[patch 06/17] x86 - Enhance DEBUG_RODATA support for hotplug and kprobes

[Mathieu Desnoyers]

Standardize DEBUG_RODATA, removing special cases for hotplug and kprobes.

Changelog :
- Use is_rodata_addr to check which pages must be set RW/RO under DEBUG_RODATA.

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@xxxxxxxxxx>
CC: Andi Kleen <andi@xxxxxxxxxxxxxx>
CC: pageexec@xxxxxxxxxxx
CC: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
CC: Ingo Molnar <mingo@xxxxxxxxxx>
CC: H. Peter Anvin <hpa@xxxxxxxxx>
CC: Ingo Molnar <mingo@xxxxxxx>
CC: Jeremy Fitzhardinge <jeremy@xxxxxxxx>
---
 arch/x86/mm/init_32.c |   24 ++++++++----------------
 arch/x86/mm/init_64.c |   20 +++-----------------
 2 files changed, 11 insertions(+), 33 deletions(-)

Index: linux-2.6-lttng.mm/arch/x86/mm/init_32.c
===================================================================
--- linux-2.6-lttng.mm.orig/arch/x86/mm/init_32.c	2008-04-09 10:24:48.000000000 -0400
+++ linux-2.6-lttng.mm/arch/x86/mm/init_32.c	2008-04-09 10:34:26.000000000 -0400
@@ -723,25 +723,17 @@ void mark_rodata_ro(void)
 	unsigned long start = PFN_ALIGN(_text);
 	unsigned long size = PFN_ALIGN(_etext) - start;
 
-#ifndef CONFIG_KPROBES
-#ifdef CONFIG_HOTPLUG_CPU
-	/* It must still be possible to apply SMP alternatives. */
-	if (num_possible_cpus() <= 1)
-#endif
-	{
-		set_pages_ro(virt_to_page(start), size >> PAGE_SHIFT);
-		printk(KERN_INFO "Write protecting the kernel text: %luk\n",
-			size >> 10);
+	set_pages_ro(virt_to_page(start), size >> PAGE_SHIFT);
+	printk(KERN_INFO "Write protecting the kernel text: %luk\n",
+		size >> 10);
 
 #ifdef CONFIG_CPA_DEBUG
-		printk(KERN_INFO "Testing CPA: Reverting %lx-%lx\n",
-			start, start+size);
-		set_pages_rw(virt_to_page(start), size>>PAGE_SHIFT);
+	printk(KERN_INFO "Testing CPA: Reverting %lx-%lx\n",
+		start, start+size);
+	set_pages_rw(virt_to_page(start), size>>PAGE_SHIFT);
 
-		printk(KERN_INFO "Testing CPA: write protecting again\n");
-		set_pages_ro(virt_to_page(start), size>>PAGE_SHIFT);
-#endif
-	}
+	printk(KERN_INFO "Testing CPA: write protecting again\n");
+	set_pages_ro(virt_to_page(start), size>>PAGE_SHIFT);
 #endif
 	start += size;
 	size = (unsigned long)__end_rodata - start;
Index: linux-2.6-lttng.mm/arch/x86/mm/init_64.c
===================================================================
--- linux-2.6-lttng.mm.orig/arch/x86/mm/init_64.c	2008-04-09 10:25:48.000000000 -0400
+++ linux-2.6-lttng.mm/arch/x86/mm/init_64.c	2008-04-09 10:34:26.000000000 -0400
@@ -632,23 +632,8 @@ EXPORT_SYMBOL_GPL(rodata_test_data);
 
 void mark_rodata_ro(void)
 {
-	unsigned long start = (unsigned long)_stext, end;
-
-#ifdef CONFIG_HOTPLUG_CPU
-	/* It must still be possible to apply SMP alternatives. */
-	if (num_possible_cpus() > 1)
-		start = (unsigned long)_etext;
-#endif
-
-#ifdef CONFIG_KPROBES
-	start = (unsigned long)__start_rodata;
-#endif
-
-	end = (unsigned long)__end_rodata;
-	start = (start + PAGE_SIZE - 1) & PAGE_MASK;
-	end &= PAGE_MASK;
-	if (end <= start)
-		return;
+	unsigned long start = PFN_ALIGN(_stext),
+			end = PFN_ALIGN(__end_rodata);
 
 
 	printk(KERN_INFO "Write protecting the kernel read-only data: %luk\n",
@@ -679,6 +664,7 @@ void free_initrd_mem(unsigned long start
 {
 	free_init_pages("initrd memory", start, end);
 }
+
 #endif
 
 void __init reserve_bootmem_generic(unsigned long phys, unsigned len)

-- 
Mathieu Desnoyers
Computer Engineering Ph.D. Student, Ecole Polytechnique de Montreal
OpenPGP key fingerprint: 8CD5 52C3 8E3C 4140 715F  BA06 3F25 A8FE 3BAE 9A68
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