal E., and David O'Hallaron. *Computer Systems: A Programmer's Perspective*. Third edition, Global edition. Always Learning. Pearson, 2016.
|
||
|
|
<!--ID: 1728559336834-->
|
||
|
|
END%%
|
||
|
|
|
||
|
|
%%ANKI
|
||
|
|
Basic
|
||
|
|
How many bytes make up the `%sil` register?
|
||
|
|
Back: $1$
|
||
|
|
Reference: Bryant, Randal E., and David O'Hallaron. *Computer Systems: A Programmer's Perspective*. Third edition, Global edition. Always Learning. Pearson, 2016.
|
||
|
|
<!--ID: 1728559336838-->
|
||
|
|
END%%
|
||
|
|
|
||
|
|
%%ANKI
|
||
|
|
Basic
|
||
|
|
How many bytes make up the `%esi` register?
|
||
|
|
Back: $4$
|
||
|
|
Reference: Bryant, Randal E., and David O'Hallaron. *Computer Systems: A Programmer's Perspective*. Third edition, Global edition. Always Learning. Pearson, 2016.
|
||
|
|
<!--ID: 1728559336843-->
|
||
|
|
END%%
|
||
|
|
|
||
|
|
%%ANKI
|
||
|
|
Cloze
|
||
|
|
By convention, register {`%rsi`} is used for {the second integral argument}.
|
||
|
|
Reference: Bryant, Randal E., and David O'Hallaron. *Computer Systems: A Programmer's Perspective*. Third edition, Global edition. Always Learning. Pearson, 2016.
|
||
|
|
<!--ID: 1728559336847-->
|
||
|
|
END%%
|
||
|
|
|
||
|
|
%%ANKI
|
||
|
|
Cloze
|
||
|
|
{1:Words} are to {2:`%si`} whereas {2:double words} are to {1:`%esi`}.
|
||
|
|
Reference: Bryant, Randal E., and David O'Hallaron. *Computer Systems: A Programmer's Perspective*. Third edition, Global edition. Always Learning. Pearson, 2016.
|
||
|
|
<!--ID: 1728559336852-->
|
||
|
|
END%%
|
||
|
|
|
||
|
|
%%ANKI
|
||
|
|
Cloze
|
||
|
|
{1:Bytes} are to {2:`%sil`} whereas {2:quad words} are to {1:`%rsi`}.
|
||
|
|
Reference: Bryant, Randal E., and David O'Hallaron. *Computer Systems: A Programmer's Perspective*. Third edition, Global edition. Always Learning. Pearson, 2016.
|
||
|
|
<!--ID: 1728559336856-->
|
||
|
|
END%%
|
||
|
|
|
||
|
|
%%ANKI
|
||
|
|
Basic
|
||
|
|
How do you access the low-order 2 bytes of `%rsi`?
|
||
|
|
Back: By using `%si`.
|
||
|
|
Reference: Bryant, Randal E., and David O'Hallaron. *Computer Systems: A Programmer's Perspective*. Third edition, Global edition. Always Learning. Pearson, 2016.
|
||
|
|
<!--ID: 1728559336860-->
|
||
|
|
END%%
|
||
|
|
|
||
|
|
%%ANKI
|
||
|
|
Basic
|
||
|
|
How do you access the low-order 4 bytes of `%rsi`?
|
||
|
|
Back: By using `%esi`.
|
||
|
|
Reference: Bryant, Randal E., and David O'Hallaron. *Computer Systems: A Programmer's Perspective*. Third edition, Global edition. Always Learning. Pearson, 2016.
|
||
|
|
<!--ID: 1728559336864-->
|
||
|
|
END%%
|
||
|
|
|
||
|
|
%%ANKI
|
||
|
|
Basic
|
||
|
|
How do you access the low-order byte of `%rsi`?
|
||
|
|
Back: By using `%sil`.
|
||
|
|
Reference: Bryant, Randal E., and David O'Hallaron. *Computer Systems: A Programmer's Perspective*. Third edition, Global edition. Always Learning. Pearson, 2016.
|
||
|
|
<!--ID: 1728559336868-->
|
||
|
|
END%%
|
||
|
|
|
||
|
|
%%ANKI
|
||
|
|
Basic
|
||
|
|
Which register should the second integral argument of a procedure be placed in?
|
||
|
|
Back: `%rsi`
|
||
|
|
Reference: Bryant, Randal E., and David O'Hallaron. *Computer Systems: A Programmer's Perspective*. Third edition, Global edition. Always Learning. Pearson, 2016.
|
||
|
|
<!--ID: 1728559336872-->
|
||
|
|
END%%
|
||
|
|
|
||
|
|
%%ANKI
|
||
|
|
Basic
|
||
|
|
From smallest to largest, list the four "second integral argument" registers.
|
||
|
|
Back: `%sil`, `%si`, `%esi`, and `%rsi`.
|
||
|
|
Reference: Bryant, Randal E., and David O'Hallaron. *Computer Systems: A Programmer's Perspective*. Third edition, Global edition. Always Learning. Pearson, 2016.
|
||
|
|
<!--ID: 1728559336876-->
|
||
|
|
END%%
|
||
|
|
|
||
|
|
%%ANKI
|
||
|
|
Cloze
|
||
|
|
{1:`%rdi`} is to the {2:first} integral argument whereas {2:`%rsi`} is to the {1:second} integral argument.
|
||
|
|
Reference: Bryant, Randal E., and David O'Hallaron. *Computer Systems: A Programmer's Perspective*. Third edition, Global edition. Always Learning. Pearson, 2016.
|
||
|
|
<!--ID: 1728559336879-->
|
||
|
|
END%%
|
||
|
|
|
||
|
|
## Bibliography
|
||
|
|
|
||
|
|
* Bryant, Randal E., and David O'Hallaron. *Computer Systems: A Programmer's Perspective*. Third edition, Global edition. Always Learning. Pearson, 2016.
|