From: Alexey Kardashevskiy aik@ozlabs.ru
commit b460b512417ae9c8b51a3bdcc09020cd6c60ff69 upstream.
The bhrb_filter_map ("The Branch History Rolling Buffer") callback is only defined in raw CPUs' power_pmu structs. The "architected" CPUs use generic_compat_pmu, which does not have this callback, and crashes occur if a user tries to enable branch stack for an event.
This add a NULL pointer check for bhrb_filter_map() which behaves as if the callback returned an error.
This does not add the same check for config_bhrb() as the only caller checks for cpuhw->bhrb_users which remains zero if bhrb_filter_map==0.
Fixes: be80e758d0c2 ("powerpc/perf: Add generic compat mode pmu driver") Cc: stable@vger.kernel.org # v5.2+ Signed-off-by: Alexey Kardashevskiy aik@ozlabs.ru Reviewed-by: Madhavan Srinivasan maddy@linux.ibm.com Signed-off-by: Michael Ellerman mpe@ellerman.id.au Link: https://lore.kernel.org/r/20200602025612.62707-1-aik@ozlabs.ru Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- arch/powerpc/perf/core-book3s.c | 19 ++++++++++++++----- 1 file changed, 14 insertions(+), 5 deletions(-)
--- a/arch/powerpc/perf/core-book3s.c +++ b/arch/powerpc/perf/core-book3s.c @@ -1522,9 +1522,16 @@ nocheck: ret = 0; out: if (has_branch_stack(event)) { - power_pmu_bhrb_enable(event); - cpuhw->bhrb_filter = ppmu->bhrb_filter_map( - event->attr.branch_sample_type); + u64 bhrb_filter = -1; + + if (ppmu->bhrb_filter_map) + bhrb_filter = ppmu->bhrb_filter_map( + event->attr.branch_sample_type); + + if (bhrb_filter != -1) { + cpuhw->bhrb_filter = bhrb_filter; + power_pmu_bhrb_enable(event); + } }
perf_pmu_enable(event->pmu); @@ -1846,7 +1853,6 @@ static int power_pmu_event_init(struct p int n; int err; struct cpu_hw_events *cpuhw; - u64 bhrb_filter;
if (!ppmu) return -ENOENT; @@ -1952,7 +1958,10 @@ static int power_pmu_event_init(struct p err = power_check_constraints(cpuhw, events, cflags, n + 1);
if (has_branch_stack(event)) { - bhrb_filter = ppmu->bhrb_filter_map( + u64 bhrb_filter = -1; + + if (ppmu->bhrb_filter_map) + bhrb_filter = ppmu->bhrb_filter_map( event->attr.branch_sample_type);
if (bhrb_filter == -1) {