Re: [PATCH 3.14 186/228] PCI: Wrong register used to check pending traffic

Re: [PATCH 3.14 186/228] PCI: Wrong register used to check pending traffic

[Ben Hutchings]

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On Wed, 2014-06-04 at 16:23 -0700, Greg Kroah-Hartman wrote:
> 3.14-stable review patch.  If anyone has any objections, please let me know.
> 
> ------------------
> 
> From: Gavin Shan <gwshan@linux.vnet.ibm.com>
> 
> commit d0b4cc4e32705ff00d90d32da7783c266c702c04 upstream.
> 
> The incorrect register offset is passed to pci_wait_for_pending(), which is
> caused by commit 157e876ffe ("PCI: Add pci_wait_for_pending() (refactor
> pci_wait_for_pending_transaction())").
> 
> Fixes: 157e876ffe ("PCI: Add pci_wait_for_pending() (refactor pci_wait_for_pending_transaction())
> Signed-off-by: Gavin Shan <gwshan@linux.vnet.ibm.com>
> Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
> Acked-by: Alex Williamson <alex.williamson@gmail.com>
> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
> 
> ---
>  drivers/pci/pci.c |    5 +++--
>  1 file changed, 3 insertions(+), 2 deletions(-)
> 
> --- a/drivers/pci/pci.c
> +++ b/drivers/pci/pci.c
> @@ -3043,7 +3043,8 @@ int pci_wait_for_pending_transaction(str
>  	if (!pci_is_pcie(dev))
>  		return 1;
>  
> -	return pci_wait_for_pending(dev, PCI_EXP_DEVSTA, PCI_EXP_DEVSTA_TRPND);
> +	return pci_wait_for_pending(dev, pci_pcie_cap(dev) + PCI_EXP_DEVSTA,
> +				    PCI_EXP_DEVSTA_TRPND);
>  }
>  EXPORT_SYMBOL(pci_wait_for_pending_transaction);
>  
> @@ -3085,7 +3086,7 @@ static int pci_af_flr(struct pci_dev *de
>  		return 0;
>  
>  	/* Wait for Transaction Pending bit clean */
> -	if (pci_wait_for_pending(dev, PCI_AF_STATUS, PCI_AF_STATUS_TP))
> +	if (pci_wait_for_pending(dev, pos + PCI_AF_STATUS, PCI_AF_STATUS_TP))
>  		goto clear;
>  
>  	dev_err(&dev->dev, "transaction is not cleared; "

This still seems to be broken because pci_wait_for_pending() does
pci_read_config_word() but PCI_AF_STATUS is not word-aligned.

Ben.

-- 
Ben Hutchings
Never attribute to conspiracy what can adequately be explained by stupidity.

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Re: [PATCH 3.14 186/228] PCI: Wrong register used to check pending traffic

[Bjorn Helgaas]

On Sat, Jun 7, 2014 at 9:02 PM, Ben Hutchings <ben@decadent.org.uk> wrote:
> On Wed, 2014-06-04 at 16:23 -0700, Greg Kroah-Hartman wrote:
>> 3.14-stable review patch.  If anyone has any objections, please let me know.
>>
>> ------------------
>>
>> From: Gavin Shan <gwshan@linux.vnet.ibm.com>
>>
>> commit d0b4cc4e32705ff00d90d32da7783c266c702c04 upstream.
>>
>> The incorrect register offset is passed to pci_wait_for_pending(), which is
>> caused by commit 157e876ffe ("PCI: Add pci_wait_for_pending() (refactor
>> pci_wait_for_pending_transaction())").
>>
>> Fixes: 157e876ffe ("PCI: Add pci_wait_for_pending() (refactor pci_wait_for_pending_transaction())
>> Signed-off-by: Gavin Shan <gwshan@linux.vnet.ibm.com>
>> Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
>> Acked-by: Alex Williamson <alex.williamson@gmail.com>
>> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
>>
>> ---
>>  drivers/pci/pci.c |    5 +++--
>>  1 file changed, 3 insertions(+), 2 deletions(-)
>>
>> --- a/drivers/pci/pci.c
>> +++ b/drivers/pci/pci.c
>> @@ -3043,7 +3043,8 @@ int pci_wait_for_pending_transaction(str
>>       if (!pci_is_pcie(dev))
>>               return 1;
>>
>> -     return pci_wait_for_pending(dev, PCI_EXP_DEVSTA, PCI_EXP_DEVSTA_TRPND);
>> +     return pci_wait_for_pending(dev, pci_pcie_cap(dev) + PCI_EXP_DEVSTA,
>> +                                 PCI_EXP_DEVSTA_TRPND);
>>  }
>>  EXPORT_SYMBOL(pci_wait_for_pending_transaction);
>>
>> @@ -3085,7 +3086,7 @@ static int pci_af_flr(struct pci_dev *de
>>               return 0;
>>
>>       /* Wait for Transaction Pending bit clean */
>> -     if (pci_wait_for_pending(dev, PCI_AF_STATUS, PCI_AF_STATUS_TP))
>> +     if (pci_wait_for_pending(dev, pos + PCI_AF_STATUS, PCI_AF_STATUS_TP))
>>               goto clear;
>>
>>       dev_err(&dev->dev, "transaction is not cleared; "
>
> This still seems to be broken because pci_wait_for_pending() does
> pci_read_config_word() but PCI_AF_STATUS is not word-aligned.

