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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>
This commit is contained in:
Arjan van de Ven 2007-06-20 22:23:21 -07:00 committed by Linus Torvalds
parent 79d9a72f87
commit 0864a4e201
4 changed files with 7 additions and 3 deletions
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1
arch/i386/Kconfig.debug
View File

@ -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

3
arch/i386/mm/init.c
View File

@ -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),

1
arch/x86_64/Kconfig.debug
View File

@ -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.

5
arch/x86_64/mm/init.c
View File

@ -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;