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Re: V2 [PATCH 04/12] x86/CET: Extend arch_prctl syscall for CET control
On 07/24/2018 10:28 AM, Joseph Myers wrote:
> On Tue, 24 Jul 2018, H.J. Lu wrote:
>
>> Note: sysdeps/unix/sysv/linux/x86/bits/prctl-internal.h should be
>> renamed to sysdeps/unix/sysv/linux/x86/bits/prctl.h after the CET
>> kernel interface has been committed into the public kernel.
>
> bits/ should not be used for any internal headers; it's purely a naming
> convention for public headers. So there should be no
> bits/prctl-internal.h header.
OK.
> I don't think there should be bits/prctl.h at all either. Not with this
> patch (because there isn't anything for it to do), and not once the
> interface is in the kernel (because existing practice is that we rely on
> the include of <linux/prctl.h> from <sys/prctl.h> to provide the values to
> users of glibc).
Good point.
> Rather, for the uses of these constants within glibc, to avoid relying on
> new kernel headers, provide an x86 include/sys/prctl.h that does
> #include_next <sys/prctl.h> and then defines these constants if not
> already defined. And make sure that header gets a prominent comment
> naming the upstream kernel version with the constants (once they are
> upstream), so it's obvious at what point we can remove that header.
OK, that makes sense, so a purely internal header via include/ wrapping
with the constants there.
Cheers,
Carlos.