Re: [Qemu-devel] [PATCH v2 09/27] linux-user/sh4: Clean env->flags on signal boundaries

[Aurelien Jarno]

On 2017-07-06 16:20, Richard Henderson wrote:
> If a signal is delivered during the execution of a delay slot,
> or a gUSA region, clear those bits from the environment so that
> the signal handler does not start in that same state.

How are signals delivered in linux-user? At least in system mode we
forbid interrupts in the delay slot (see commit 5c6f3eb7db), as the
manual clearly declare them as indivisible. Maybe the same should be
done for linux-user?

> 
> Cleaning the bits on signal return is paranoid good sense.
> 
> Signed-off-by: Richard Henderson <address@hidden>
> ---
>  linux-user/signal.c | 3 +++
>  1 file changed, 3 insertions(+)
> 
> diff --git a/linux-user/signal.c b/linux-user/signal.c
> index a537778..8c0b851 100644
> --- a/linux-user/signal.c
> +++ b/linux-user/signal.c
> @@ -3544,6 +3544,7 @@ static void restore_sigcontext(CPUSH4State *regs, 
> struct target_sigcontext *sc)
>      __get_user(regs->fpul, &sc->sc_fpul);
>  
>      regs->tra = -1;         /* disable syscall checks */
> +    regs->flags &= ~(DELAY_SLOT_MASK | GUSA_MASK);
>  }
>  
>  static void setup_frame(int sig, struct target_sigaction *ka,

Why not using TB_FLAG_ENVFLAGS_MASK introduced earlier in this patch
series?

-- 
Aurelien Jarno                          GPG: 4096R/1DDD8C9B
address@hidden                 http://www.aurel32.net