CPUs affected by Neoverse-N1 #1542419 may execute a stale instruction if
it was recently modified. The affected sequence requires freshly written
instructions to be executable before a branch to them is updated.
There are very few places in the kernel that modify executable text,
all but one come with sufficient synchronisation:
* The module loader's flush_module_icache() calls flush_icache_range(),
which does a kick_all_cpus_sync()
* bpf_int_jit_compile() calls flush_icache_range().
* Kprobes calls aarch64_insn_patch_text(), which does its work in
stop_machine().
* static keys and ftrace both patch between nops and branches to
existing kernel code (not generated code).
The affected sequence is the interaction between ftrace and modules.
The module PLT is cleaned using __flush_icache_range() as the trampoline
shouldn't be executable until we update the branch to it.
Drop the double-underscore so that this path runs kick_all_cpus_sync()
too.
Signed-off-by: James Morse <email address hidden>
Reference: https://lore<email address hidden>/
Signed-off-by: Kamal Mostafa <email address hidden>
Compat user-space is unable to perform ICIMVAU instructions from
user-space. Instead it uses a compat-syscall. Add the workaround for
Neoverse-N1 #1542419 to this code path.
Signed-off-by: James Morse <email address hidden>
Reference: https://lore<email address hidden>/
Signed-off-by: Kamal Mostafa <email address hidden>
Systems affected by Neoverse-N1 #1542419 support DIC so do not need to
perform icache maintenance once new instructions are cleaned to the PoU.
For the errata workaround, the kernel hides DIC from user-space, so that
the unnecessary cache maintenance can be trapped by firmware.
To reduce the number of traps, produce a fake IminLine value based on
PAGE_SIZE.
Signed-off-by: James Morse <email address hidden>
Reference: https://lore<email address hidden>/
Signed-off-by: Kamal Mostafa <email address hidden>
Neoverse-N1 affected by #1349291 may report an Uncontained RAS Error
as Unrecoverable. The kernel's architecture code already considers
Unrecoverable errors as fatal as without kernel-first support no
further error-handling is possible.
Now that KVM attributes SError to the host/guest more precisely
the host's architecture code will always handle host errors that
become pending during world-switch.
Errors misclassified by this errata that affected the guest will be
re-injected to the guest as an implementation-defined SError, which can
be uncontained.
Until kernel-first support is implemented, no workaround is needed
for this issue.
Signed-off-by: James Morse <email address hidden>
Signed-off-by: Marc Zyngier <email address hidden>
(cherry picked from commit 3276cc2489641f7f37e9558f5fe9d6ae17a25528)
Signed-off-by: Kamal Mostafa <email address hidden>
We already mitigate erratum 1188873 affecting Cortex-A76 and
Neoverse-N1 r0p0 to r2p0. It turns out that revisions r0p0 to
r3p1 of the same cores are affected by erratum 1418040, which
has the same workaround as 1188873.
Let's expand the range of affected revisions to match 1418040,
and repaint all occurences of 1188873 to 1418040. Whilst we're
there, do a bit of reformating in silicon-errata.txt and drop
a now unnecessary dependency on ARM_ARCH_TIMER_OOL_WORKAROUND.
Signed-off-by: Marc Zyngier <email address hidden>
Signed-off-by: Will Deacon <email address hidden>
(backported from commit a5325089bd05a7b0259cc4038479d36308edbda2)
Signed-off-by: Kamal Mostafa <email address hidden>
