Re: [PATCH v3 04/12] linux-user: more debug for init_guest_space

[Philippe Mathieu-Daudé]

On 4/3/20 9:11 PM, Alex Bennée wrote:
> Searching for memory space can cause problems so lets extend the
> CPU_LOG_PAGE output so you can watch init_guest_space fail to
> allocate memory. A more involved fix is actually required to make this
> function play nicely with the large guard pages the sanitiser likes to

TIL "in an effort to differentiate British English from American, many 
British publishers have begun giving -ise endings even to words that 
have always been spelled -ize."

https://grammarist.com/spelling/sanitise-sanitize/

> use.
>
> Signed-off-by: Alex Bennée <address@hidden>
> Reviewed-by: Laurent Vivier <address@hidden>

Reviewed-by: Philippe Mathieu-Daudé <address@hidden>

> ---
>   linux-user/elfload.c | 8 +++++++-
>   1 file changed, 7 insertions(+), 1 deletion(-)
>
> diff --git a/linux-user/elfload.c b/linux-user/elfload.c
> index 8198be04460..619c054cc48 100644
> --- a/linux-user/elfload.c
> +++ b/linux-user/elfload.c
> @@ -2172,6 +2172,8 @@ unsigned long init_guest_space(unsigned long host_start,
>   
>           /* Check to see if the address is valid.  */
>           if (host_start && real_start != current_start) {
> +            qemu_log_mask(CPU_LOG_PAGE, "invalid %lx && %lx != %lx\n",
> +                          host_start, real_start, current_start);
>               goto try_again;
>           }
>   
> @@ -2240,7 +2242,11 @@ unsigned long init_guest_space(unsigned long host_start,
>            * probably a bad strategy if not, which means we got here
>            * because of trouble with ARM commpage setup.
>            */
> -        munmap((void *)real_start, real_size);
> +        if (munmap((void *)real_start, real_size) != 0) {
> +            error_report("%s: failed to unmap %lx:%lx (%s)", __func__,
> +                         real_start, real_size, strerror(errno));
> +            abort();
> +        }
>           current_start += align;
>           if (host_start == current_start) {
>               /* Theoretically possible if host doesn't have any suitably