misc: pci_endpoint_test: Handle BAR sizes larger than INT_MAX

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.

In order to handle 64-bit resource_type_t on 32-bit platforms, we would
have needed to use a function like div_u64() or similar. Instead, change
the code to use addition instead of division. This avoids the need for
div_u64() or similar, while also simplifying the code.

Fixes: cda370e ("misc: pci_endpoint_test: Avoid using hard-coded BAR sizes")
Co-developed-by: Hans Zhang <[email protected]>
Signed-off-by: Hans Zhang <[email protected]>
Signed-off-by: Niklas Cassel <[email protected]>
Reviewed-by: Manivannan Sadhasivam <[email protected]>
Tested-by: Jon Hunter <[email protected]>
Reviewed-by: Frank Li <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
[mani: added fixes tag]
Signed-off-by: Manivannan Sadhasivam <[email protected]>
Signed-off-by: Krzysztof Wilczyński <[email protected]>

Author: floatious

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;
 
 	bar_size = pci_resource_len(pdev, barno);
 	if (!bar_size)
@@ -316,11 +317,12 @@ 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;
+	}
 
 	return 0;
 }