From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from e28smtp03.in.ibm.com (e28smtp03.in.ibm.com [122.248.162.3]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (Client CN "e28smtp03.in.ibm.com", Issuer "Equifax" (verified OK)) by ozlabs.org (Postfix) with ESMTPS id BEB6FB7CE2 for ; Mon, 22 Feb 2010 19:19:42 +1100 (EST) Received: from d28relay01.in.ibm.com (d28relay01.in.ibm.com [9.184.220.58]) by e28smtp03.in.ibm.com (8.14.3/8.13.1) with ESMTP id o1M8Jc9b030360 for ; Mon, 22 Feb 2010 13:49:38 +0530 Received: from d28av01.in.ibm.com (d28av01.in.ibm.com [9.184.220.63]) by d28relay01.in.ibm.com (8.13.8/8.13.8/NCO v10.0) with ESMTP id o1M8JcOQ2850904 for ; Mon, 22 Feb 2010 13:49:38 +0530 Received: from d28av01.in.ibm.com (loopback [127.0.0.1]) by d28av01.in.ibm.com (8.14.3/8.13.1/NCO v10.0 AVout) with ESMTP id o1M8JcB5027339 for ; Mon, 22 Feb 2010 13:49:38 +0530 Date: Mon, 22 Feb 2010 13:49:30 +0530 From: Vaidyanathan Srinivasan To: Benjamin Herrenschmidt , Anton Blanchard Subject: [PATCH] powerpc: reset kernel stack on cpu online from cede state Message-ID: <20100222081930.GK5268@dirshya.in.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Cc: linuxppc-dev@ozlabs.org Reply-To: svaidy@linux.vnet.ibm.com List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , 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 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