Interface to use for code patching : makes sure the page is writable between calls to kernel_text_mark_rw() and kernel_text_unmark(). Signed-off-by: Mathieu Desnoyers CC: Andi Kleen --- arch/i386/mm/init.c | 65 ++++++++++++++++++++++++++++++++++-------- include/asm-i386/cacheflush.h | 7 ++++ 2 files changed, 60 insertions(+), 12 deletions(-) Index: linux-2.6-lttng/arch/i386/mm/init.c =================================================================== --- linux-2.6-lttng.orig/arch/i386/mm/init.c 2007-08-10 16:44:23.000000000 -0400 +++ linux-2.6-lttng/arch/i386/mm/init.c 2007-08-10 16:47:14.000000000 -0400 @@ -31,6 +31,7 @@ #include #include #include +#include #include #include @@ -794,23 +795,15 @@ static int noinline do_test_wp_bit(void) } #ifdef CONFIG_DEBUG_RODATA - 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 - { - change_page_attr(virt_to_page(start), - size >> PAGE_SHIFT, PAGE_KERNEL_RX); - printk("Write protecting the kernel text: %luk\n", size >> 10); - } -#endif + change_page_attr(virt_to_page(start), + size >> PAGE_SHIFT, PAGE_KERNEL_RX); + printk("Write protecting the kernel text: %luk\n", size >> 10); + start += size; size = (unsigned long)__end_rodata - start; change_page_attr(virt_to_page(start), @@ -826,6 +819,54 @@ void mark_rodata_ro(void) */ global_flush_tlb(); } + +/** + * kernel_text_mark_rw - Change kernel core text flags to RW + * @address: location of the code + * @len: size of code to mark + * + * Change kernel text flags to RW. Useful for code patching. + */ + +void __kprobes kernel_text_mark_rw(unsigned long address, size_t len) +{ + if (address >= PFN_ALIGN(_text) + && (address + len) <= PFN_ALIGN(_etext)) { + unsigned long nr_pages; + nr_pages = ((address + len) >> PAGE_SHIFT) + - (address >> PAGE_SHIFT) + 1; + change_page_attr(virt_to_page(address), nr_pages, + PAGE_KERNEL_EXEC); + mb(); + global_flush_tlb(); + mb(); + } +} +EXPORT_SYMBOL_GPL(kernel_text_mark_rw); + +/** + * kernel_text_unmark - Unmap a kernel text rw mapping. + * @address: location of the mapping + * @len: size of code to mark + * + * Remove RW flag from kernel text. + */ + +void __kprobes kernel_text_unmark(unsigned long address, size_t len) +{ + if (address >= PFN_ALIGN(_text) + && (address + len) <= PFN_ALIGN(_etext)) { + unsigned long nr_pages; + nr_pages = ((address + len) >> PAGE_SHIFT) + - (address >> PAGE_SHIFT) + 1; + change_page_attr(virt_to_page(address), nr_pages, + PAGE_KERNEL_RX); + mb(); + global_flush_tlb(); + mb(); + } +} +EXPORT_SYMBOL_GPL(kernel_text_unmark); #endif void free_init_pages(char *what, unsigned long begin, unsigned long end) Index: linux-2.6-lttng/include/asm-i386/cacheflush.h =================================================================== --- linux-2.6-lttng.orig/include/asm-i386/cacheflush.h 2007-08-10 16:44:23.000000000 -0400 +++ linux-2.6-lttng/include/asm-i386/cacheflush.h 2007-08-10 16:44:46.000000000 -0400 @@ -34,6 +34,13 @@ void kernel_map_pages(struct page *page, #ifdef CONFIG_DEBUG_RODATA void mark_rodata_ro(void); + +/* mark kernel text pages writable */ +extern void kernel_text_mark_rw(unsigned long address, size_t len); +extern void kernel_text_unmark(unsigned long address, size_t len); +#else +void kernel_text_mark_rw(unsigned long address, size_t len) { } +void kernel_text_unmark(unsigned long address, size_t len) { } #endif #endif /* _I386_CACHEFLUSH_H */ -- Mathieu Desnoyers Computer Engineering Ph.D. Student, Ecole Polytechnique de Montreal OpenPGP key fingerprint: 8CD5 52C3 8E3C 4140 715F BA06 3F25 A8FE 3BAE 9A68 - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/