[PATCH] swsusp: Support i386 systems with PAE or without PSE

Make swsusp support i386 systems with PAE or without PSE.

This is done by creating temporary page tables located in resume-safe page
frames before the suspend image is restored in the same way as x86_64 does
it.

Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Cc: Andi Kleen <ak@suse.de>
Cc: Dave Jones <davej@redhat.com>
Cc: Nigel Cunningham <ncunningham@linuxmail.org>
Cc: Pavel Machek <pavel@ucw.cz>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

5 files changed, 168 insertions, 16 deletions

diff --git a/arch/i386/power/Makefile b/arch/i386/power/Makefile
index 8cfa4e8a719..2de7bbf03cd 100644
--- a/arch/i386/power/Makefile
+++ b/arch/i386/power/Makefile
@@ -1,2 +1,2 @@
 obj-$(CONFIG_PM)                += cpu.o
-obj-$(CONFIG_SOFTWARE_SUSPEND)  += swsusp.o
+obj-$(CONFIG_SOFTWARE_SUSPEND)  += swsusp.o suspend.o
diff --git a/arch/i386/power/suspend.c b/arch/i386/power/suspend.c
new file mode 100644
index 00000000000..db5e98d2eb7
--- /dev/null
+++ b/arch/i386/power/suspend.c
@@ -0,0 +1,158 @@
+/*
+ * Suspend support specific for i386 - temporary page tables
+ *
+ * Distribute under GPLv2
+ *
+ * Copyright (c) 2006 Rafael J. Wysocki <rjw@sisk.pl>
+ */
+
+#include <linux/suspend.h>
+#include <linux/bootmem.h>
+
+#include <asm/system.h>
+#include <asm/page.h>
+#include <asm/pgtable.h>
+
+/* Defined in arch/i386/power/swsusp.S */
+extern int restore_image(void);
+
+/* Pointer to the temporary resume page tables */
+pgd_t *resume_pg_dir;
+
+/* The following three functions are based on the analogous code in
+ * arch/i386/mm/init.c
+ */
+
+/*
+ * Create a middle page table on a resume-safe page and put a pointer to it in
+ * the given global directory entry.  This only returns the gd entry
+ * in non-PAE compilation mode, since the middle layer is folded.
+ */
+static pmd_t *resume_one_md_table_init(pgd_t *pgd)
+{
+        pud_t *pud;
+        pmd_t *pmd_table;
+
+#ifdef CONFIG_X86_PAE
+        pmd_table = (pmd_t *)get_safe_page(GFP_ATOMIC);
+        if (!pmd_table)
+                return NULL;
+
+        set_pgd(pgd, __pgd(__pa(pmd_table) | _PAGE_PRESENT));
+        pud = pud_offset(pgd, 0);
+
+        BUG_ON(pmd_table != pmd_offset(pud, 0));
+#else
+        pud = pud_offset(pgd, 0);
+        pmd_table = pmd_offset(pud, 0);
+#endif
+
+        return pmd_table;
+}
+
+/*
+ * Create a page table on a resume-safe page and place a pointer to it in
+ * a middle page directory entry.
+ */
+static pte_t *resume_one_page_table_init(pmd_t *pmd)
+{
+        if (pmd_none(*pmd)) {
+                pte_t *page_table = (pte_t *)get_safe_page(GFP_ATOMIC);
+                if (!page_table)
+                        return NULL;
+
+                set_pmd(pmd, __pmd(__pa(page_table) | _PAGE_TABLE));
+
+                BUG_ON(page_table != pte_offset_kernel(pmd, 0));
+
+                return page_table;
+        }
+
+        return pte_offset_kernel(pmd, 0);
+}
+
+/*
+ * This maps the physical memory to kernel virtual address space, a total
+ * of max_low_pfn pages, by creating page tables starting from address
+ * PAGE_OFFSET.  The page tables are allocated out of resume-safe pages.
+ */
+static int resume_physical_mapping_init(pgd_t *pgd_base)
+{
+        unsigned long pfn;
+        pgd_t *pgd;
+        pmd_t *pmd;
+        pte_t *pte;
+        int pgd_idx, pmd_idx;
+
+        pgd_idx = pgd_index(PAGE_OFFSET);
+        pgd = pgd_base + pgd_idx;
+        pfn = 0;
+
+        for (; pgd_idx < PTRS_PER_PGD; pgd++, pgd_idx++) {
+                pmd = resume_one_md_table_init(pgd);
+                if (!pmd)
+                        return -ENOMEM;
+
+                if (pfn >= max_low_pfn)
+                        continue;
+
+                for (pmd_idx = 0; pmd_idx < PTRS_PER_PMD; pmd++, pmd_idx++) {
+                        if (pfn >= max_low_pfn)
+                                break;
+
+                        /* Map with big pages if possible, otherwise create
+                         * normal page tables.
+                         * NOTE: We can mark everything as executable here
+                         */
+                        if (cpu_has_pse) {
+                                set_pmd(pmd, pfn_pmd(pfn, PAGE_KERNEL_LARGE_EXEC));
+                                pfn += PTRS_PER_PTE;
+                        } else {
+                                pte_t *max_pte;
+
+                                pte = resume_one_page_table_init(pmd);
+                                if (!pte)
+                                        return -ENOMEM;
+
+                                max_pte = pte + PTRS_PER_PTE;
+                                for (; pte < max_pte; pte++, pfn++) {
+                                        if (pfn >= max_low_pfn)
+                                                break;
+
+                                        set_pte(pte, pfn_pte(pfn, PAGE_KERNEL_EXEC));
+                                }
+                        }
+                }
+        }
+        return 0;
+}
+
+static inline void resume_init_first_level_page_table(pgd_t *pg_dir)
+{
+#ifdef CONFIG_X86_PAE
+        int i;
+
+        /* Init entries of the first-level page table to the zero page */
+        for (i = 0; i < PTRS_PER_PGD; i++)
+                set_pgd(pg_dir + i,
+                        __pgd(__pa(empty_zero_page) | _PAGE_PRESENT));
+#endif
+}
+
+int swsusp_arch_resume(void)
+{
+        int error;
+
+        resume_pg_dir = (pgd_t *)get_safe_page(GFP_ATOMIC);
+        if (!resume_pg_dir)
+                return -ENOMEM;
+
+        resume_init_first_level_page_table(resume_pg_dir);
+        error = resume_physical_mapping_init(resume_pg_dir);
+        if (error)
+                return error;
+
+        /* We have got enough memory and from now on we cannot recover */
+        restore_image();
+        return 0;
+}
diff --git a/arch/i386/power/swsusp.S b/arch/i386/power/swsusp.S
index 8a2b50a0aaa..53662e05b39 100644
--- a/arch/i386/power/swsusp.S
+++ b/arch/i386/power/swsusp.S
@@ -28,8 +28,9 @@ ENTRY(swsusp_arch_suspend)
         call swsusp_save
         ret
 
