| Message ID | 1343256304-32029-1-git-send-email-tylerwhall@gmail.com |
|---|---|
| State | New |
| Headers | show |
On Wed, Jul 25, 2012 at 06:45:03PM -0400, Tyler Hall wrote: > subpage_register() expects "end" to be the last byte in the mapping. > Registering a non-page-aligned memory region that extends up to or > beyond a page boundary causes subpage_register() to silently fail > through the (end >= PAGE_SIZE) check. > > This bug does not cause noticeable problems for mappings that do not > extend to a page boundary, though they do register an extra byte. > > Signed-off-by: Tyler Hall <tylerwhall@gmail.com> > --- > exec.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/exec.c b/exec.c > index feb4795..27b100c 100644 > --- a/exec.c > +++ b/exec.c > @@ -2271,7 +2271,7 @@ static void register_subpage(MemoryRegionSection *section) > subpage = container_of(existing->mr, subpage_t, iomem); > } > start = section->offset_within_address_space & ~TARGET_PAGE_MASK; > - end = start + section->size; > + end = start + section->size - 1; > subpage_register(subpage, start, end, phys_section_add(section)); > } I would really like to see an Acked-by: or Signed-off-by: from Avi or someone else who is familiar with the memory regions code. Especially for Patch 2/2. Stefan
On 1 August 2012 11:42, Stefan Hajnoczi <stefanha@gmail.com> wrote: > On Wed, Jul 25, 2012 at 06:45:03PM -0400, Tyler Hall wrote: >> subpage_register() expects "end" to be the last byte in the mapping. >> Registering a non-page-aligned memory region that extends up to or >> beyond a page boundary causes subpage_register() to silently fail >> through the (end >= PAGE_SIZE) check. >> >> This bug does not cause noticeable problems for mappings that do not >> extend to a page boundary, though they do register an extra byte. >> >> Signed-off-by: Tyler Hall <tylerwhall@gmail.com> >> --- >> exec.c | 2 +- >> 1 file changed, 1 insertion(+), 1 deletion(-) >> >> diff --git a/exec.c b/exec.c >> index feb4795..27b100c 100644 >> --- a/exec.c >> +++ b/exec.c >> @@ -2271,7 +2271,7 @@ static void register_subpage(MemoryRegionSection *section) >> subpage = container_of(existing->mr, subpage_t, iomem); >> } >> start = section->offset_within_address_space & ~TARGET_PAGE_MASK; >> - end = start + section->size; >> + end = start + section->size - 1; >> subpage_register(subpage, start, end, phys_section_add(section)); >> } > > I would really like to see an Acked-by: or Signed-off-by: from Avi or > someone else who is familiar with the memory regions code. Especially > for Patch 2/2. I think this patch is OK (compare the subpage_register() call in subpage_init(), the guards in subpage_register(), etc), so Reviewed-by: Peter Maydell <peter.maydell@linaro.org> though I dunno that I'd claim to be familiar with the memory region code ;-) 2/2 is definitely not a trivial patch, though -- it's trying to fix a long standing deficiency in qemu's mmio region handling. I gave 2/2 a quick test and it seems to pass the right offset through to the read/write handlers, but Avi should definitely review it... On a related note, the comment above register_subpage which includes remarks about how this special case doesn't work seems to now be rather out of date since it's still talking about function parameter names which no longer exist. -- PMM
On 07/26/2012 01:45 AM, Tyler Hall wrote: > subpage_register() expects "end" to be the last byte in the mapping. > Registering a non-page-aligned memory region that extends up to or > beyond a page boundary causes subpage_register() to silently fail > through the (end >= PAGE_SIZE) check. > > This bug does not cause noticeable problems for mappings that do not > extend to a page boundary, though they do register an extra byte. Reviewed-by: Avi Kivity <avi@redhat.com>
On Wed, Aug 1, 2012 at 1:56 PM, Avi Kivity <avi@redhat.com> wrote: > On 07/26/2012 01:45 AM, Tyler Hall wrote: >> subpage_register() expects "end" to be the last byte in the mapping. >> Registering a non-page-aligned memory region that extends up to or >> beyond a page boundary causes subpage_register() to silently fail >> through the (end >= PAGE_SIZE) check. >> >> This bug does not cause noticeable problems for mappings that do not >> extend to a page boundary, though they do register an extra byte. > > Reviewed-by: Avi Kivity <avi@redhat.com> Thanks Avi. Does this include Patch 2/2 too? https://lists.gnu.org/archive/html/qemu-devel/2012-07/msg03573.html Stefan
On 08/01/2012 04:01 PM, Stefan Hajnoczi wrote: > On Wed, Aug 1, 2012 at 1:56 PM, Avi Kivity <avi@redhat.com> wrote: >> On 07/26/2012 01:45 AM, Tyler Hall wrote: >>> subpage_register() expects "end" to be the last byte in the mapping. >>> Registering a non-page-aligned memory region that extends up to or >>> beyond a page boundary causes subpage_register() to silently fail >>> through the (end >= PAGE_SIZE) check. >>> >>> This bug does not cause noticeable problems for mappings that do not >>> extend to a page boundary, though they do register an extra byte. >> >> Reviewed-by: Avi Kivity <avi@redhat.com> > > Thanks Avi. Does this include Patch 2/2 too? I reviewed that as well with similar results.
On Wed, Jul 25, 2012 at 06:45:03PM -0400, Tyler Hall wrote: > subpage_register() expects "end" to be the last byte in the mapping. > Registering a non-page-aligned memory region that extends up to or > beyond a page boundary causes subpage_register() to silently fail > through the (end >= PAGE_SIZE) check. > > This bug does not cause noticeable problems for mappings that do not > extend to a page boundary, though they do register an extra byte. > > Signed-off-by: Tyler Hall <tylerwhall@gmail.com> > --- > exec.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) Thanks, both applied to the trivial patches tree: https://github.com/stefanha/qemu/commits/trivial-patches Stefan
diff --git a/exec.c b/exec.c index feb4795..27b100c 100644 --- a/exec.c +++ b/exec.c @@ -2271,7 +2271,7 @@ static void register_subpage(MemoryRegionSection *section) subpage = container_of(existing->mr, subpage_t, iomem); } start = section->offset_within_address_space & ~TARGET_PAGE_MASK; - end = start + section->size; + end = start + section->size - 1; subpage_register(subpage, start, end, phys_section_add(section)); }
subpage_register() expects "end" to be the last byte in the mapping. Registering a non-page-aligned memory region that extends up to or beyond a page boundary causes subpage_register() to silently fail through the (end >= PAGE_SIZE) check. This bug does not cause noticeable problems for mappings that do not extend to a page boundary, though they do register an extra byte. Signed-off-by: Tyler Hall <tylerwhall@gmail.com> --- exec.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)