From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932669Ab0EJWyN (ORCPT ); Mon, 10 May 2010 18:54:13 -0400 Received: from kroah.org ([198.145.64.141]:33289 "EHLO coco.kroah.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932484Ab0EJWwj (ORCPT ); Mon, 10 May 2010 18:52:39 -0400 X-Mailbox-Line: From gregkh@kvm.kroah.org Mon May 10 15:33:24 2010 Message-Id: <20100510223324.525294385@kvm.kroah.org> User-Agent: quilt/0.48-4.4 Date: Mon, 10 May 2010 15:32:50 -0700 From: Greg KH To: linux-kernel@vger.kernel.org, stable@kernel.org Cc: stable-review@kernel.org, torvalds@linux-foundation.org, akpm@linux-foundation.org, alan@lxorguk.ukuu.org.uk, Vaidyanathan Srinivasan , Gautham R Shenoy , Benjamin Herrenschmidt Subject: [079/117] powerpc: Reset kernel stack on cpu online from cede state In-Reply-To: <20100510223700.GA18404@kroah.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 2.6.33-stable review patch. If anyone has any objections, please let us know. ------------------ From: Vaidyanathan Srinivasan 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 Cc: Gautham R Shenoy Signed-off-by: Benjamin Herrenschmidt Signed-off-by: Greg Kroah-Hartman --- 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