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authorIngo Molnar <mingo@elte.hu>2011-03-25 10:24:23 +0100
committerIngo Molnar <mingo@elte.hu>2011-03-25 11:23:41 +0100
commit45daae575e08bbf7405c5a3633e956fa364d1b4f (patch)
tree453f4ffc48012c14e57259e2ad95231b396e0ebc /arch/x86
parent242214f9c1eeaae40eca11e3b4d37bfce960a7cd (diff)
downloadop-kernel-dev-45daae575e08bbf7405c5a3633e956fa364d1b4f.zip
op-kernel-dev-45daae575e08bbf7405c5a3633e956fa364d1b4f.tar.gz
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 <eric.dumazet@gmail.com> Suggested-by: Linus Torvalds <torvalds@linux-foundation.org> Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Arnaldo Carvalho de Melo <acme@redhat.com> Cc: Frederic Weisbecker <fweisbec@gmail.com> Cc: Mike Galbraith <efault@gmx.de> Cc: Steven Rostedt <rostedt@goodmis.org> LKML-Reference: <new-submission> Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'arch/x86')
-rw-r--r--arch/x86/kernel/cpu/perf_event.c9
1 files changed, 7 insertions, 2 deletions
diff --git a/arch/x86/kernel/cpu/perf_event.c b/arch/x86/kernel/cpu/perf_event.c
index ec46eea..eb00677 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;
}
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