| Message ID | 20220209184758.56578-1-andriy.shevchenko@linux.intel.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | [v1,1/1] perf/smmuv3: Don't cast parameter in bit operations | expand |
On 2022-02-09 18:47, Andy Shevchenko wrote: > While in this particular case it would not be a (critical) issue, > the pattern itself is bad and error prone in case somebody blindly > copies to their code. > > Don't cast parameter to unsigned long pointer in the bit operations. > Instead copy to a local variable on stack of a proper type and use. Seems reasonable, in fact in my build it appears to save a spill and reload from the stack so the code actually gets a teeny bit better. Not sure a cleanup warrants a "Fixes" tag, but either way, Reviewed-by: Robin Murphy <robin.murphy@arm.com> > Note, new compilers might warn on this line for potential outbound access. > > Fixes: 7d839b4b9e00 ("perf/smmuv3: Add arm64 smmuv3 pmu driver") > Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com> > --- > drivers/perf/arm_smmuv3_pmu.c | 4 +++- > 1 file changed, 3 insertions(+), 1 deletion(-) > > diff --git a/drivers/perf/arm_smmuv3_pmu.c b/drivers/perf/arm_smmuv3_pmu.c > index c49108a72865..00d4c45a8017 100644 > --- a/drivers/perf/arm_smmuv3_pmu.c > +++ b/drivers/perf/arm_smmuv3_pmu.c > @@ -654,6 +654,7 @@ static int smmu_pmu_offline_cpu(unsigned int cpu, struct hlist_node *node) > static irqreturn_t smmu_pmu_handle_irq(int irq_num, void *data) > { > struct smmu_pmu *smmu_pmu = data; > + DECLARE_BITMAP(ovs, BITS_PER_TYPE(u64)); > u64 ovsr; > unsigned int idx; > > @@ -663,7 +664,8 @@ static irqreturn_t smmu_pmu_handle_irq(int irq_num, void *data) > > writeq(ovsr, smmu_pmu->reloc_base + SMMU_PMCG_OVSCLR0); > > - for_each_set_bit(idx, (unsigned long *)&ovsr, smmu_pmu->num_counters) { > + bitmap_from_u64(ovs, ovsr); > + for_each_set_bit(idx, ovs, smmu_pmu->num_counters) { > struct perf_event *event = smmu_pmu->events[idx]; > struct hw_perf_event *hwc; >
On Wed, 9 Feb 2022 20:47:58 +0200, Andy Shevchenko wrote: > While in this particular case it would not be a (critical) issue, > the pattern itself is bad and error prone in case somebody blindly > copies to their code. > > Don't cast parameter to unsigned long pointer in the bit operations. > Instead copy to a local variable on stack of a proper type and use. > > [...] Applied to will (for-joerg/arm-smmu/updates), thanks! [1/1] perf/smmuv3: Don't cast parameter in bit operations https://git.kernel.org/will/c/8ddf4eff71e1 Cheers,
diff --git a/drivers/perf/arm_smmuv3_pmu.c b/drivers/perf/arm_smmuv3_pmu.c index c49108a72865..00d4c45a8017 100644 --- a/drivers/perf/arm_smmuv3_pmu.c +++ b/drivers/perf/arm_smmuv3_pmu.c @@ -654,6 +654,7 @@ static int smmu_pmu_offline_cpu(unsigned int cpu, struct hlist_node *node) static irqreturn_t smmu_pmu_handle_irq(int irq_num, void *data) { struct smmu_pmu *smmu_pmu = data; + DECLARE_BITMAP(ovs, BITS_PER_TYPE(u64)); u64 ovsr; unsigned int idx; @@ -663,7 +664,8 @@ static irqreturn_t smmu_pmu_handle_irq(int irq_num, void *data) writeq(ovsr, smmu_pmu->reloc_base + SMMU_PMCG_OVSCLR0); - for_each_set_bit(idx, (unsigned long *)&ovsr, smmu_pmu->num_counters) { + bitmap_from_u64(ovs, ovsr); + for_each_set_bit(idx, ovs, smmu_pmu->num_counters) { struct perf_event *event = smmu_pmu->events[idx]; struct hw_perf_event *hwc;
While in this particular case it would not be a (critical) issue, the pattern itself is bad and error prone in case somebody blindly copies to their code. Don't cast parameter to unsigned long pointer in the bit operations. Instead copy to a local variable on stack of a proper type and use. Note, new compilers might warn on this line for potential outbound access. Fixes: 7d839b4b9e00 ("perf/smmuv3: Add arm64 smmuv3 pmu driver") Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com> --- drivers/perf/arm_smmuv3_pmu.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-)