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author | Guilherme G. Piccoli <gpiccoli@igalia.com> | 2022-04-27 19:49:02 -0300 |
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committer | Michael Ellerman <mpe@ellerman.id.au> | 2022-05-19 23:11:26 +1000 |
commit | e2aa34ce80a26d24a0333da9402d533885f239c9 (patch) | |
tree | fe681376c127c534493fc0e0dc076cc3f07a815d /Documentation/tools | |
parent | b104e41cda1ef9c5e851a7de3f30b53535e7d528 (diff) | |
download | linux-stable-e2aa34ce80a26d24a0333da9402d533885f239c9.tar.gz linux-stable-e2aa34ce80a26d24a0333da9402d533885f239c9.tar.bz2 linux-stable-e2aa34ce80a26d24a0333da9402d533885f239c9.zip |
powerpc/setup: Refactor/untangle panic notifiers
The panic notifiers infrastructure is a bit limited in the scope of
the callbacks - basically every kind of functionality is dropped
in a list that runs in the same point during the kernel panic path.
This is not really on par with the complexities and particularities
of architecture / hypervisors' needs, and a refactor is ongoing.
As part of this refactor, it was observed that powerpc has 2 notifiers,
with mixed goals: one is just a KASLR offset dumper, whereas the other
aims to hard-disable IRQs (necessary on panic path), warn firmware of
the panic event (fadump) and run low-level platform-specific machinery
that might stop kernel execution and never come back.
Clearly, the 2nd notifier has opposed goals: disable IRQs / fadump
should run earlier while low-level platform actions should
run late since it might not even return. Hence, this patch decouples
the notifiers splitting them in three:
- First one is responsible for hard-disable IRQs and fadump,
should run early;
- The kernel KASLR offset dumper is really an informative notifier,
harmless and may run at any moment in the panic path;
- The last notifier should run last, since it aims to perform
low-level actions for specific platforms, and might never return.
It is also only registered for 2 platforms, pseries and ps3.
The patch better documents the notifiers and clears the code too,
also removing a useless header.
Currently no functionality change should be observed, but after
the planned panic refactor we should expect more panic reliability
with this patch.
Signed-off-by: Guilherme G. Piccoli <gpiccoli@igalia.com>
Reviewed-by: Hari Bathini <hbathini@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20220427224924.592546-9-gpiccoli@igalia.com
Diffstat (limited to 'Documentation/tools')
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