Commit 40c75399 authored by Sourabh Jain's avatar Sourabh Jain Committed by Michael Ellerman
Browse files

powerpc/kexec_file: Use current CPU info while setting up FDT 



kexec_file_load() uses initial_boot_params in setting up the device tree
for the kernel to be loaded. Though initial_boot_params holds info about
CPUs at the time of boot, it doesn't account for hot added CPUs.

So, kexec'ing with kexec_file_load() syscall leaves the kexec'ed kernel
with inaccurate CPU info.

If kdump kernel is loaded with kexec_file_load() syscall and the system
crashes on a hot added CPU, the capture kernel hangs failing to identify
the boot CPU, with no output.

To avoid this from happening, extract current CPU info from of_root
device node and use it for setting up the fdt in kexec_file_load case.

Fixes: 6ecd0163 ("powerpc/kexec_file: Add appropriate regions for memory reserve map")
Cc: stable@vger.kernel.org # v5.9+
Signed-off-by: default avatarSourabh Jain <sourabhjain@linux.ibm.com>
Reviewed-by: default avatarHari Bathini <hbathini@linux.ibm.com>
Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20210429060256.199714-1-sourabhjain@linux.ibm.com
parent 8abddd96

arch/powerpc/kexec/file_load_64.c

+92 −0
Original line number Diff line number Diff line
@@ -950,6 +950,93 @@ unsigned int kexec_extra_fdt_size_ppc64(struct kimage *image) 
	return (unsigned int)(usm_entries * sizeof(u64));

}



/**

 * add_node_props - Reads node properties from device node structure and add

 *                  them to fdt.

 * @fdt:            Flattened device tree of the kernel

 * @node_offset:    offset of the node to add a property at

 * @dn:             device node pointer

 *

 * Returns 0 on success, negative errno on error.

 */

static int add_node_props(void *fdt, int node_offset, const struct device_node *dn)

{

	int ret = 0;

	struct property *pp;



	if (!dn)

		return -EINVAL;



	for_each_property_of_node(dn, pp) {

		ret = fdt_setprop(fdt, node_offset, pp->name, pp->value, pp->length);

		if (ret < 0) {

			pr_err("Unable to add %s property: %s\n", pp->name, fdt_strerror(ret));

			return ret;

		}

	}

	return ret;

}



/**

 * update_cpus_node - Update cpus node of flattened device tree using of_root

 *                    device node.

 * @fdt:              Flattened device tree of the kernel.

 *

 * Returns 0 on success, negative errno on error.

 */

static int update_cpus_node(void *fdt)

{

	struct device_node *cpus_node, *dn;

	int cpus_offset, cpus_subnode_offset, ret = 0;



	cpus_offset = fdt_path_offset(fdt, "/cpus");

	if (cpus_offset < 0 && cpus_offset != -FDT_ERR_NOTFOUND) {

		pr_err("Malformed device tree: error reading /cpus node: %s\n",

		       fdt_strerror(cpus_offset));

		return cpus_offset;

	}



	if (cpus_offset > 0) {

		ret = fdt_del_node(fdt, cpus_offset);

		if (ret < 0) {

			pr_err("Error deleting /cpus node: %s\n", fdt_strerror(ret));

			return -EINVAL;

		}

	}



	/* Add cpus node to fdt */

	cpus_offset = fdt_add_subnode(fdt, fdt_path_offset(fdt, "/"), "cpus");

	if (cpus_offset < 0) {

		pr_err("Error creating /cpus node: %s\n", fdt_strerror(cpus_offset));

		return -EINVAL;

	}



	/* Add cpus node properties */

	cpus_node = of_find_node_by_path("/cpus");

	ret = add_node_props(fdt, cpus_offset, cpus_node);

	of_node_put(cpus_node);

	if (ret < 0)

		return ret;



	/* Loop through all subnodes of cpus and add them to fdt */

	for_each_node_by_type(dn, "cpu") {

		cpus_subnode_offset = fdt_add_subnode(fdt, cpus_offset, dn->full_name);

		if (cpus_subnode_offset < 0) {

			pr_err("Unable to add %s subnode: %s\n", dn->full_name,

			       fdt_strerror(cpus_subnode_offset));

			ret = cpus_subnode_offset;

			goto out;

		}



		ret = add_node_props(fdt, cpus_subnode_offset, dn);

		if (ret < 0)

			goto out;

	}

out:

	of_node_put(dn);

	return ret;

}



/**

 * setup_new_fdt_ppc64 - Update the flattend device-tree of the kernel

 *                       being loaded.
@@ -1006,6 +1093,11 @@ int setup_new_fdt_ppc64(const struct kimage *image, void *fdt, 
		}

	}



	/* Update cpus nodes information to account hotplug CPUs. */

	ret =  update_cpus_node(fdt);

	if (ret < 0)

		goto out;



	/* Update memory reserve map */

	ret = get_reserved_memory_ranges(&rmem);

	if (ret)