From 91c15a951091a64a5f048ff93292057e3b590b6f Mon Sep 17 00:00:00 2001 From: Michael Holzheu Date: Mon, 8 Apr 2013 16:09:31 +0200 Subject: [PATCH] s390/hibernate: Save and restore absolute zero pages Since commit 5f954c34 ([S390] hibernation: fix lowcore handling) the absolute zero lowcore is lost during suspend/resume. For example, this leads to the problem that the re-IPL device for kdump is no longer set after resume. With this patch during suspend a buffer is allocated in the new PM notifier "suspend_pm_cb" and then the absolute zero lowcore is saved to that buffer. The resume code then copies back this buffer to absolute zero and afterwards the PM notifier releases the memory. Signed-off-by: Michael Holzheu Signed-off-by: Martin Schwidefsky --- arch/s390/kernel/entry.h | 1 + arch/s390/kernel/suspend.c | 31 +++++++++++++++++++++++++++++++ arch/s390/kernel/swsusp_asm64.S | 29 ++++++++++++++++++++++++++--- 3 files changed, 58 insertions(+), 3 deletions(-) diff --git a/arch/s390/kernel/entry.h b/arch/s390/kernel/entry.h index c3a736a3ed44..aa0ab02e9595 100644 --- a/arch/s390/kernel/entry.h +++ b/arch/s390/kernel/entry.h @@ -7,6 +7,7 @@ #include extern void *restart_stack; +extern unsigned long suspend_zero_pages; void system_call(void); void pgm_check_handler(void); diff --git a/arch/s390/kernel/suspend.c b/arch/s390/kernel/suspend.c index aa1494d0e380..c479d2f9605b 100644 --- a/arch/s390/kernel/suspend.c +++ b/arch/s390/kernel/suspend.c @@ -41,6 +41,7 @@ struct page_key_data { static struct page_key_data *page_key_data; static struct page_key_data *page_key_rp, *page_key_wp; static unsigned long page_key_rx, page_key_wx; +unsigned long suspend_zero_pages; /* * For each page in the hibernation image one additional byte is @@ -149,6 +150,36 @@ int pfn_is_nosave(unsigned long pfn) return 0; } +/* + * PM notifier callback for suspend + */ +static int suspend_pm_cb(struct notifier_block *nb, unsigned long action, + void *ptr) +{ + switch (action) { + case PM_SUSPEND_PREPARE: + case PM_HIBERNATION_PREPARE: + suspend_zero_pages = __get_free_pages(GFP_KERNEL, LC_ORDER); + if (!suspend_zero_pages) + return NOTIFY_BAD; + break; + case PM_POST_SUSPEND: + case PM_POST_HIBERNATION: + free_pages(suspend_zero_pages, LC_ORDER); + break; + default: + return NOTIFY_DONE; + } + return NOTIFY_OK; +} + +static int __init suspend_pm_init(void) +{ + pm_notifier(suspend_pm_cb, 0); + return 0; +} +arch_initcall(suspend_pm_init); + void save_processor_state(void) { /* swsusp_arch_suspend() actually saves all cpu register contents. diff --git a/arch/s390/kernel/swsusp_asm64.S b/arch/s390/kernel/swsusp_asm64.S index d4ca4e0617b5..c487be4cfc81 100644 --- a/arch/s390/kernel/swsusp_asm64.S +++ b/arch/s390/kernel/swsusp_asm64.S @@ -36,8 +36,8 @@ ENTRY(swsusp_arch_suspend) /* Store prefix register on stack */ stpx __SF_EMPTY(%r15) - /* Save prefix register contents for lowcore */ - llgf %r4,__SF_EMPTY(%r15) + /* Save prefix register contents for lowcore copy */ + llgf %r10,__SF_EMPTY(%r15) /* Get pointer to save area */ lghi %r1,0x1000 @@ -91,7 +91,18 @@ ENTRY(swsusp_arch_suspend) xc __SF_EMPTY(4,%r15),__SF_EMPTY(%r15) spx __SF_EMPTY(%r15) + /* Save absolute zero pages */ + larl %r2,suspend_zero_pages + lg %r2,0(%r2) + lghi %r4,0 + lghi %r3,2*PAGE_SIZE + lghi %r5,2*PAGE_SIZE +1: mvcle %r2,%r4,0 + jo 1b + + /* Copy lowcore to absolute zero lowcore */ lghi %r2,0 + lgr %r4,%r10 lghi %r3,2*PAGE_SIZE lghi %r5,2*PAGE_SIZE 1: mvcle %r2,%r4,0 @@ -248,8 +259,20 @@ restore_registers: /* Load old stack */ lg %r15,0x2f8(%r13) + /* Save prefix register */ + mvc __SF_EMPTY(4,%r15),0x318(%r13) + + /* Restore absolute zero pages */ + lghi %r2,0 + larl %r4,suspend_zero_pages + lg %r4,0(%r4) + lghi %r3,2*PAGE_SIZE + lghi %r5,2*PAGE_SIZE +1: mvcle %r2,%r4,0 + jo 1b + /* Restore prefix register */ - spx 0x318(%r13) + spx __SF_EMPTY(%r15) /* Activate DAT */ stosm __SF_EMPTY(%r15),0x04 -- 2.20.1