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Re: [RFC PATCH] linux-user: don't adjust base of found hole
From: |
Alex Bennée |
Subject: |
Re: [RFC PATCH] linux-user: don't adjust base of found hole |
Date: |
Fri, 17 Dec 2021 13:18:33 +0000 |
User-agent: |
mu4e 1.7.5; emacs 28.0.90 |
Laurent Vivier <laurent@vivier.eu> writes:
> Le 16/12/2021 à 15:44, Alex Bennée a écrit :
>> The pgb_find_hole function goes to the trouble of taking account of
>> both mmap_min_addr and any offset we've applied to decide the starting
>> address of a potential hole. This is especially important for
>> emulating 32bit ARM in a 32bit build as we have applied the offset to
>> ensure there will be space to map the ARM_COMMPAGE bellow the main
>> guest map (using wrapped arithmetic).
>> Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
>> Resolves: https://gitlab.com/qemu-project/qemu/-/issues/690
>> ---
>> linux-user/elfload.c | 2 +-
>> 1 file changed, 1 insertion(+), 1 deletion(-)
>> diff --git a/linux-user/elfload.c b/linux-user/elfload.c
>> index 238979b8b6..8d839b79fb 100644
>> --- a/linux-user/elfload.c
>> +++ b/linux-user/elfload.c
>> @@ -2334,7 +2334,7 @@ static uintptr_t pgb_find_hole(uintptr_t guest_loaddr,
>> uintptr_t guest_size,
>> /* Record the lowest successful match. */
>> if (ret < 0) {
>> - ret = align_start - guest_loaddr;
>> + ret = align_start;
>> }
>> /* If this hole contains the identity map, select it. */
>> if (align_start <= guest_loaddr &&
>>
>
> It seems not consistent with what we have with fallback where we substract
> the guest_loadaddr:
>
> 2289 if (!maps) {
> 2290 ret = pgd_find_hole_fallback(guest_size, brk, align, offset);
> 2291 return ret == -1 ? -1 : ret - guest_loaddr;
> 2292 }
Hmm yeah. I can just make that a straight:
return pgd_find_hole_fallback(guest_size, brk, align, offset);
>
> Thanks,
> Laurent
--
Alex Bennée