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Andrew Cooper
3667f7f8f7
CET Indirect Branch Tracking is a hardware feature designed to provide
forward-edge control flow integrity, protecting against jump/call oriented
programming.
IBT requires the placement of endbr{32,64} instructions at the target of every
indirect call/jmp, and every entrypoint.
However, the default -fcf-protection=branch places an endbr{32,64} on every
function which far more than necessary, and reduces the quantity of protection
afforded. Therefore, we use manual placement using the cf_check attribute.
It is necessary to check for both compiler and assembler support, as the
notrack prefix can be emitted in certain cases.
Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Acked-by: Jan Beulich <jbeulich@suse.com>