Daniel Borkmann 289fa6af73 bpf, arm64: remove prefetch insn in xadd mapping
commit 8968c67a82ab7501bc3b9439c3624a49b42fe54c upstream.

Prefetch-with-intent-to-write is currently part of the XADD mapping in
the AArch64 JIT and follows the kernel's implementation of atomic_add.
This may interfere with other threads executing the LDXR/STXR loop,
leading to potential starvation and fairness issues. Drop the optional
prefetch instruction.

Fixes: 85f68fe89832 ("bpf, arm64: implement jiting of BPF_XADD")
Reported-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Jean-Philippe Brucker <jean-philippe.brucker@arm.com>
Acked-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2019-05-21 18:50:16 +02:00
..
2019-02-20 10:20:53 +01:00
2018-02-28 10:19:44 +01:00
2019-03-23 14:35:21 +01:00