Re: [Qemu-devel] [PATCH for-2.11 5/6] ppc: simplify cpu model lookup by PVR

[Igor Mammedov <imammedo@redhat.com>]

On Fri, 25 Aug 2017 14:16:44 +1000
David Gibson <david@gibson.dropbear.id.au> wrote:

> On Thu, Aug 24, 2017 at 10:21:50AM +0200, Igor Mammedov wrote:
> > Signed-off-by: Igor Mammedov <imammedo@redhat.com>
> > ---
> >  target/ppc/translate_init.c | 27 +++++++++++----------------
> >  1 file changed, 11 insertions(+), 16 deletions(-)
> > 
> > diff --git a/target/ppc/translate_init.c b/target/ppc/translate_init.c
> > index f1a559d..ca9f1e3 100644
> > --- a/target/ppc/translate_init.c
> > +++ b/target/ppc/translate_init.c
> > @@ -34,6 +34,7 @@
> >  #include "hw/ppc/ppc.h"
> >  #include "mmu-book3s-v3.h"
> >  #include "sysemu/qtest.h"
> > +#include "qemu/cutils.h"
> >  
> >  //#define PPC_DUMP_CPU
> >  //#define PPC_DEBUG_SPR
> > @@ -10203,22 +10204,16 @@ static ObjectClass *ppc_cpu_class_by_name(const char *name)
> >      char *cpu_model, *typename;
> >      ObjectClass *oc;
> >      const char *p;
> > -    int i, len;
> > -
> > -    /* Check if the given name is a PVR */
> > -    len = strlen(name);
> > -    if (len == 10 && name[0] == '0' && name[1] == 'x') {
> > -        p = name + 2;
> > -        goto check_pvr;
> > -    } else if (len == 8) {
> > -        p = name;
> > -    check_pvr:
> > -        for (i = 0; i < 8; i++) {
> > -            if (!qemu_isxdigit(*p++))
> > -                break;
> > -        }
> > -        if (i == 8) {
> > -            return OBJECT_CLASS(ppc_cpu_class_by_pvr(strtoul(name, NULL, 16)));
> > +    unsigned long pvr;
> > +
> > +    /* Lookup by PVR if cpu_model is valid 8 digit hex number
> > +     * (excl: 0x prefix if present)
> > +     */
> > +    if (!qemu_strtoul(name, &p, 16, &pvr)) {
> > +        int len = p - name;
> > +        len = (len == 10) && (name[1] == 'x') ? len - 2 : len;
> > +        if (len == 8) {
> > +            return OBJECT_CLASS(ppc_cpu_class_by_pvr(pvr));  
> 
> This doesn't look quite right.  A hex string of a PVR followed by
> other stuff isn't a valid option, so if p (endptr) doesn't point to
> the end of the string, then we shouldn't be using this path
yep, my mistake, I've lost somewhere *p == '\0' check when cleaning up the patch

>(from the
> looks of qemu_strtoul() we can simply omit the endptr parameter to get
> that behaviour).  I'm not sure what the messing around with len is
> for, either.  If it's a valid hex string we can try this, I don't see
> that we need further checks.
I've tried to keep current limitation here i.e. 8 hex symbols,
but if any hex number is fine then doing
 qemu_strtoul(name, NULL, 16, &pvr)
is even better, so would you prefer to drop 8 symbol check altogether?

> 
> >          }
> >      }
> >    
>