Re: [PATCH 11/30] bsd-user/host/arm/host-signal.h: Implement host_signal_*

[Peter Maydell]

On Sun, 9 Jan 2022 at 16:33, Warner Losh <imp@bsdimp.com> wrote:
>
> Implement host_signal_pc, host_signal_set_pc and host_signal_write for
> arm.
>
> Signed-off-by: Kyle Evans <kevans@freebsd.org>
> Signed-off-by: Warner Losh <imp@bsdimp.com>

> +static inline bool host_signal_write(siginfo_t *info, ucontext_t *uc)
> +{
> +    /*
> +     * In the FSR, bit 11 is WnR. FreeBSD returns this as part of the
> +     * si_info.si_trapno which we don't have access to here.  We assume that 
> uc
> +     * is part of a trapframe and reach around to get to the si_info that's 
> in
> +     * the sigframe just before it, though this may be unwise.
> +     */

Yeah, that's pretty nasty. But this function is passed a
siginfo_t pointer -- isn't that the one you need ?

> +    siginfo_t *si;
> +    si = &((siginfo_t *)uc)[-1];
> +    uint32_t fsr = si->si_trapno;
> +
> +    return extract32(fsr, 11, 1);
> +}

thanks
-- PMM