net: stmmac: dump gmac4 DMA registers correctly

Unlike gmac100, gmac1000, gmac4 has 27 DMA registers and they are
located at DMA_CHAN_BASE_ADDR (0x1100). In order for ethtool to dump
gmac4 DMA registers correctly, this commit checks if a net_device has
gmac4 and uses different logic to dump its DMA registers.

This fixes the following KASAN warning, which can normally be triggered
by a command similar like "ethtool -d eth0":

BUG: KASAN: vmalloc-out-of-bounds in dwmac4_dump_dma_regs+0x6d4/0xb30
Write of size 4 at addr ffffffc010177100 by task ethtool/1839
 kasan_report+0x200/0x21c
 __asan_report_store4_noabort+0x34/0x60
 dwmac4_dump_dma_regs+0x6d4/0xb30
 stmmac_ethtool_gregs+0x110/0x204
 ethtool_get_regs+0x200/0x4b0
 dev_ethtool+0x1dac/0x3800
 dev_ioctl+0x7c0/0xb50
 sock_ioctl+0x298/0x6c4
 ...

Fixes: fbf6822 ("net: stmmac: unify registers dumps methods")
Signed-off-by: Camel Guo <camelg@axis.com>
Link: https://lore.kernel.org/r/20220131083841.3346801-1-camel.guo@axis.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

Author: Camel Guo

drivers/net/ethernet/stmicro/stmmac/dwmac_dma.h

@@ -150,6 +150,7 @@
 
 #define NUM_DWMAC100_DMA_REGS	9
 #define NUM_DWMAC1000_DMA_REGS	23
+#define NUM_DWMAC4_DMA_REGS	27
 
 void dwmac_enable_dma_transmission(void __iomem *ioaddr);
 void dwmac_enable_dma_irq(void __iomem *ioaddr, u32 chan, bool rx, bool tx);

drivers/net/ethernet/stmicro/stmmac/stmmac_ethtool.c

@@ -21,10 +21,18 @@
 #include "dwxgmac2.h"
 
 #define REG_SPACE_SIZE	0x1060
+#define GMAC4_REG_SPACE_SIZE	0x116C
 #define MAC100_ETHTOOL_NAME	"st_mac100"
 #define GMAC_ETHTOOL_NAME	"st_gmac"
 #define XGMAC_ETHTOOL_NAME	"st_xgmac"
 
+/* Same as DMA_CHAN_BASE_ADDR defined in dwmac4_dma.h
+ *
+ * It is here because dwmac_dma.h and dwmac4_dam.h can not be included at the
+ * same time due to the conflicting macro names.
+ */
+#define GMAC4_DMA_CHAN_BASE_ADDR  0x00001100
+
 #define ETHTOOL_DMA_OFFSET	55
 
 struct stmmac_stats {
@@ -434,6 +442,8 @@ static int stmmac_ethtool_get_regs_len(struct net_device *dev)
 
 	if (priv->plat->has_xgmac)
 		return XGMAC_REGSIZE * 4;
+	else if (priv->plat->has_gmac4)
+		return GMAC4_REG_SPACE_SIZE;
 	return REG_SPACE_SIZE;
 }
 
@@ -446,8 +456,13 @@ static void stmmac_ethtool_gregs(struct net_device *dev,
 	stmmac_dump_mac_regs(priv, priv->hw, reg_space);
 	stmmac_dump_dma_regs(priv, priv->ioaddr, reg_space);
 
-	if (!priv->plat->has_xgmac) {
-		/* Copy DMA registers to where ethtool expects them */
+	/* Copy DMA registers to where ethtool expects them */
+	if (priv->plat->has_gmac4) {
+		/* GMAC4 dumps its DMA registers at its DMA_CHAN_BASE_ADDR */
+		memcpy(&reg_space[ETHTOOL_DMA_OFFSET],
+		       &reg_space[GMAC4_DMA_CHAN_BASE_ADDR / 4],
+		       NUM_DWMAC4_DMA_REGS * 4);
+	} else if (!priv->plat->has_xgmac) {
 		memcpy(&reg_space[ETHTOOL_DMA_OFFSET],
 		       &reg_space[DMA_BUS_MODE / 4],
 		       NUM_DWMAC1000_DMA_REGS * 4);