+ kexec-provide-arch_kexec_protectunprotect_crashkres.patch added to -mm tree

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The patch titled
     Subject: kexec: provide arch_kexec_protect(unprotect)_crashkres()
has been added to the -mm tree.  Its filename is
     kexec-provide-arch_kexec_protectunprotect_crashkres.patch

This patch should soon appear at
    http://ozlabs.org/~akpm/mmots/broken-out/kexec-provide-arch_kexec_protectunprotect_crashkres.patch
and later at
    http://ozlabs.org/~akpm/mmotm/broken-out/kexec-provide-arch_kexec_protectunprotect_crashkres.patch

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------------------------------------------------------
From: Xunlei Pang <xlpang@xxxxxxxxxx>
Subject: kexec: provide arch_kexec_protect(unprotect)_crashkres()

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

Signed-off-by: Xunlei Pang <xlpang@xxxxxxxxxx>
Cc: Eric Biederman <ebiederm@xxxxxxxxxxxx>
Cc: Dave Young <dyoung@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---

 arch/x86/kernel/machine_kexec_64.c |   43 +++++++++++++++++++++++++++
 1 file changed, 43 insertions(+)

diff -puN arch/x86/kernel/machine_kexec_64.c~kexec-provide-arch_kexec_protectunprotect_crashkres arch/x86/kernel/machine_kexec_64.c
--- a/arch/x86/kernel/machine_kexec_64.c~kexec-provide-arch_kexec_protectunprotect_crashkres
+++ a/arch/x86/kernel/machine_kexec_64.c
@@ -538,3 +538,46 @@ overflow:
 	return -ENOEXEC;
 }
 #endif /* CONFIG_KEXEC_FILE */
+
+#ifdef CONFIG_KEXEC_CORE
+static int
+kexec_mark_range(unsigned long start, unsigned long end, bool protect)
+{
+	struct page *page;
+	unsigned int nr_pages;
+
+	if (!start || !end || start >= end)
+		return 0;
+
+	page = pfn_to_page(start >> PAGE_SHIFT);
+	nr_pages = (end + 1 - start) >> PAGE_SHIFT;
+	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. */
+	control = control + PAGE_SIZE;
+	kexec_mark_range(crashk_res.start, control - 1, protect);
+	kexec_mark_range(control + PAGE_SIZE, crashk_res.end, protect);
+}
+
+void arch_kexec_protect_crashkres(void)
+{
+	kexec_mark_crashkres(true);
+}
+
+void arch_kexec_unprotect_crashkres(void)
+{
+	kexec_mark_crashkres(false);
+}
+#endif
_

Patches currently in -mm which might be from xlpang@xxxxxxxxxx are

kexec-set-kexec_type_crash-before-sanity_check_segment_list.patch
kexec-move-some-memembers-and-definitions-within-the-scope-of-config_kexec_file.patch
kexec-introduce-a-protection-mechanism-for-the-crashkernel-reserved-memory.patch
kexec-provide-arch_kexec_protectunprotect_crashkres.patch

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