Is there any situation where you’d want to remember the opcodes? Disassemblers should give you user-friendly assembly code, without any need to look at the raw numbers. Maybe it’s useful to remember which instructions are pseudo instructions (so you know stuff like
jz(jump if zero) being the same asje(jump if equal) making it easier to understand the disassembly), but I don’t think you need to remember the opcode numbers for that.Edit: Maybe with malware analysis where the malware in question may be obfuscated in interesting ways to make the job of binary analysis harder?
The important thing is to be important. Engineering has to deal with teammates that don’t have these problems, so they equalize.
I mean I’m only missing int3
I didn’t even know they released int2
You guys have int?
I’ve got intelligible but that’s about it
It’s one of my six dump stats.
Bro missing the wis gains
I rolled a 14, so I have a +2 modifier.
I think it is 0xCC, or in long form 0xCD03
You’re sixteen, you’re beautiful, I’m under arrest
what ? I’m nowhere near sixteen
I love that I’m getting downvoted for a Ringo Starr reference
It’s insane how close that handwriting is to randall’s, did he make multiple versions of this comic or was this written by a professional forger?
There was that one comic that Randall did (Lorenz) where you could choose one of several paths and write your own text in the last panel. In order to implement that Randall had to create a font of his own handwriting. I wouldn’t be surprised if OP just ripped the .woff file or similar.
For context, here’s the original comic:
Holy shit. I remembered the original comic, but didn’t remember what the subject matter of it was. So if you hadn’t left this comment, I would have just gone on believing that the OP’s version was Randall’s version.
Yeah, I’ve seen people riff on xkcd comics before but they usually do a bad job of matching the handwriting/font (I don’t know if Randall hand-letters these or if he types in a handwritey font). It’s often a deliberately bad job, because indicating that they are changing the original is a part of the message/artistic expression. Like when a word is covered with a black bar with white letters in it in a different font, an obvious revision, it’s like hearing a different voice interrupt.
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Their format and style makes them highly meme-able.
Why does it not surprise me at all that this exists?
Wait, that’s actually a great font
They are talking about computer things, that’s about how familiar I am with whatever they are talking about.
Yeah, it’s intentionally obscure. Basically, x86 assembly code is a way of telling a processor what to calculate, at a very low level.
So, it’s similar to programming languages, but those actually get translated into x86 assembly code, before it’s told to the processor. (“x86” is a certain processor architecture. Others exist, too, most prominently “ARM”.)But yeah, even with me knowing that much, I’d need to guess what
retandint3might do.Everyone knows
jmpandnop, though, of course. 🙃That’s the exact same thing. x86 Assembly Code isn’t that hard(to know what it is, understanding it is something different),but I havent heard of the other stuff.
return from subroutine, int3 would be something relating to interrupts off the top of my head.Int3 is a special single-byte (CC, if I recall correctly) form of the INT instruction (which is CD imm8, I think) to raise an interrupt. Interrupt #3 is the debugging interrupt, so by overwriting any instruction with CC, you place a breakpoint there.
Of course
There’s an old joke about two mathematicians in a cafe. They’re arguing about whether ordinary people understand basic mathematics. The first mathematician says yes, of course they do! And the second disagrees.
The second mathematician goes to the toilet, and the first calls over their blonde waitress. He says to her, "in a minute my friend is going to come back from the toilet, and I’m going to ask you a question. I want you to reply, “one third x cubed.'”
“One ther desque,” she repeats.
“One third x cubed,” the mathematician tries again.
“One thir dek scubed.”
“That’ll do,” he says, and she heads off. The second mathematician returns from the toilet and the first lays him a challenge. “I’ll prove it. I’ll call over that blonde waitress and ask her a simple integration question, and see if she can answer.” The second mathematician agrees, and they call her over.
“My friend and I have a question,” the first mathematician asks the waitress. “Do you know what is the integral of x squared?”
“One thir dek scubed,” she answers and the second mathematician is impressed and concedes the point.
