Re: [Qemu-arm] [PATCH 1/3] tcg: Fix off-by-one in assert in page_set_flags

[Philippe Mathieu-Daudé]

On 07/07/2017 11:50 PM, Richard Henderson wrote:
> Most of the users of page_set_flags offset (page, page + len) as
> the end points.  One might consider this an error, since the other
> users do supply an endpoint as the last byte of the region.
>
> However, the first thing that page_set_flags does is round end UP
> to the start of the next page.  Which means computing page + len - 1
> is in the end pointless.  Therefore, accept this usage and do not
> assert when given the exact size of the vm as the endpoint.
>
> Signed-off-by: Richard Henderson <address@hidden>
> ---
>   accel/tcg/translate-all.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/accel/tcg/translate-all.c b/accel/tcg/translate-all.c
> index dfb9f0d..57578a4 100644
> --- a/accel/tcg/translate-all.c
> +++ b/accel/tcg/translate-all.c
> @@ -2068,7 +2068,7 @@ void page_set_flags(target_ulong start, target_ulong end, 
> int flags)
>          guest address space.  If this assert fires, it probably indicates
>          a missing call to h2g_valid.  */
>   #if TARGET_ABI_BITS > L1_MAP_ADDR_SPACE_BITS
> -    assert(end < ((target_ulong)1 << L1_MAP_ADDR_SPACE_BITS));
> +    assert(end <= ((target_ulong)1 << L1_MAP_ADDR_SPACE_BITS));

worth adding a comment /* end rounded up */ ?

anyway for this tricky catch:
Reviewed-by: Philippe Mathieu-Daudé <address@hidden>

>   #endif
>       assert(start < end);
>       assert_memory_lock();