From patchwork Fri Aug 9 07:29:30 2013 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Michael Neuling X-Patchwork-Id: 265918 Return-Path: X-Original-To: patchwork-incoming@ozlabs.org Delivered-To: patchwork-incoming@ozlabs.org Received: from ozlabs.org (localhost [IPv6:::1]) by ozlabs.org (Postfix) with ESMTP id 572002C0525 for ; Fri, 9 Aug 2013 17:31:44 +1000 (EST) Received: from localhost.localdomain (localhost [127.0.0.1]) by ozlabs.org (Postfix) with ESMTP id DBC9D2C0092; Fri, 9 Aug 2013 17:29:35 +1000 (EST) Received: by localhost.localdomain (Postfix, from userid 1000) id 6E53FD42B56; Fri, 9 Aug 2013 17:29:35 +1000 (EST) From: Michael Neuling To: Benjamin Herrenschmidt Subject: [PATCH 4/5] powerpc: Save the TAR register earlier Date: Fri, 9 Aug 2013 17:29:30 +1000 Message-Id: <1376033371-28713-4-git-send-email-mikey@neuling.org> X-Mailer: git-send-email 1.8.1.2 In-Reply-To: <1376033371-28713-1-git-send-email-mikey@neuling.org> References: <1376033371-28713-1-git-send-email-mikey@neuling.org> In-Reply-To: <25550.1375872955@ale.ozlabs.ibm.com> References: <25550.1375872955@ale.ozlabs.ibm.com> Cc: linuxppc-dev@lists.ozlabs.org X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , MIME-Version: 1.0 Errors-To: linuxppc-dev-bounces+patchwork-incoming=ozlabs.org@lists.ozlabs.org Sender: "Linuxppc-dev" This moves us to save the Target Address Register (TAR) a earlier in __switch_to. It introduces a new function save_tar() to do this. We need to save the TAR earlier as we will overwrite it in the transactional memory reclaim/recheckpoint path. We are going to do this in a subsequent patch which will fix saving the TAR register when it's modified inside a transaction. Signed-off-by: Michael Neuling Cc: [v3.10] --- arch/powerpc/include/asm/switch_to.h | 9 +++++++++ arch/powerpc/kernel/entry_64.S | 9 --------- arch/powerpc/kernel/process.c | 10 ++++++++++ 3 files changed, 19 insertions(+), 9 deletions(-) diff --git a/arch/powerpc/include/asm/switch_to.h b/arch/powerpc/include/asm/switch_to.h index 49a13e0..294c2ce 100644 --- a/arch/powerpc/include/asm/switch_to.h +++ b/arch/powerpc/include/asm/switch_to.h @@ -15,6 +15,15 @@ extern struct task_struct *__switch_to(struct task_struct *, struct thread_struct; extern struct task_struct *_switch(struct thread_struct *prev, struct thread_struct *next); +#ifdef CONFIG_PPC_BOOK3S_64 +static inline void save_tar(struct thread_struct *prev) +{ + if (cpu_has_feature(CPU_FTR_ARCH_207S)) + prev->tar = mfspr(SPRN_TAR); +} +#else +static inline void save_tar(struct thread_struct *prev) {} +#endif extern void giveup_fpu(struct task_struct *); extern void load_up_fpu(void); diff --git a/arch/powerpc/kernel/entry_64.S b/arch/powerpc/kernel/entry_64.S index 4674fe6..2bd0b88 100644 --- a/arch/powerpc/kernel/entry_64.S +++ b/arch/powerpc/kernel/entry_64.S @@ -449,15 +449,6 @@ END_FTR_SECTION_IFSET(CPU_FTR_DSCR) #ifdef CONFIG_PPC_BOOK3S_64 BEGIN_FTR_SECTION - /* - * Back up the TAR across context switches. Note that the TAR is not - * available for use in the kernel. (To provide this, the TAR should - * be backed up/restored on exception entry/exit instead, and be in - * pt_regs. FIXME, this should be in pt_regs anyway (for debug).) - */ - mfspr r0,SPRN_TAR - std r0,THREAD_TAR(r3) - /* Event based branch registers */ mfspr r0, SPRN_BESCR std r0, THREAD_BESCR(r3) diff --git a/arch/powerpc/kernel/process.c b/arch/powerpc/kernel/process.c index c517dbe..8083be2 100644 --- a/arch/powerpc/kernel/process.c +++ b/arch/powerpc/kernel/process.c @@ -600,6 +600,16 @@ struct task_struct *__switch_to(struct task_struct *prev, struct ppc64_tlb_batch *batch; #endif + /* Back up the TAR across context switches. + * Note that the TAR is not available for use in the kernel. (To + * provide this, the TAR should be backed up/restored on exception + * entry/exit instead, and be in pt_regs. FIXME, this should be in + * pt_regs anyway (for debug).) + * Save the TAR here before we do treclaim/trecheckpoint as these + * will change the TAR. + */ + save_tar(&prev->thread); + __switch_to_tm(prev); #ifdef CONFIG_SMP