Re: [PATCH] kexec: Export memory sections virtual addresses to vmcoreinfo

Dave Young
2016-11-01T05:10:33Z

On 10/06/16 at 04:46pm, Baoquan He wrote:
> KASLR memory randomization can randomize the base of the physical memory
> mapping (PAGE_OFFSET), vmalloc (VMALLOC_START) and vmemmap
> (VMEMMAP_START). These need be exported to VMCOREINFO so that user space
> utility, mainly makedumpfile can use them to identify the base of each
> memory section. Here using VMCOREINFO_NUMBER we can reuse the existing
> struct number_table in makedumpfile to import data easily.
>
> Since they are related to x86_64 only, put them into
> arch_crash_save_vmcoreinfo. And move the exportion of KERNEL_IMAGE_SIZE
> together since it's also for x86_64 only.
>
> Signed-off-by: Baoquan He <bhe@redhat.com>
> ---
> arch/x86/kernel/machine_kexec_64.c | 4 ++++
> kernel/kexec_core.c | 3 ---
> 2 files changed, 4 insertions(+), 3 deletions(-)
>
> diff --git a/arch/x86/kernel/machine_kexec_64.c b/arch/x86/kernel/machine_kexec_64.c
> index 5a294e4..e150dd7 100644
> --- a/arch/x86/kernel/machine_kexec_64.c
> +++ b/arch/x86/kernel/machine_kexec_64.c
> @@ -337,6 +337,10 @@ void arch_crash_save_vmcoreinfo(void)
> #endif
> vmcoreinfo_append_str("KERNELOFFSET=%lx\n",
> kaslr_offset());
> + VMCOREINFO_NUMBER(KERNEL_IMAGE_SIZE);
> + VMCOREINFO_NUMBER(PAGE_OFFSET);
> + VMCOREINFO_NUMBER(VMALLOC_START);
> + VMCOREINFO_NUMBER(VMEMMAP_START);

Pratyush has posted makedumpfile patches below to avoid the VMCOREINFO:
http://lists.infradead.org/pipermail/kexec/2016-October/017540.html

But we have this in mainline which also introduced the VMCOREINFO
numbers, can you send a patch to revert them?
commit 0549a3c02efb350776bc869685a361045efd3a29
Author: Thomas Garnier <thgarnie@google.com>
Date: Tue Oct 11 13:55:08 2016 -0700

kdump, vmcoreinfo: report memory sections virtual addresses
[snip]]

> }
>
> /* arch-dependent functionality related to kexec file-based syscall */
> diff --git a/kernel/kexec_core.c b/kernel/kexec_core.c
> index 5616755..8ad3a29e 100644
> --- a/kernel/kexec_core.c
> +++ b/kernel/kexec_core.c
> @@ -1467,9 +1467,6 @@ static int __init crash_save_vmcoreinfo_init(void)
> #endif
> VMCOREINFO_NUMBER(PG_head_mask);
> VMCOREINFO_NUMBER(PAGE_BUDDY_MAPCOUNT_VALUE);
> -#ifdef CONFIG_X86
> - VMCOREINFO_NUMBER(KERNEL_IMAGE_SIZE);
> -#endif

Moving KERNEL_IMAGE_SIZE to x86 should be a standalone patch.
I remember Dave Anderson said he use it in crash utility, cced him.

> #ifdef CONFIG_HUGETLB_PAGE
> VMCOREINFO_NUMBER(HUGETLB_PAGE_DTOR);
> #endif
> --
> 2.5.5
>
>
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Thanks
Dave