BACKPORT: x86/cfi,bpf: Fix BPF JIT call

The current BPF call convention is __nocfi, except when it calls !JIT things,
then it calls regular C functions.

It so happens that with FineIBT the __nocfi and C calling conventions are
incompatible. Specifically __nocfi will call at func+0, while FineIBT will have
endbr-poison there, which is not a valid indirect target. Causing #CP.

Notably this only triggers on IBT enabled hardware, which is probably why this
hasn't been reported (also, most people will have JIT on anyway).

Implement proper CFI prologues for the BPF JIT codegen and drop __nocfi for
x86.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/r/20231215092707.345270396@infradead.org


Signed-off-by: Alexei Starovoitov <ast@kernel.org>

Bug: 452811419
Change-Id: I84f6d7464da9d3d6ffa64a8ae6c8972121d70c3f
(cherry picked from commit 4f9087f1)
[liwei: discard the including of <asm/cfi.h> because it already exists
 and fix some minor conflicts]
Signed-off-by: wei li <sirius.liwei@honor.corp-partner.google.com>