From: Paolo Bonzini <pbonzini@redhat.com>
To: Peter Maydell <peter.maydell@linaro.org>
Cc: Michael Roth <mdroth@linux.vnet.ibm.com>,
"qemu-ppc@nongnu.org" <qemu-ppc@nongnu.org>,
Alexander Graf <agraf@suse.de>,
QEMU Developers <qemu-devel@nongnu.org>
Subject: Re: [Qemu-devel] [PULL 00/40] ppc patch queue 2015-06-03
Date: Fri, 05 Jun 2015 17:02:43 +0200 [thread overview]
Message-ID: <5571BA13.3040507@redhat.com> (raw)
In-Reply-To: <CAFEAcA9ZrQPf1phr5ffuzXMcVGFuGDQWqK=YmGzY2faC36p49A@mail.gmail.com>
On 05/06/2015 16:40, Peter Maydell wrote:
> > Speaking in general, I find that this makes code worse. If you're using
> > ~0 you probably want the value to extend with infinite ones.
> >
> > Using ~0u instead of ~0ull may cause problems down the line, and ~0ul
> > is even worse because it is not 64-bit safe.
>
> I agree that C's semantics are terrible here (ideally
> left shift of negative values should Just Work in the 2s
> complement style, and right shift of negative values should
> be an arithmetic shift). Unfortunately we're stuck with
> the standard, which says this is undefined behaviour :-(
But this is not something that C compiler writers can reasonably change.
Can someone add a checkpatch rule that forbids shifting left U or UL
constants (i.e. only ULL)? That would alleviate my concerns with these
ubsan warnings.
Paolo
next prev parent reply other threads:[~2015-06-05 15:02 UTC|newest]
Thread overview: 62+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-06-03 21:45 [Qemu-devel] [PULL 00/40] ppc patch queue 2015-06-03 Alexander Graf
2015-06-03 21:45 ` [Qemu-devel] [PULL 01/40] macio: Convert to realize() Alexander Graf
2015-06-03 21:53 ` Peter Maydell
2015-06-03 22:00 ` Alexander Graf
2015-06-03 21:45 ` [Qemu-devel] [PULL 02/40] dtc: Update dtc / libfdt submodule to version 1.4.0 Alexander Graf
2015-06-03 21:45 ` [Qemu-devel] [PULL 03/40] configure: Check for libfdt " Alexander Graf
2015-06-03 21:45 ` [Qemu-devel] [PULL 04/40] spapr_pci: Fix unsafe signed/unsigned comparisons Alexander Graf
2015-06-03 21:45 ` [Qemu-devel] [PULL 05/40] spapr_iommu: Disable in-kernel IOMMU tables for >4GB windows Alexander Graf
2015-06-03 21:45 ` [Qemu-devel] [PULL 06/40] spapr_iommu: Make H_PUT_TCE_INDIRECT endian-safe Alexander Graf
2015-06-03 21:45 ` [Qemu-devel] [PULL 07/40] spapr_pci: Introduce a liobn number generating macros Alexander Graf
2015-06-03 21:45 ` [Qemu-devel] [PULL 08/40] spapr_vio: " Alexander Graf
2015-06-03 21:45 ` [Qemu-devel] [PULL 09/40] spapr_pci: Define default DMA window size as a macro Alexander Graf
2015-06-03 21:45 ` [Qemu-devel] [PULL 10/40] spapr_iommu: Add separate trace points for PCI DMA operations Alexander Graf
2015-06-03 21:45 ` [Qemu-devel] [PULL 11/40] spapr_pci: Make find_phb()/find_dev() public Alexander Graf
2015-06-03 21:45 ` [Qemu-devel] [PULL 12/40] spapr_iommu: Make spapr_tce_find_by_liobn() public Alexander Graf
2015-06-03 21:45 ` [Qemu-devel] [PULL 13/40] spapr_pci: Rework device-tree rendering Alexander Graf
2015-06-03 21:45 ` [Qemu-devel] [PULL 14/40] spapr_iommu: Give unique QOM name to TCE table Alexander Graf
2015-06-03 21:45 ` [Qemu-devel] [PULL 15/40] hw/ppc/spapr_iommu: Fix the check for invalid upper bits in liobn Alexander Graf
2015-06-03 21:45 ` [Qemu-devel] [PULL 16/40] pseries: Add pseries-2.4 machine type Alexander Graf
2015-06-03 21:45 ` [Qemu-devel] [PULL 17/40] hw/ppc/spapr: Fix error message when firmware could not be loaded Alexander Graf
