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Anju T Sudhakar committed 685a1e317a6
powerpc/perf: Implement a global lock to avoid races between trace, core and thread imc events. [ Upstream commit a36e8ba60b991d563677227f172db69e030797e6 ] IMC(In-memory Collection Counters) does performance monitoring in two different modes, i.e accumulation mode(core-imc and thread-imc events), and trace mode(trace-imc events). A cpu thread can either be in accumulation-mode or trace-mode at a time and this is done via the LDBAR register in POWER architecture. The current design does not address the races between thread-imc and trace-imc events. Patch implements a global id and lock to avoid the races between core, trace and thread imc events. With this global id-lock implementation, the system can either run core, thread or trace imc events at a time. i.e. to run any core-imc events, thread/trace imc events should not be enabled/monitored. Signed-off-by: Anju T Sudhakar <anju@linux.vnet.ibm.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/20200313055238.8656-1-anju@linux.vnet.ibm.com Signed-off-by: Sasha Levin <sashal@kernel.org>