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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: 6ecd0163d3 ("powerpc/kexec_file: Add appropriate regions for memory reserve map")
Cc: stable@vger.kernel.org # v5.9+
Signed-off-by: Sourabh Jain <sourabhjain@linux.ibm.com>
Reviewed-by: Hari Bathini <hbathini@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20210429060256.199714-1-sourabhjain@linux.ibm.com
This commit is contained in:
Sourabh Jain 2021-04-29 11:32:56 +05:30 committed by Michael Ellerman
parent 8abddd968a
commit 40c753993e
1 changed files with 92 additions and 0 deletions
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92
arch/powerpc/kexec/file_load_64.c
View File

@ -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)