Hisilicon fixes for v5.3-rc

- Fixed RCU usage in logical PIO
 - Added a function to unregister a logical PIO range in logical PIO
   to support the fixes in the hisi-lpc driver
 - Fixed and optimized hisi-lpc driver to avoid potential use-after-free
   and driver unbind crash
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Merge tag 'hisi-fixes-for-5.3' of git://github.com/hisilicon/linux-hisi into arm/fixes

Hisilicon fixes for v5.3-rc

- Fixed RCU usage in logical PIO
- Added a function to unregister a logical PIO range in logical PIO
  to support the fixes in the hisi-lpc driver
- Fixed and optimized hisi-lpc driver to avoid potential use-after-free
  and driver unbind crash

* tag 'hisi-fixes-for-5.3' of git://github.com/hisilicon/linux-hisi:
  bus: hisi_lpc: Add .remove method to avoid driver unbind crash
  bus: hisi_lpc: Unregister logical PIO range to avoid potential use-after-free
  lib: logic_pio: Add logic_pio_unregister_range()
  lib: logic_pio: Avoid possible overlap for unregistering regions
  lib: logic_pio: Fix RCU usage

Link: https://lore.kernel.org/r/5D562335.7000902@hisilicon.com
Signed-off-by: Arnd Bergmann <arnd@arndb.de>

drivers/bus/hisi_lpc.c

@@ -456,6 +456,17 @@ struct hisi_lpc_acpi_cell {
 	size_t pdata_size;
 };
 
+static void hisi_lpc_acpi_remove(struct device *hostdev)
+{
+	struct acpi_device *adev = ACPI_COMPANION(hostdev);
+	struct acpi_device *child;
+
+	device_for_each_child(hostdev, NULL, hisi_lpc_acpi_remove_subdev);
+
+	list_for_each_entry(child, &adev->children, node)
+		acpi_device_clear_enumerated(child);
+}
+
 /*
  * hisi_lpc_acpi_probe - probe children for ACPI FW
  * @hostdev: LPC host device pointer
@@ -555,8 +566,7 @@ static int hisi_lpc_acpi_probe(struct device *hostdev)
 	return 0;
 
 fail:
-	device_for_each_child(hostdev, NULL,
-			      hisi_lpc_acpi_remove_subdev);
+	hisi_lpc_acpi_remove(hostdev);
 	return ret;
 }
 
@@ -569,6 +579,10 @@ static int hisi_lpc_acpi_probe(struct device *dev)
 {
 	return -ENODEV;
 }
+
+static void hisi_lpc_acpi_remove(struct device *hostdev)
+{
+}
 #endif // CONFIG_ACPI
 
 /*
@@ -606,24 +620,27 @@ static int hisi_lpc_probe(struct platform_device *pdev)
 	range->fwnode = dev->fwnode;
 	range->flags = LOGIC_PIO_INDIRECT;
 	range->size = PIO_INDIRECT_SIZE;
+	range->hostdata = lpcdev;
+	range->ops = &hisi_lpc_ops;
+	lpcdev->io_host = range;
 
 	ret = logic_pio_register_range(range);
 	if (ret) {
 		dev_err(dev, "register IO range failed (%d)!\n", ret);
 		return ret;
 	}
-	lpcdev->io_host = range;
 
 	/* register the LPC host PIO resources */
 	if (acpi_device)
 		ret = hisi_lpc_acpi_probe(dev);
 	else
 		ret = of_platform_populate(dev->of_node, NULL, NULL, dev);
-	if (ret)
+	if (ret) {
+		logic_pio_unregister_range(range);
 		return ret;
+	}
 
-	lpcdev->io_host->hostdata = lpcdev;
-	lpcdev->io_host->ops = &hisi_lpc_ops;
+	dev_set_drvdata(dev, lpcdev);
 
 	io_end = lpcdev->io_host->io_start + lpcdev->io_host->size;
 	dev_info(dev, "registered range [%pa - %pa]\n",
@@ -632,6 +649,23 @@ static int hisi_lpc_probe(struct platform_device *pdev)
 	return ret;
 }
 
+static int hisi_lpc_remove(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct acpi_device *acpi_device = ACPI_COMPANION(dev);
+	struct hisi_lpc_dev *lpcdev = dev_get_drvdata(dev);
+	struct logic_pio_hwaddr *range = lpcdev->io_host;
+
+	if (acpi_device)
+		hisi_lpc_acpi_remove(dev);
+	else
+		of_platform_depopulate(dev);
+
+	logic_pio_unregister_range(range);
+
+	return 0;
+}
+
 static const struct of_device_id hisi_lpc_of_match[] = {
 	{ .compatible = "hisilicon,hip06-lpc", },
 	{ .compatible = "hisilicon,hip07-lpc", },
@@ -645,5 +679,6 @@ static struct platform_driver hisi_lpc_driver = {
 		.acpi_match_table = ACPI_PTR(hisi_lpc_acpi_match),
 	},
 	.probe = hisi_lpc_probe,
+	.remove = hisi_lpc_remove,
 };
 builtin_platform_driver(hisi_lpc_driver);

include/linux/logic_pio.h

@@ -117,6 +117,7 @@ struct logic_pio_hwaddr *find_io_range_by_fwnode(struct fwnode_handle *fwnode);
 unsigned long logic_pio_trans_hwaddr(struct fwnode_handle *fwnode,
 			resource_size_t hw_addr, resource_size_t size);
 int logic_pio_register_range(struct logic_pio_hwaddr *newrange);
+void logic_pio_unregister_range(struct logic_pio_hwaddr *range);
 resource_size_t logic_pio_to_hwaddr(unsigned long pio);
 unsigned long logic_pio_trans_cpuaddr(resource_size_t hw_addr);
 

lib/logic_pio.c

@@ -35,7 +35,7 @@ int logic_pio_register_range(struct logic_pio_hwaddr *new_range)
 	struct logic_pio_hwaddr *range;
 	resource_size_t start;
 	resource_size_t end;
-	resource_size_t mmio_sz = 0;
+	resource_size_t mmio_end = 0;
 	resource_size_t iio_sz = MMIO_UPPER_LIMIT;
 	int ret = 0;
 
