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linux-user: Unset MAP_FIXED_NOREPLACE for host

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Passing MAP_FIXED_NOREPLACE to host will fail for reserved_va because
the address space is reserved with mmap.  Replace it with MAP_FIXED
in that case.

Signed-off-by: Akihiko Odaki <akihiko.odaki@daynix.com>
Message-Id: <20230802071754.14876-2-akihiko.odaki@daynix.com>
[rth: Expand inline commentary.]
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
This commit is contained in:
Akihiko Odaki 2023-08-02 16:17:47 +09:00 committed by Richard Henderson
parent 4333f0924c
commit c3dd50da0f
1 changed files with 20 additions and 5 deletions
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25
linux-user/mmap.c
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@ -603,11 +603,26 @@ abi_long target_mmap(abi_ulong start, abi_ulong len, int target_prot,
goto fail;
}
/* Validate that the chosen range is empty. */
if ((flags & MAP_FIXED_NOREPLACE)
&& !page_check_range_empty(start, last)) {
errno = EEXIST;
goto fail;
if (flags & MAP_FIXED_NOREPLACE) {
/* Validate that the chosen range is empty. */
if (!page_check_range_empty(start, last)) {
errno = EEXIST;
goto fail;
}
/*
* With reserved_va, the entire address space is mmaped in the
* host to ensure it isn't accidentally used for something else.
* We have just checked that the guest address is not mapped
* within the guest, but need to replace the host reservation.
*
* Without reserved_va, despite the guest address check above,
* keep MAP_FIXED_NOREPLACE so that the guest does not overwrite
* any host address mappings.
*/
if (reserved_va) {
flags = (flags & ~MAP_FIXED_NOREPLACE) | MAP_FIXED;
}
}
/*