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242214f9c1
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 <dzickus@redhat.com> Signed-off-by: Cyrill Gorcunov <gorcunov@openvz.org> Cc: Lin Ming <ming.m.lin@intel.com> LKML-Reference: <4D8BAB49.3080701@openvz.org> Signed-off-by: Ingo Molnar <mingo@elte.hu> |
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| boot | ||
| configs | ||
| crypto | ||
| ia32 | ||
| include/asm | ||
| kernel | ||
| kvm | ||
| lguest | ||
| lib | ||
| math-emu | ||
| mm | ||
| oprofile | ||
| pci | ||
| platform | ||
| power | ||
| tools | ||
| vdso | ||
| video | ||
| xen | ||
| .gitignore | ||
| Kbuild | ||
| Kconfig | ||
| Kconfig.cpu | ||
| Kconfig.debug | ||
| Makefile | ||
| Makefile_32.cpu | ||