Re: [PATCH] misc: pci_endpoint_test: Handle BAR sizes larger than INT_MAX

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On Thu, Jan 23, 2025 at 07:35:06PM +0100, Niklas Cassel wrote:
> On Thu, Jan 23, 2025 at 10:54:19AM -0500, Frank Li wrote:
> > On Thu, Jan 23, 2025 at 10:59:07AM +0100, Niklas Cassel wrote:
> > > Running 'pcitest -b 0' fails with "TEST FAILED" when the BAR0 size
> > > is e.g. 8 GB.
> > >
> > > The return value of the pci_resource_len() macro can be larger than that
> > > of a signed integer type. Thus, when using 'pcitest' with an 8 GB BAR,
> > > the bar_size of the integer type will overflow.
> > >
> > > Change bar_size from integer to resource_size_t to prevent integer
> > > overflow for large BAR sizes with 32-bit compilers.
> > >
> > > Co-developed-by: Hans Zhang <18255117159@xxxxxxx>
> > > Signed-off-by: Hans Zhang <18255117159@xxxxxxx>
> > > Signed-off-by: Niklas Cassel <cassel@xxxxxxxxxx>
> > > ---
> > > Hans submitted a patch for this that was reverted because apparently some
> > > gcc-7 arm32 compiler doesn't like div_u64(). In order to avoid debugging
> > > gcc-7 arm32 compiler issues, simply replace the division with addition,
> > > which arguably makes the code simpler as well.
> > >
> > >  drivers/misc/pci_endpoint_test.c | 18 ++++++++++--------
> > >  1 file changed, 10 insertions(+), 8 deletions(-)
> > >
> > > diff --git a/drivers/misc/pci_endpoint_test.c b/drivers/misc/pci_endpoint_test.c
> > > index d5ac71a49386..8e48a15100f1 100644
> > > --- a/drivers/misc/pci_endpoint_test.c
> > > +++ b/drivers/misc/pci_endpoint_test.c
> > > @@ -272,9 +272,9 @@ static const u32 bar_test_pattern[] = {
> > >  };
> > >
> > >  static int pci_endpoint_test_bar_memcmp(struct pci_endpoint_test *test,
> > > -					enum pci_barno barno, int offset,
> > > -					void *write_buf, void *read_buf,
> > > -					int size)
> > > +					enum pci_barno barno,
> > > +					resource_size_t offset, void *write_buf,
> > > +					void *read_buf, int size)
> > >  {
> > >  	memset(write_buf, bar_test_pattern[barno], size);
> > >  	memcpy_toio(test->bar[barno] + offset, write_buf, size);
> > > @@ -287,10 +287,11 @@ static int pci_endpoint_test_bar_memcmp(struct pci_endpoint_test *test,
> > >  static int pci_endpoint_test_bar(struct pci_endpoint_test *test,
> > >  				  enum pci_barno barno)
> > >  {
> > > -	int j, bar_size, buf_size, iters;
> > > +	resource_size_t bar_size, offset = 0;
> > >  	void *write_buf __free(kfree) = NULL;
> > >  	void *read_buf __free(kfree) = NULL;
> > >  	struct pci_dev *pdev = test->pdev;
> > > +	int buf_size;
> > >
> > >  	if (!test->bar[barno])
> > >  		return -ENOMEM;
> > > @@ -314,11 +315,12 @@ static int pci_endpoint_test_bar(struct pci_endpoint_test *test,
> > >  	if (!read_buf)
> > >  		return -ENOMEM;
> > >
> > > -	iters = bar_size / buf_size;
> > > -	for (j = 0; j < iters; j++)
> > > -		if (pci_endpoint_test_bar_memcmp(test, barno, buf_size * j,
> > > -						 write_buf, read_buf, buf_size))
> > > +	while (offset < bar_size) {
> > > +		if (pci_endpoint_test_bar_memcmp(test, barno, offset, write_buf,
> > > +						 read_buf, buf_size))
> > >  			return -EIO;
> > > +		offset += buf_size;
> > > +	}
> >
> > Actually, you change code logic although functionality is the same. I feel
> > like you should mention at commit message or use origial code by just
> > change variable type.
> >
> > #ifdef CONFIG_PHYS_ADDR_T_64BIT
> > typedef u64 phys_addr_t;
> > #else
> > typedef u32 phys_addr_t;
> > #endif
>
> Hello Frank,
>
> I personally think that is a horrible idea :)
>
> We do not want to introduce ifdefs in the middle of the code, unless
> in exceptional circumstances, like architecture specific optimized code.

You miss understand what my means. I copy it from type.h to indicate
resource_size_t is not 64bit at all platforms.

Frank
>
>
> Kind regards,
> Niklas




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