Re: [v11 2/2] misc: pci_endpoint_test: Fix overflow of bar_size

[Jon Hunter <jonathanh@xxxxxxxxxx>]

Hi Hans,

On 09/01/2025 09:45, Hans Zhang wrote:
> With 8GB BAR2, running pcitest -b 2 fails with "TEST FAILED".
>
> The return value of the `pci_resource_len` interface is not an integer.
> Using `pcitest` with an 8GB BAR2, the bar_size of integer type will
> overflow.
>
> Change the data type of bar_size from integer to resource_size_t, to fix
> the above issue.
>
> Signed-off-by: Hans Zhang <18255117159@xxxxxxx>
> Suggested-by: Niklas Cassel <cassel@xxxxxxxxxx>
> Reviewed-by: Niklas Cassel <cassel@xxxxxxxxxx>
> ---
> Changes since v10:
> https://lore.kernel.org/linux-pci/20250108080951.1700230-3-18255117159@xxxxxxx/
>
> - Replace do_div with the div_u64 API.
>
> Changes since v8-v9:
> https://lore.kernel.org/linux-pci/20250104151652.1652181-1-18255117159@xxxxxxx/
>
> - Split the patch.
>
> Changes since v4-v7:
> https://lore.kernel.org/linux-pci/20250102120222.1403906-1-18255117159@xxxxxxx/
>
> - Fix 32-bit OS warnings and errors.
> - Fix undefined reference to `__udivmoddi4`
>
> Changes since v3:
> https://lore.kernel.org/linux-pci/20241221141009.27317-1-18255117159@xxxxxxx/
>
> - The patch subject were modified.
>
> Changes since v2:
> https://lore.kernel.org/linux-pci/20241220075253.16791-1-18255117159@xxxxxxx/
>
> - Fix "changes" part goes below the --- line
> - The patch commit message were modified.
>
> Changes since v1:
> https://lore.kernel.org/linux-pci/20241217121220.19676-1-18255117159@xxxxxxx/
>
> - The patch subject and commit message were modified.
> ---
>   drivers/misc/pci_endpoint_test.c | 5 +++--
>   1 file changed, 3 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/misc/pci_endpoint_test.c b/drivers/misc/pci_endpoint_test.c
> index f78c7540c52c..0f6291801078 100644
> --- a/drivers/misc/pci_endpoint_test.c
> +++ b/drivers/misc/pci_endpoint_test.c
> @@ -280,10 +280,11 @@ static int pci_endpoint_test_bar_memcmp(struct pci_endpoint_test *test,
>   static bool pci_endpoint_test_bar(struct pci_endpoint_test *test,
>   				  enum pci_barno barno)
>   {
> -	int j, bar_size, buf_size, iters;
> +	int j, buf_size, iters;
>   	void *write_buf __free(kfree) = NULL;
>   	void *read_buf __free(kfree) = NULL;
>   	struct pci_dev *pdev = test->pdev;
> +	resource_size_t bar_size;
>   
>   	if (!test->bar[barno])
>   		return false;
> @@ -307,7 +308,7 @@ static bool pci_endpoint_test_bar(struct pci_endpoint_test *test,
>   	if (!read_buf)
>   		return false;
>   
> -	iters = bar_size / buf_size;
> +	iters = div_u64(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))


This change breaks building the kernel with GCC v7 and I see ...

ERROR: modpost: "__aeabi_uldivmod" [drivers/misc/pci_endpoint_test.ko] 
undefined!
ERROR: modpost: "__aeabi_ldivmod" [drivers/misc/pci_endpoint_test.ko] 
undefined!

I know that this is an old GCC version, but this is a farm builder and 
the kernel still indicates that GCC v5.1 is still supported [0].

Jon

[0] 
https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git/tree/Documentation/process/changes.rst

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