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/x86_64/mm/init.c | 64 +++++++++++++++++++++++++++------------- include/asm-x86_64/cacheflush.h | 9 +++++ 2 files changed, 53 insertions(+), 20 deletions(-) Index: linux-2.6-lttng/arch/x86_64/mm/init.c =================================================================== --- linux-2.6-lttng.orig/arch/x86_64/mm/init.c 2007-07-13 16:08:14.000000000 -0400 +++ linux-2.6-lttng/arch/x86_64/mm/init.c 2007-07-13 16:36:40.000000000 -0400 @@ -56,6 +56,10 @@ DEFINE_PER_CPU(struct mmu_gather, mmu_gathers); +#ifdef CONFIG_DEBUG_RODATA +static int rodata_marked; +#endif + /* * NOTE: pagetable_init alloc all the fixmap pagetables contiguous on the * physical space so we can cache the place of the first one and move @@ -596,31 +600,15 @@ } #ifdef CONFIG_DEBUG_RODATA - void mark_rodata_ro(void) { - unsigned long start = (unsigned long)_stext, end; + unsigned long start = PFN_ALIGN(_stext); + unsigned long end = PFN_ALIGN(__end_rodata); kernel_text_is_ro = 1; -#ifdef CONFIG_HOTPLUG_CPU - /* It must still be possible to apply SMP alternatives. */ - if (num_possible_cpus() > 1) { - start = (unsigned long)_etext; - kernel_text_is_ro = 0; - } -#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; - if (end <= start) - return; - - change_page_attr_addr(start, (end - start) >> PAGE_SHIFT, PAGE_KERNEL_RO); + change_page_attr_addr(start, (end - start) >> PAGE_SHIFT, + PAGE_KERNEL_RO); printk(KERN_INFO "Write protecting the kernel read-only data: %luk\n", (end - start) >> 10); @@ -632,7 +620,43 @@ * of who is the culprit. */ global_flush_tlb(); + rodata_marked = 1; +} + +/* + * Mark kernel text pages writable. + */ +void kernel_text_mark_rw(unsigned long address, size_t len) +{ + if (rodata_marked && 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); + +void kernel_text_unmark(unsigned long address, size_t len) +{ + if (rodata_marked && address >= PFN_ALIGN(_text) + && (address + len) <= PFN_ALIGN(_etext)) { + unsigned long nr_pages; + nr_pages = ((address + len) >> PAGE_SHIFT) + - (address >> PAGE_SHIFT) + 1; + mb(); + change_page_attr(virt_to_page(address), nr_pages, + PAGE_KERNEL_RO); + mb(); + global_flush_tlb(); + } } +EXPORT_SYMBOL_GPL(kernel_text_unmark); #endif #ifdef CONFIG_BLK_DEV_INITRD Index: linux-2.6-lttng/include/asm-x86_64/cacheflush.h =================================================================== --- linux-2.6-lttng.orig/include/asm-x86_64/cacheflush.h 2007-07-13 16:08:14.000000000 -0400 +++ linux-2.6-lttng/include/asm-x86_64/cacheflush.h 2007-07-13 16:34:32.000000000 -0400 @@ -33,4 +33,13 @@ void mark_rodata_ro(void); #endif +#if defined(CONFIG_DEBUG_RODATA) +/* 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 /* _X8664_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/