From: Thomas Richter tmricht@linux.ibm.com
commit 78d732e1f326f74f240d416af9484928303d9951 upstream.
This file is installed by the s390 CPU Measurement sampling facility device driver to export supported minimum and maximum sample buffer sizes. This file is read by lscpumf tool to display the details of the device driver capabilities. The lscpumf tool might be invoked by a non-root user. In this case it does not print anything because the file contents can not be read.
Fix this by allowing read access for all users. Reading the file contents is ok, changing the file contents is left to the root user only.
For further reference and details see: [1] https://github.com/ibm-s390-tools/s390-tools/issues/97
Fixes: 69f239ed335a ("s390/cpum_sf: Dynamically extend the sampling buffer if overflows occur") Cc: stable@vger.kernel.org # 3.14 Signed-off-by: Thomas Richter tmricht@linux.ibm.com Acked-by: Sumanth Korikkar sumanthk@linux.ibm.com Signed-off-by: Heiko Carstens hca@linux.ibm.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- arch/s390/kernel/perf_cpum_sf.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
--- a/arch/s390/kernel/perf_cpum_sf.c +++ b/arch/s390/kernel/perf_cpum_sf.c @@ -2228,4 +2228,4 @@ out: }
arch_initcall(init_cpum_sampling_pmu); -core_param(cpum_sfb_size, CPUM_SF_MAX_SDB, sfb_size, 0640); +core_param(cpum_sfb_size, CPUM_SF_MAX_SDB, sfb_size, 0644);