From: Sourabh Jain sourabhjain@linux.ibm.com
commit 40c753993e3aad51a12c21233486e2037417a4d6 upstream.
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: 6ecd0163d360 ("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 Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- arch/powerpc/kexec/file_load_64.c | 92 ++++++++++++++++++++++++++++++++++++++ 1 file changed, 92 insertions(+)
--- a/arch/powerpc/kexec/file_load_64.c +++ b/arch/powerpc/kexec/file_load_64.c @@ -961,6 +961,93 @@ unsigned int kexec_fdt_totalsize_ppc64(s }
/** + * 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. * @image: kexec image being loaded. @@ -1020,6 +1107,11 @@ int setup_new_fdt_ppc64(const struct kim } }
+ /* 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)