-ENTRY(swsusp_arch_resume)
-        movl    $swsusp_pg_dir-__PAGE_OFFSET, %ecx
+ENTRY(restore_image)
+        movl    resume_pg_dir, %ecx
+        subl    $__PAGE_OFFSET, %ecx
         movl    %ecx, %cr3
 
         movl    restore_pblist, %edx
@@ -51,6 +52,10 @@ copy_loop:
         .p2align 4,,7
 
 done:
+        /* go back to the original page tables */
+        movl    $swapper_pg_dir, %ecx
+        subl    $__PAGE_OFFSET, %ecx
+        movl    %ecx, %cr3
         /* Flush TLB, including "global" things (vmalloc) */
         movl    mmu_cr4_features, %eax
         movl    %eax, %edx
diff --git a/include/asm-i386/suspend.h b/include/asm-i386/suspend.h
index 08be1e5009d..c1da5caafaf 100644
--- a/include/asm-i386/suspend.h
+++ b/include/asm-i386/suspend.h
@@ -6,18 +6,7 @@
 #include <asm/desc.h>
 #include <asm/i387.h>
 
-static inline int
-arch_prepare_suspend(void)
-{
-        /* If you want to make non-PSE machine work, turn off paging
-           in swsusp_arch_suspend. swsusp_pg_dir should have identity mapping, so
-           it could work...  */
-        if (!cpu_has_pse) {
-                printk(KERN_ERR "PSE is required for swsusp.\n");
-                return -EPERM;
-        }
-        return 0;
-}
+static inline int arch_prepare_suspend(void) { return 0; }
 
 /* image of the saved processor state */
 struct saved_context {
diff --git a/kernel/power/Kconfig b/kernel/power/Kconfig
index 825068ca347..710ed084e7c 100644
--- a/kernel/power/Kconfig
+++ b/kernel/power/Kconfig
@@ -78,7 +78,7 @@ config PM_SYSFS_DEPRECATED
 
 config SOFTWARE_SUSPEND
         bool "Software Suspend"
-        depends on PM && SWAP && ((X86 && (!SMP || SUSPEND_SMP) && !X86_PAE) || ((FRV || PPC32) && !SMP))
+        depends on PM && SWAP && ((X86 && (!SMP || SUSPEND_SMP)) || ((FRV || PPC32) && !SMP))
         ---help---
           Enable the possibility of suspending the machine.
           It doesn't need ACPI or APM.