22 Sep
2021
22 Sep
'21
9:05 p.m.
On Wed, Sep 22, 2021 at 09:52:07PM +0200, Borislav Petkov wrote:
On Wed, Sep 22, 2021 at 05:30:15PM +0300, Kirill A. Shutemov wrote:
Not fine, but waiting to blowup with random build environment change.
Why is it not fine?
Are you suspecting that the compiler might generate something else and not a rip-relative access?
Yes. We had it before for __supported_pte_mask and other users of fixup_pointer().
See for instance 4a09f0210c8b ("x86/boot/64/clang: Use fixup_pointer() to access '__supported_pte_mask'")
Unless we find other way to guarantee RIP-relative access, we must use fixup_pointer() to access any global variables.
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Kirill A. Shutemov