2015-06-03 21:45 ` [Qemu-devel] [PULL 18/40] hw/ppc/spapr: Use error_report() instead of hw_error() Alexander Graf
2015-06-03 21:45 ` [Qemu-devel] [PULL 19/40] docs: add sPAPR hotplug/dynamic-reconfiguration documentation Alexander Graf
2015-06-03 21:45 ` [Qemu-devel] [PULL 20/40] spapr_drc: initial implementation of sPAPRDRConnector device Alexander Graf
2015-07-09 14:16 ` Paolo Bonzini
2015-06-03 21:45 ` [Qemu-devel] [PULL 21/40] spapr_rtas: add get/set-power-level RTAS interfaces Alexander Graf
2015-06-03 21:45 ` [Qemu-devel] [PULL 22/40] spapr_rtas: add set-indicator RTAS interface Alexander Graf
2015-06-03 21:45 ` [Qemu-devel] [PULL 23/40] spapr_rtas: add get-sensor-state " Alexander Graf
2015-06-03 21:45 ` [Qemu-devel] [PULL 24/40] spapr: add rtas_st_buffer_direct() helper Alexander Graf
2015-06-03 21:45 ` [Qemu-devel] [PULL 25/40] spapr_rtas: add ibm, configure-connector RTAS interface Alexander Graf
2015-06-03 21:45 ` [Qemu-devel] [PULL 26/40] spapr_events: re-use EPOW event infrastructure for hotplug events Alexander Graf
2015-06-03 21:45 ` [Qemu-devel] [PULL 27/40] spapr_events: event-scan RTAS interface Alexander Graf
2015-06-03 21:45 ` [Qemu-devel] [PULL 28/40] spapr_drc: add spapr_drc_populate_dt() Alexander Graf
2015-06-03 21:45 ` [Qemu-devel] [PULL 29/40] spapr_pci: add dynamic-reconfiguration option for spapr-pci-host-bridge Alexander Graf
2015-06-03 21:45 ` [Qemu-devel] [PULL 30/40] spapr_pci: create DRConnectors for each PCI slot during PHB realize Alexander Graf
2015-06-03 21:45 ` [Qemu-devel] [PULL 31/40] pci: make pci_bar useable outside pci.c Alexander Graf
2015-06-03 21:45 ` [Qemu-devel] [PULL 32/40] spapr_pci: enable basic hotplug operations Alexander Graf
2015-06-03 21:45 ` [Qemu-devel] [PULL 33/40] spapr_pci: emit hotplug add/remove events during hotplug Alexander Graf
2015-06-03 21:45 ` [Qemu-devel] [PULL 34/40] machine: add default_ram_size to machine class Alexander Graf
2015-06-05 7:27 ` Laurent Desnogues
2015-06-03 21:45 ` [Qemu-devel] [PULL 35/40] spapr: override default ram size to 512MB Alexander Graf
2015-06-03 21:45 ` [Qemu-devel] [PULL 36/40] pseries: Enable in-kernel H_LOGICAL_CI_{LOAD, STORE} implementations Alexander Graf
2015-06-03 21:45 ` [Qemu-devel] [PULL 37/40] Add David Gibson for sPAPR in MAINTAINERS file Alexander Graf
2015-11-18 20:46 ` Andreas Färber
2015-11-18 20:51 ` Eric Blake
2015-11-18 20:58 ` Andreas Färber
2015-06-03 21:45 ` [Qemu-devel] [PULL 38/40] tci: do not use CPUArchState in tcg-target.h Alexander Graf
2015-06-03 21:45 ` [Qemu-devel] [PULL 39/40] tcg: add TCG_TARGET_TLB_DISPLACEMENT_BITS Alexander Graf
2015-06-03 21:45 ` [Qemu-devel] [PULL 40/40] softmmu: support up to 12 MMU modes Alexander Graf
2015-06-04 17:28 ` [Qemu-devel] [PULL 00/40] ppc patch queue 2015-06-03 Peter Maydell
2015-06-05 13:33 ` Peter Maydell
2015-06-05 14:35 ` Paolo Bonzini
2015-06-05 14:40 ` Peter Maydell
2015-06-05 15:02 ` Paolo Bonzini [this message]
2015-06-05 15:08 ` Peter Maydell
2015-06-05 15:20 ` Paolo Bonzini
2015-06-05 15:45 ` Peter Maydell
2015-06-05 15:55 ` [Qemu-devel] undefined behavior of signed left shifts (was Re: [PULL 00/40] ppc patch queue 2015-06-03) Paolo Bonzini
2015-06-05 17:21 ` Joseph Myers
2015-06-05 17:33 ` Peter Maydell
2015-07-21 11:42 ` [Qemu-devel] [PULL 00/40] ppc patch queue 2015-06-03 Peter Maydell
2015-07-21 23:32 ` Michael Roth
2015-06-05 15:24 ` Eric Blake
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