| Message ID | 20220630063959.27226-1-burzalodowa@gmail.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | iommu/arm-smmu-v3: Fix undefined behavior in GBPA_UPDATE | expand |
On Thu, Jun 30, 2022 at 09:39:59AM +0300, Xenia Ragiadakou wrote: > The expression 1 << 31 results in undefined behaviour because the type of > integer constant 1 is (signed) int and the result of shifting 1 by 31 bits > is not representable in the (signed) int type. > > Change the type of 1 to unsigned int by adding the U suffix. > > Signed-off-by: Xenia Ragiadakou <burzalodowa@gmail.com> > --- > drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h > index cd48590ada30..44fbd499edea 100644 > --- a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h > +++ b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h > @@ -96,7 +96,7 @@ > #define CR2_E2H (1 << 0) > > #define ARM_SMMU_GBPA 0x44 > -#define GBPA_UPDATE (1 << 31) > +#define GBPA_UPDATE (1U << 31) There are loads of these kicking around in the kernel sources and we compile with -fno-strict-overflow. If you really want to change these, then let's use the BIT() macro instead, but I think it's really just churn. Will
On 7/1/22 17:34, Will Deacon wrote: > On Thu, Jun 30, 2022 at 09:39:59AM +0300, Xenia Ragiadakou wrote: >> The expression 1 << 31 results in undefined behaviour because the type of >> integer constant 1 is (signed) int and the result of shifting 1 by 31 bits >> is not representable in the (signed) int type. >> >> Change the type of 1 to unsigned int by adding the U suffix. >> >> Signed-off-by: Xenia Ragiadakou <burzalodowa@gmail.com> >> --- >> drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h | 2 +- >> 1 file changed, 1 insertion(+), 1 deletion(-) >> >> diff --git a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h >> index cd48590ada30..44fbd499edea 100644 >> --- a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h >> +++ b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h >> @@ -96,7 +96,7 @@ >> #define CR2_E2H (1 << 0) >> >> #define ARM_SMMU_GBPA 0x44 >> -#define GBPA_UPDATE (1 << 31) >> +#define GBPA_UPDATE (1U << 31) > There are loads of these kicking around in the kernel sources and we compile > with -fno-strict-overflow. > > If you really want to change these, then let's use the BIT() macro instead, > but I think it's really just churn. > > Will Hi Will, I thought that since in commit 587e6c10a7ce89a5924fdbeff2ec524fbd6a124b there was a similar fix to Q_OVERFLOW_FLAG (see below) --- a/drivers/iommu/arm-smmu-v3.c +++ b/drivers/iommu/arm-smmu-v3.c @@ -183,7 +183,7 @@ #define Q_IDX(llq, p) ((p) & ((1 << (llq)->max_n_shift) - 1)) #define Q_WRP(llq, p) ((p) & (1 << (llq)->max_n_shift)) -#define Q_OVERFLOW_FLAG (1 << 31) +#define Q_OVERFLOW_FLAG (1U << 31) #define Q_OVF(p) ((p) & Q_OVERFLOW_FLAG) #define Q_ENT(q, p) ((q)->base + \ Q_IDX(&((q)->llq), p) * \ then it would make sense to fix GBPA_UPDATE in the same way. Xenia
diff --git a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h index cd48590ada30..44fbd499edea 100644 --- a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h +++ b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h @@ -96,7 +96,7 @@ #define CR2_E2H (1 << 0) #define ARM_SMMU_GBPA 0x44 -#define GBPA_UPDATE (1 << 31) +#define GBPA_UPDATE (1U << 31) #define GBPA_ABORT (1 << 20) #define ARM_SMMU_IRQ_CTRL 0x50
The expression 1 << 31 results in undefined behaviour because the type of integer constant 1 is (signed) int and the result of shifting 1 by 31 bits is not representable in the (signed) int type. Change the type of 1 to unsigned int by adding the U suffix. Signed-off-by: Xenia Ragiadakou <burzalodowa@gmail.com> --- drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)