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kexec: provide arch_kexec_protect(unprotect)_crashkres()

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Implement the protection method for the crash kernel memory reservation
for the 64-bit x86 kdump.

Signed-off-by: Xunlei Pang <xlpang@redhat.com>
Cc: Eric Biederman <ebiederm@xmission.com>
Cc: Dave Young <dyoung@redhat.com>
Cc: Minfei Huang <mhuang@redhat.com>
Cc: Vivek Goyal <vgoyal@redhat.com>
Cc: Baoquan He <bhe@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Xunlei Pang 2016-05-23 16:24:13 -07:00 committed by Linus Torvalds
parent 9b492cf580
commit 1e5768ae75
1 changed files with 45 additions and 0 deletions
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45
arch/x86/kernel/machine_kexec_64.c
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@ -538,3 +538,48 @@ overflow:
return -ENOEXEC;
}
#endif /* CONFIG_KEXEC_FILE */
static int
kexec_mark_range(unsigned long start, unsigned long end, bool protect)
{
struct page *page;
unsigned int nr_pages;
/*
* For physical range: [start, end]. We must skip the unassigned
* crashk resource with zero-valued "end" member.
*/
if (!end || start > end)
return 0;
page = pfn_to_page(start >> PAGE_SHIFT);
nr_pages = (end >> PAGE_SHIFT) - (start >> PAGE_SHIFT) + 1;
if (protect)
return set_pages_ro(page, nr_pages);
else
return set_pages_rw(page, nr_pages);
}
static void kexec_mark_crashkres(bool protect)
{
unsigned long control;
kexec_mark_range(crashk_low_res.start, crashk_low_res.end, protect);
/* Don't touch the control code page used in crash_kexec().*/
control = PFN_PHYS(page_to_pfn(kexec_crash_image->control_code_page));
/* Control code page is located in the 2nd page. */
kexec_mark_range(crashk_res.start, control + PAGE_SIZE - 1, protect);
control += KEXEC_CONTROL_PAGE_SIZE;
kexec_mark_range(control, crashk_res.end, protect);
}
void arch_kexec_protect_crashkres(void)
{
kexec_mark_crashkres(true);
}
void arch_kexec_unprotect_crashkres(void)
{
kexec_mark_crashkres(false);
}