From: Mikael Pettersson <mikpe@csd.uu.se>
This patch fixes a bug in perfctr's x86 driver, which can cause it to clear
one of the counter control registers at driver initialisation time. At
this point the HW is either free or owned by the lapic NMI watchdog. In
the former case the bug is harmless, but in the latter case the effect on
P6 and AMD is that the watchdog stops ticking.
Signed-off-by: Mikael Pettersson <mikpe@csd.uu.se>
Signed-off-by: Andrew Morton <akpm@osdl.org>
---
25-akpm/drivers/perfctr/x86.c | 2 +-
25-akpm/include/asm-i386/perfctr.h | 9 ++++++++-
2 files changed, 9 insertions(+), 2 deletions(-)
diff -puN drivers/perfctr/x86.c~perfctr-x86-init-bug drivers/perfctr/x86.c
--- 25/drivers/perfctr/x86.c~perfctr-x86-init-bug 2004-07-26 16:50:40.350090712 -0700
+++ 25-akpm/drivers/perfctr/x86.c 2004-07-26 16:50:40.356089800 -0700
@@ -1142,7 +1142,7 @@ static void __init finalise_backpatching
memset(&state, 0, sizeof state);
state.cstatus =
(perfctr_info.cpu_features & PERFCTR_FEATURE_PCINT)
- ? perfctr_mk_cstatus(0, 0, 1)
+ ? __perfctr_mk_cstatus(0, 1, 0, 0)
: 0;
perfctr_cpu_sample(&state);
perfctr_cpu_resume(&state);
diff -puN include/asm-i386/perfctr.h~perfctr-x86-init-bug include/asm-i386/perfctr.h
--- 25/include/asm-i386/perfctr.h~perfctr-x86-init-bug 2004-07-26 16:50:40.351090560 -0700
+++ 25-akpm/include/asm-i386/perfctr.h 2004-07-26 16:50:40.357089648 -0700
@@ -73,10 +73,17 @@ struct perfctr_cpu_state {
which should have less overhead in most cases */
static inline
+unsigned int __perfctr_mk_cstatus(unsigned int tsc_on, unsigned int have_ictrs,
+ unsigned int nrictrs, unsigned int nractrs)
+{
+ return (tsc_on<<31) | (have_ictrs<<16) | ((nractrs+nrictrs)<<8) | nractrs;
+}
+
+static inline
unsigned int perfctr_mk_cstatus(unsigned int tsc_on, unsigned int nractrs,
unsigned int nrictrs)
{
- return (tsc_on<<31) | (nrictrs<<16) | ((nractrs+nrictrs)<<8) | nractrs;
+ return __perfctr_mk_cstatus(tsc_on, nrictrs, nrictrs, nractrs);
}
static inline unsigned int perfctr_cstatus_enabled(unsigned int cstatus)
_