Re: [Qemu-devel] [PATCH 05/11] linux-user/sh4: Notice gUSA regions during signal delivery

[Laurent Vivier <laurent@vivier.eu>]

Le 06/07/2017 à 02:23, Richard Henderson a écrit :
> We translate gUSA regions atomically in a parallel context.
> But in a serial context a gUSA region may be interrupted.
> In that case, restart the region as the kernel would.
> 
> Signed-off-by: Richard Henderson <rth@twiddle.net>
> ---
>  linux-user/signal.c | 21 +++++++++++++++++++++
>  1 file changed, 21 insertions(+)
> 
> diff --git a/linux-user/signal.c b/linux-user/signal.c
> index 3d18d1b..1e716a9 100644
> --- a/linux-user/signal.c
> +++ b/linux-user/signal.c
> @@ -3471,6 +3471,23 @@ static abi_ulong get_sigframe(struct target_sigaction *ka,
>      return (sp - frame_size) & -8ul;
>  }
>  
> +/* Notice when we're in the middle of a gUSA region and reset.
> +   Note that this will only occur for !parallel_cpus, as we will
> +   translate such sequences differently in a parallel context.  */
> +static void unwind_gusa(CPUSH4State *regs)
> +{
> +    /* If the stack pointer is sufficiently negative... */
> +    if ((regs->gregs[15] & 0xc0000000u) == 0xc0000000u) {

kernel also checks PC < gUSA region end point,
try this:

diff --git a/linux-user/signal.c b/linux-user/signal.c
index 1e716a9..4e1e4f0 100644
--- a/linux-user/signal.c
+++ b/linux-user/signal.c
@@ -3477,7 +3477,8 @@ static abi_ulong get_sigframe(struct
target_sigaction *ka,
 static void unwind_gusa(CPUSH4State *regs)
 {
     /* If the stack pointer is sufficiently negative... */
-    if ((regs->gregs[15] & 0xc0000000u) == 0xc0000000u) {
+    if ((regs->gregs[15] & 0xc0000000u) == 0xc0000000u &&
+        regs->pc < regs->gregs[0]) {
         /* Reset the PC to before the gUSA region, as computed from
            R0 = region end, SP = -(region size), plus one more insn
            that actually sets SP to the region size.  */

Laurent