From: Ingo Molnar <mingo@elte.hu>
Date: Wed, 30 Jan 2008 12:34:09 +0000 (+0100)
Subject: x86: init memory debugging
X-Git-Tag: v2.6.25-rc1~1143^2~29
X-Git-Url: https://err.no/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=ee01f1122ceb02a2c9b7142c5dd17b49e59ba774;p=linux-2.6

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 a72737c057..8d7f723cfc 100644
--- 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 f51180c02b..e0c1e98ad1 100644
--- 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)