Re: [PATCH V13 2/5] PCI: Create device tree node for bridge

Herve Codina
2023-09-11T21:39:00Z

Hi Lizhi,

On Tue, 15 Aug 2023 10:19:57 -0700
Lizhi Hou <lizhi.hou@amd.com> wrote:
...
> +void of_pci_make_dev_node(struct pci_dev *pdev)
> +{
> + struct device_node *ppnode, *np = NULL;
> + const char *pci_type;
> + struct of_changeset *cset;
> + const char *name;
> + int ret;
> +
> + /*
> + * If there is already a device tree node linked to this device,
> + * return immediately.
> + */
> + if (pci_device_to_OF_node(pdev))
> + return;
> +
> + /* Check if there is device tree node for parent device */
> + if (!pdev->bus->self)
> + ppnode = pdev->bus->dev.of_node;
> + else
> + ppnode = pdev->bus->self->dev.of_node;
> + if (!ppnode)
> + return;
> +
> + if (pci_is_bridge(pdev))
> + pci_type = "pci";
> + else
> + pci_type = "dev";
> +
> + name = kasprintf(GFP_KERNEL, "%s@%x,%x", pci_type,
> + PCI_SLOT(pdev->devfn), PCI_FUNC(pdev->devfn));
> + if (!name)
> + return;
> +
> + cset = kmalloc(sizeof(*cset), GFP_KERNEL);
> + if (!cset)
> + goto failed;
> + of_changeset_init(cset);
> +
> + np = of_changeset_create_node(ppnode, name, cset);
> + if (!np)
> + goto failed;

The "goto failed" will leak the cset previously allocated.

np->data = cset; (next line) allows to free the cset when the node is destroyed
(of_node_put() calls). When the node cannot be created, the allocated cset should
be freed.

> + np->data = cset;
> +
> + ret = of_pci_add_properties(pdev, cset, np);
> + if (ret)
> + goto failed;
> +
> + ret = of_changeset_apply(cset);
> + if (ret)
> + goto failed;
> +
> + pdev->dev.of_node = np;
> + kfree(name);
> +
> + return;
> +
> +failed:
> + if (np)
> + of_node_put(np);
> + kfree(name);
> +}
> +#endif
> +
> #endif /* CONFIG_PCI */
>
...
> +static int of_pci_prop_intr_map(struct pci_dev *pdev, struct of_changeset *ocs,
> + struct device_node *np)
> +{
> + struct of_phandle_args out_irq[OF_PCI_MAX_INT_PIN];
> + u32 i, addr_sz[OF_PCI_MAX_INT_PIN], map_sz = 0;
> + __be32 laddr[OF_PCI_ADDRESS_CELLS] = { 0 };
> + u32 int_map_mask[] = { 0xffff00, 0, 0, 7 };
> + struct device_node *pnode;
> + struct pci_dev *child;
> + u32 *int_map, *mapp;
> + int ret;
> + u8 pin;
> +
> + pnode = pci_device_to_OF_node(pdev->bus->self);
> + if (!pnode)
> + pnode = pci_bus_to_OF_node(pdev->bus);
> +
> + if (!pnode) {
> + pci_err(pdev, "failed to get parent device node");
> + return -EINVAL;
> + }
> +
> + laddr[0] = cpu_to_be32((pdev->bus->number << 16) | (pdev->devfn << 8));
> + for (pin = 1; pin <= OF_PCI_MAX_INT_PIN; pin++) {
> + i = pin - 1;
> + out_irq[i].np = pnode;
> + out_irq[i].args_count = 1;
> + out_irq[i].args[0] = pin;
> + ret = of_irq_parse_raw(laddr, &out_irq[i]);
> + if (ret) {
> + pci_err(pdev, "parse irq %d failed, ret %d", pin, ret);
> + continue;
> + }
> + ret = of_property_read_u32(out_irq[i].np, "#address-cells",
> + &addr_sz[i]);
> + if (ret)
> + addr_sz[i] = 0;
> + }

if of_irq_parse_raw() fails, addr_sz[i] is not initialized and map_sz bellow is
computed with uninitialized values.
On the test I did, this lead to a kernel crash due to the following kcalloc()
called with incorrect values.

Are interrupt-map and interrupt-map-mask properties needed in all cases ?
I mean are they mandatory for the host pci bridge ?

> +
> + list_for_each_entry(child, &pdev->subordinate->devices, bus_list) {
> + for (pin = 1; pin <= OF_PCI_MAX_INT_PIN; pin++) {
> + i = pci_swizzle_interrupt_pin(child, pin) - 1;
> + map_sz += 5 + addr_sz[i] + out_irq[i].args_count;

of_irq_parse_raw() can fail on some pins.
Is it correct to set map_sz based on information related to all pins even if
of_irq_parse_raw() previously failed on some pins ?

> + }
> + }
> +
> + int_map = kcalloc(map_sz, sizeof(u32), GFP_KERNEL);
> + mapp = int_map;
> +
> + list_for_each_entry(child, &pdev->subordinate->devices, bus_list) {
> + for (pin = 1; pin <= OF_PCI_MAX_INT_PIN; pin++) {
> + *mapp = (child->bus->number << 16) |
> + (child->devfn << 8);
> + mapp += OF_PCI_ADDRESS_CELLS;
> + *mapp = pin;
> + mapp++;
> + i = pci_swizzle_interrupt_pin(child, pin) - 1;
> + *mapp = out_irq[i].np->phandle;
> + mapp++;
> + if (addr_sz[i]) {
> + ret = of_property_read_u32_array(out_irq[i].np,
> + "reg", mapp,
> + addr_sz[i]);
> + if (ret)
> + goto failed;
> + }
> + mapp += addr_sz[i];
> + memcpy(mapp, out_irq[i].args,
> + out_irq[i].args_count * sizeof(u32));
> + mapp += out_irq[i].args_count;
> + }
> + }
> +
> + ret = of_changeset_add_prop_u32_array(ocs, np, "interrupt-map", int_map,
> + map_sz);
> + if (ret)
> + goto failed;
> +
> + ret = of_changeset_add_prop_u32(ocs, np, "#interrupt-cells", 1);
> + if (ret)
> + goto failed;
> +
> + ret = of_changeset_add_prop_u32_array(ocs, np, "interrupt-map-mask",
> + int_map_mask,
> + ARRAY_SIZE(int_map_mask));
> + if (ret)
> + goto failed;
> +
> + kfree(int_map);
> + return 0;
> +
> +failed:
> + kfree(int_map);
> + return ret;
> +}
> +
...

Regards,
Hervé

--
Hervé Codina, Bootlin
Embedded Linux and Kernel engineering