https://bugs.kde.org/show_bug.cgi?id=408091
Bug ID: 408091
Summary: Missing pkey syscalls
Product: valgrind
Version: 3.15 SVN
Platform: Other
OS: Linux
Status: REPORTED
Severity: normal
Priority: NOR
Component: general
Assignee: jsew...@acm.org
Reporter: m...@klomp.org
Target Milestone: ---
Since linux 4.9 there are a couple of syscalls to handle memory protection
keys.
Valgrind doesn't support memory protection keys and the RDPKRU/WRPKRU
instructions to update the new PKRU register.
But the syscalls have some use without that support.
First pkey_alloc () can be used to check whether memory protection keys are
usage:
pkey_alloc() is always safe to call regardless of whether or not the
operating system supports protection keys. It can be used in lieu of
any other mechanism for detecting pkey support and will simply fail
with the error ENOSPC if the operating system has no pkey support.
Secondly pkey_mprotect can be used even without a real pkey:
If the key allocation fails due to lack of support for memory protection keys,
the pkey_mprotect call can usually be skipped. In this case, the region will
not be protected by default. It is also possible to call pkey_mprotect with a
key value of -1, in which case it will behave in the same way as mprotect.
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