BACKPORT: arm64/bpf: Remove 128MB limit for BPF JIT programs

(Backport: resolve conflicts due to missing f4693c27 and present
 d3578ba7, and also drop in_bpf_jit from fixup_exception the same way
 5.15 backport 9c82ce59 does it.)

Commit 91fc957c ("arm64/bpf: don't allocate BPF JIT programs in module
memory") restricts BPF JIT program allocation to a 128MB region to ensure
BPF programs are still in branching range of each other. However this
restriction should not apply to the aarch64 JIT, since BPF_JMP | BPF_CALL
are implemented as a 64-bit move into a register and then a BLR instruction -
which has the effect of being able to call anything without proximity
limitation.

The practical reason to relax this restriction on JIT memory is that 128MB of
JIT memory can be quickly exhausted, especially where PAGE_SIZE is 64KB - one
page is needed per program. In cases where seccomp filters are applied to
multiple VMs on VM launch - such filters are classic BPF but converted to
BPF - this can severely limit the number of VMs that can be launched. In a
world where we support BPF JIT always on, turning off the JIT isn't always an
option either.

Fixes: 91fc957c ("arm64/bpf: don't allocate BPF JIT programs in module memory")
Suggested-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Russell King <russell.king@oracle.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Tested-by: Alan Maguire <alan.maguire@oracle.com>
Link: https://lore.kernel.org/bpf/1636131046-5982-2-git-send-email-alan.maguire@oracle.com


(cherry picked from commit b89ddf4c)
Bug: 252919296
Bug: 269045366
Change-Id: Iec7d0b2bba001df94c2e21fcd5883ff002111cd5
Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
(cherry picked from commit b901e6de)