Binary Loader's bug

[coyotebean]

The thing is ABI & EABI defines that only s registers are preserved. Any software (compilers) compliance to the standard will ignore the value of other registers returned in a function.

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[m0skit0]

You already said that before. We're talking about two different levels. You're talking about ABI and I'm talking about C prototypes. Yes, aX can be modified, but if a C prototype declares them by value, the C compiler (because it's a C compiler, it should enforce C protocols, on top of ABI ones) should make sure they're not modified. If the arguments were passed by reference, they can be modified. That's why the ABI leaves aX as modifiable by callee: it's defined on a higher level (like C).

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[wololo]

I don't really understand why you think a compiled C program should stick to the ABI rules, as long as gcc knows it's equivalent, I think you can trust it.
Or am I missing a bigger problem here?

Edit: It could be that parameters such as -O allow your C compiler to not follow some rules that would hurt performance.

[m0skit0]

I don't really understand why you think a compiled C program should stick to the ABI rules

In fact, the C compiler also MUST preserve the ABI rules, but also the C rules. They're layers. First is the ABI set of rules, then the C set of rules, and so on. I hope this clears what I mean.

Edit: It could be that parameters such as -O allow your C compiler to not follow some rules that would hurt performance.

I don't think you can skip ABI & C rules by using compiler parameters. AFAIK GCC optimization flags only adapt your code to be optimized based on the ABI and C rules.