sparc/ppc/arm compat siginfo ABI regressions: sending SIGFPE via kill() returns wrong values in si_pid and si_uid

[Linus Torvalds]

On Fri, Apr 13, 2018 at 10:54 AM, Russell King - ARM Linux
<linux at armlinux.org.uk> wrote:
>
> FPE_FLTINV means "floating point invalid operation".  Does it really
> cover the case where hardware has failed, or is it intended to cover
> the case where userspace did something wrong and asked for an invalid
> operation from the FP hardware?

Note that the number of people who actually look at the si_code is
approximately zero.

But the ones that _do_ check the si_code are certainly not going to
check it against a new code that they don't know about.

I suspect that if you start searching for FLT_xyz occurrences in code,
approximately 100% of them are from the kernel code that generates
them, not from any actual users.

So I'd be very surprised if you can find *anybody* who cares about
that exact value (with the possible exceptions of test-suites).

Sadly, google code-search is no more. It was useful for things like that.

                Linus