From b97601563704751162b122c652d7f390b8f480d2 Mon Sep 17 00:00:00 2001 From: Harvey Harrison Date: Wed, 30 Jan 2008 13:32:19 +0100 Subject: [PATCH] x86: kprobes change kprobe_handler flow Make the control flow of kprobe_handler more obvious. Collapse the separate if blocks/gotos with if/else blocks this unifies the duplication of the check for a breakpoint instruction race with another cpu. Create two jump targets: preempt_out: re-enables preemption before returning ret out: only returns ret Signed-off-by: Harvey Harrison Signed-off-by: Ingo Molnar Signed-off-by: Thomas Gleixner --- arch/x86/kernel/kprobes.c | 60 ++++++++++++++++++--------------------- 1 file changed, 28 insertions(+), 32 deletions(-) diff --git a/arch/x86/kernel/kprobes.c b/arch/x86/kernel/kprobes.c index 80bcb763546..a72e02bf113 100644 --- a/arch/x86/kernel/kprobes.c +++ b/arch/x86/kernel/kprobes.c @@ -494,32 +494,28 @@ static int __kprobes kprobe_handler(struct pt_regs *regs) preempt_disable(); kcb = get_kprobe_ctlblk(); - /* Check we're not actually recursing */ - if (kprobe_running()) { - p = get_kprobe(addr); - if (p) { + p = get_kprobe(addr); + if (p) { + /* Check we're not actually recursing */ + if (kprobe_running()) { ret = reenter_kprobe(p, regs, kcb); if (kcb->kprobe_status == KPROBE_REENTER) - return 1; + { + ret = 1; + goto out; + } + goto preempt_out; } else { - if (*addr != BREAKPOINT_INSTRUCTION) { - /* The breakpoint instruction was removed by - * another cpu right after we hit, no further - * handling of this interrupt is appropriate - */ - regs->ip = (unsigned long)addr; + set_current_kprobe(p, regs, kcb); + kcb->kprobe_status = KPROBE_HIT_ACTIVE; + if (p->pre_handler && p->pre_handler(p, regs)) + { + /* handler set things up, skip ss setup */ ret = 1; - goto no_kprobe; + goto out; } - p = __get_cpu_var(current_kprobe); - if (p->break_handler && p->break_handler(p, regs)) - goto ss_probe; } - goto no_kprobe; - } - - p = get_kprobe(addr); - if (!p) { + } else { if (*addr != BREAKPOINT_INSTRUCTION) { /* * The breakpoint instruction was removed right @@ -532,34 +528,34 @@ static int __kprobes kprobe_handler(struct pt_regs *regs) */ regs->ip = (unsigned long)addr; ret = 1; + goto preempt_out; + } + if (kprobe_running()) { + p = __get_cpu_var(current_kprobe); + if (p->break_handler && p->break_handler(p, regs)) + goto ss_probe; } /* Not one of ours: let kernel handle it */ - goto no_kprobe; + goto preempt_out; } - set_current_kprobe(p, regs, kcb); - kcb->kprobe_status = KPROBE_HIT_ACTIVE; - - if (p->pre_handler && p->pre_handler(p, regs)) - /* handler has already set things up, so skip ss setup */ - return 1; - ss_probe: + ret = 1; #if !defined(CONFIG_PREEMPT) || defined(CONFIG_PM) if (p->ainsn.boostable == 1 && !p->post_handler) { /* Boost up -- we can execute copied instructions directly */ reset_current_kprobe(); regs->ip = (unsigned long)p->ainsn.insn; - preempt_enable_no_resched(); - return 1; + goto preempt_out; } #endif prepare_singlestep(p, regs); kcb->kprobe_status = KPROBE_HIT_SS; - return 1; + goto out; -no_kprobe: +preempt_out: preempt_enable_no_resched(); +out: return ret; } -- 2.41.1