6.1-stable review patch. If anyone has any objections, please let me know.
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From: Thomas Richter tmricht@linux.ibm.com
[ Upstream commit e6ce1f12d777f6ee22b20e10ae6a771e7e6f44f5 ]
Event CF_DIAG reads out complete counter sets using stcctm instruction. This is done at event start time when the process starts execution and at event stop time when the process is removed from the CPU. During removal the difference of each counter in the counter sets is calculated and saved as raw data in the ring buffer. This works fine unless the number of counters in a counter set is zero. This may happen for the extended counter set. This set is machine specific and the size of the counter set can be zero even when extended counter set is authorized for read access.
This case is not handled. cfdiag_diffctr() checks authorization of the extended counter set. If true the functions assumes the extended counter set has been saved in a data buffer. However this is not the case, cfdiag_getctrset() does not save a counter set with counter set size of zero. This mismatch causes an endless loop in the counter set readout during event stop handling.
The calculation of the difference of the counters in each counter now verifies the size of the counter set is non-zero. A counter set with size zero is skipped.
Fixes: a029a4eab39e ("s390/cpumf: Allow concurrent access for CPU Measurement Counter Facility") Signed-off-by: Thomas Richter tmricht@linux.ibm.com Acked-by: Sumanth Korikkar sumanthk@linux.ibm.com Acked-by: Heiko Carstens hca@linux.ibm.com Cc: Heiko Carstens hca@linux.ibm.com Cc: Vasily Gorbik gor@linux.ibm.com Cc: Alexander Gordeev agordeev@linux.ibm.com Signed-off-by: Vasily Gorbik gor@linux.ibm.com Signed-off-by: Sasha Levin sashal@kernel.org --- arch/s390/kernel/perf_cpum_cf.c | 14 ++++++++++---- 1 file changed, 10 insertions(+), 4 deletions(-)
diff --git a/arch/s390/kernel/perf_cpum_cf.c b/arch/s390/kernel/perf_cpum_cf.c index 28fa80fd69fa0..3b7fbc14aa4a4 100644 --- a/arch/s390/kernel/perf_cpum_cf.c +++ b/arch/s390/kernel/perf_cpum_cf.c @@ -213,25 +213,31 @@ static int cfdiag_diffctr(struct cpu_cf_events *cpuhw, unsigned long auth) struct cf_trailer_entry *trailer_start, *trailer_stop; struct cf_ctrset_entry *ctrstart, *ctrstop; size_t offset = 0; + int i;
- auth &= (1 << CPUMF_LCCTL_ENABLE_SHIFT) - 1; - do { + for (i = CPUMF_CTR_SET_BASIC; i < CPUMF_CTR_SET_MAX; ++i) { ctrstart = (struct cf_ctrset_entry *)(cpuhw->start + offset); ctrstop = (struct cf_ctrset_entry *)(cpuhw->stop + offset);
+ /* Counter set not authorized */ + if (!(auth & cpumf_ctr_ctl[i])) + continue; + /* Counter set size zero was not saved */ + if (!cpum_cf_read_setsize(i)) + continue; + if (memcmp(ctrstop, ctrstart, sizeof(*ctrstop))) { pr_err_once("cpum_cf_diag counter set compare error " "in set %i\n", ctrstart->set); return 0; } - auth &= ~cpumf_ctr_ctl[ctrstart->set]; if (ctrstart->def == CF_DIAG_CTRSET_DEF) { cfdiag_diffctrset((u64 *)(ctrstart + 1), (u64 *)(ctrstop + 1), ctrstart->ctr); offset += ctrstart->ctr * sizeof(u64) + sizeof(*ctrstart); } - } while (ctrstart->def && auth); + }
/* Save time_stamp from start of event in stop's trailer */ trailer_start = (struct cf_trailer_entry *)(cpuhw->start + offset);