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    Subject[tip:x86/urgent] x86: oprofile: don't set counter width from cpuid on Core2
    Commit-ID:  780eef9492b16a1543a3b2ae9f9526a735fc9856
    Gitweb: http://git.kernel.org/tip/780eef9492b16a1543a3b2ae9f9526a735fc9856
    Author: "Tim Blechmann" <tim@klingt.org>
    AuthorDate: Thu, 19 Feb 2009 17:34:03 +0100
    Commit: Ingo Molnar <mingo@elte.hu>
    CommitDate: Tue, 3 Mar 2009 12:04:22 +0100

    x86: oprofile: don't set counter width from cpuid on Core2

    Impact: fix stuck NMIs and non-working oprofile on certain CPUs

    Resetting the counter width of the performance counters on Intel's
    Core2 CPUs, breaks the delivery of NMIs, when running in x86_64 mode.

    This should fix bug #12395:

    http://bugzilla.kernel.org/show_bug.cgi?id=12395

    Signed-off-by: Tim Blechmann <tim@klingt.org>
    Signed-off-by: Robert Richter <robert.richter@amd.com>
    LKML-Reference: <20090303100412.GC10085@erda.amd.com>
    Cc: <stable@kernel.org>
    Signed-off-by: Ingo Molnar <mingo@elte.hu>


    ---
    arch/x86/oprofile/op_model_ppro.c | 14 ++++++++++++--
    1 files changed, 12 insertions(+), 2 deletions(-)

    diff --git a/arch/x86/oprofile/op_model_ppro.c b/arch/x86/oprofile/op_model_ppro.c
    index e9f80c7..10131fb 100644
    --- a/arch/x86/oprofile/op_model_ppro.c
    +++ b/arch/x86/oprofile/op_model_ppro.c
    @@ -78,8 +78,18 @@ static void ppro_setup_ctrs(struct op_msrs const * const msrs)
    if (cpu_has_arch_perfmon) {
    union cpuid10_eax eax;
    eax.full = cpuid_eax(0xa);
    - if (counter_width < eax.split.bit_width)
    - counter_width = eax.split.bit_width;
    +
    + /*
    + * For Core2 (family 6, model 15), don't reset the
    + * counter width:
    + */
    + if (!(eax.split.version_id == 0 &&
    + current_cpu_data.x86 == 6 &&
    + current_cpu_data.x86_model == 15)) {
    +
    + if (counter_width < eax.split.bit_width)
    + counter_width = eax.split.bit_width;
    + }
    }

    /* clear all counters */

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