arm64: hibernate: preserve kdump image around hibernation

Since arch_kexec_protect_crashkres() removes a mapping for crash dump
kernel image, the loaded data won't be preserved around hibernation.

In this patch, helper functions, crash_prepare_suspend()/
crash_post_resume(), are additionally called before/after hibernation so
that the relevant memory segments will be mapped again and preserved just
as the others are.

In addition, to minimize the size of hibernation image, crash_is_nosave()
is added to pfn_is_nosave() in order to recognize only the pages that hold
loaded crash dump kernel image as saveable. Hibernation excludes any pages
that are marked as Reserved and yet "nosave."

Signed-off-by: AKASHI Takahiro <takahiro.akashi@linaro.org>
Reviewed-by: James Morse <james.morse@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>

1 files changed, 27 insertions, 0 deletions

diff --git a/arch/arm64/mm/init.c b/arch/arm64/mm/init.c
index 083e8fc..e4b4227 100644
--- a/arch/arm64/mm/init.c
+++ b/arch/arm64/mm/init.c
@@ -133,10 +133,35 @@ static void __init reserve_crashkernel(void)
 	crashk_res.start = crash_base;
 	crashk_res.end = crash_base + crash_size - 1;
 }
+
+static void __init kexec_reserve_crashkres_pages(void)
+{
+#ifdef CONFIG_HIBERNATION
+	phys_addr_t addr;
+	struct page *page;
+
+	if (!crashk_res.end)
+		return;
+
+	/*
+	 * To reduce the size of hibernation image, all the pages are
+	 * marked as Reserved initially.
+	 */
+	for (addr = crashk_res.start; addr < (crashk_res.end + 1);
+			addr += PAGE_SIZE) {
+		page = phys_to_page(addr);
+		SetPageReserved(page);
+	}
+#endif
+}
 #else
 static void __init reserve_crashkernel(void)
 {
 }
+
+static void __init kexec_reserve_crashkres_pages(void)
+{
+}
 #endif /* CONFIG_KEXEC_CORE */
 
 /*
@@ -516,6 +541,8 @@ void __init mem_init(void)
 	/* this will put all unused low memory onto the freelists */
 	free_all_bootmem();
 
+	kexec_reserve_crashkres_pages();
+
 	mem_init_print_info(NULL);
 
 #define MLK(b, t) b, t, ((t) - (b)) >> 10