Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S935811AbXFGEX7 (ORCPT ); Thu, 7 Jun 2007 00:23:59 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752346AbXFGEXv (ORCPT ); Thu, 7 Jun 2007 00:23:51 -0400 Received: from e3.ny.us.ibm.com ([32.97.182.143]:58843 "EHLO e3.ny.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752024AbXFGEXu (ORCPT ); Thu, 7 Jun 2007 00:23:50 -0400 Date: Thu, 7 Jun 2007 09:54:21 +0530 From: "S. P. Prasanna" To: Ian McDonald , Andrew Morton , Andi Kleen Cc: Jim Keniston , Chuck Ebbert , Linux Kernel Mailing List , ananth@in.ibm.com, anil.s.keshavamurthy@intel.com, "David S. Miller" , Patrick Andrieux , DCCP Mailing List , jbeulich@novell.com, systemtap@sources.redhat.com Subject: Re: [PATCH] Kprobes x86_64 fix for mark ro data Message-ID: <20070607042421.GB9350@in.ibm.com> Reply-To: prasanna@in.ibm.com References: <5640c7e00706061347v42c9ecbahb5354f6687a70a78@mail.gmail.com> <46673B76.2090508@redhat.com> <5640c7e00706061612h62074699wdbd2725654a164@mail.gmail.com> <20070607042229.GA9350@in.ibm.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20070607042229.GA9350@in.ibm.com> User-Agent: Mutt/1.4.1i Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 4164 Lines: 125 This patch fixes the problem of page protection introduced by CONFIG_DEBUG_RODATA for x86_64 architecture. As per Andi Kleen's suggestion, the kernel text pages are marked writeable only for a short duration to insert or remove the breakpoints. Signed-off-by: Prasanna S P Ack-ed-by: Jim Keniston arch/x86_64/kernel/kprobes.c | 26 ++++++++++++++++++++++++++ arch/x86_64/mm/init.c | 6 +++++- include/asm-x86_64/kprobes.h | 10 ++++++++++ 3 files changed, 41 insertions(+), 1 deletion(-) diff -puN arch/x86_64/kernel/kprobes.c~kprobes-mark-ro-data-fix-x86_64 arch/x86_64/kernel/kprobes.c --- linux-2.6.22-rc2/arch/x86_64/kernel/kprobes.c~kprobes-mark-ro-data-fix-x86_64 2007-06-07 09:20:33.000000000 +0530 +++ linux-2.6.22-rc2-prasanna/arch/x86_64/kernel/kprobes.c 2007-06-07 09:20:33.000000000 +0530 @@ -209,16 +209,42 @@ static void __kprobes arch_copy_kprobe(s void __kprobes arch_arm_kprobe(struct kprobe *p) { + unsigned long addr = (unsigned long)p->addr; + int page_readonly = 0; + + if (kernel_readonly_text(addr)) { + change_page_attr_addr(addr, 1, PAGE_KERNEL_EXEC); + global_flush_tlb(); + page_readonly = 1; + } *p->addr = BREAKPOINT_INSTRUCTION; flush_icache_range((unsigned long) p->addr, (unsigned long) p->addr + sizeof(kprobe_opcode_t)); + if (page_readonly) { + change_page_attr_addr(addr, 1, PAGE_KERNEL_RO); + global_flush_tlb(); + } } void __kprobes arch_disarm_kprobe(struct kprobe *p) { + unsigned long addr = (unsigned long)p->addr; + int page_readonly = 0; + + if (kernel_readonly_text(addr)) { + change_page_attr_addr(addr, 1, PAGE_KERNEL_EXEC); + global_flush_tlb(); + page_readonly = 1; + } + *p->addr = p->opcode; flush_icache_range((unsigned long) p->addr, (unsigned long) p->addr + sizeof(kprobe_opcode_t)); + + if (page_readonly) { + change_page_attr_addr(addr, 1, PAGE_KERNEL_RO); + global_flush_tlb(); + } } void __kprobes arch_remove_kprobe(struct kprobe *p) diff -puN include/asm-x86_64/kprobes.h~kprobes-mark-ro-data-fix-x86_64 include/asm-x86_64/kprobes.h --- linux-2.6.22-rc2/include/asm-x86_64/kprobes.h~kprobes-mark-ro-data-fix-x86_64 2007-06-07 09:20:33.000000000 +0530 +++ linux-2.6.22-rc2-prasanna/include/asm-x86_64/kprobes.h 2007-06-07 09:20:33.000000000 +0530 @@ -26,6 +26,7 @@ #include #include #include +#include #define __ARCH_WANT_KPROBES_INSN_SLOT @@ -88,4 +89,13 @@ extern int kprobe_handler(struct pt_regs extern int kprobe_exceptions_notify(struct notifier_block *self, unsigned long val, void *data); +extern int kernel_text_is_ro; +static inline int kernel_readonly_text(unsigned long address) +{ + if (kernel_text_is_ro && ((address >= (unsigned long)_stext) + && (address < (unsigned long) _etext))) + return 1; + + return 0; +} #endif /* _ASM_KPROBES_H */ diff -puN arch/x86_64/mm/init.c~kprobes-mark-ro-data-fix-x86_64 arch/x86_64/mm/init.c --- linux-2.6.22-rc2/arch/x86_64/mm/init.c~kprobes-mark-ro-data-fix-x86_64 2007-06-07 09:20:33.000000000 +0530 +++ linux-2.6.22-rc2-prasanna/arch/x86_64/mm/init.c 2007-06-07 09:20:33.000000000 +0530 @@ -48,6 +48,7 @@ #define Dprintk(x...) #endif +int kernel_text_is_ro; const struct dma_mapping_ops* dma_ops; EXPORT_SYMBOL(dma_ops); @@ -598,10 +599,13 @@ void mark_rodata_ro(void) { unsigned long start = (unsigned long)_stext, end; + kernel_text_is_ro = 1; #ifdef CONFIG_HOTPLUG_CPU /* It must still be possible to apply SMP alternatives. */ - if (num_possible_cpus() > 1) + if (num_possible_cpus() > 1) { start = (unsigned long)_etext; + kernel_text_is_ro = 0; + } #endif end = (unsigned long)__end_rodata; start = (start + PAGE_SIZE - 1) & PAGE_MASK; _ -- Prasanna S.P. Linux Technology Center India Software Labs, IBM Bangalore Email: prasanna@in.ibm.com Ph: 91-80-41776329 - 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/