net: bcmgenet: synchronize UMAC_CMD access

The UMAC_CMD register is written from different execution
contexts and has insufficient synchronization protections to
prevent possible corruption. Of particular concern are the
acceses from the phy_device delayed work context used by the
adjust_link call and the BH context that may be used by the
ndo_set_rx_mode call.

A spinlock is added to the driver to protect contended register
accesses (i.e. reg_lock) and it is used to synchronize accesses
to UMAC_CMD.

Fixes: 1c1008c7 ("net: bcmgenet: add main driver file")
Cc: stable@vger.kernel.org
Signed-off-by: Doug Berger <opendmb@gmail.com>
Acked-by: Florian Fainelli <florian.fainelli@broadcom.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/broadcom/genet/bcmgenet.c

@@ -2467,14 +2467,18 @@ static void umac_enable_set(struct bcmgenet_priv *priv, u32 mask, bool enable)
 {
 	u32 reg;
 
+	spin_lock_bh(&priv->reg_lock);
 	reg = bcmgenet_umac_readl(priv, UMAC_CMD);
-	if (reg & CMD_SW_RESET)
+	if (reg & CMD_SW_RESET) {
+		spin_unlock_bh(&priv->reg_lock);
 		return;
+	}
 	if (enable)
 		reg |= mask;
 	else
 		reg &= ~mask;
 	bcmgenet_umac_writel(priv, reg, UMAC_CMD);
+	spin_unlock_bh(&priv->reg_lock);
 
 	/* UniMAC stops on a packet boundary, wait for a full-size packet
 	 * to be processed
@@ -2490,8 +2494,10 @@ static void reset_umac(struct bcmgenet_priv *priv)
 	udelay(10);
 
 	/* issue soft reset and disable MAC while updating its registers */
+	spin_lock_bh(&priv->reg_lock);
 	bcmgenet_umac_writel(priv, CMD_SW_RESET, UMAC_CMD);
 	udelay(2);
+	spin_unlock_bh(&priv->reg_lock);
 }
 
 static void bcmgenet_intr_disable(struct bcmgenet_priv *priv)
@@ -3597,16 +3603,19 @@ static void bcmgenet_set_rx_mode(struct net_device *dev)
 	 * 3. The number of filters needed exceeds the number filters
 	 *    supported by the hardware.
 	*/
+	spin_lock(&priv->reg_lock);
 	reg = bcmgenet_umac_readl(priv, UMAC_CMD);
 	if ((dev->flags & (IFF_PROMISC | IFF_ALLMULTI)) ||
 	    (nfilter > MAX_MDF_FILTER)) {
 		reg |= CMD_PROMISC;
 		bcmgenet_umac_writel(priv, reg, UMAC_CMD);
+		spin_unlock(&priv->reg_lock);
 		bcmgenet_umac_writel(priv, 0, UMAC_MDF_CTRL);
 		return;
 	} else {
 		reg &= ~CMD_PROMISC;
 		bcmgenet_umac_writel(priv, reg, UMAC_CMD);
+		spin_unlock(&priv->reg_lock);
 	}
 
 	/* update MDF filter */
@@ -4005,6 +4014,7 @@ static int bcmgenet_probe(struct platform_device *pdev)
 		goto err;
 	}
 
+	spin_lock_init(&priv->reg_lock);
 	spin_lock_init(&priv->lock);
 
 	/* Set default pause parameters */

drivers/net/ethernet/broadcom/genet/bcmgenet.h

 /* SPDX-License-Identifier: GPL-2.0-only */
 /*
- * Copyright (c) 2014-2020 Broadcom
+ * Copyright (c) 2014-2024 Broadcom
  */
 
