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Fix madvise(MADV_DONTDUMP) #115

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Merged
merged 1 commit into from
May 8, 2025
Merged

Fix madvise(MADV_DONTDUMP) #115

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15 changes: 14 additions & 1 deletion linux-user/mmap.c
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Original file line number Diff line number Diff line change
Expand Up @@ -1248,7 +1248,20 @@ abi_long target_madvise(abi_ulong start, abi_ulong len_in, int advice)
switch (advice) {
case MADV_DONTDUMP:
if (len > 0) {
page_set_flags(start, start + len - 1, PAGE_DONTDUMP);
/*
* To set the page permissons, we must OR our new flags with the
* existing flags. Only mark the pages as PAGE_DONTDUMP if the
* entire range has the same flags. If any part of the range
* differs, we would need to process it one page at a time which
* might not be very performant. Since we are not obliged to respect
* this flag, we will support it for the most likely usage scenario.
* Note that we don't set PAGE_ANON, since this can only be set with
* new mappings.
*/
int flg = page_get_flags(start);
if (page_check_range(start, len, flg)) {
page_set_flags(start, start + len - 1, PAGE_DONTDUMP | (flg & ~PAGE_ANON) );
}
}
break;
case MADV_WIPEONFORK:
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