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Commit 8dbce53c authored Mar 01, 2010 by Vaidyanathan Srinivasan Committed by Benjamin Herrenschmidt Mar 09, 2010

powerpc: Reset kernel stack on cpu online from cede state



Cpu hotplug (offline) without dlpar operation will place cpu
in cede state and the extended_cede_processor() function will
return when resumed.

Kernel stack pointer needs to be reset before
start_secondary() is called to continue the online operation.

Added new function start_secondary_resume() to do the above
steps.

Signed-off-by: Vaidyanathan Srinivasan <svaidy@linux.vnet.ibm.com>
Cc: Gautham R Shenoy <ego@in.ibm.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

parent de0b632b

arch/powerpc/kernel/head_64.S

+11 −0

Original line number	Diff line number	Diff line
		@@ -617,6 +617,17 @@ _GLOBAL(start_secondary_prolog)
		std r3,0(r1) /* Zero the stack frame pointer */
		bl .start_secondary
		b .
		/*
		* Reset stack pointer and call start_secondary
		* to continue with online operation when woken up
		* from cede in cpu offline.
		*/
		_GLOBAL(start_secondary_resume)
		ld r1,PACAKSAVE(r13) /* Reload kernel stack pointer */
		li r3,0
		std r3,0(r1) /* Zero the stack frame pointer */
		bl .start_secondary
		b .
		#endif

		/*

arch/powerpc/platforms/pseries/hotplug-cpu.c

+4 −5

Original line number	Diff line number	Diff line
		@@ -146,12 +146,11 @@ static void pseries_mach_cpu_die(void)
		unregister_slb_shadow(hwcpu, __pa(get_slb_shadow()));

		/*
		* NOTE: Calling start_secondary() here for now to
		* start new context.
		* However, need to do it cleanly by resetting the
		* stack pointer.
		* Call to start_secondary_resume() will not return.
		* Kernel stack will be reset and start_secondary()
		* will be called to continue the online operation.
		*/
		start_secondary();
		start_secondary_resume();

		} else if (get_preferred_offline_state(cpu) == CPU_STATE_OFFLINE) {

arch/powerpc/platforms/pseries/offline_states.h

+1 −0

Original line number	Diff line number	Diff line
		@@ -35,4 +35,5 @@ static inline void set_default_offline_state(int cpu)

		extern enum cpu_state_vals get_preferred_offline_state(int cpu);
		extern int start_secondary(void);
		extern void start_secondary_resume(void);
		#endif