Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1030380AbVIAUt5 (ORCPT ); Thu, 1 Sep 2005 16:49:57 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1030381AbVIAUt5 (ORCPT ); Thu, 1 Sep 2005 16:49:57 -0400 Received: from fmr23.intel.com ([143.183.121.15]:50396 "EHLO scsfmr003.sc.intel.com") by vger.kernel.org with ESMTP id S1030370AbVIAUt4 (ORCPT ); Thu, 1 Sep 2005 16:49:56 -0400 Date: Thu, 1 Sep 2005 13:49:37 -0700 From: Keshavamurthy Anil S To: Linux Kernel , akpm@osdl.org Cc: systemtap@sources.redhat.com, ananth@in.ibm.com, prasanna@in.ibm.com, anil.s.keshavamurthy@intel.com Subject: [PATCH]kprobes fix bug when probed on task and isr functions Message-ID: <20050901134937.A29041@unix-os.sc.intel.com> Reply-To: Keshavamurthy Anil S Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.2.5.1i Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 7242 Lines: 203 This patch fixes a race condition where in system used to hang or sometime crash within minutes when kprobes are inserted on ISR routine and a task routine. The fix has been stress tested on i386, ia64, pp64 and on x86_64. To reproduce the problem insert kprobes on schedule() and do_IRQ() functions and you should see hang or system crash. This patch should apply cleanly on 2.6.13-mm1 kernel. Please apply. Signed-off-by: Anil S Keshavamurthy Signed-off-by: Ananth N Mavinakayanahalli Acked-by: Prasanna S Panchamukhi ===================================================== arch/i386/kernel/kprobes.c | 3 ++- arch/ia64/kernel/kprobes.c | 22 +++++++++++++++++++--- arch/ppc64/kernel/kprobes.c | 11 ++++++----- arch/x86_64/kernel/kprobes.c | 3 ++- include/asm-ia64/kprobes.h | 1 + include/asm-ppc64/kprobes.h | 3 +++ kernel/kprobes.c | 8 ++++++++ 7 files changed, 41 insertions(+), 10 deletions(-) Index: linux-2.6.13-mm1/arch/i386/kernel/kprobes.c =================================================================== --- linux-2.6.13-mm1.orig/arch/i386/kernel/kprobes.c +++ linux-2.6.13-mm1/arch/i386/kernel/kprobes.c @@ -190,7 +190,8 @@ static int __kprobes kprobe_handler(stru Disarm the probe we just hit, and ignore it. */ p = get_kprobe(addr); if (p) { - if (kprobe_status == KPROBE_HIT_SS) { + if (kprobe_status == KPROBE_HIT_SS && + *p->ainsn.insn == BREAKPOINT_INSTRUCTION) { regs->eflags &= ~TF_MASK; regs->eflags |= kprobe_saved_eflags; unlock_kprobes(); Index: linux-2.6.13-mm1/arch/ia64/kernel/kprobes.c =================================================================== --- linux-2.6.13-mm1.orig/arch/ia64/kernel/kprobes.c +++ linux-2.6.13-mm1/arch/ia64/kernel/kprobes.c @@ -95,6 +95,17 @@ static void __kprobes update_kprobe_inst p->ainsn.inst_flag = 0; p->ainsn.target_br_reg = 0; + /* Check for Break instruction + * Bits 37:40 Major opcode to be zero + * Bits 27:32 X6 to be zero + * Bits 32:35 X3 to be zero + */ + if ((!major_opcode) && (!((kprobe_inst >> 27) & 0x1FF)) ) { + /* is a break instruction */ + p->ainsn.inst_flag |= INST_FLAG_BREAK_INST; + return; + } + if (bundle_encoding[template][slot] == B) { switch (major_opcode) { case INDIRECT_CALL_OPCODE: @@ -542,8 +553,11 @@ static void __kprobes prepare_ss(struct unsigned long bundle_addr = (unsigned long) &p->opcode.bundle; unsigned long slot = (unsigned long)p->addr & 0xf; - /* Update instruction pointer (IIP) and slot number (IPSR.ri) */ - regs->cr_iip = bundle_addr & ~0xFULL; + /* single step inline if break instruction */ + if (p->ainsn.inst_flag == INST_FLAG_BREAK_INST) + regs->cr_iip = (unsigned long)p->addr & ~0xFULL; + else + regs->cr_iip = bundle_addr & ~0xFULL; if (slot > 2) slot = 0; @@ -599,7 +613,9 @@ static int __kprobes pre_kprobes_handler if (kprobe_running()) { p = get_kprobe(addr); if (p) { - if (kprobe_status == KPROBE_HIT_SS) { + if ( (kprobe_status == KPROBE_HIT_SS) && + (p->ainsn.inst_flag == INST_FLAG_BREAK_INST)) { + ia64_psr(regs)->ss = 0; unlock_kprobes(); goto no_kprobe; } Index: linux-2.6.13-mm1/arch/ppc64/kernel/kprobes.c =================================================================== --- linux-2.6.13-mm1.orig/arch/ppc64/kernel/kprobes.c +++ linux-2.6.13-mm1/arch/ppc64/kernel/kprobes.c @@ -102,7 +102,7 @@ static inline void prepare_singlestep(st regs->msr |= MSR_SE; /* single step inline if it is a trap variant */ - if (IS_TW(insn) || IS_TD(insn) || IS_TWI(insn) || IS_TDI(insn)) + if (is_trap(insn)) regs->nip = (unsigned long)p->addr; else regs->nip = (unsigned long)p->ainsn.insn; @@ -152,7 +152,9 @@ static inline int kprobe_handler(struct Disarm the probe we just hit, and ignore it. */ p = get_kprobe(addr); if (p) { - if (kprobe_status == KPROBE_HIT_SS) { + kprobe_opcode_t insn = *p->ainsn.insn; + if (kprobe_status == KPROBE_HIT_SS && + is_trap(insn)) { regs->msr &= ~MSR_SE; regs->msr |= kprobe_saved_msr; unlock_kprobes(); @@ -192,8 +194,7 @@ static inline int kprobe_handler(struct * trap variant, it could belong to someone else */ kprobe_opcode_t cur_insn = *addr; - if (IS_TW(cur_insn) || IS_TD(cur_insn) || - IS_TWI(cur_insn) || IS_TDI(cur_insn)) + if (is_trap(cur_insn)) goto no_kprobe; /* * The breakpoint instruction was removed right @@ -403,7 +404,7 @@ int __kprobes kprobe_exceptions_notify(s default: break; } - preempt_enable(); + preempt_enable_no_resched(); return ret; } Index: linux-2.6.13-mm1/arch/x86_64/kernel/kprobes.c =================================================================== --- linux-2.6.13-mm1.orig/arch/x86_64/kernel/kprobes.c +++ linux-2.6.13-mm1/arch/x86_64/kernel/kprobes.c @@ -311,7 +311,8 @@ int __kprobes kprobe_handler(struct pt_r Disarm the probe we just hit, and ignore it. */ p = get_kprobe(addr); if (p) { - if (kprobe_status == KPROBE_HIT_SS) { + if (kprobe_status == KPROBE_HIT_SS && + *p->ainsn.insn == BREAKPOINT_INSTRUCTION) { regs->eflags &= ~TF_MASK; regs->eflags |= kprobe_saved_rflags; unlock_kprobes(); Index: linux-2.6.13-mm1/include/asm-ia64/kprobes.h =================================================================== --- linux-2.6.13-mm1.orig/include/asm-ia64/kprobes.h +++ linux-2.6.13-mm1/include/asm-ia64/kprobes.h @@ -92,6 +92,7 @@ struct arch_specific_insn { kprobe_opcode_t insn; #define INST_FLAG_FIX_RELATIVE_IP_ADDR 1 #define INST_FLAG_FIX_BRANCH_REG 2 + #define INST_FLAG_BREAK_INST 4 unsigned long inst_flag; unsigned short target_br_reg; }; Index: linux-2.6.13-mm1/include/asm-ppc64/kprobes.h =================================================================== --- linux-2.6.13-mm1.orig/include/asm-ppc64/kprobes.h +++ linux-2.6.13-mm1/include/asm-ppc64/kprobes.h @@ -42,6 +42,9 @@ typedef unsigned int kprobe_opcode_t; #define JPROBE_ENTRY(pentry) (kprobe_opcode_t *)((func_descr_t *)pentry) +#define is_trap(instr) (IS_TW(instr) || IS_TD(instr) || \ + IS_TWI(instr) || IS_TDI(instr)) + #define ARCH_SUPPORTS_KRETPROBES void kretprobe_trampoline(void); Index: linux-2.6.13-mm1/kernel/kprobes.c =================================================================== --- linux-2.6.13-mm1.orig/kernel/kprobes.c +++ linux-2.6.13-mm1/kernel/kprobes.c @@ -155,14 +155,22 @@ void __kprobes free_insn_slot(kprobe_opc /* Locks kprobe: irqs must be disabled */ void __kprobes lock_kprobes(void) { + unsigned long flags = 0; + + local_irq_save(flags); spin_lock(&kprobe_lock); kprobe_cpu = smp_processor_id(); + local_irq_restore(flags); } void __kprobes unlock_kprobes(void) { + unsigned long flags = 0; + + local_irq_save(flags); kprobe_cpu = NR_CPUS; spin_unlock(&kprobe_lock); + local_irq_restore(flags); } /* You have to be holding the kprobe_lock */ - 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/