Allow DEBUG_RODATA and KPROBES to co-exist

Do not mark the kernel text read only if KPROBES is in the kernel;
kprobes needs to hot-patch the kernel text to insert it's
instrumentation.

In this case, only mark the .rodata segment as read only.

Signed-off-by: Arjan van de Ven <[e-mail]>
Tested-by: S. P. Prasanna <[e-mail]>
Cc: Andi Kleen <[e-mail]>
Cc: William Cohen <[e-mail]>
Cc: Ian McDonald <[e-mail]>
Signed-off-by: Linus Torvalds <[e-mail]>

arch/i386/Kconfig.debug

···
 config DEBUG_RODATA
 	bool "Write protect kernel read-only data structures"
 	depends on DEBUG_KERNEL
-	depends on !KPROBES # temporary for 2.6.22
 	help
 	  Mark the kernel read-only data as write-protected in the pagetables,
 	  in order to catch accidental (and incorrect) writes to such const

arch/i386/mm/init.c

···
 	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)
···
 		                 size >> PAGE_SHIFT, PAGE_KERNEL_RX);
 		printk("Write protecting the kernel text: %luk\n", size >> 10);
 	}
-
+#endif
 	start += size;
 	size = (unsigned long)__end_rodata - start;
 	change_page_attr(virt_to_page(start),

arch/x86_64/Kconfig.debug

···
 config DEBUG_RODATA
        bool "Write protect kernel read-only data structures"
        depends on DEBUG_KERNEL
-       depends on !KPROBES # temporary for 2.6.22
        help
 	 Mark the kernel read-only data as write-protected in the pagetables,
 	 in order to catch accidental (and incorrect) writes to such const data.

arch/x86_64/mm/init.c

···
 	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;