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linux-user: Implement finer grained madivse() syscall

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Although most madvise() values are hints, some are important and are
checked by userspace, especially by security-relevant applications like
BoringSLL.  So, return -EINVAL for those functions which we don't emulate.

Signed-off-by: Helge Deller <deller@gmx.de>
Resolves: https://gitlab.com/qemu-project/qemu/-/work_items/3489
This commit is contained in:
Helge Deller
2026-05-24 23:06:01 +02:00
parent 2762cd51ee
commit e519832b25
1 changed files with 33 additions and 1 deletions
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34
linux-user/mmap.c
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@@ -1282,7 +1282,7 @@ abi_long target_madvise(abi_ulong start, abi_ulong len_in, int advice)
case TARGET_MADV_KEEPONFORK: /* parisc */
advice = MADV_KEEPONFORK;
break;
/* we do not care about the other MADV_xxx values yet */
/* all other MADV_xxx values are the same across architectures */
}
/*
@@ -1307,6 +1307,19 @@ abi_long target_madvise(abi_ulong start, abi_ulong len_in, int advice)
*/
mmap_lock();
switch (advice) {
case MADV_NORMAL:
case MADV_RANDOM:
case MADV_SEQUENTIAL:
case MADV_WILLNEED:
case MADV_DOFORK:
case MADV_FREE:
case MADV_COLD:
case MADV_PAGEOUT:
ret = 0; /* OK */
break;
case MADV_REMOVE:
ret = -EOPNOTSUPP;
break;
case MADV_DONTDUMP:
page_set_flags(start, start + len - 1, PAGE_DONTDUMP, 0);
break;
@@ -1324,6 +1337,25 @@ abi_long target_madvise(abi_ulong start, abi_ulong len_in, int advice)
page_reset_target_data(start, start + len - 1);
}
}
break;
case MADV_DONTFORK:
case MADV_HWPOISON:
case MADV_MERGEABLE:
case MADV_UNMERGEABLE:
case MADV_HUGEPAGE:
case MADV_NOHUGEPAGE:
case MADV_POPULATE_READ:
case MADV_POPULATE_WRITE:
#ifdef MADV_COLLAPSE
case MADV_COLLAPSE:
#endif
case -1: /* BoringSSL uses -1 to check if the environment is broken */
ret = -EINVAL;
break;
default:
qemu_log_mask(LOG_UNIMP, "Unhandled madvise(%d) call.\n", advice);
ret = -EINVAL; /* not yet known advise */
break;
}
mmap_unlock();