Improve first chapter #27
Open
Conversation
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
0xAX
force-pushed
the
chapter-1-update
branch
2 times, most recently
from
42a39fc
to
ce606fa
Compare
klaudiagrz
reviewed
Jun 22, 2024
|
Hi ! I started working on rewording the first article, but then saw you already had a big head start. |
klaudiagrz
reviewed
Jul 15, 2024
| - `rsi` - Used to pass `2nd` argument to a function. | ||
| - `rdx` - Used to pass `3rd` argument to a function. | ||
|
|
||
| There is more details related to the Linux `x86_64` calling conventions but the description above should be enough for now. Knowing the meaning and the way of use of these registers we can return to the code. What do we need to write a `hello world` program? Usually we just pass a `hello world` string to a library function like [printf](https://en.wikipedia.org/wiki/Printf) or so. But these functions usually goes from a [standard library](https://en.wikipedia.org/wiki/Standard_library) of a programming languages we are using. Assembly does not have a standard library. What to do in this case? Well, we have at least the two following approaches: |
There was a problem hiding this comment.
Suggested change
| There is more details related to the Linux `x86_64` calling conventions but the description above should be enough for now. Knowing the meaning and the way of use of these registers we can return to the code. What do we need to write a `hello world` program? Usually we just pass a `hello world` string to a library function like [printf](https://en.wikipedia.org/wiki/Printf) or so. But these functions usually goes from a [standard library](https://en.wikipedia.org/wiki/Standard_library) of a programming languages we are using. Assembly does not have a standard library. What to do in this case? Well, we have at least the two following approaches: | |
| This knowledge about Linux `x86_64` calling conventions should be enough for now. Knowing the meaning and the usage of the registers, we can return to the code. What do we need to write a `hello world` program? Usually, we just pass a `hello world` string to a library function like [printf](https://en.wikipedia.org/wiki/Printf). But this function usually goes from a [standard library](https://en.wikipedia.org/wiki/Standard_library) of a programming language we use. Assembly does not have a standard library. What to do in this case? Well, we have at least two options: |
There was a problem hiding this comment.
this function usually goes from...
I don't like "goes from", can we replace it with another verb?
| - Link our assembly program with C standard library and use [printf](https://man7.org/linux/man-pages/man3/printf.3.html) or any other function that may help us to write a text to the [standard output](https://en.wikipedia.org/wiki/Standard_streams). | ||
| - Use the operating system API | ||
|
|
||
| We will go through the second way. Each operating system provides an interface that a user level application may use to interact with the operating system. Usually the functions of this API are called `system calls`. Linux kernel also provides set of system calls to interact with it. The full list of system calls with the respective numbers for the Linux `x86_64` could be found [here](https://github.com/torvalds/linux/blob/master/arch/x86/entry/syscalls/syscall_64.tbl). Looking in this table, we may see: |
There was a problem hiding this comment.
Maybe it's good to mention why we do not explain the first option?
Signed-off-by: Alexander Kuleshov <[email protected]>
Signed-off-by: Alexander Kuleshov <[email protected]>
Signed-off-by: Alexander Kuleshov <[email protected]>
Signed-off-by: Alexander Kuleshov <[email protected]>
Signed-off-by: Alexander Kuleshov <[email protected]>
Signed-off-by: Alexander Kuleshov <[email protected]>
Signed-off-by: Alexander Kuleshov <[email protected]>
0xAX
force-pushed
the
chapter-1-update
branch
3 times, most recently
from
eb6f132
to
4b8ead1
Compare
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
Add this suggestion to a batch that can be applied as a single commit.
This suggestion is invalid because no changes were made to the code.
Suggestions cannot be applied while the pull request is closed.
Suggestions cannot be applied while viewing a subset of changes.
Only one suggestion per line can be applied in a batch.
Add this suggestion to a batch that can be applied as a single commit.
Applying suggestions on deleted lines is not supported.
You must change the existing code in this line in order to create a valid suggestion.
Outdated suggestions cannot be applied.
This suggestion has been applied or marked resolved.
Suggestions cannot be applied from pending reviews.
Suggestions cannot be applied on multi-line comments.
Suggestions cannot be applied while the pull request is queued to merge.
Suggestion cannot be applied right now. Please check back later.
This PR provides significant rework for the first chapter.