| Message ID | 1455738711-32328-1-git-send-email-andrew.cooper3@citrix.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
> -----Original Message----- > From: Andrew Cooper [mailto:andrew.cooper3@citrix.com] > Sent: Thursday, February 18, 2016 3:52 AM > To: Xen-devel <xen-devel@lists.xen.org> > Cc: Andrew Cooper <andrew.cooper3@citrix.com>; Jan Beulich > <JBeulich@suse.com>; Tim Deegan <tim@xen.org>; Ian Campbell > <Ian.Campbell@citrix.com>; Tian, Kevin <kevin.tian@intel.com>; Wu, Feng > <feng.wu@intel.com> > Subject: [PATCH] xen: Avoid left shifting into a sign bit > > Clang 3.8 notices, and objects because it is undefined behaviour. > > "error: shifting a negative signed value is undefined [-Werror,-Wshift-negative- > value]" > > Use unsigned constants rather than signed ones. > > Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com> > --- > CC: Jan Beulich <JBeulich@suse.com> > CC: Tim Deegan <tim@xen.org> > CC: Ian Campbell <Ian.Campbell@citrix.com> > CC: Kevin Tian <kevin.tian@intel.com> > CC: Feng Wu <feng.wu@intel.com> > --- > xen/common/page_alloc.c | 2 +- > xen/drivers/passthrough/vtd/x86/ats.c | 4 ++-- > 2 files changed, 3 insertions(+), 3 deletions(-) Acked-by: Feng Wu <feng.wu@intel.com> for the VT-d part. Thanks, Feng
diff --git a/xen/common/page_alloc.c b/xen/common/page_alloc.c index 624a266..7179d67 100644 --- a/xen/common/page_alloc.c +++ b/xen/common/page_alloc.c @@ -1675,7 +1675,7 @@ void *alloc_xenheap_pages(unsigned int order, unsigned int memflags) ASSERT(!in_irq()); if ( xenheap_bits && (memflags >> _MEMF_bits) > xenheap_bits ) - memflags &= ~MEMF_bits(~0); + memflags &= ~MEMF_bits(~0U); if ( !(memflags >> _MEMF_bits) ) memflags |= MEMF_bits(xenheap_bits); diff --git a/xen/drivers/passthrough/vtd/x86/ats.c b/xen/drivers/passthrough/vtd/x86/ats.c index 7c797f6..334b9c1 100644 --- a/xen/drivers/passthrough/vtd/x86/ats.c +++ b/xen/drivers/passthrough/vtd/x86/ats.c @@ -133,7 +133,7 @@ int dev_invalidate_iotlb(struct iommu *iommu, u16 did, case DMA_TLB_GLOBAL_FLUSH: /* invalidate all translations: sbit=1,bit_63=0,bit[62:12]=1 */ sbit = 1; - addr = (~0 << PAGE_SHIFT_4K) & 0x7FFFFFFFFFFFFFFF; + addr = (~0UL << PAGE_SHIFT_4K) & 0x7FFFFFFFFFFFFFFF; rc = qinval_device_iotlb(iommu, pdev->ats_queue_depth, sid, sbit, addr); break; @@ -145,7 +145,7 @@ int dev_invalidate_iotlb(struct iommu *iommu, u16 did, sbit = size_order ? 1 : 0; /* clear lower bits */ - addr &= ~0 << PAGE_SHIFT_4K; + addr &= ~0UL << PAGE_SHIFT_4K; /* if sbit == 1, zero out size_order bit and set lower bits to 1 */ if ( sbit )
Clang 3.8 notices, and objects because it is undefined behaviour. "error: shifting a negative signed value is undefined [-Werror,-Wshift-negative-value]" Use unsigned constants rather than signed ones. Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com> --- CC: Jan Beulich <JBeulich@suse.com> CC: Tim Deegan <tim@xen.org> CC: Ian Campbell <Ian.Campbell@citrix.com> CC: Kevin Tian <kevin.tian@intel.com> CC: Feng Wu <feng.wu@intel.com> --- xen/common/page_alloc.c | 2 +- xen/drivers/passthrough/vtd/x86/ats.c | 4 ++-- 2 files changed, 3 insertions(+), 3 deletions(-)