kgdb: Fix spurious true from in_dbg_master()
[ Upstream commit5.4-rM2-2.2.x-imx-squashed3fec4aecb3
] Currently there is a small window where a badly timed migration could cause in_dbg_master() to spuriously return true. Specifically if we migrate to a new core after reading the processor id and the previous core takes a breakpoint then we will evaluate true if we read kgdb_active before we get the IPI to bring us to halt. Fix this by checking irqs_disabled() first. Interrupts are always disabled when we are executing the kgdb trap so this is an acceptable prerequisite. This also allows us to replace raw_smp_processor_id() with smp_processor_id() since the short circuit logic will prevent warnings from PREEMPT_DEBUG. Fixes:dcc7871128
("kgdb: core changes to support kdb") Suggested-by: Will Deacon <will@kernel.org> Link: https://lore.kernel.org/r/20200506164223.2875760-1-daniel.thompson@linaro.org Reviewed-by: Douglas Anderson <dianders@chromium.org> Signed-off-by: Daniel Thompson <daniel.thompson@linaro.org> Signed-off-by: Sasha Levin <sashal@kernel.org>
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fe99bb25c4
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4f1a132115
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@ -323,7 +323,7 @@ extern void gdbstub_exit(int status);
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extern int kgdb_single_step;
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extern atomic_t kgdb_active;
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#define in_dbg_master() \
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(raw_smp_processor_id() == atomic_read(&kgdb_active))
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(irqs_disabled() && (smp_processor_id() == atomic_read(&kgdb_active)))
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extern bool dbg_is_early;
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extern void __init dbg_late_init(void);
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extern void kgdb_panic(const char *msg);
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