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 would leave the kexec'ed
kernel with inaccurate CPU info. Also, if kdump kernel is loaded with
kexec_file_load syscall and the system crashes on a hot added CPU,
capture kernel hangs failing to identify the boot CPU.
Kernel panic - not syncing: sysrq triggered crash
CPU: 24 PID: 6065 Comm: echo Kdump: loaded Not tainted 5.12.0-rc5upstream #54
Call Trace:
[c0000000e590fac0] [c0000000007b2400] dump_stack+0xc4/0x114 (unreliable)
[c0000000e590fb00] [c000000000145290] panic+0x16c/0x41c
[c0000000e590fba0] [c0000000008892e0] sysrq_handle_crash+0x30/0x40
[c0000000e590fc00] [c000000000889cdc] __handle_sysrq+0xcc/0x1f0
[c0000000e590fca0] [c00000000088a538] write_sysrq_trigger+0xd8/0x178
[c0000000e590fce0] [c0000000005e9b7c] proc_reg_write+0x10c/0x1b0
[c0000000e590fd10] [c0000000004f26d0] vfs_write+0xf0/0x330
[c0000000e590fd60] [c0000000004f2aec] ksys_write+0x7c/0x140
[c0000000e590fdb0] [c000000000031ee0] system_call_exception+0x150/0x290
[c0000000e590fe10] [c00000000000ca5c] system_call_common+0xec/0x278
--- interrupt: c00 at 0x7fff905b9664
NIP: 00007fff905b9664 LR: 00007fff905320c4 CTR: 0000000000000000
REGS: c0000000e590fe80 TRAP: 0c00 Not tainted (5.12.0-rc5upstream)
MSR: 800000000280f033 <SF,VEC,VSX,EE,PR,FP,ME,IR,DR,RI,LE> CR: 28000242
XER: 00000000
IRQMASK: 0
GPR00: 0000000000000004 00007ffff5fedf30 00007fff906a7300 0000000000000001
GPR04: 000001002a7355b0 0000000000000002 0000000000000001 00007ffff5fef616
GPR08: 0000000000000001 0000000000000000 0000000000000000 0000000000000000
GPR12: 0000000000000000 00007fff9073a160 0000000000000000 0000000000000000
GPR16: 0000000000000000 0000000000000000 0000000000000000 0000000000000000
GPR20: 0000000000000000 00007fff906a4ee0 0000000000000002 0000000000000001
GPR24: 00007fff906a0898 0000000000000000 0000000000000002 000001002a7355b0
GPR28: 0000000000000002 00007fff906a1790 000001002a7355b0 0000000000000002
NIP [00007fff905b9664] 0x7fff905b9664
LR [00007fff905320c4] 0x7fff905320c4
--- interrupt: c00
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")
Signed-off-by: Sourabh Jain <sourabhjain@xxxxxxxxxxxxx>
Reviewed-by: Hari Bathini <hbathini@xxxxxxxxxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx>
---
arch/powerpc/kexec/file_load_64.c | 92 +++++++++++++++++++++++++++++++
1 file changed, 92 insertions(+)
---
Changelog:
v1 -> v5
- https://lists.ozlabs.org/pipermail/linuxppc-dev/2021-April/227950.html
v5 -> v6
- use exiting macro (for_each_property_of_node) to loop through all
properties of a node.
- removed devtree_lock while accessing the node properties.
- function name update, add_node_prop to add_node_props.
v6 -> v7
- decrement the cpus_node refcount.
---
diff --git a/arch/powerpc/kexec/file_load_64.c b/arch/powerpc/kexec/file_load_64.c
index 02b9e4d0dc40..a8a7cb71086b 100644
--- a/arch/powerpc/kexec/file_load_64.c
+++ b/arch/powerpc/kexec/file_load_64.c
@@ -960,6 +960,93 @@ unsigned int kexec_fdt_totalsize_ppc64(struct kimage *image)
return fdt_size;
}
+/**
+ * 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.
@@ -1020,6 +1107,11 @@ 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)
--
2.26.3