And as she walks away, the waitress calls over her shoulder,
“Plus a constant.”
I would not consider integration to be basic maths, honestly. Basic maths is addition and multiplication, and maybe vector geometry.
You probably wouldn’t consider x86 opcodes to be basic computer literacy either ;-)
I mean who hasnt watched “Assembly Language in 100 seconds” by Fireship
Just looked this up and subscribed to the channel.
Blue collar fucking aircraft worker and I get it.
I recently took a class on ARM assembly, and yet I don’t even know half of these x86 instructions.
‘I recently took a french class, and yet I don’t even know half of these german words’
I had 5 years of Latin classes and I still know lipke 19 Latin words.
Lupus vorat agnum = my tailor is rich
there’s your rosetta stoned
Ubi est Quintus? Quintus in Hortus est. Quinte, Quinte, Caecilia clamat. - where is Quintus? Quintus is in the garden. Quintus Quintus shouts Caecilia.
Those were the First three sentences from my first Latin Book. I still know them.
It still confuses what basic computer skills the average person lacks. Like, how are you even supposed to troubleshoot your computer, if you don’t know the basics about your computer?
you don’t you just call the most technical person you know and ask them to do it
You got a point there. I also regularly forget that you don’t have to know shit about PCs do use windows/Mac.
Everyone has a limited time on this earth. Some of us don’t mind or actively enjoy spending that time learning about the technology we use. Others, not so much. I think this comic is really spot on because it’s hard to understand as a tech literate person just how little other people may know. “What browser are you using?” “What’s a browser?”
The foundational knowledge is not that tough, but when you’re just interested in getting the damn thing to work so you can get on with your life, it’s easy to get frustrated by having to take a crash course on what the hell a BIOS is before you can try to fix it. And when you learn all that just for it to still be broken, patience quickly runs out.
As long as people have the general understanding that power cycling will solve a good 75% of issues, I’m happy. I hope people give me the same grace when I pay a someone to fix my car or replace my phone screen (I love building computers, but god I hate working on phones).
For the phone bit, I started off with really old smartphones like a Galaxy S1, but basically any old old phones are really built like mini laptops and are usually pretty modular as they weren’t often water resistant or actively anti-repair
However I fully get your point and fall into the same boat with cars
Dude I’m the same with my car.
I mean, cars can be demystified the same way computers can: By building and maintaining it yourself. Everyone is afraid to build their first computer, because it seems way too complicated and delicate. Then you actually build your first one, and go “oh hey this actually isn’t so bad after all.”
Yes, cars (especially modern cars) have a lot more difficult-to-build parts. But modern cars are also a lot like computers in the sense that you don’t need to know every single component on an GPU to be able to install one. You don’t need to be able to build a car part from scratch. The same way you can slot a GPU into a motherboard, you can just buy the entire car part preassembled and bolt it into place. The important part is learning what the different components do, so you can troubleshoot them.
Problem is I have zero interest in cars. If I could I’d live car free.
As a bytecode tinkerer, I’d say considering NOP to be global knowledge is a slippery slope.
Might want a sled and a ROPe to have a smooth descent
Careful you aren’t thrown off by a retpoline
Just yesterday I ran into some chucklehead here on Lemmy that had convinced themselves that the average person would interpret “crypto” to mean SSL rather than cryptocurrency.
I had one last week here on claiming the average person could feed themselves for years by growing cherry tomatoes from 6 tiny plants. Bro is supposed to be a big-time agricultural bigwig
As a small time backyard gardener I can say from experience that 4 plants made more cherry tomatoes than I could reasonably eat. I was giving ziplock bags of cherry tomatoes away to people at work for a couple months. They probably did produce a year’s worth of cherry tomatoes, but they don’t refrigerate or freeze particularly well and they’re not a great choice for making tomato sauce because of their liquid/pulp/skin ratio.
Similarly I’ve found that I can grow a year’s supply of red pepper flakes with a whopping two cayenne plants. The rate at which I consume red pepper flakes, I’m about out by the time this year’s peppers start ripening.
