Re: [PATCH 1/9] bsd-user: Apply e6deac9cf99 from linux-user (zero anonymous memory)

[Warner Losh <imp@bsdimp.com>]

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On Fri, Sep 17, 2021 at 9:02 AM Philippe Mathieu-Daudé <f4bug@amsat.org>
wrote:

> On 9/17/21 4:56 AM, Warner Losh wrote:
> > From: Mikaël Urankar <mikael.urankar@gmail.com>
> >
> > linux-user/mmap.c: Always zero MAP_ANONYMOUS memory in mmap_frag()
>
> Please use it as subject, "bsd-user/mmap: Always zero MAP_ANONYMOUS
> memory in mmap_frag()"
>
> Then describe:
>
> Similar to the equivalent linux-user commit e6deac9cf99, ...
>

OK. I have three commits like this, so I'll go ahead and edit all three.


> >
> > When mapping MAP_ANONYMOUS memory fragments, still need notice about to
> > set it zero, or it will cause issues.
> >
> > Signed-off-by: Chen Gang <gang.chen.5i5j@gmail.com>
> > Reviewed-by: Laurent Vivier <laurent@vivier.eu>
> > Signed-off-by: Riku Voipio <riku.voipio@linaro.org>
>
> ^ These tags were for another file, not this one, please
> remove them.
>

Gotcha. I wasn't completely sure what to do in this case since they
describe that the work is able to be contributed so I could make a case
either way.

I'll remove them.

Warner


> > [ bsd-user merge by Mikaël Urankar, updated for untagged by Warner Losh ]
> > Signed-off-by: Mikaël Urankar <mikael.urankar@gmail.com>
> > Signed-off-by: Warner Losh <imp@bsdimp.com>
> > ---
> >  bsd-user/mmap.c | 4 +++-
> >  1 file changed, 3 insertions(+), 1 deletion(-)
> >
> > diff --git a/bsd-user/mmap.c b/bsd-user/mmap.c
> > index b40ab9045f..fc3c1480f5 100644
> > --- a/bsd-user/mmap.c
> > +++ b/bsd-user/mmap.c
> > @@ -180,10 +180,12 @@ static int mmap_frag(abi_ulong real_start,
> >          if (prot_new != (prot1 | PROT_WRITE))
> >              mprotect(host_start, qemu_host_page_size, prot_new);
> >      } else {
> > -        /* just update the protection */
> >          if (prot_new != prot1) {
> >              mprotect(host_start, qemu_host_page_size, prot_new);
> >          }
> > +        if (prot_new & PROT_WRITE) {
> > +            memset(g2h_untagged(start), 0, end - start);
> > +        }
> >      }
> >      return 0;
> >  }
> >
>
>

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