Commit 0864a4e2 authored by Arjan van de Ven's avatar Arjan van de Ven Committed by Linus Torvalds
Browse files

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: default avatarArjan van de Ven <arjan@linux.intel.com>
Tested-by: default avatarS. P. Prasanna <prasanna@in.ibm.com>
Cc: Andi Kleen <ak@suse.de>
Cc: William Cohen <wcohen@redhat.com>
Cc: Ian McDonald <ian.mcdonald@jandi.co.nz>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 79d9a72f

arch/i386/Kconfig.debug

+0 −1
Original line number Diff line number Diff line
@@ -49,7 +49,6 @@ config DEBUG_PAGEALLOC 
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

+2 −1
Original line number Diff line number Diff line
@@ -799,6 +799,7 @@ 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)
@@ -808,7 +809,7 @@ void mark_rodata_ro(void) 
		                 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

+0 −1
Original line number Diff line number Diff line
@@ -9,7 +9,6 @@ source "lib/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

+5 −0
Original line number Diff line number Diff line
@@ -605,6 +605,11 @@ void mark_rodata_ro(void) 
	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;

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