From deac66ae454cacf942c051b86d9232af546fb187 Mon Sep 17 00:00:00 2001 From: Keshavamurthy Anil S Date: Tue, 6 Sep 2005 15:19:35 -0700 Subject: [PATCH] [PATCH] kprobes: fix bug when probed on task and isr functions 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. Signed-off-by: Anil S Keshavamurthy Signed-off-by: Ananth N Mavinakayanahalli Acked-by: Prasanna S Panchamukhi Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- 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 | 22 ++++++++++++++++++++++ 7 files changed, 55 insertions(+), 10 deletions(-) diff --git a/arch/i386/kernel/kprobes.c b/arch/i386/kernel/kprobes.c index e5cec32018a..6345b430b10 100644 --- a/arch/i386/kernel/kprobes.c +++ b/arch/i386/kernel/kprobes.c @@ -177,7 +177,8 @@ static int __kprobes kprobe_handler(struct pt_regs *regs) 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(); diff --git a/arch/ia64/kernel/kprobes.c b/arch/ia64/kernel/kprobes.c index 4b1bd539ec4..471086b808a 100644 --- a/arch/ia64/kernel/kprobes.c +++ b/arch/ia64/kernel/kprobes.c @@ -95,6 +95,17 @@ static void __kprobes update_kprobe_inst_flag(uint template, uint slot, 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 kprobe *p, struct pt_regs *regs) 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(struct die_args *args) 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; } diff --git a/arch/ppc64/kernel/kprobes.c b/arch/ppc64/kernel/kprobes.c index 591e4b67b5a..7e80d49c589 100644 --- a/arch/ppc64/kernel/kprobes.c +++ b/arch/ppc64/kernel/kprobes.c @@ -102,7 +102,7 @@ static inline void prepare_singlestep(struct kprobe *p, struct pt_regs *regs) 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 pt_regs *regs) 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 pt_regs *regs) * 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(struct notifier_block *self, default: break; } - preempt_enable(); + preempt_enable_no_resched(); return ret; } diff --git a/arch/x86_64/kernel/kprobes.c b/arch/x86_64/kernel/kprobes.c index 2d7658fbbb2..df08c43276a 100644 --- a/arch/x86_64/kernel/kprobes.c +++ b/arch/x86_64/kernel/kprobes.c @@ -311,7 +311,8 @@ int __kprobes kprobe_handler(struct pt_regs *regs) 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(); diff --git a/include/asm-ia64/kprobes.h b/include/asm-ia64/kprobes.h index bf36a32e37e..573a3574a24 100644 --- a/include/asm-ia64/kprobes.h +++ b/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; }; diff --git a/include/asm-ppc64/kprobes.h b/include/asm-ppc64/kprobes.h index 0802919c323..d9129d2b038 100644 --- a/include/asm-ppc64/kprobes.h +++ b/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); diff --git a/kernel/kprobes.c b/kernel/kprobes.c index 3b7653f2e7a..f3ea492ab44 100644 --- a/kernel/kprobes.c +++ b/kernel/kprobes.c @@ -155,14 +155,36 @@ void __kprobes free_insn_slot(kprobe_opcode_t *slot) /* Locks kprobe: irqs must be disabled */ void __kprobes lock_kprobes(void) { + unsigned long flags = 0; + + /* Avoiding local interrupts to happen right after we take the kprobe_lock + * and before we get a chance to update kprobe_cpu, this to prevent + * deadlock when we have a kprobe on ISR routine and a kprobe on task + * routine + */ + 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; + + /* Avoiding local interrupts to happen right after we update + * kprobe_cpu and before we get a a chance to release kprobe_lock, + * this to prevent deadlock when we have a kprobe on ISR routine and + * a kprobe on task routine + */ + local_irq_save(flags); + kprobe_cpu = NR_CPUS; spin_unlock(&kprobe_lock); + + local_irq_restore(flags); } /* You have to be holding the kprobe_lock */ -- 2.41.1