Clarify syscall ABI. Clear caller saved regs.

gsilvis / silvos

half-baked Silvis OS kernel

MIT License

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Clarify syscall ABI. Clear caller saved regs. #62

Closed allanlw closed 7 years ago

allanlw commented 7 years ago

This fixes #2

gsilvis commented 7 years ago

Ugh, this is really persnickety, but we technically need to make sure we're not leaking information in the top half of %rax, which won't necessarily get written to when returning an int.

allanlw commented 7 years ago

Yeah I considered that but don't have a good answer.

Maybe there should really be a series of trampoline functions for wrapping syscalls in? Also it would be really nice to have a way to programmatically catch regressions here.