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https://github.com/torvalds/linux
27 March 2024, 02:37:15 UTC
Revision f56029410a13cae3652d1f34788045c40a13ffc7 authored by Anton Blanchard on 28 May 2014, 22:15:38 UTC, committed by Benjamin Herrenschmidt on 11 July 2014, 03:50:47 UTC 
powerpc/perf: Never program book3s PMCs with values >= 0x80000000
 
We are seeing a lot of PMU warnings on POWER8:

    Can't find PMC that caused IRQ

Looking closer, the active PMC is 0 at this point and we took a PMU
exception on the transition from negative to 0. Some versions of POWER8
have an issue where they edge detect and not level detect PMC overflows.

A number of places program the PMC with (0x80000000 - period_left),
where period_left can be negative. We can either fix all of these or
just ensure that period_left is always >= 1.

This patch takes the second option.

Cc: <stable@vger.kernel.org>
Signed-off-by: Anton Blanchard <anton@samba.org>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
1 parent fb43e84
History
Tip revision: f56029410a13cae3652d1f34788045c40a13ffc7 authored by Anton Blanchard on 28 May 2014, 22:15:38 UTC
powerpc/perf: Never program book3s PMCs with values >= 0x80000000
Tip revision: f560294
File Mode Size
Kconfig -rw-r--r-- 60.9 KB
Makefile -rw-r--r-- 1.1 KB
calibrate.c -rw-r--r-- 8.3 KB
do_mounts.c -rw-r--r-- 14.3 KB
do_mounts.h -rw-r--r-- 1.4 KB
do_mounts_initrd.c -rw-r--r-- 3.4 KB
do_mounts_md.c -rw-r--r-- 8.2 KB
do_mounts_rd.c -rw-r--r-- 8.6 KB
init_task.c -rw-r--r-- 728 bytes
initramfs.c -rw-r--r-- 13.1 KB
main.c -rw-r--r-- 24.7 KB
noinitramfs.c -rw-r--r-- 1.5 KB
version.c -rw-r--r-- 1.2 KB
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