[PATCH] mfd: ls2kbmc: Fix iomem pointer handling in video mode parsing

[Binbin Zhou]

Use pointers annotated with the __iomem marker for all iomem map calls,
and creates a local copy of the mapped IO memory for future access in
the code. memcpy_fromio() and memcpy_toio() are used to read/write data
from/to mapped IO memory

Fixes: 0d64f6d1ffe9 ("mfd: ls2kbmc: Introduce Loongson-2K BMC core driver")
Reported-by: kernel test robot <lkp@xxxxxxxxx>
Closes: https://lore.kernel.org/oe-kbuild-all/202603021730.Yy3QXYTw-lkp@xxxxxxxxx/
Closes: https://lore.kernel.org/oe-kbuild-all/202606120639.WG6eb8VU-lkp@xxxxxxxxx/
Signed-off-by: Binbin Zhou <zhoubinbin@xxxxxxxxxxx>
---
 drivers/mfd/ls2k-bmc-core.c | 13 ++++++++++---
 1 file changed, 10 insertions(+), 3 deletions(-)

diff --git a/drivers/mfd/ls2k-bmc-core.c b/drivers/mfd/ls2k-bmc-core.c
index 408056bfb2fe..c40b1a7c4ea4 100644
--- a/drivers/mfd/ls2k-bmc-core.c
+++ b/drivers/mfd/ls2k-bmc-core.c
@@ -427,14 +427,21 @@ static int ls2k_bmc_init(struct ls2k_bmc_ddata *ddata)
  */
 static int ls2k_bmc_parse_mode(struct pci_dev *pdev, struct simplefb_platform_data *pd)
 {
-	char *mode;
+	void *buf __free(kfree) = NULL;
+	void __iomem *base;
 	int depth, ret;
+	char *mode;
 
 	/* The last 16M of PCI BAR0 is used to store the resolution string. */
-	mode = devm_ioremap(&pdev->dev, pci_resource_start(pdev, 0) + SZ_16M, SZ_16M);
-	if (!mode)
+	base = devm_ioremap(&pdev->dev, pci_resource_start(pdev, 0) + SZ_16M, SZ_16M);
+	if (!base)
+		return -ENOMEM;
+
+	buf = kmalloc(SZ_16M, GFP_KERNEL);
+	if (!buf)
 		return -ENOMEM;
 
+	mode = (char *)buf;
 	/* The resolution field starts with the flag "video=". */
 	if (!strncmp(mode, "video=", 6))
 		mode = mode + 6;

base-commit: b07f7904e0523170856876e4412be852377d492a
-- 
2.52.0