arm64: hibernate: preserve kdump image around hibernation

BugLink: https://bugs.launchpad.net/bugs/1694859
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>
(cherry picked from commit 254a41c0ba0573fa23272945d3fbe39efcc5d07d)
Signed-off-by: dann frazier <dann.frazier@canonical.com>
Acked-by: Stefan Bader <stefan.bader@canonical.com>
Acked-by: Colin King <colin.king@canonical.com>
Signed-off-by: Stefan Bader <stefan.bader@canonical.com>

diff --git a/arch/arm64/include/asm/kexec.h b/arch/arm64/include/asm/kexec.h
index 04744dc5fb6127ac532b2fccdba54d9a4ff4a9b0..90aabbe893b75e30584e20b314679b757a81983e 100644 (file)
--- 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 fe301cbcb44284055125aeb8ed622f2009d75e33..af0400673fd278cb57c0e09876ecf1b1cf1e9df0 100644 (file)
--- 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>
@@ -105,7 +106,8 @@ int pfn_is_nosave(unsigned long pfn)
        unsigned long nosave_begin_pfn = virt_to_pfn(&__nosave_begin);
        unsigned long nosave_end_pfn = virt_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)
@@ -289,6 +291,9 @@ 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 {
@@ -300,6 +305,9 @@ 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 b63baa7496090099b0ed5975140d99ca322e715e..a6d66b98d795855e30b961c4ae333140d568f124 100644 (file)
--- 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 083e8fc9b7713e16812e0c1d1525abd19daa5470..e4b422729a8a9e4829a0f4b599c29ffb8a68c63e 100644 (file)
--- 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