x86: init memory debugging

debug incorrect/late access to init memory, by permanently unmapping
the init memory ranges. Depends on CONFIG_DEBUG_PAGEALLOC=y.

Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

diff --git a/arch/x86/mm/init_32.c b/arch/x86/mm/init_32.c
index a72737c057470912f9d3b794e8f869121df34f71..8d7f723cfc28181786f78c63c894198a6dcc0cb3 100644 (file)
--- a/arch/x86/mm/init_32.c
+++ b/arch/x86/mm/init_32.c
@@ -783,6 +783,16 @@ void free_init_pages(char *what, unsigned long begin, unsigned long end)
 {
        unsigned long addr;
 
+#ifdef CONFIG_DEBUG_PAGEALLOC
+       /*
+        * If debugging page accesses then do not free this memory but
+        * mark them not present - any buggy init-section access will
+        * create a kernel page fault:
+        */
+       printk(KERN_INFO "debug: unmapping init memory %08lx..%08lx\n",
+               begin, PAGE_ALIGN(end));
+       set_memory_np(begin, (end - begin) >> PAGE_SHIFT);
+#else
        /*
         * We just marked the kernel text read only above, now that
         * we are going to free part of that, we need to make that
@@ -798,6 +808,7 @@ void free_init_pages(char *what, unsigned long begin, unsigned long end)
                totalram_pages++;
        }
        printk(KERN_INFO "Freeing %s: %luk freed\n", what, (end - begin) >> 10);
+#endif
 }
 
 void free_initmem(void)

diff --git a/arch/x86/mm/init_64.c b/arch/x86/mm/init_64.c
index f51180c02b8fafd94d41f1c91b0a57e5cdbaf244..e0c1e98ad1bf4c80935b31010e18299199c5761a 100644 (file)
--- a/arch/x86/mm/init_64.c
+++ b/arch/x86/mm/init_64.c
@@ -550,6 +550,16 @@ void free_init_pages(char *what, unsigned long begin, unsigned long end)
        if (begin >= end)
                return;
 
+       /*
+        * If debugging page accesses then do not free this memory but
+        * mark them not present - any buggy init-section access will
+        * create a kernel page fault:
+        */
+#ifdef CONFIG_DEBUG_PAGEALLOC
+       printk(KERN_INFO "debug: unmapping init memory %08lx..%08lx\n",
+               begin, PAGE_ALIGN(end));
+       set_memory_np(begin, (end - begin) >> PAGE_SHIFT);
+#else
        printk(KERN_INFO "Freeing %s: %luk freed\n", what, (end - begin) >> 10);
        for (addr = begin; addr < end; addr += PAGE_SIZE) {
                ClearPageReserved(virt_to_page(addr));
@@ -575,6 +585,7 @@ void free_init_pages(char *what, unsigned long begin, unsigned long end)
                set_memory_nx(begin, (end - begin)/PAGE_SIZE);
        }
 #endif
+#endif
 }
 
 void free_initmem(void)