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From:   "Reshetova, Elena" <elena.reshetova@intel.com>
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Subject: RE: [PATCH v5 12/16] PCI: Add pci_iomap_host_shared(),
 pci_iomap_host_shared_range()
Thread-Topic: [PATCH v5 12/16] PCI: Add pci_iomap_host_shared(),
 pci_iomap_host_shared_range()
Thread-Index: AQHXvKYONYCiLR7qcUWwBEZSAUzHCavKbb0AgAC0m4CAAavhgIAC4/bggAAwBACAAi5lAIAAB66AgAAFYFA=
Date:   Thu, 14 Oct 2021 07:27:42 +0000
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> On Thu, Oct 14, 2021 at 06:32:32AM +0000, Reshetova, Elena wrote:
> > > On Tue, Oct 12, 2021 at 06:36:16PM +0000, Reshetova, Elena wrote:
> > > > > The 5.15 tree has something like ~2.4k IO accesses (including MMI=
O and
> > > > > others) in init functions that also register drivers (thanks Elen=
a for
> > > > > the number)
> > > >
> > > > To provide more numbers on this. What I can see so far from a smatc=
h-based
> > > > analysis, we have 409 __init style functions (.probe & builtin/modu=
le_
> > > > _platform_driver_probe excluded) for 5.15 with allyesconfig.
> > >
> > > I don't think we care about allyesconfig at all though.
> > > Just don't do that.
> > > How about allmodconfig? This is closer to what distros actually do.
> >
> > It does not make any difference really for the content of the /drivers/=
*:
> > gives 408 __init style functions doing IO (.probe & builtin/module_
> > > > _platform_driver_probe excluded) for 5.15 with allmodconfig:
> >
> > ['doc200x_ident_chip',
> > 'doc_probe', 'doc2001_init', 'mtd_speedtest_init',
> > 'mtd_nandbiterrs_init', 'mtd_oobtest_init', 'mtd_pagetest_init',
> > 'tort_init', 'mtd_subpagetest_init', 'fixup_pmc551',
> > 'doc_set_driver_info', 'init_amd76xrom', 'init_l440gx',
> > 'init_sc520cdp', 'init_ichxrom', 'init_ck804xrom', 'init_esb2rom',
> > 'probe_acpi_namespace_devices', 'amd_iommu_init_pci', 'state_next',
> > 'arm_v7s_do_selftests', 'arm_lpae_run_tests', 'init_iommu_one',
>=20
> Um. ARM? Which architecture is this build for?

The list of smatch IO findings is built for x86, but the smatch cross funct=
ion
database covers all archs, so when queried for all potential function calle=
rs,
it would show non x86 arch call chains also.=20

Here is the original x86 finding and call chain for the 'arm_v7s_do_selftes=
ts':

  Detected low-level IO from arm_v7s_do_selftests in fun
__iommu_queue_command_sync

drivers/iommu/amd/iommu.c:1025 __iommu_queue_command_sync() error:
{15002074744551330002}
    'check_host_input' read from the host using function 'readl' to a
member of the structure 'iommu->cmd_buf_head';

__iommu_queue_command_sync()
  iommu_completion_wait()
    amd_iommu_domain_flush_complete()
      iommu_v1_map_page()
        arm_v7s_do_selftests()

So, the results can be further filtered if you want a specified arch.=20