[PATCH v34 07/14] arm64: hibernate: preserve kdump image around hibernation
AKASHI Takahiro
takahiro.akashi at linaro.org
Mon Mar 27 23:51:25 PDT 2017
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 at linaro.org>
Reviewed-by: James Morse <james.morse at arm.com>
---
arch/arm64/include/asm/kexec.h | 10 ++++++
arch/arm64/kernel/hibernate.c | 10 +++++-
arch/arm64/kernel/machine_kexec.c | 71 +++++++++++++++++++++++++++++++++++++++
arch/arm64/mm/init.c | 27 +++++++++++++++
4 files changed, 117 insertions(+), 1 deletion(-)
diff --git a/arch/arm64/include/asm/kexec.h b/arch/arm64/include/asm/kexec.h
index 04744dc5fb61..90aabbe893b7 100644
--- a/arch/arm64/include/asm/kexec.h
+++ b/arch/arm64/include/asm/kexec.h
@@ -43,6 +43,16 @@ static inline void crash_setup_regs(struct pt_regs *newregs,
/* Empty routine needed to avoid build errors. */
}
+#if defined(CONFIG_KEXEC_CORE) && defined(CONFIG_HIBERNATION)
+extern bool crash_is_nosave(unsigned long pfn);
+extern void crash_prepare_suspend(void);
+extern void crash_post_resume(void);
+#else
+static inline bool crash_is_nosave(unsigned long pfn) {return false; }
+static inline void crash_prepare_suspend(void) {}
+static inline void crash_post_resume(void) {}
+#endif
+
#endif /* __ASSEMBLY__ */
#endif
diff --git a/arch/arm64/kernel/hibernate.c b/arch/arm64/kernel/hibernate.c
index 97a7384100f3..a44e13942d30 100644
--- a/arch/arm64/kernel/hibernate.c
+++ b/arch/arm64/kernel/hibernate.c
@@ -28,6 +28,7 @@
#include <asm/cacheflush.h>
#include <asm/cputype.h>
#include <asm/irqflags.h>
+#include <asm/kexec.h>
#include <asm/memory.h>
#include <asm/mmu_context.h>
#include <asm/pgalloc.h>
@@ -102,7 +103,8 @@ int pfn_is_nosave(unsigned long pfn)
unsigned long nosave_begin_pfn = sym_to_pfn(&__nosave_begin);
unsigned long nosave_end_pfn = sym_to_pfn(&__nosave_end - 1);
- return (pfn >= nosave_begin_pfn) && (pfn <= nosave_end_pfn);
+ return ((pfn >= nosave_begin_pfn) && (pfn <= nosave_end_pfn)) ||
+ crash_is_nosave(pfn);
}
void notrace save_processor_state(void)
@@ -286,6 +288,9 @@ int swsusp_arch_suspend(void)
local_dbg_save(flags);
if (__cpu_suspend_enter(&state)) {
+ /* make the crash dump kernel image visible/saveable */
+ crash_prepare_suspend();
+
sleep_cpu = smp_processor_id();
ret = swsusp_save();
} else {
@@ -297,6 +302,9 @@ int swsusp_arch_suspend(void)
if (el2_reset_needed())
dcache_clean_range(__hyp_idmap_text_start, __hyp_idmap_text_end);
+ /* make the crash dump kernel image protected again */
+ crash_post_resume();
+
/*
* Tell the hibernation core that we've just restored
* the memory
diff --git a/arch/arm64/kernel/machine_kexec.c b/arch/arm64/kernel/machine_kexec.c
index b63baa749609..a6d66b98d795 100644
--- a/arch/arm64/kernel/machine_kexec.c
+++ b/arch/arm64/kernel/machine_kexec.c
@@ -10,6 +10,7 @@
*/
#include <linux/kexec.h>
+#include <linux/page-flags.h>
#include <linux/smp.h>
#include <asm/cacheflush.h>
@@ -230,3 +231,73 @@ void arch_kexec_unprotect_crashkres(void)
__phys_to_virt(kexec_crash_image->segment[i].mem),
kexec_crash_image->segment[i].memsz >> PAGE_SHIFT, 1);
}
+
+#ifdef CONFIG_HIBERNATION
+/*
+ * To preserve the crash dump kernel image, the relevant memory segments
+ * should be mapped again around the hibernation.
+ */
+void crash_prepare_suspend(void)
+{
+ if (kexec_crash_image)
+ arch_kexec_unprotect_crashkres();
+}
+
+void crash_post_resume(void)
+{
+ if (kexec_crash_image)
+ arch_kexec_protect_crashkres();
+}
+
+/*
+ * crash_is_nosave
+ *
+ * Return true only if a page is part of reserved memory for crash dump kernel,
+ * but does not hold any data of loaded kernel image.
+ *
+ * Note that all the pages in crash dump kernel memory have been initially
+ * marked as Reserved in kexec_reserve_crashkres_pages().
+ *
+ * In hibernation, the pages which are Reserved and yet "nosave" are excluded
+ * from the hibernation iamge. crash_is_nosave() does thich check for crash
+ * dump kernel and will reduce the total size of hibernation image.
+ */
+
+bool crash_is_nosave(unsigned long pfn)
+{
+ int i;
+ phys_addr_t addr;
+
+ if (!crashk_res.end)
+ return false;
+
+ /* in reserved memory? */
+ addr = __pfn_to_phys(pfn);
+ if ((addr < crashk_res.start) || (crashk_res.end < addr))
+ return false;
+
+ if (!kexec_crash_image)
+ return true;
+
+ /* not part of loaded kernel image? */
+ for (i = 0; i < kexec_crash_image->nr_segments; i++)
+ if (addr >= kexec_crash_image->segment[i].mem &&
+ addr < (kexec_crash_image->segment[i].mem +
+ kexec_crash_image->segment[i].memsz))
+ return false;
+
+ return true;
+}
+
+void crash_free_reserved_phys_range(unsigned long begin, unsigned long end)
+{
+ unsigned long addr;
+ struct page *page;
+
+ for (addr = begin; addr < end; addr += PAGE_SIZE) {
+ page = phys_to_page(addr);
+ ClearPageReserved(page);
+ free_reserved_page(page);
+ }
+}
+#endif /* CONFIG_HIBERNATION */
diff --git a/arch/arm64/mm/init.c b/arch/arm64/mm/init.c
index 09d19207362d..89ba3cd0fe44 100644
--- a/arch/arm64/mm/init.c
+++ b/arch/arm64/mm/init.c
@@ -134,10 +134,35 @@ 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 */
/*
@@ -517,6 +542,8 @@ 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
--
2.11.1
More information about the linux-arm-kernel
mailing list