From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from e38.co.us.ibm.com (e38.co.us.ibm.com [32.97.110.159]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (Client CN "e38.co.us.ibm.com", Issuer "Equifax" (verified OK)) by ozlabs.org (Postfix) with ESMTPS id 498D4DDF82 for ; Fri, 8 May 2009 01:48:44 +1000 (EST) Received: from d03relay02.boulder.ibm.com (d03relay02.boulder.ibm.com [9.17.195.227]) by e38.co.us.ibm.com (8.13.1/8.13.1) with ESMTP id n47Fk1gN029907 for ; Thu, 7 May 2009 09:46:01 -0600 Received: from d03av02.boulder.ibm.com (d03av02.boulder.ibm.com [9.17.195.168]) by d03relay02.boulder.ibm.com (8.13.8/8.13.8/NCO v9.2) with ESMTP id n47FmZL0056686 for ; Thu, 7 May 2009 09:48:36 -0600 Received: from d03av02.boulder.ibm.com (loopback [127.0.0.1]) by d03av02.boulder.ibm.com (8.12.11.20060308/8.13.3) with ESMTP id n47FmYMS027612 for ; Thu, 7 May 2009 09:48:34 -0600 Received: from [9.65.81.158] (sig-9-65-81-158.mts.ibm.com [9.65.81.158]) by d03av02.boulder.ibm.com (8.12.11.20060308/8.12.11) with ESMTP id n47FmX4h027488 for ; Thu, 7 May 2009 09:48:33 -0600 Subject: [PATCH] powerpc: Fix oprofile sampling of marked events on POWER7 From: Mike Wolf To: linuxppc-dev@ozlabs.org Content-Type: text/plain Date: Thu, 07 May 2009 10:48:32 -0500 Message-Id: <1241711312.13502.5.camel@mx3> Mime-Version: 1.0 Reply-To: mjw@linux.vnet.ibm.com List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , From: Maynard Johnson Description ----------- Change ppc64 oprofile kernel driver to use the SLOT bits (MMCRA[37:39]only on older processors where those bits are defined. Background ---------- The performance monitor unit of the 64-bit POWER processor family has the ability to collect accurate instruction-level samples when profiling on marked events (i.e., "PM_MRK_"). In processors prior to POWER6, the MMCRA register contained "slot information" that the oprofile kernel driver used to adjust the value latched in the SIAR at the time of a PMU interrupt. But as of POWER6, these slot bits in MMCRA are no longer necessary for oprofile to use, since the SIAR itself holds the accurate sampled instruction address. With POWER6, these MMCRA slot bits were zero'ed out by hardware so oprofile's use of these slot bits was, in effect, a NOP. But with POWER7, these bits are no longer zero'ed out; however, they serve some other purpose rather than slot information. Thus, using these bits on POWER7 to adjust the SIAR value results in samples being attributed to the wrong instructions. The attached patch changes the oprofile kernel driver to ignore these slot bits on all newer processors starting with POWER6. Signed-off-by: Maynard Johnson Signed-off-by: Michael Wolf --- diff -paur linux/arch/powerpc/oprofile/op_model_power4.c linux-p7-oprofile-patch//arch/powerpc/oprofile/op_model_power4.c --- linux/arch/powerpc/oprofile/op_model_power4.c 2009-05-01 08:20:21.000000000 -0500 +++ linux-p7-oprofile-patch//arch/powerpc/oprofile/op_model_power4.c 2009-05-01 08:20:05.000000000 -0500 @@ -26,6 +26,7 @@ static unsigned long reset_value[OP_MAX_COUNTER]; static int oprofile_running; +static int use_slot_nums; /* mmcr values are set in power4_reg_setup, used in power4_cpu_setup */ static u32 mmcr0_val; @@ -61,6 +62,12 @@ static int power4_reg_setup(struct op_co else mmcr0_val |= MMCR0_PROBLEM_DISABLE; + if (__is_processor(PV_POWER4) || __is_processor(PV_POWER4p) || + __is_processor(PV_970) || __is_processor(PV_970FX) || + __is_processor(PV_970MP) || __is_processor(PV_970GX) || + __is_processor(PV_POWER5) || __is_processor(PV_POWER5p)) + use_slot_nums = 1; + return 0; } @@ -206,7 +213,7 @@ static unsigned long get_pc(struct pt_re mmcra = mfspr(SPRN_MMCRA); - if (mmcra & MMCRA_SAMPLE_ENABLE) { + if (use_slot_nums && (mmcra & MMCRA_SAMPLE_ENABLE)) { slot = ((mmcra & MMCRA_SLOT) >> MMCRA_SLOT_SHIFT); if (slot > 1) pc += 4 * (slot - 1);