Messages in this thread Patch in this message | | | Date | Mon, 10 May 2010 15:32:50 -0700 | From | Greg KH <> | Subject | [079/117] powerpc: Reset kernel stack on cpu online from cede state |
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2.6.33-stable review patch. If anyone has any objections, please let us know.
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From: Vaidyanathan Srinivasan <svaidy@linux.vnet.ibm.com>
commit 8dbce53cc249a76e9450708d291fce5a7e29c6a1 upstream.
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> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
--- arch/powerpc/kernel/head_64.S | 11 +++++++++++ arch/powerpc/platforms/pseries/hotplug-cpu.c | 9 ++++----- arch/powerpc/platforms/pseries/offline_states.h | 1 + 3 files changed, 16 insertions(+), 5 deletions(-)
--- a/arch/powerpc/kernel/head_64.S +++ b/arch/powerpc/kernel/head_64.S @@ -615,6 +615,17 @@ _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 /* --- a/arch/powerpc/platforms/pseries/hotplug-cpu.c +++ b/arch/powerpc/platforms/pseries/hotplug-cpu.c @@ -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) { --- a/arch/powerpc/platforms/pseries/offline_states.h +++ b/arch/powerpc/platforms/pseries/offline_states.h @@ -35,4 +35,5 @@ static inline void set_default_offline_s extern enum cpu_state_vals get_preferred_offline_state(int cpu); extern int start_secondary(void); +extern void start_secondary_resume(void); #endif
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