 #ifndef __BCMGENET_H__
@@ -573,6 +573,8 @@ struct bcmgenet_rxnfc_rule {
 /* device context */
 struct bcmgenet_priv {
 	void __iomem *base;
+	/* reg_lock: lock to serialize access to shared registers */
+	spinlock_t reg_lock;
 	enum bcmgenet_version version;
 	struct net_device *dev;
 

drivers/net/ethernet/broadcom/genet/bcmgenet_wol.c

@@ -2,7 +2,7 @@
 /*
  * Broadcom GENET (Gigabit Ethernet) Wake-on-LAN support
  *
- * Copyright (c) 2014-2020 Broadcom
+ * Copyright (c) 2014-2024 Broadcom
  */
 
 #define pr_fmt(fmt)				"bcmgenet_wol: " fmt
@@ -151,6 +151,7 @@ int bcmgenet_wol_power_down_cfg(struct bcmgenet_priv *priv,
 	}
 
 	/* Can't suspend with WoL if MAC is still in reset */
+	spin_lock_bh(&priv->reg_lock);
 	reg = bcmgenet_umac_readl(priv, UMAC_CMD);
 	if (reg & CMD_SW_RESET)
 		reg &= ~CMD_SW_RESET;
@@ -158,6 +159,7 @@ int bcmgenet_wol_power_down_cfg(struct bcmgenet_priv *priv,
 	/* disable RX */
 	reg &= ~CMD_RX_EN;
 	bcmgenet_umac_writel(priv, reg, UMAC_CMD);
+	spin_unlock_bh(&priv->reg_lock);
 	mdelay(10);
 
 	if (priv->wolopts & (WAKE_MAGIC | WAKE_MAGICSECURE)) {
@@ -203,6 +205,7 @@ int bcmgenet_wol_power_down_cfg(struct bcmgenet_priv *priv,
 	}
 
 	/* Enable CRC forward */
+	spin_lock_bh(&priv->reg_lock);
 	reg = bcmgenet_umac_readl(priv, UMAC_CMD);
 	priv->crc_fwd_en = 1;
 	reg |= CMD_CRC_FWD;
@@ -210,6 +213,7 @@ int bcmgenet_wol_power_down_cfg(struct bcmgenet_priv *priv,
 	/* Receiver must be enabled for WOL MP detection */
 	reg |= CMD_RX_EN;
 	bcmgenet_umac_writel(priv, reg, UMAC_CMD);
+	spin_unlock_bh(&priv->reg_lock);
 
 	reg = UMAC_IRQ_MPD_R;
 	if (hfb_enable)
@@ -256,7 +260,9 @@ void bcmgenet_wol_power_up_cfg(struct bcmgenet_priv *priv,
 	}
 
 	/* Disable CRC Forward */
+	spin_lock_bh(&priv->reg_lock);
 	reg = bcmgenet_umac_readl(priv, UMAC_CMD);
 	reg &= ~CMD_CRC_FWD;
 	bcmgenet_umac_writel(priv, reg, UMAC_CMD);
+	spin_unlock_bh(&priv->reg_lock);
 }

drivers/net/ethernet/broadcom/genet/bcmmii.c

@@ -76,6 +76,7 @@ static void bcmgenet_mac_config(struct net_device *dev)
 	reg |= RGMII_LINK;
 	bcmgenet_ext_writel(priv, reg, EXT_RGMII_OOB_CTRL);
 
+	spin_lock_bh(&priv->reg_lock);
 	reg = bcmgenet_umac_readl(priv, UMAC_CMD);
 	reg &= ~((CMD_SPEED_MASK << CMD_SPEED_SHIFT) |
 		       CMD_HD_EN |
@@ -88,6 +89,7 @@ static void bcmgenet_mac_config(struct net_device *dev)
 		reg |= CMD_TX_EN | CMD_RX_EN;
 	}
 	bcmgenet_umac_writel(priv, reg, UMAC_CMD);
+	spin_unlock_bh(&priv->reg_lock);
 
 	active = phy_init_eee(phydev, 0) >= 0;
 	bcmgenet_eee_enable_set(dev,