Re: [PATCH v3 21/33] linux-user: Split out mmap_h_eq_g

[Richard Henderson <richard.henderson@linaro.org>]

On 1/29/24 05:12, Ilya Leoshkevich wrote:
> On Tue, Jan 02, 2024 at 12:57:56PM +1100, Richard Henderson wrote:
>> Move the MAX_FIXED_NOREPLACE check for reserved_va earlier.
>> Move the computation of host_prot earlier.
>>
>> Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
>> ---
>>   linux-user/mmap.c | 66 +++++++++++++++++++++++++++++++++++++----------
>>   1 file changed, 53 insertions(+), 13 deletions(-)
>>
>> diff --git a/linux-user/mmap.c b/linux-user/mmap.c
>> index 42eb3eb2b4..00003b8329 100644
>> --- a/linux-user/mmap.c
>> +++ b/linux-user/mmap.c
>> @@ -527,6 +527,31 @@ static abi_long mmap_end(abi_ulong start, abi_ulong last,
>>       return start;
>>   }
>>   
>> +/*
>> + * Special case host page size == target page size,
>> + * where there are no edge conditions.
>> + */
>> +static abi_long mmap_h_eq_g(abi_ulong start, abi_ulong len,
>> +                            int host_prot, int flags, int page_flags,
>> +                            int fd, off_t offset)
>> +{
>> +    void *p, *want_p = g2h_untagged(start);
>> +    abi_ulong last;
>> +
>> +    p = mmap(want_p, len, host_prot, flags, fd, offset);
>> +    if (p == MAP_FAILED) {
>> +        return -1;
>> +    }
>> +    if ((flags & MAP_FIXED_NOREPLACE) && p != want_p) {
> 
> Should we munmap() here?
> I've seen this situation in some of the previous patches as well, but
> there we were about to exit, and here the program may continue
> running.

Yes, when the host kernel does not support MAP_FIXED_NOREPLACE.
Which is rare these days, admittedly.  I'll comment as well.


r~