From fc66c5210ec2539e800e87d7b3a985323c7be96e Mon Sep 17 00:00:00 2001 From: Stephane Eranian Date: Sat, 19 Mar 2011 18:20:05 +0100 Subject: perf, x86: Fix Intel fixed counters base initialization The following patch solves the problems introduced by Robert's commit 41bf498 and reported by Arun Sharma. This commit gets rid of the base + index notation for reading and writing PMU msrs. The problem is that for fixed counters, the new calculation for the base did not take into account the fixed counter indexes, thus all fixed counters were read/written from fixed counter 0. Although all fixed counters share the same config MSR, they each have their own counter register. Without: $ task -e unhalted_core_cycles -e instructions_retired -e baclears noploop 1 noploop for 1 seconds 242202299 unhalted_core_cycles (0.00% scaling, ena=1000790892, run=1000790892) 2389685946 instructions_retired (0.00% scaling, ena=1000790892, run=1000790892) 49473 baclears (0.00% scaling, ena=1000790892, run=1000790892) With: $ task -e unhalted_core_cycles -e instructions_retired -e baclears noploop 1 noploop for 1 seconds 2392703238 unhalted_core_cycles (0.00% scaling, ena=1000840809, run=1000840809) 2389793744 instructions_retired (0.00% scaling, ena=1000840809, run=1000840809) 47863 baclears (0.00% scaling, ena=1000840809, run=1000840809) Signed-off-by: Stephane Eranian Cc: peterz@infradead.org Cc: ming.m.lin@intel.com Cc: robert.richter@amd.com Cc: asharma@fb.com Cc: perfmon2-devel@lists.sf.net LKML-Reference: <20110319172005.GB4978@quad> Signed-off-by: Ingo Molnar --- arch/x86/kernel/cpu/perf_event.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'arch') diff --git a/arch/x86/kernel/cpu/perf_event.c b/arch/x86/kernel/cpu/perf_event.c index e8dbe179587f..ec46eea0c4ed 100644 --- a/arch/x86/kernel/cpu/perf_event.c +++ b/arch/x86/kernel/cpu/perf_event.c @@ -912,7 +912,7 @@ static inline void x86_assign_hw_event(struct perf_event *event, hwc->event_base = 0; } else if (hwc->idx >= X86_PMC_IDX_FIXED) { hwc->config_base = MSR_ARCH_PERFMON_FIXED_CTR_CTRL; - hwc->event_base = MSR_ARCH_PERFMON_FIXED_CTR0; + hwc->event_base = MSR_ARCH_PERFMON_FIXED_CTR0 + (hwc->idx - X86_PMC_IDX_FIXED); } else { hwc->config_base = x86_pmu_config_addr(hwc->idx); hwc->event_base = x86_pmu_event_addr(hwc->idx); -- cgit v1.2.3 From 242214f9c1eeaae40eca11e3b4d37bfce960a7cd Mon Sep 17 00:00:00 2001 From: Don Zickus Date: Thu, 24 Mar 2011 23:36:25 +0300 Subject: perf, x86: P4 PMU - Read proper MSR register to catch unflagged overflows The read of a proper MSR register was missed and instead of counter the configration register was tested (it has ARCH_P4_UNFLAGGED_BIT always cleared) leading to unknown NMI hitting the system. As result the user may obtain "Dazed and confused, but trying to continue" message. Fix it by reading a proper MSR register. When an NMI happens on a P4, the perf nmi handler checks the configuration register to see if the overflow bit is set or not before taking appropriate action. Unfortunately, various P4 machines had a broken overflow bit, so a backup mechanism was implemented. This mechanism checked to see if the counter rolled over or not. A previous commit that implemented this backup mechanism was broken. Instead of reading the counter register, it used the configuration register to determine if the counter rolled over or not. Reading that bit would give incorrect results. This would lead to 'Dazed and confused' messages for the end user when using the perf tool (or if the nmi watchdog is running). The fix is to read the counter register before determining if the counter rolled over or not. Signed-off-by: Don Zickus Signed-off-by: Cyrill Gorcunov Cc: Lin Ming LKML-Reference: <4D8BAB49.3080701@openvz.org> Signed-off-by: Ingo Molnar --- arch/x86/kernel/cpu/perf_event_p4.c | 1 + 1 file changed, 1 insertion(+) (limited to 'arch') diff --git a/arch/x86/kernel/cpu/perf_event_p4.c b/arch/x86/kernel/cpu/perf_event_p4.c index 3769ac822f96..d3d7b59841e5 100644 --- a/arch/x86/kernel/cpu/perf_event_p4.c +++ b/arch/x86/kernel/cpu/perf_event_p4.c @@ -777,6 +777,7 @@ static inline int p4_pmu_clear_cccr_ovf(struct hw_perf_event *hwc) * the counter has reached zero value and continued counting before * real NMI signal was received: */ + rdmsrl(hwc->event_base, v); if (!(v & ARCH_P4_UNFLAGGED_BIT)) return 1; -- cgit v1.2.3 From 45daae575e08bbf7405c5a3633e956fa364d1b4f Mon Sep 17 00:00:00 2001 From: Ingo Molnar Date: Fri, 25 Mar 2011 10:24:23 +0100 Subject: perf, x86: Complain louder about BIOSen corrupting CPU/PMU state and continue Eric Dumazet reported that hardware PMU events do not work on his system, due to the BIOS corrupting PMU state: Performance Events: PEBS fmt0+, Core2 events, Broken BIOS detected, using software events only. [Firmware Bug]: the BIOS has corrupted hw-PMU resources (MSR 186 is 43003c) Linus suggested that we continue in the face of such BIOS-induced CPU state corruption: http://lkml.org/lkml/2011/3/24/608 Such BIOSes will have to be fixed - Linux developers rely on a working and fully capable PMU and the BIOS interfering with the CPU's PMU state is simply not acceptable. So this patch changes perf to continue when it detects such BIOS interaction, some hardware events may be unreliable due to the BIOS writing and re-writing them - there's not much the kernel can do about that but to detect the corruption and report it. Reported-and-tested-by: Eric Dumazet Suggested-by: Linus Torvalds Acked-by: Peter Zijlstra Cc: Thomas Gleixner Cc: Arnaldo Carvalho de Melo Cc: Frederic Weisbecker Cc: Mike Galbraith Cc: Steven Rostedt LKML-Reference: Signed-off-by: Ingo Molnar --- arch/x86/kernel/cpu/perf_event.c | 9 +++++++-- 1 file changed, 7 insertions(+), 2 deletions(-) (limited to 'arch') diff --git a/arch/x86/kernel/cpu/perf_event.c b/arch/x86/kernel/cpu/perf_event.c index ec46eea0c4ed..eb00677ee2ae 100644 --- a/arch/x86/kernel/cpu/perf_event.c +++ b/arch/x86/kernel/cpu/perf_event.c @@ -500,12 +500,17 @@ static bool check_hw_exists(void) return true; bios_fail: - printk(KERN_CONT "Broken BIOS detected, using software events only.\n"); + /* + * We still allow the PMU driver to operate: + */ + printk(KERN_CONT "Broken BIOS detected, complain to your hardware vendor.\n"); printk(KERN_ERR FW_BUG "the BIOS has corrupted hw-PMU resources (MSR %x is %Lx)\n", reg, val); - return false; + + return true; msr_fail: printk(KERN_CONT "Broken PMU hardware detected, using software events only.\n"); + return false; } -- cgit v1.2.3