[PATCH] powerpc: reset kernel stack on cpu online from cede state
DORMANTno replies
From: Vaidyanathan Srinivasan <hidden>
Date: 2010-02-22 08:19:42
Subsystem:
linux for powerpc (32-bit and 64-bit), the rest · Maintainers:
Madhavan Srinivasan, Linus Torvalds
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 <redacted>
diff --git a/arch/powerpc/kernel/head_64.S b/arch/powerpc/kernel/head_64.S
index 9258074..567cd57 100644
--- 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 /*
diff --git a/arch/powerpc/platforms/pseries/hotplug-cpu.c b/arch/powerpc/platforms/pseries/hotplug-cpu.c
index 6ea4698..9be7af4 100644
--- 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) {
diff --git a/arch/powerpc/platforms/pseries/offline_states.h b/arch/powerpc/platforms/pseries/offline_states.h
index 22574e0..da07256 100644
--- a/arch/powerpc/platforms/pseries/offline_states.h
+++ b/arch/powerpc/platforms/pseries/offline_states.h@@ -14,5 +14,5 @@ extern void set_cpu_current_state(int cpu, enum cpu_state_vals state); extern enum cpu_state_vals get_preferred_offline_state(int cpu); extern void set_preferred_offline_state(int cpu, enum cpu_state_vals state); extern void set_default_offline_state(int cpu); -extern int start_secondary(void); +extern void start_secondary_resume(void); #endif