[v8] misc: pci_endpoint_test: Fix overflow of bar_size

[Hans Zhang]

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>
Reviewed-by: Niklas Cassel <cassel@xxxxxxxxxx>
Reviewed-by: Manivannan Sadhasivam <manivannan.sadhasivam@xxxxxxxxxx>
---
Changes since v8:

- Add reviewer.

Changes since v4-v7:
https://lore.kernel.org/linux-pci/20250102120222.1403906-1-18255117159@xxxxxxx/
https://lore.kernel.org/linux-pci/20250101151509.570341-1-18255117159@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 | 12 +++++++++---
 1 file changed, 9 insertions(+), 3 deletions(-)

diff --git a/drivers/misc/pci_endpoint_test.c b/drivers/misc/pci_endpoint_test.c
index 3aaaf47fa4ee..50d4616119af 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, remain;
 	void *write_buf __free(kfree) = NULL;
 	void *read_buf __free(kfree) = NULL;
 	struct pci_dev *pdev = test->pdev;
+	int j, buf_size, iters, remain;
+	resource_size_t bar_size;
 
 	if (!test->bar[barno])
 		return false;
@@ -307,13 +308,18 @@ static bool pci_endpoint_test_bar(struct pci_endpoint_test *test,
 	if (!read_buf)
 		return false;
 
-	iters = bar_size / buf_size;
+	if (IS_ENABLED(CONFIG_PHYS_ADDR_T_64BIT)) {
+		remain = do_div(bar_size, buf_size);
+		iters = bar_size;
+	} else {
+		iters = bar_size / buf_size;
+		remain = 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))
 			return false;
 
-	remain = bar_size % buf_size;
 	if (remain)
 		if (pci_endpoint_test_bar_memcmp(test, barno, buf_size * iters,
 						 write_buf, read_buf, remain))

base-commit: ccb98ccef0e543c2bd4ef1a72270461957f3d8d0
-- 
2.25.1