Re: [PATCH v2] powerpc/kexec_file: use current CPU info while setting up FDT

[Hari Bathini <hbathini@linux.ibm.com>]

On 16/04/21 6:16 pm, Sourabh Jain wrote:
> 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")

Missed marking stable@vger.kernel.org on Cc for this fix..


> +int add_node_prop(void *fdt, int node_offset, const struct device_node *np)
> +{

<SNIP>

> +int update_cpus_node(void *fdt)
> +{

I think the above two new functions should be marked 'static'...

Thanks
Hari