I agree; this does seem broken.  I think pci_read_config_word() will
return PCIBIOS_BAD_REGISTER_NUMBER without updating the value
returned, so I think we'll test garbage from the stack.

What do you think, Alex?

Bjorn

Re: [PATCH 3.14 186/228] PCI: Wrong register used to check pending traffic

[Alex Williamson]

On Wed, 2014-06-11 at 15:15 -0600, Bjorn Helgaas wrote:
> On Sat, Jun 7, 2014 at 9:02 PM, Ben Hutchings <ben@decadent.org.uk> wrote:
> > On Wed, 2014-06-04 at 16:23 -0700, Greg Kroah-Hartman wrote:
> >> 3.14-stable review patch.  If anyone has any objections, please let me know.
> >>
> >> ------------------
> >>
> >> From: Gavin Shan <gwshan@linux.vnet.ibm.com>
> >>
> >> commit d0b4cc4e32705ff00d90d32da7783c266c702c04 upstream.
> >>
> >> The incorrect register offset is passed to pci_wait_for_pending(), which is
> >> caused by commit 157e876ffe ("PCI: Add pci_wait_for_pending() (refactor
> >> pci_wait_for_pending_transaction())").
> >>
> >> Fixes: 157e876ffe ("PCI: Add pci_wait_for_pending() (refactor pci_wait_for_pending_transaction())
> >> Signed-off-by: Gavin Shan <gwshan@linux.vnet.ibm.com>
> >> Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
> >> Acked-by: Alex Williamson <alex.williamson@gmail.com>
> >> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
> >>
> >> ---
> >>  drivers/pci/pci.c |    5 +++--
> >>  1 file changed, 3 insertions(+), 2 deletions(-)
> >>
> >> --- a/drivers/pci/pci.c
> >> +++ b/drivers/pci/pci.c
> >> @@ -3043,7 +3043,8 @@ int pci_wait_for_pending_transaction(str
> >>       if (!pci_is_pcie(dev))
> >>               return 1;
> >>
> >> -     return pci_wait_for_pending(dev, PCI_EXP_DEVSTA, PCI_EXP_DEVSTA_TRPND);
> >> +     return pci_wait_for_pending(dev, pci_pcie_cap(dev) + PCI_EXP_DEVSTA,
> >> +                                 PCI_EXP_DEVSTA_TRPND);
> >>  }
> >>  EXPORT_SYMBOL(pci_wait_for_pending_transaction);
> >>
> >> @@ -3085,7 +3086,7 @@ static int pci_af_flr(struct pci_dev *de
> >>               return 0;
> >>
> >>       /* Wait for Transaction Pending bit clean */
> >> -     if (pci_wait_for_pending(dev, PCI_AF_STATUS, PCI_AF_STATUS_TP))
> >> +     if (pci_wait_for_pending(dev, pos + PCI_AF_STATUS, PCI_AF_STATUS_TP))
> >>               goto clear;
> >>
> >>       dev_err(&dev->dev, "transaction is not cleared; "
> >
> > This still seems to be broken because pci_wait_for_pending() does
> > pci_read_config_word() but PCI_AF_STATUS is not word-aligned.
> 
> I agree; this does seem broken.  I think pci_read_config_word() will
> return PCIBIOS_BAD_REGISTER_NUMBER without updating the value
> returned, so I think we'll test garbage from the stack.
> 
> What do you think, Alex?

