[Xen-devel] [PATCH] linux/x86-64: allow kernel init memory to be freed

["Jan Beulich" <jbeulich@xxxxxxxxxx>]

Signed-off-by: Jan Beulich <jbeulich@xxxxxxxxxx>

Index: head-2007-02-08/arch/x86_64/mm/init-xen.c
===================================================================
--- head-2007-02-08.orig/arch/x86_64/mm/init-xen.c      2007-02-27 
15:00:16.000000000 +0100
+++ head-2007-02-08/arch/x86_64/mm/init-xen.c   2007-02-27 15:00:42.000000000 
+0100
@@ -102,14 +102,11 @@ static void __meminit early_make_page_re
                BUG();
 }
 
-void make_page_readonly(void *va, unsigned int feature)
+static void __make_page_readonly(void *va)
 {
        pgd_t *pgd; pud_t *pud; pmd_t *pmd; pte_t pte, *ptep;
        unsigned long addr = (unsigned long) va;
 
-       if (xen_feature(feature))
-               return;
-
        pgd = pgd_offset_k(addr);
        pud = pud_offset(pgd, addr);
        pmd = pmd_offset(pud, addr);
@@ -120,17 +117,14 @@ void make_page_readonly(void *va, unsign
                xen_l1_entry_update(ptep, pte); /* fallback */
 
        if ((addr >= VMALLOC_START) && (addr < VMALLOC_END))
-               make_page_readonly(__va(pte_pfn(pte) << PAGE_SHIFT), feature);
+               __make_page_readonly(__va(pte_pfn(pte) << PAGE_SHIFT));
 }
 
-void make_page_writable(void *va, unsigned int feature)
+static void __make_page_writable(void *va)
 {
        pgd_t *pgd; pud_t *pud; pmd_t *pmd; pte_t pte, *ptep;
        unsigned long addr = (unsigned long) va;
 
-       if (xen_feature(feature))
-               return;
-
        pgd = pgd_offset_k(addr);
        pud = pud_offset(pgd, addr);
        pmd = pmd_offset(pud, addr);
@@ -141,7 +135,19 @@ void make_page_writable(void *va, unsign
                xen_l1_entry_update(ptep, pte); /* fallback */
 
        if ((addr >= VMALLOC_START) && (addr < VMALLOC_END))
-               make_page_writable(__va(pte_pfn(pte) << PAGE_SHIFT), feature);
+               __make_page_writable(__va(pte_pfn(pte) << PAGE_SHIFT));
+}
+
+void make_page_readonly(void *va, unsigned int feature)
+{
+       if (!xen_feature(feature))
+               __make_page_readonly(va);
+}
+
+void make_page_writable(void *va, unsigned int feature)
+{
+       if (!xen_feature(feature))
+               __make_page_writable(va);
 }
 
 void make_pages_readonly(void *va, unsigned nr, unsigned int feature)
@@ -150,7 +156,7 @@ void make_pages_readonly(void *va, unsig
                return;
 
        while (nr-- != 0) {
-               make_page_readonly(va, feature);
+               __make_page_readonly(va);
                va = (void*)((unsigned long)va + PAGE_SIZE);
        }
 }
@@ -161,7 +167,7 @@ void make_pages_writable(void *va, unsig
                return;
 
        while (nr-- != 0) {
-               make_page_writable(va, feature);
+               __make_page_writable(va);
                va = (void*)((unsigned long)va + PAGE_SIZE);
        }
 }
@@ -1028,11 +1034,6 @@ void free_init_pages(char *what, unsigne
 
 void free_init_pages(char *what, unsigned long begin, unsigned long end)
 {
-#ifdef __DO_LATER__
-       /*
-        * Some pages can be pinned, but some are not. Unpinning such pages 
-        * triggers BUG(). 
-        */
        unsigned long addr;
 
        if (begin >= end)
@@ -1044,25 +1045,20 @@ void free_init_pages(char *what, unsigne
                init_page_count(virt_to_page(addr));
                memset((void *)(addr & ~(PAGE_SIZE-1)),
                       POISON_FREE_INITMEM, PAGE_SIZE); 
-               make_page_writable(
-                       __va(__pa(addr)), XENFEAT_writable_page_tables);
-               /*
-                * Make pages from __PAGE_OFFSET address as well
-                */
-               make_page_writable(
-                       (void *)addr, XENFEAT_writable_page_tables);
+               if (addr >= __START_KERNEL_map) {
+                       /* make_readonly() reports all kernel addresses. */
+                       __make_page_writable(__va(__pa(addr)));
+                       __make_page_readonly((void *)addr);
+               }
                free_page(addr);
                totalram_pages++;
        }
-#endif
 }
 
 void free_initmem(void)
 {
-#ifdef __DO_LATER__
        memset(__initdata_begin, POISON_FREE_INITDATA,
                __initdata_end - __initdata_begin);
-#endif
        free_init_pages("unused kernel memory",
                        (unsigned long)(&__init_begin),
                        (unsigned long)(&__init_end));



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