From patchwork Mon Aug 5 11:00:35 2013 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Michael Neuling X-Patchwork-Id: 264631 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 97F832C0277 for ; Mon, 5 Aug 2013 21:01:10 +1000 (EST) Received: from localhost.localdomain (localhost [127.0.0.1]) by ozlabs.org (Postfix) with ESMTP id C26162C007E; Mon, 5 Aug 2013 21:00:36 +1000 (EST) Received: by localhost.localdomain (Postfix, from userid 1000) id 98FCCD43B51; Mon, 5 Aug 2013 21:00:35 +1000 (EST) Received: from ale.ozlabs.ibm.com (localhost [127.0.0.1]) by localhost.localdomain (Postfix) with ESMTP id 979E0D41B31; Mon, 5 Aug 2013 21:00:35 +1000 (EST) From: Michael Neuling To: Stephen Rothwell Subject: [PATCH v2 3/3] powerpc: Correctly context switch DSCR on POWER8 In-reply-to: <21599.1375697783@ale.ozlabs.ibm.com> References: <1375687686-5633-1-git-send-email-mikey@neuling.org> <1375687686-5633-3-git-send-email-mikey@neuling.org> <20130805184205.79cafb9ac299313228ec53cc@canb.auug.org.au> <15850.1375694796@ale.ozlabs.ibm.com> <21599.1375697783@ale.ozlabs.ibm.com> Comments: In-reply-to Michael Neuling message dated "Mon, 05 Aug 2013 20:16:23 +1000." X-Mailer: MH-E 8.2; nmh 1.5; GNU Emacs 23.4.1 Date: Mon, 05 Aug 2013 21:00:35 +1000 Message-ID: <30983.1375700435@ale.ozlabs.ibm.com> Cc: linuxppc-dev@lists.ozlabs.org, Anton Blanchard 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" POWER8 allows the DSCR to be accessed directly from userspace via a new SPR number 0x3 (Rather than 0x11. DSCR SPR number 0x11 is still used on POWER8 but like POWER7, is only accessible in HV and OS modes). Currently, we allow this by setting H/FSCR DSCR bit on boot. Unfortunately this doesn't work, as the kernel needs to see the DSCR change so that it knows to no longer restore the system wide version of DSCR on context switch (ie. to set thread.dscr_inherit). This clears the H/FSCR DSCR bit initially. If a process then accesses the DSCR (via SPR 0x3), it'll trap into the kernel where we set thread.dscr_inherit in facility_unavailable_exception(). We also change _switch() so that we set or clear the H/FSCR DSCR bit based on the thread.dscr_inherit. Signed-off-by: Michael Neuling diff --git a/arch/powerpc/kernel/cpu_setup_power.S b/arch/powerpc/kernel/cpu_setup_power.S index 18b5b9c..c7a3b81 100644 --- a/arch/powerpc/kernel/cpu_setup_power.S +++ b/arch/powerpc/kernel/cpu_setup_power.S @@ -123,14 +123,18 @@ __init_LPCR: __init_FSCR: mfspr r3,SPRN_FSCR - ori r3,r3,FSCR_TAR|FSCR_DSCR|FSCR_EBB + ori r3,r3,FSCR_TAR|FSCR_EBB + li r5,HFSCR_DSCR + andc r3,r3,r5 mtspr SPRN_FSCR,r3 blr __init_HFSCR: mfspr r3,SPRN_HFSCR ori r3,r3,HFSCR_TAR|HFSCR_TM|HFSCR_BHRB|HFSCR_PM|\ - HFSCR_DSCR|HFSCR_VECVSX|HFSCR_FP|HFSCR_EBB + HFSCR_VECVSX|HFSCR_FP|HFSCR_EBB + li r5,HFSCR_DSCR + andc r3,r3,r5 mtspr SPRN_HFSCR,r3 blr diff --git a/arch/powerpc/kernel/entry_64.S b/arch/powerpc/kernel/entry_64.S index ab15b8d..4674fe6 100644 --- a/arch/powerpc/kernel/entry_64.S +++ b/arch/powerpc/kernel/entry_64.S @@ -584,9 +584,34 @@ BEGIN_FTR_SECTION ld r7,DSCR_DEFAULT@toc(2) ld