Re: [Xen-devel] [bug report] xen-pcifront: Xen PCI frontend driver.

[Juergen Gross <jgross@xxxxxxxx>]

On 25.06.19 14:31, Dan Carpenter wrote:
> Hi Xen devs,
>
> I get the following static checker warning:
>
>         drivers/pci/xen-pcifront.c:107 schedule_pcifront_aer_op()
>         warn: passing casted pointer '&pdev->sh_info->flags' to 'test_bit()' 32 
> vs 64.
>
> drivers/pci/xen-pcifront.c
>     105  static inline void schedule_pcifront_aer_op(struct pcifront_device 
> *pdev)
>     106  {
>     107          if (test_bit(_XEN_PCIB_active, (unsigned long 
> *)&pdev->sh_info->flags)
>
> ->flags is a u32 so this cast only works on little endian systems.  I
> don't know if that matters at all.  This driver has a bunch of similar
> issues.  Is Xen x86 only?  It's pretty normal for Intel code to rely on
> little endianness...
Xen is running on ARM, too. AFAIK it only supports little endian mode
for guests, though.

>     108                  && !test_and_set_bit(_PDEVB_op_active, &pdev->flags)) {
>     109                  dev_dbg(&pdev->xdev->dev, "schedule aer frontend 
> job\n");
>     110                  schedule_work(&pdev->op_work);
>     111          }
>     112  }
>
> drivers/pci/xen-pcifront.c:107 schedule_pcifront_aer_op() warn: passing casted pointer 
> '&pdev->sh_info->flags' to 'test_bit()' 32 vs 64.
> drivers/pci/xen-pcifront.c:129 do_pci_op() warn: passing casted pointer 
> '&pdev->sh_info->flags' to 'set_bit()' 32 vs 64.
> drivers/pci/xen-pcifront.c:142 do_pci_op() warn: passing casted pointer 
> '&pdev->sh_info->flags' to 'test_bit()' 32 vs 64.
> drivers/pci/xen-pcifront.c:150 do_pci_op() warn: passing casted pointer 
> '&pdev->sh_info->flags' to 'clear_bit()' 32 vs 64.
> drivers/pci/xen-pcifront.c:162 do_pci_op() warn: passing casted pointer 
> '&pdev->sh_info->flags' to 'test_bit()' 32 vs 64.
> drivers/pci/xen-pcifront.c:670 pcifront_do_aer() warn: passing casted pointer 
> '&pdev->sh_info->flags' to 'clear_bit()' 32 vs 64.
> drivers/xen/mcelog.c:209 xen_mce_log() warn: passing casted pointer 
> '&xen_mcelog.flags' to 'set_bit()' 32 vs 64.
> drivers/xen/privcmd.c:350 mmap_batch_fn() warn: passing casted pointer 'gfnp' 
> to 'xen_remap_domain_gfn_array()' 64 vs 32.
> drivers/xen/privcmd.c:827 privcmd_ioctl_mmap_resource() warn: passing casted 
> pointer 'pfns' to 'xen_remap_domain_mfn_array()' 64 vs 32.
> drivers/xen/xen-pciback/conf_space.c:172 xen_pcibk_config_read() warn: passing 
> casted pointer '&value' to 'pci_read_config_word()' 32 vs 16.
> drivers/xen/xen-pciback/conf_space.c:57 conf_space_read() warn: passing casted 
> pointer 'value' to 'field->u.w.read()' 32 vs 16.
> drivers/xen/xen-pciback/pciback_ops.c:310 xen_pcibk_test_and_schedule_op() warn: passing 
> casted pointer '&pdev->sh_info->flags' to 'test_bit()' 32 vs 64.
> drivers/xen/xen-pciback/pciback_ops.c:316 xen_pcibk_test_and_schedule_op() warn: passing 
> casted pointer '&pdev->sh_info->flags' to 'test_bit()' 32 vs 64.
> drivers/xen/xen-pciback/pciback_ops.c:396 xen_pcibk_do_op() warn: passing casted pointer 
> '&pdev->sh_info->flags' to 'clear_bit()' 32 vs 64.
> drivers/xen/xen-pciback/pci_stub.c:731 common_process() warn: passing casted pointer 
> '&sh_info->flags' to 'set_bit()' 32 vs 64.
> drivers/xen/xen-pciback/pci_stub.c:736 common_process() warn: passing casted pointer 
> '&sh_info->flags' to 'test_bit()' 32 vs 64.
> drivers/xen/xen-pciback/pci_stub.c:741 common_process() warn: passing casted pointer 
> '&sh_info->flags' to 'test_bit()' 32 vs 64.
> drivers/xen/xen-pciback/pci_stub.c:745 common_process() warn: passing casted pointer 
> '&sh_info->flags' to 'clear_bit()' 32 vs 64.
> drivers/xen/xen-pciback/pci_stub.c:753 common_process() warn: passing casted pointer 
> '&sh_info->flags' to 'test_bit()' 32 vs 64.
> drivers/xen/xen-pciback/pci_stub.c:799 xen_pcibk_slot_reset() warn: passing casted pointer 
> '&psdev->pdev->sh_info->flags' to 'test_bit()' 32 vs 64.
> drivers/xen/xen-pciback/pci_stub.c:857 xen_pcibk_mmio_enabled() warn: passing casted pointer 
> '&psdev->pdev->sh_info->flags' to 'test_bit()' 32 vs 64.
> drivers/xen/xen-pciback/pci_stub.c:916 xen_pcibk_error_detected() warn: passing casted 
> pointer '&psdev->pdev->sh_info->flags' to 'test_bit()' 32 vs 64.
> drivers/xen/xen-pciback/pci_stub.c:969 xen_pcibk_error_resume() warn: passing casted pointer 
> '&psdev->pdev->sh_info->flags' to 'test_bit()' 32 vs 64.
The sh_info->flags accesses would need to be modified in order to fix
the warnings. Either by adding *_bit32() variants to the kernel or by
using atomic() accesses instead.

Patches welcome. :-)


Juergen

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