I’m able, in my tiny little garden, to grow more of single kinds of foods than I can reasonably eat. I cannot grow enough to sustain my entire diet; I’d need more land than I own to grow grain.
Makes sense. Human beings don’t actually need proteins or fats.
Proteins and fats are for the weak. ARE YOU A FUCKING WEAK LOOSER?? No? THEN WHATS STOPPING YOU???
At least dead ones dont
Cherry tomatoes are the things you put in a salad at a restaurant to feel healthy, then pick them out once you get back to the table.
What? Cherry tomatoes are good
For compost, yeah
Wut? Are we talking about one of those “salads” with mayo, eggs, bacon strips, croutons, sugary dressing and whatnot?
Because if not, then cherry tomatoes are going to be pretty much the sweetest thing you’ll find for your salad. I’d definitely still call them healthy, but not more so than the other ingredients of a salad…
Yep, that’s pretty much the standard salad where I live. Most people understand that’s not really healthy, but it still feels healthier than bread sticks and butter. The cherry tomatoes are the extra convincing we need to actually call it “healthy”
Look I’m not saying you’re wrong or anything just that I really don’t appreciate you stalking me.
That seems like the opposite problem
Holy shit that was weird.
I saw that thread, I think. Or the same person in another thread talking about the same thing.
That’s ludicrous.
It obviously stands for cryptography in general, not just TLS.
You know, I think I agree with the spirit of that assertion but not the letter of that assertion.
There are people who are kind of at their limit knowing that on your phone there’s a Facebook app, but you have to use your browser and go to the website on a computer. These folks will hear dial tones and TV static in their heads if you say “secure socket layer” to them. These folks have probably also sat through NordVPN ads and heard words like “secure” and “encrypted” used together, and will probably make understandable mistakes like “how’d someone steal bitcoins? I thought it was encrypted?”
You mean things like Bigfoot?
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That’s the one
Now I want to know what int3 does.
https://en.wikipedia.org/wiki/INT_(x86_instruction) (scroll down to INT3)
https://stackoverflow.com/a/61946177
The TL;DR is that it’s used by debuggers to set a breakpoint in code.
For example, if you’re familiar with gdb, one of the simplest ways to make code stop executing at a particular point in the code is to add a breakpoint there.
Gdb replaces the instruction at the breakpoint with 0xCC, which happens to be the opcode for INT 3 — generate interrupt 3. When the CPU encounters the instruction, it generates interrupt 3, following which the kernel’s interrupt handler sends a signal (SIGTRAP) to the debugger. Thus, the debugger will know it’s meant to start a debugging loop there.
Hey thank you!
Not what I thought it was for sure 😃
How does it work if an instruction gets replaced by the INT3 though?
Excellent question!
Before replacing the instruction with INT 3, the debugger keeps a note of what instruction was at that point in the code. When the CPU encounters INT 3, it hands control to the debugger.
When the debugging operations are done, the debugger replaces the INT 3 with the original instruction and makes the instruction pointer go back one step, thereby ensuring that the original instruction is executed.
Whoo that seems complicated, I mean you akready compile a debug version.
Thanks for the explanation!
The debug version you compile doesn’t affect the code; it just stores more information about symbols. The whole shtick about the debugger replacing instructions with INT3 still happens.
You can validate that the code isn’t affected yourself by running objdump on two binaries, one compiled with debug symbols and one without. Otherwise if you’re lazy (like me 😄):
https://stackoverflow.com/a/8676610
And for completeness: https://gcc.gnu.org/onlinedocs/gcc-14.1.0/gcc/Debugging-Options.html
Thanks, excellent information!
How come debug exes are bigger? Is the nifty stuff tucked on at the end?
Here’s the source:
And the alt text:
How could anyone consider themselves a well-rounded adult without a basic understanding of silicate geochemistry? Silicates are everywhere! It’s hard to throw a rock without throwing one!
I’m pretty sure I’ve had this exact conversation. Took me a minute to understand what the point was.
NOP
0x90
