Re: System Call trashing registers

[Thomas Gleixner]

On Fri, Sep 01 2023 at 10:38, Joshua Hudson wrote:
> On Fri, Sep 1, 2023 at 9:24 AM Ammar Faizi <ammarfaizi2@xxxxxxxxxxx> wrote:
>
> Correction: it's been fixed again. Sorry about that.

When exactly was it broken? Which kernel version?

The save/restore mechanism is not changing every other day.

> I know the asmutils tools have been broken for a decade, but they're
> working now.
>
> What would happen is system calls that take arguments in ecx and edx would find
> ecx and edx trashed, but only a few calls actually did this, the
> primary offender
> being open(). The best regression test seems to be hexdump from
> asmutils because the
> corruption would reliably crash the binary. sched_yeild was never an
> affected syscall.

It does absolutely not matter which syscall is used. The save/restore
mechanism is identical for all syscalls.

Thanks,

        tglx