On Wed, Dec 14, 2016 at 2:11 PM, Pingfan Liu <piliu at redhat.com> wrote:
> kexec-tools always allocates program headers for each possible cpu. This
The code is in the file: kexec-tools/kexec/crashdump-elf.c
nr_cpus = sysconf(_SC_NPROCESSORS_CONF);
> incurs zero PT_NOTE for offline cpu. We mark this case so that later,
> the capture kernel can distinguish it from the mistake of allocated
> program header.
> The counterpart of the capture kernel comes in next patch.
>
> Signed-off-by: Pingfan Liu <piliu at redhat.com>
> ---
> This unnecessary warning buzz on all archs when there is offline cpu
>
> include/uapi/linux/elf.h | 1 +
> kernel/kexec_core.c | 9 +++++++++
> 2 files changed, 10 insertions(+)
>
> diff --git a/include/uapi/linux/elf.h b/include/uapi/linux/elf.h
> index b59ee07..9744f1e 100644
> --- a/include/uapi/linux/elf.h
> +++ b/include/uapi/linux/elf.h
> @@ -367,6 +367,7 @@ typedef struct elf64_shdr {
> * using the corresponding note types via the PTRACE_GETREGSET and
> * PTRACE_SETREGSET requests.
> */
> +#define NT_DUMMY 0
> #define NT_PRSTATUS 1
> #define NT_PRFPREG 2
> #define NT_PRPSINFO 3
> diff --git a/kernel/kexec_core.c b/kernel/kexec_core.c
> index 5616755..aeac16e 100644
> --- a/kernel/kexec_core.c
> +++ b/kernel/kexec_core.c
> @@ -891,9 +891,12 @@ void __crash_kexec(struct pt_regs *regs)
> if (mutex_trylock(&kexec_mutex)) {
> if (kexec_crash_image) {
> struct pt_regs fixed_regs;
> + unsigned int cpu;
>
> crash_setup_regs(&fixed_regs, regs);
> crash_save_vmcoreinfo();
> + for_each_cpu_not(cpu, cpu_online_mask)
> + crash_save_cpu(NULL, cpu);
> machine_crash_shutdown(&fixed_regs);
> machine_kexec(kexec_crash_image);
> }
> @@ -1040,6 +1043,12 @@ void crash_save_cpu(struct pt_regs *regs, int cpu)
> buf = (u32 *)per_cpu_ptr(crash_notes, cpu);
> if (!buf)
> return;
> + if (regs == NULL) {
> + buf = append_elf_note(buf, KEXEC_CORE_NOTE_NAME, NT_DUMMY,
> + NULL, 0);
> + final_note(buf);
> + return;
> + }
> memset(&prstatus, 0, sizeof(prstatus));
> prstatus.pr_pid = current->pid;
> elf_core_copy_kernel_regs(&prstatus.pr_reg, regs);
> --
> 2.7.4
>
