From: Jeremy Linton <jlin...@redhat.com>

redhat/configs: For aarch64/RT, default kstack randomization off

Unlike other architectures which use their cycles counters to
seed the kstack randomization (which is sketchy) aarch64 uses
the kernel random number generator. For a list of reasons starting
with the lack of an enabled/fast cycle counter, a ubiquitous high
frequency timer, nor machines which have the v8.5 FEAT_RNG.

Using the kernel rng is largely an acceptable solution except
for RT workloads which can experience quite large latency spikes
as a result.

So, lets invert the default kstack randomization for RT kernels
on aarch64 until FEAT_RNG is common or a better solution is
found.

Signed-off-by: Jeremy Linton <jlin...@redhat.com>

diff --git 
a/redhat/configs/common/rt/generic/arm/aarch64/CONFIG_RANDOMIZE_KSTACK_OFFSET_DEFAULT
 
b/redhat/configs/common/rt/generic/arm/aarch64/CONFIG_RANDOMIZE_KSTACK_OFFSET_DEFAULT
new file mode 100644
index blahblah..blahblah 100644
--- /dev/null
+++ 
b/redhat/configs/common/rt/generic/arm/aarch64/CONFIG_RANDOMIZE_KSTACK_OFFSET_DEFAULT
@@ -0,0 +1 @@
+# CONFIG_RANDOMIZE_KSTACK_OFFSET_DEFAULT is not set

--
https://gitlab.com/cki-project/kernel-ark/-/merge_requests/2933
--
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