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Masami Hiramatsu (Google)
a494d3c8d5
On real hardware, panic and machine reboot may not flush hardware cache
to memory. This means the persistent ring buffer, which relies on a
coherent state of memory, may not have its events written to the buffer
and they may be lost. Moreover, there may be inconsistency with the
counters which are used for validation of the integrity of the
persistent ring buffer which may cause all data to be discarded.
To avoid this issue, stop recording of the ring buffer on panic and
flush the cache of the ring buffer's memory.
Fixes: e645535a95 ("tracing: Add option to use memmapped memory for trace boot instance")
Cc: [email protected]
Cc: Will Deacon <[email protected]>
Cc: Mathieu Desnoyers <[email protected]>
Cc: Ian Rogers <[email protected]>
Link: https://patch.msgid.link/177751969602.2136606.12031934362587643488.stgit@mhiramat.tok.corp.google.com
Signed-off-by: Masami Hiramatsu (Google) <[email protected]>
Acked-by: Catalin Marinas <[email protected]>
Acked-by: Geert Uytterhoeven <[email protected]>
Signed-off-by: Steven Rostedt <[email protected]>