Re: [Qemu-ppc] [Qemu-devel] [PATCH] linux-user: fill target sigcontext struct accordingly

[David Gibson]

On Tue, Feb 28, 2017 at 11:22:54AM +0100, Laurent Vivier wrote:
> Le 28/02/2017 à 02:09, David Gibson a écrit :
> > On Wed, Feb 01, 2017 at 09:43:57PM +0100, Laurent Vivier wrote:
> >> Le 31/01/2017 à 23:05, Jose Ricardo Ziviani a écrit :
> >>> A segfault is noticed when an emulated program uses any of ucontext
> >>> regs fields. Risu detected this issue in the following operation when
> >>> handling a signal:
> >>>   ucontext_t *uc = (ucontext_t*)uc;
> >>>   uc->uc_mcontext.regs->nip += 4;
> >>>
> >>> but this works fine:
> >>>   uc->uc_mcontext.gp_regs[PT_NIP] += 4;
> >>>
> >>> This patch set regs to a valid location as well as other sigcontext
> >>> fields.
> >>>
> >>> Signed-off-by: Jose Ricardo Ziviani <address@hidden>
> >>> ---
> >>>  linux-user/signal.c | 5 +++++
> >>>  1 file changed, 5 insertions(+)
> >>>
> >>> diff --git a/linux-user/signal.c b/linux-user/signal.c
> >>> index 5064de0..8209539 100644
> >>> --- a/linux-user/signal.c
> >>> +++ b/linux-user/signal.c
> >>> @@ -5155,6 +5155,7 @@ static void setup_rt_frame(int sig, struct 
> >>> target_sigaction *ka,
> >>>      target_ulong rt_sf_addr, newsp = 0;
> >>>      int i, err = 0;
> >>>  #if defined(TARGET_PPC64)
> >>> +    struct target_sigcontext *sc = 0;
> >>>      struct image_info *image = ((TaskState *)thread_cpu->opaque)->info;
> >>>  #endif
> >>>  
> >>> @@ -5183,6 +5184,10 @@ static void setup_rt_frame(int sig, struct 
> >>> target_sigaction *ka,
> >>>  #if defined(TARGET_PPC64)
> >>>      mctx = &rt_sf->uc.tuc_sigcontext.mcontext;
> >>>      trampptr = &rt_sf->trampoline[0];
> >>> +
> >>> +    sc = &rt_sf->uc.tuc_sigcontext;
> >>> +    __put_user(h2g(mctx), &sc->regs);
> >>> +    __put_user(sig, &sc->signal);
> >>>  #else
> >>>      mctx = &rt_sf->uc.tuc_mcontext;
> >>>      trampptr = (uint32_t *)&rt_sf->uc.tuc_mcontext.tramp;
> >>>
> >>
> >> Reviewed-by: Laurent Vivier <address@hidden>
> >>
> >> This is correct, but QEMU and kernel implementation are really
> >> different.
> > 
> 
> Hi David,
> 
> > Laurent, I'm a bit clear on what the upshot is here.
> > 
> > Should I merge the patch above?
> 
> I've already included this patch in a linux-user pull request a couple
> of weeks ago, and it is now in the master.
> 
> So you have nothing to do :)

Excellent, thanks for the clarification.

-- 
David Gibson                    | I'll have my music baroque, and my code
david AT gibson.dropbear.id.au  | minimalist, thank you.  NOT _the_ _other_
                                | _way_ _around_!
http://www.ozlabs.org/~dgibson

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