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Re: [Qemu-devel] [PATCH] linux-user: correctly align types in thunking c


From: Laurent Vivier
Subject: Re: [Qemu-devel] [PATCH] linux-user: correctly align types in thunking code
Date: Sat, 26 Jan 2013 12:20:29 +0100

Le mercredi 02 janvier 2013 à 00:08 +0100, Laurent Vivier a écrit :
> Ping !

ping

> Le jeudi 20 décembre 2012 à 21:55 +0100, Laurent Vivier a écrit :
> > This is a follow up
> > of patch:
> > 
> >         commit c2e3dee6e03527baf8698698cce76b1a3174969a
> >         Author: Laurent Vivier <address@hidden>
> >         Date:   Sun Feb 13 23:37:34 2011 +0100
> > 
> >             linux-user: Define target alignment size
> > 
> > In my case m68k aligns "int" on 2 not 4. You can check this with the
> > following program:
> > 
> > int main(void)
> > {
> >         struct rtentry rt;
> >         printf("rt_pad1 %ld %zd\n", offsetof(struct rtentry, rt_pad1),
> >                 sizeof(rt.rt_pad1));
> >         printf("rt_dst %ld %zd\n", offsetof(struct rtentry, rt_dst),
> >                 sizeof(rt.rt_dst));
> >         printf("rt_gateway %ld %zd\n", offsetof(struct rtentry, rt_gateway),
> >                 sizeof(rt.rt_gateway));
> >         printf("rt_genmask %ld %zd\n", offsetof(struct rtentry, rt_genmask),
> >                 sizeof(rt.rt_genmask));
> >         printf("rt_flags %ld %zd\n", offsetof(struct rtentry, rt_flags),
> >                 sizeof(rt.rt_flags));
> >         printf("rt_pad2 %ld %zd\n", offsetof(struct rtentry, rt_pad2),
> >                 sizeof(rt.rt_pad2));
> >         printf("rt_pad3 %ld %zd\n", offsetof(struct rtentry, rt_pad3),
> >                 sizeof(rt.rt_pad3));
> >         printf("rt_pad4 %ld %zd\n", offsetof(struct rtentry, rt_pad4),
> >                 sizeof(rt.rt_pad4));
> >         printf("rt_metric %ld %zd\n", offsetof(struct rtentry, rt_metric),
> >                 sizeof(rt.rt_metric));
> >         printf("rt_dev %ld %zd\n", offsetof(struct rtentry, rt_dev),
> >                 sizeof(rt.rt_dev));
> >         printf("rt_mtu %ld %zd\n", offsetof(struct rtentry, rt_mtu),
> >                 sizeof(rt.rt_mtu));
> >         printf("rt_window %ld %zd\n", offsetof(struct rtentry, rt_window),
> >                 sizeof(rt.rt_window));
> >         printf("rt_irtt %ld %zd\n", offsetof(struct rtentry, rt_irtt),
> >                 sizeof(rt.rt_irtt));
> > }
> > 
> > And result is :
> > 
> > i386
> > 
> > rt_pad1 0 4
> > rt_dst 4 16
> > rt_gateway 20 16
> > rt_genmask 36 16
> > rt_flags 52 2
> > rt_pad2 54 2
> > rt_pad3 56 4
> > rt_pad4 62 2
> > rt_metric 64 2
> > rt_dev 68 4
> > rt_mtu 72 4
> > rt_window 76 4
> > rt_irtt 80 2
> > 
> > m68k
> > 
> > rt_pad1 0 4
> > rt_dst 4 16
> > rt_gateway 20 16
> > rt_genmask 36 16
> > rt_flags 52 2
> > rt_pad2 54 2
> > rt_pad3 56 4
> > rt_pad4 62 2
> > rt_metric 64 2
> > rt_dev 66 4
> > rt_mtu 70 4
> > rt_window 74 4
> > rt_irtt 78 2
> > 
> > This affects the "route" command :
> > 
> > WITHOUT this patch:
> > 
> > $ sudo route add -net default gw 10.0.3.1 window 1024 irtt 2 eth0
> > $ netstat -nr
> > Kernel IP routing table
> > Destination     Gateway         Genmask         Flags   MSS Window  irtt 
> > Iface
> > 0.0.0.0         10.0.3.1        0.0.0.0         UG        0 67108866  32768 
> > eth0
> > 10.0.3.0        0.0.0.0         255.255.255.0   U         0 0          0 
> > eth0
> > 
> > WITH this patch:
> > 
> > $ sudo route add -net default gw 10.0.3.1 window 1024 irtt 2 eth0
> > $ netstat -nr
> > Kernel IP routing table
> > Destination     Gateway         Genmask         Flags   MSS Window  irtt 
> > Iface
> > 0.0.0.0         10.0.3.1        0.0.0.0         UG        0 1024       2 
> > eth0
> > 10.0.3.0        0.0.0.0         255.255.255.0   U         0 0          0 
> > eth0
> > 
> > Signed-off-by: Laurent Vivier <address@hidden>
> > ---
> >  include/exec/user/thunk.h |   22 +++++++++++++++++-----
> >  1 file changed, 17 insertions(+), 5 deletions(-)
> > 
> > diff --git a/include/exec/user/thunk.h b/include/exec/user/thunk.h
> > index 87025c3..d3e9f3d 100644
> > --- a/include/exec/user/thunk.h
> > +++ b/include/exec/user/thunk.h
> > @@ -151,20 +151,32 @@ static inline int thunk_type_align(const argtype 
> > *type_ptr, int is_host)
> >      case TYPE_CHAR:
> >          return 1;
> >      case TYPE_SHORT:
> > -        return 2;
> > +        if (is_host) {
> > +            return __alignof__(short);
> > +        } else {
> > +            return TARGET_SHORT_ALIGNMENT;
> > +        }
> >      case TYPE_INT:
> > -        return 4;
> > +        if (is_host) {
> > +            return __alignof__(int);
> > +        } else {
> > +            return TARGET_INT_ALIGNMENT;
> > +        }
> >      case TYPE_LONGLONG:
> >      case TYPE_ULONGLONG:
> > -        return 8;
> > +        if (is_host) {
> > +            return __alignof__(long long);
> > +        } else {
> > +            return TARGET_LLONG_ALIGNMENT;
> > +        }
> >      case TYPE_LONG:
> >      case TYPE_ULONG:
> >      case TYPE_PTRVOID:
> >      case TYPE_PTR:
> >          if (is_host) {
> > -            return sizeof(void *);
> > +            return __alignof__(long);
> >          } else {
> > -            return TARGET_ABI_BITS / 8;
> > +            return TARGET_LONG_ALIGNMENT;
> >          }
> >          break;
> >      case TYPE_OLDDEVT:
> 

-- 
"Just play. Have fun. Enjoy the game."
- Michael Jordan
"Just play. Have fun. Enjoy the game."
- Michael Jordan




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