r0,THREAD_DSCR(r4) cmpwi r6,0 + li r8, FSCR_DSCR bne 1f ld r0,0(r7) -1: cmpd r0,r25 + b 3f +1: + BEGIN_FTR_SECTION_NESTED(70) + mfspr r6, SPRN_FSCR + or r6, r6, r8 + mtspr SPRN_FSCR, r6 + BEGIN_FTR_SECTION_NESTED(69) + mfspr r6, SPRN_HFSCR + or r6, r6, r8 + mtspr SPRN_HFSCR, r6 + END_FTR_SECTION_NESTED(CPU_FTR_HVMODE, CPU_FTR_HVMODE, 69) + b 4f + END_FTR_SECTION_NESTED(CPU_FTR_ARCH_207S, CPU_FTR_ARCH_207S, 70) +3: + BEGIN_FTR_SECTION_NESTED(70) + mfspr r6, SPRN_FSCR + andc r6, r6, r8 + mtspr SPRN_FSCR, r6 + BEGIN_FTR_SECTION_NESTED(69) + mfspr r6, SPRN_HFSCR + andc r6, r6, r8 + mtspr SPRN_HFSCR, r6 + END_FTR_SECTION_NESTED(CPU_FTR_HVMODE, CPU_FTR_HVMODE, 69) + END_FTR_SECTION_NESTED(CPU_FTR_ARCH_207S, CPU_FTR_ARCH_207S, 70) +4: cmpd r0,r25 beq 2f mtspr SPRN_DSCR,r0 2: diff --git a/arch/powerpc/kernel/traps.c b/arch/powerpc/kernel/traps.c index bf33c22..e435bc0 100644 --- a/arch/powerpc/kernel/traps.c +++ b/arch/powerpc/kernel/traps.c @@ -44,9 +44,7 @@ #include #include #include -#ifdef CONFIG_PPC32 #include -#endif #ifdef CONFIG_PMAC_BACKLIGHT #include #endif @@ -1296,43 +1294,54 @@ void vsx_unavailable_exception(struct pt_regs *regs) die("Unrecoverable VSX Unavailable Exception", regs, SIGABRT); } +#ifdef CONFIG_PPC64 void facility_unavailable_exception(struct pt_regs *regs) { static char *facility_strings[] = { - "FPU", - "VMX/VSX", - "DSCR", - "PMU SPRs", - "BHRB", - "TM", - "AT", - "EBB", - "TAR", + [FSCR_FP_LG] = "FPU", + [FSCR_VECVSX_LG] = "VMX/VSX", + [FSCR_DSCR_LG] = "DSCR", + [FSCR_PM_LG] = "PMU SPRs", + [FSCR_BHRB_LG] = "BHRB", + [FSCR_TM_LG] = "TM", + [FSCR_EBB_LG] = "EBB", + [FSCR_TAR_LG] = "TAR", }; - char *facility, *prefix; + char *facility = "unknown"; u64 value; + u8 status; + bool hv; - if (regs->trap == 0xf60) { - value = mfspr(SPRN_FSCR); - prefix = ""; - } else { + hv = (regs->trap == 0xf80); + if (hv) value = mfspr(SPRN_HFSCR); - prefix = "Hypervisor "; + else + value = mfspr(SPRN_FSCR); + + status = value >> 56; + if (status == FSCR_DSCR_LG) { + /* User is acessing the DSCR. Set the inherit bit and allow + * the user to set it directly in future by setting via the + * H/FSCR DSCR bit. + */ + current->thread.dscr_inherit = 1; + if (hv) + mtspr(SPRN_HFSCR, value | HFSCR_DSCR); + else + mtspr(SPRN_FSCR, value | FSCR_DSCR); + return; } - value = value >> 56; + if ((status < ARRAY_SIZE(facility_strings)) && + facility_strings[status]) + facility = facility_strings[status]; /* We restore the interrupt state now */ if (!arch_irq_disabled_regs(regs)) local_irq_enable(); - if (value < ARRAY_SIZE(facility_strings)) - facility = facility_strings[value]; - else - facility = "unknown"; - pr_err("%sFacility '%s' unavailable, exception at 0x%lx, MSR=%lx\n", - prefix, facility, regs->nip, regs->msr); + hv ? "Hypervisor " : "", facility, regs->nip, regs->msr); if (user_mode(regs)) { _exception(SIGILL, regs, ILL_ILLOPC, regs->nip); @@ -1341,6 +1350,7 @@ void facility_unavailable_exception(struct pt_regs *regs) die("Unexpected facility unavailable exception", regs, SIGABRT); } +#endif #ifdef CONFIG_PPC_TRANSACTIONAL_MEM