[PATCH v3] misc: pci_endpoint_test: Use memcpy_toio()/memcpy_fromio() for BAR tests

[Niklas Cassel <cassel@xxxxxxxxxx>]

The current code uses writel()/readl(), which has an implicit memory
barrier for every single readl()/writel().

Additionally, reading 4 bytes at a time over the PCI bus is not really
optimal, considering that this code is running in an ioctl handler.

Use memcpy_toio()/memcpy_fromio() for BAR tests.

Before patch with a 4MB BAR:
$ time /usr/bin/pcitest -b 1
BAR1:           OKAY
real    0m 1.56s

After patch with a 4MB BAR:
$ time /usr/bin/pcitest -b 1
BAR1:           OKAY
real    0m 0.54s

Signed-off-by: Niklas Cassel <cassel@xxxxxxxxxx>
---
Changes since v2:
-Actually free the allocated memory... (thank you Kuppuswamy)

 drivers/misc/pci_endpoint_test.c | 68 ++++++++++++++++++++++++++------
 1 file changed, 55 insertions(+), 13 deletions(-)

diff --git a/drivers/misc/pci_endpoint_test.c b/drivers/misc/pci_endpoint_test.c
index 705029ad8eb5..1d361589fb61 100644
--- a/drivers/misc/pci_endpoint_test.c
+++ b/drivers/misc/pci_endpoint_test.c
@@ -272,33 +272,75 @@ static const u32 bar_test_pattern[] = {
 	0xA5A5A5A5,
 };
 
+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)
+{
+	memset(write_buf, bar_test_pattern[barno], size);
+	memcpy_toio(test->bar[barno] + offset, write_buf, size);
+
+	memcpy_fromio(read_buf, test->bar[barno] + offset, size);
+
+	return memcmp(write_buf, read_buf, size);
+}
+
 static bool pci_endpoint_test_bar(struct pci_endpoint_test *test,
 				  enum pci_barno barno)
 {
-	int j;
-	u32 val;
-	int size;
+	int j, bar_size, buf_size, iters, remain;
+	void *write_buf;
+	void *read_buf;
 	struct pci_dev *pdev = test->pdev;
+	bool ret;
 
 	if (!test->bar[barno])
 		return false;
 
-	size = pci_resource_len(pdev, barno);
+	bar_size = pci_resource_len(pdev, barno);
 
 	if (barno == test->test_reg_bar)
-		size = 0x4;
+		bar_size = 0x4;
 
-	for (j = 0; j < size; j += 4)
-		pci_endpoint_test_bar_writel(test, barno, j,
-					     bar_test_pattern[barno]);
+	buf_size = min(SZ_1M, bar_size);
 
-	for (j = 0; j < size; j += 4) {
-		val = pci_endpoint_test_bar_readl(test, barno, j);
-		if (val != bar_test_pattern[barno])
-			return false;
+	write_buf = kmalloc(buf_size, GFP_KERNEL);
+	if (!write_buf)
+		return false;
+
+	read_buf = kmalloc(buf_size, GFP_KERNEL);
+	if (!read_buf) {
+		ret = false;
+		goto err;
 	}
 
-	return true;
+	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)) {
+			ret = false;
+			goto err;
+		}
+	}
+
+	remain = bar_size % buf_size;
+	if (remain) {
+		if (pci_endpoint_test_bar_memcmp(test, barno, buf_size * iters,
+						 write_buf, read_buf,
+						 remain)) {
+			ret = false;
+			goto err;
+		}
+	}
+
+	ret = true;
+
+err:
+	kfree(write_buf);
+	kfree(read_buf);
+
+	return ret;
 }
 
 static bool pci_endpoint_test_intx_irq(struct pci_endpoint_test *test)
-- 
2.44.0