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 <arjan@linux.intel.com>
Tested-by: S. 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: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/arch/i386/Kconfig.debug b/arch/i386/Kconfig.debug
index 6293920cd1be394c32d7161dc05858fedfed6ef3..b31c0802e1ccf53f1e5a677e802c5e34166ebc54 100644 (file)
--- a/arch/i386/Kconfig.debug
+++ b/arch/i386/Kconfig.debug
@@ -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

diff --git a/arch/i386/mm/init.c b/arch/i386/mm/init.c
index b22ce8d6b1ba64c76db039bccdf2920ca9a20061..7135946d366322ade4cb529372f7389647a91d31 100644 (file)
--- a/arch/i386/mm/init.c
+++ b/arch/i386/mm/init.c
@@ -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),

diff --git a/arch/x86_64/Kconfig.debug b/arch/x86_64/Kconfig.debug
index 8a8677518447ca6624fa0e7b9545772ee6a77959..775d211a5cf93983ca1fd97c64f56fc18c3f8213 100644 (file)
--- a/arch/x86_64/Kconfig.debug
+++ b/arch/x86_64/Kconfig.debug
@@ -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.

diff --git a/arch/x86_64/mm/init.c b/arch/x86_64/mm/init.c
index efb6e845114ec727430860981b03b22495f9d299..9a0e98accf04aae3e11282e3079fd747afa646a3 100644 (file)
--- a/arch/x86_64/mm/init.c
+++ b/arch/x86_64/mm/init.c
@@ -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;