From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from e23smtp08.au.ibm.com (e23smtp08.au.ibm.com [202.81.31.141]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (Client CN "e23smtp08.au.ibm.com", Issuer "Equifax" (verified OK)) by ozlabs.org (Postfix) with ESMTPS id 7D86BB6F06 for ; Tue, 8 Mar 2011 17:37:40 +1100 (EST) Received: from d23relay03.au.ibm.com (d23relay03.au.ibm.com [202.81.31.245]) by e23smtp08.au.ibm.com (8.14.4/8.13.1) with ESMTP id p286WWC7019351 for ; Tue, 8 Mar 2011 17:32:32 +1100 Received: from d23av03.au.ibm.com (d23av03.au.ibm.com [9.190.234.97]) by d23relay03.au.ibm.com (8.13.8/8.13.8/NCO v10.0) with ESMTP id p286bcQR2343020 for ; Tue, 8 Mar 2011 17:37:38 +1100 Received: from d23av03.au.ibm.com (loopback [127.0.0.1]) by d23av03.au.ibm.com (8.14.4/8.13.1/NCO v10.0 AVout) with ESMTP id p286bcNu021083 for ; Tue, 8 Mar 2011 17:37:38 +1100 From: Benjamin Herrenschmidt To: linuxppc-dev@ozlabs.org Subject: [PATCH 02/18] powerpc/smp: soft-replugged CPUs must go back to start_secondary Date: Tue, 8 Mar 2011 17:37:14 +1100 Message-Id: <1299566250-10516-3-git-send-email-benh@kernel.crashing.org> In-Reply-To: <1299566250-10516-1-git-send-email-benh@kernel.crashing.org> References: <1299566250-10516-1-git-send-email-benh@kernel.crashing.org> List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Various thing are torn down when a CPU is hot-unplugged. That CPU is expected to go back to start_secondary when re-plugged to re initialize everything, such as clock sources, maps, ... Some implementations just return from cpu_die() callback in the idle loop when the CPU is "re-plugged". This is not enough. We fix it using a little asm trampoline which resets the stack and calls back into start_secondary as if we were all fresh from boot. The trampoline already existed on ppc64, but we add it for ppc32 Signed-off-by: Benjamin Herrenschmidt --- arch/powerpc/include/asm/smp.h | 1 + arch/powerpc/kernel/head_32.S | 9 +++++++++ arch/powerpc/kernel/smp.c | 9 +++++++-- arch/powerpc/platforms/pseries/offline_states.h | 2 -- 4 files changed, 17 insertions(+), 4 deletions(-) diff --git a/arch/powerpc/include/asm/smp.h b/arch/powerpc/include/asm/smp.h index 66e237b..1de0e97 100644 --- a/arch/powerpc/include/asm/smp.h +++ b/arch/powerpc/include/asm/smp.h @@ -36,6 +36,7 @@ extern void cpu_die(void); extern void smp_send_debugger_break(int cpu); extern void smp_message_recv(int); +extern void start_secondary_resume(void); DECLARE_PER_CPU(unsigned int, cpu_pvr); diff --git a/arch/powerpc/kernel/head_32.S b/arch/powerpc/kernel/head_32.S index 98c4b29..c5c24be 100644 --- a/arch/powerpc/kernel/head_32.S +++ b/arch/powerpc/kernel/head_32.S @@ -890,6 +890,15 @@ __secondary_start: mtspr SPRN_SRR1,r4 SYNC RFI + +_GLOBAL(start_secondary_resume) + /* Reset stack */ + rlwinm r1,r1,0,0,(31-THREAD_SHIFT) /* current_thread_info() */ + addi r1,r1,THREAD_SIZE-STACK_FRAME_OVERHEAD + li r3,0 + std r3,0(r1) /* Zero the stack frame pointer */ + bl start_secondary + b . #endif /* CONFIG_SMP */ #ifdef CONFIG_KVM_BOOK3S_HANDLER diff --git a/arch/powerpc/kernel/smp.c b/arch/powerpc/kernel/smp.c index 9813605..1c9956c 100644 --- a/arch/powerpc/kernel/smp.c +++ b/arch/powerpc/kernel/smp.c @@ -502,7 +502,7 @@ static struct device_node *cpu_to_l2cache(int cpu) } /* Activate a secondary processor. */ -int __devinit start_secondary(void *unused) +void __devinit start_secondary(void *unused) { unsigned int cpu = smp_processor_id(); struct device_node *l2_cache; @@ -558,7 +558,8 @@ int __devinit start_secondary(void *unused) local_irq_enable(); cpu_idle(); - return 0; + + BUG(); } int setup_profiling_timer(unsigned int multiplier) @@ -660,5 +661,9 @@ void cpu_die(void) { if (ppc_md.cpu_die) ppc_md.cpu_die(); + + /* If we return, we re-enter start_secondary */ + start_secondary_resume(); } + #endif diff --git a/arch/powerpc/platforms/pseries/offline_states.h b/arch/powerpc/platforms/pseries/offline_states.h index 75a6f48..08672d9 100644 --- a/arch/powerpc/platforms/pseries/offline_states.h +++ b/arch/powerpc/platforms/pseries/offline_states.h @@ -34,6 +34,4 @@ static inline void set_default_offline_state(int cpu) #endif extern enum cpu_state_vals get_preferred_offline_state(int cpu); -extern int start_secondary(void); -extern void start_secondary_resume(void); #endif -- 1.7.1