On Fri, Jan 14, 2022 at 6:18 AM Peter Maydell <peter.maydell@linaro.org>
wrote:

> On Sun, 9 Jan 2022 at 17:08, Warner Losh <imp@bsdimp.com> wrote:
> >
> > Implement the meat of the sigaltstack(2) system call with do_sigaltstack.
> >
> > Signed-off-by: Stacey Son <sson@FreeBSD.org>
> > Signed-off-by: Kyle Evans <kevans@freebsd.org>
> > Signed-off-by: Warner Losh <imp@bsdimp.com>
> > ---
> >  bsd-user/qemu.h   |  1 +
> >  bsd-user/signal.c | 66 +++++++++++++++++++++++++++++++++++++++++++++++
> >  2 files changed, 67 insertions(+)
> >
> > diff --git a/bsd-user/qemu.h b/bsd-user/qemu.h
> > index c643d6ba246..fcdea460ed2 100644
> > --- a/bsd-user/qemu.h
> > +++ b/bsd-user/qemu.h
> > @@ -226,6 +226,7 @@ int host_to_target_signal(int sig);
> >  void host_to_target_sigset(target_sigset_t *d, const sigset_t *s);
> >  void target_to_host_sigset(sigset_t *d, const target_sigset_t *s);
> >  long do_sigreturn(CPUArchState *regs, abi_ulong addr);
> > +abi_long do_sigaltstack(abi_ulong uss_addr, abi_ulong uoss_addr,
> abi_ulong sp);
> >  int do_sigaction(int sig, const struct target_sigaction *act,
> >                  struct target_sigaction *oact);
> >  void QEMU_NORETURN force_sig(int target_sig);
> > diff --git a/bsd-user/signal.c b/bsd-user/signal.c
> > index f055d1db407..e5e5e28c60c 100644
> > --- a/bsd-user/signal.c
> > +++ b/bsd-user/signal.c
> > @@ -528,6 +528,72 @@ static void host_signal_handler(int host_sig,
> siginfo_t *info, void *puc)
> >      cpu_exit(thread_cpu);
> >  }
> >
> > +/* do_sigaltstack() returns target values and errnos. */
> > +/* compare to kern/kern_sig.c sys_sigaltstack() and kern_sigaltstack()
> */
> > +abi_long do_sigaltstack(abi_ulong uss_addr, abi_ulong uoss_addr,
> abi_ulong sp)
> > +{
> > +    int ret;
> > +    target_stack_t oss;
> > +
> > +    if (uoss_addr) {
> > +        /* Save current signal stack params */
> > +        oss.ss_sp = tswapl(target_sigaltstack_used.ss_sp);
> > +        oss.ss_size = tswapl(target_sigaltstack_used.ss_size);
> > +        oss.ss_flags = tswapl(sas_ss_flags(sp));
> > +    }
>
> This will need some minor changes to work with the sigaltstack
> info being per-thread and in the TaskState struct.
>

Yes. Moving it into the TaskState was easy and got rid if the global.
Thanks for that suggestion earlier in the patch series.

Warrner