Commit 1303a27c authored Sep 09, 2015 by Baoquan He Committed by Linus Torvalds Sep 10, 2015

kexec: export KERNEL_IMAGE_SIZE to vmcoreinfo



In x86_64, since v2.6.26 the KERNEL_IMAGE_SIZE is changed to 512M, and
accordingly the MODULES_VADDR is changed to 0xffffffffa0000000.  However,
in v3.12 Kees Cook introduced kaslr to randomise the location of kernel.
And the kernel text mapping addr space is enlarged from 512M to 1G.  That
means now KERNEL_IMAGE_SIZE is variable, its value is 512M when kaslr
support is not compiled in and 1G when kaslr support is compiled in.
Accordingly the MODULES_VADDR is changed too to be:

    #define MODULES_VADDR    (__START_KERNEL_map + KERNEL_IMAGE_SIZE)

So when kaslr is compiled in and enabled, the kernel text mapping addr
space and modules vaddr space need be adjusted.  Otherwise makedumpfile
will collapse since the addr for some symbols is not correct.

Hence KERNEL_IMAGE_SIZE need be exported to vmcoreinfo and got in
makedumpfile to help calculate MODULES_VADDR.

Signed-off-by: Baoquan He <bhe@redhat.com>
Acked-by: Kees Cook <keescook@chromium.org>
Acked-by: Vivek Goyal <vgoyal@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

parent bbb78b8f

kernel/kexec_core.c

+3 −0

Original line number	Diff line number	Diff line
		@@ -1417,6 +1417,9 @@ 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
		#ifdef CONFIG_HUGETLBFS
		VMCOREINFO_SYMBOL(free_huge_page);
		#endif

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