@@ -46,7 +46,7 @@ int logic_pio_register_range(struct logic_pio_hwaddr *new_range)
 	end = new_range->hw_start + new_range->size;
 
 	mutex_lock(&io_range_mutex);
-	list_for_each_entry_rcu(range, &io_range_list, list) {
+	list_for_each_entry(range, &io_range_list, list) {
 		if (range->fwnode == new_range->fwnode) {
 			/* range already there */
 			goto end_register;
@@ -56,7 +56,7 @@ int logic_pio_register_range(struct logic_pio_hwaddr *new_range)
 			/* for MMIO ranges we need to check for overlap */
 			if (start >= range->hw_start + range->size ||
 			    end < range->hw_start) {
-				mmio_sz += range->size;
+				mmio_end = range->io_start + range->size;
 			} else {
 				ret = -EFAULT;
 				goto end_register;
@@ -69,16 +69,16 @@ int logic_pio_register_range(struct logic_pio_hwaddr *new_range)
 
 	/* range not registered yet, check for available space */
 	if (new_range->flags == LOGIC_PIO_CPU_MMIO) {
-		if (mmio_sz + new_range->size - 1 > MMIO_UPPER_LIMIT) {
+		if (mmio_end + new_range->size - 1 > MMIO_UPPER_LIMIT) {
 			/* if it's too big check if 64K space can be reserved */
-			if (mmio_sz + SZ_64K - 1 > MMIO_UPPER_LIMIT) {
+			if (mmio_end + SZ_64K - 1 > MMIO_UPPER_LIMIT) {
 				ret = -E2BIG;
 				goto end_register;
 			}
 			new_range->size = SZ_64K;
 			pr_warn("Requested IO range too big, new size set to 64K\n");
 		}
-		new_range->io_start = mmio_sz;
+		new_range->io_start = mmio_end;
 	} else if (new_range->flags == LOGIC_PIO_INDIRECT) {
 		if (iio_sz + new_range->size - 1 > IO_SPACE_LIMIT) {
 			ret = -E2BIG;
@@ -98,6 +98,20 @@ int logic_pio_register_range(struct logic_pio_hwaddr *new_range)
 	return ret;
 }
 
+/**
+ * logic_pio_unregister_range - unregister a logical PIO range for a host
+ * @range: pointer to the IO range which has been already registered.
+ *
+ * Unregister a previously-registered IO range node.
+ */
+void logic_pio_unregister_range(struct logic_pio_hwaddr *range)
+{
+	mutex_lock(&io_range_mutex);
+	list_del_rcu(&range->list);
+	mutex_unlock(&io_range_mutex);
+	synchronize_rcu();
+}
+
 /**
  * find_io_range_by_fwnode - find logical PIO range for given FW node
  * @fwnode: FW node handle associated with logical PIO range
@@ -108,26 +122,38 @@ int logic_pio_register_range(struct logic_pio_hwaddr *new_range)
  */
 struct logic_pio_hwaddr *find_io_range_by_fwnode(struct fwnode_handle *fwnode)
 {
-	struct logic_pio_hwaddr *range;
+	struct logic_pio_hwaddr *range, *found_range = NULL;
 
+	rcu_read_lock();
 	list_for_each_entry_rcu(range, &io_range_list, list) {
-		if (range->fwnode == fwnode)
-			return range;
+		if (range->fwnode == fwnode) {
+			found_range = range;
+			break;
 		}
-	return NULL;
+	}
+	rcu_read_unlock();
+
+	return found_range;
 }
 
 /* Return a registered range given an input PIO token */
 static struct logic_pio_hwaddr *find_io_range(unsigned long pio)
 {
-	struct logic_pio_hwaddr *range;
+	struct logic_pio_hwaddr *range, *found_range = NULL;
 
+	rcu_read_lock();
 	list_for_each_entry_rcu(range, &io_range_list, list) {
-		if (in_range(pio, range->io_start, range->size))
-			return range;
+		if (in_range(pio, range->io_start, range->size)) {
+			found_range = range;
+			break;
 		}
-	pr_err("PIO entry token %lx invalid\n", pio);
-	return NULL;
+	}
+	rcu_read_unlock();
+
+	if (!found_range)
+		pr_err("PIO entry token 0x%lx invalid\n", pio);
+
+	return found_range;
 }
 
 /**
@@ -180,14 +206,23 @@ unsigned long logic_pio_trans_cpuaddr(resource_size_t addr)
 {
 	struct logic_pio_hwaddr *range;
 
+	rcu_read_lock();
 	list_for_each_entry_rcu(range, &io_range_list, list) {
 		if (range->flags != LOGIC_PIO_CPU_MMIO)
 			continue;
-		if (in_range(addr, range->hw_start, range->size))
-			return addr - range->hw_start + range->io_start;
+		if (in_range(addr, range->hw_start, range->size)) {
+			unsigned long cpuaddr;
+
+			cpuaddr = addr - range->hw_start + range->io_start;
+
+			rcu_read_unlock();
+			return cpuaddr;
 		}
-	pr_err("addr %llx not registered in io_range_list\n",
-	       (unsigned long long) addr);
+	}
+	rcu_read_unlock();
+
+	pr_err("addr %pa not registered in io_range_list\n", &addr);
+
 	return ~0UL;
 }