Yep, looks broken.  The simple fix would be to pass the AF control
offset instead of status, shift the mask, and maybe add a BUG_ON(pos &
1) to pci_read_config_word() to better enforce it.  Alternatively we
could make the function take a width and use an appropriate accessor for
the size.  I'm inclined to double-check the current users and take the
first option unless anyone objects.  Thanks,

Alex

Re: [PATCH 3.14 186/228] PCI: Wrong register used to check pending traffic

[Gavin Shan]

On Wed, Jun 11, 2014 at 04:07:44PM -0600, Alex Williamson wrote:
>On Wed, 2014-06-11 at 15:15 -0600, Bjorn Helgaas wrote:
>> On Sat, Jun 7, 2014 at 9:02 PM, Ben Hutchings <ben@decadent.org.uk> wrote:
>> > On Wed, 2014-06-04 at 16:23 -0700, Greg Kroah-Hartman wrote:
>> >> 3.14-stable review patch.  If anyone has any objections, please let me know.
>> >>
>> >> ------------------
>> >>
>> >> From: Gavin Shan <gwshan@linux.vnet.ibm.com>
>> >>
>> >> commit d0b4cc4e32705ff00d90d32da7783c266c702c04 upstream.
>> >>
>> >> The incorrect register offset is passed to pci_wait_for_pending(), which is
>> >> caused by commit 157e876ffe ("PCI: Add pci_wait_for_pending() (refactor
>> >> pci_wait_for_pending_transaction())").
>> >>
>> >> Fixes: 157e876ffe ("PCI: Add pci_wait_for_pending() (refactor pci_wait_for_pending_transaction())
>> >> Signed-off-by: Gavin Shan <gwshan@linux.vnet.ibm.com>
>> >> Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
>> >> Acked-by: Alex Williamson <alex.williamson@gmail.com>
>> >> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
>> >>
>> >> ---
>> >>  drivers/pci/pci.c |    5 +++--
>> >>  1 file changed, 3 insertions(+), 2 deletions(-)
>> >>
>> >> --- a/drivers/pci/pci.c
>> >> +++ b/drivers/pci/pci.c
>> >> @@ -3043,7 +3043,8 @@ int pci_wait_for_pending_transaction(str
>> >>       if (!pci_is_pcie(dev))
>> >>               return 1;
>> >>
>> >> -     return pci_wait_for_pending(dev, PCI_EXP_DEVSTA, PCI_EXP_DEVSTA_TRPND);
>> >> +     return pci_wait_for_pending(dev, pci_pcie_cap(dev) + PCI_EXP_DEVSTA,
>> >> +                                 PCI_EXP_DEVSTA_TRPND);
>> >>  }
>> >>  EXPORT_SYMBOL(pci_wait_for_pending_transaction);
>> >>
>> >> @@ -3085,7 +3086,7 @@ static int pci_af_flr(struct pci_dev *de
>> >>               return 0;
>> >>
>> >>       /* Wait for Transaction Pending bit clean */
>> >> -     if (pci_wait_for_pending(dev, PCI_AF_STATUS, PCI_AF_STATUS_TP))
>> >> +     if (pci_wait_for_pending(dev, pos + PCI_AF_STATUS, PCI_AF_STATUS_TP))
>> >>               goto clear;
>> >>
>> >>       dev_err(&dev->dev, "transaction is not cleared; "
>> >
>> > This still seems to be broken because pci_wait_for_pending() does
>> > pci_read_config_word() but PCI_AF_STATUS is not word-aligned.
>> 
>> I agree; this does seem broken.  I think pci_read_config_word() will
>> return PCIBIOS_BAD_REGISTER_NUMBER without updating the value
>> returned, so I think we'll test garbage from the stack.
>> 
>> What do you think, Alex?
>
>Yep, looks broken.  The simple fix would be to pass the AF control
>offset instead of status, shift the mask, and maybe add a BUG_ON(pos &
>1) to pci_read_config_word() to better enforce it.  Alternatively we
>could make the function take a width and use an appropriate accessor for
>the size.  I'm inclined to double-check the current users and take the
>first option unless anyone objects.  Thanks,
>

Hrm, I didn't notice that PCI_AF_STATUS isn't word-aligned. I agree with
Alex to just use PCI_AF_CTRL with shifted PCI_AF_STATUS_TP. If we're going
to add BUG_ON() for pci_read_config_word(), we have to add that for other
accessors (dword, user_word, user_dword, bus_word, bus_dword). I guess we
just need the first part here. Bjorn/Alex, please let me know if I need come
up with a followup fix for this, or Alex can handle it.

Thanks,
Gavin