> -----Original Message----- > From: Andrew Cooper [mailto:[email protected]] > Sent: 24 September 2018 14:00 > To: Xen-devel <[email protected]> > Cc: Andrew Cooper <[email protected]>; Jan Beulich > <[email protected]>; Wei Liu <[email protected]>; Paul Durrant > <[email protected]> > Subject: [PATCH 3/5] x86/hvm: Adjust hvmemul_rep_stos() to compile with - > Wvla > > For at least "gcc (Ubuntu 5.4.0-6ubuntu1~16.04.10) 5.4.0 20160609", the > typecast of buf triggers a Variable Length Array warning. > > Alter the asm expression to avoid the typecast, which necessitates the > introduction of a memory clobber as the compiler can no longer identify > the total quantity of written memory. > > Despite the memory clobber, there is no change to the generated. > > Signed-off-by: Andrew Cooper <[email protected]>
Reviewed-by: Paul Durrant <[email protected]> > --- > CC: Jan Beulich <[email protected]> > CC: Wei Liu <[email protected]> > CC: Paul Durrant <[email protected]> > --- > xen/arch/x86/hvm/emulate.c | 6 +++--- > 1 file changed, 3 insertions(+), 3 deletions(-) > > diff --git a/xen/arch/x86/hvm/emulate.c b/xen/arch/x86/hvm/emulate.c > index a577685..eab66ea 100644 > --- a/xen/arch/x86/hvm/emulate.c > +++ b/xen/arch/x86/hvm/emulate.c > @@ -1859,7 +1859,7 @@ static int hvmemul_rep_stos( > switch ( p2mt ) > { > unsigned long bytes; > - void *buf; > + char *buf; > > default: > /* Allocate temporary buffer. */ > @@ -1882,10 +1882,10 @@ static int hvmemul_rep_stos( > #define CASE(bits, suffix) \ > case (bits) / 8: \ > asm ( "rep stos" #suffix \ > - : "=m" (*(char (*)[bytes])buf), \ > + : "=m" (*buf), \ > "=D" (dummy), "=c" (dummy) \ > : "a" (*(const uint##bits##_t *)p_data), \ > - "1" (buf), "2" (*reps) ); \ > + "1" (buf), "2" (*reps) : "memory" ); \ > break > CASE(8, b); > CASE(16, w); > -- > 2.1.4 _______________________________________________ Xen-devel mailing list [email protected] https://lists.xenproject.org/mailman/listinfo/xen-devel
