Il 20/06/2013 16:18, Peter Maydell ha scritto:
> The memory API allows a MemoryRegion's size to be 2^64, as a special
> case (otherwise the size always fits in a 64 bit integer). This meant
> that attempts to access address zero in a 2^64 sized region would
> assert in address_space_translate():
>
> #3 0x00007ffff3e4d192 in __GI___assert_fail#(assertion=0x555555a43f32
> "!a.hi", file=0x555555a43ef0 "include/qemu/int128.h", line=18,
> function=0x555555a4439f "int128_get64") at assert.c:103
> #4 0x0000555555877642 in int128_get64 (a=...)
> at include/qemu/int128.h:18
> #5 0x00005555558782f2 in address_space_translate (as=0x55555668d140,
> /addr=0, xlat=0x7fffafac9918, plen=0x7fffafac9920, is_write=false)
> at exec.c:221
>
> Fix this by doing the 'min' operation in 128 bit arithmetic
> rather than 64 bit arithmetic (we know the result of the 'min'
> definitely fits in 64 bits because one of the inputs did).
>
> Signed-off-by: Peter Maydell <peter.mayd...@linaro.org>
> ---
> The other possible approach here would be:
> if (!diff.hi) {
> *plen = MIN(int128_get64(diff), *plen);
> }
> (since if diff.hi is nonzero we know plen is smaller) but
> it seems slightly cleaner not to "look inside" the Int128.
>
> exec.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/exec.c b/exec.c
> index 5b8b40d..eb200d0 100644
> --- a/exec.c
> +++ b/exec.c
> @@ -218,7 +218,7 @@ MemoryRegionSection *address_space_translate(AddressSpace
> *as, hwaddr addr,
> *xlat = addr + section->offset_within_region;
>
> diff = int128_sub(section->mr->size, int128_make64(addr));
> - *plen = MIN(int128_get64(diff), *plen);
> + *plen = int128_get64(int128_min(diff, int128_make64(*plen)));
> return section;
> }
> #endif
>
Thanks, applied.
Paolo
