Messages in this thread Patch in this message | | | Date | Tue, 18 Dec 2007 18:19:01 -0500 | From | Masami Hiramatsu <> | Subject | [PATCH 2/2] x86: add reenter_kprobe helper |
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Kprobe reenter logic from deeply indented section to helper function. This improves code readability.
Signed-off-by: Harvey Harrison <harvey.harrison@gmail.com> Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Masami Hiramatsu <mhiramat@redhat.com> --- Harvey, I picked up your patch and enhanced it. I think this idea is good for improving readability.
arch/x86/kernel/kprobes.c | 68 +++++++++++++++++++++++----------------------- 1 file changed, 35 insertions(+), 33 deletions(-)
Index: b/arch/x86/kernel/kprobes.c =================================================================== --- a/arch/x86/kernel/kprobes.c +++ b/arch/x86/kernel/kprobes.c @@ -427,6 +427,38 @@ void __kprobes arch_prepare_kretprobe(st /* Replace the return addr with trampoline addr */ *sara = (unsigned long) &kretprobe_trampoline; } +/* + * We have reentered the kprobe_handler(), since another probe was hit while + * within the handler. We save the original kprobes variables and just single + * step on the instruction of the new probe without calling any user handlers. + */ +static int __kprobes reenter_kprobe(struct kprobe *p, struct pt_regs *regs, + struct kprobe_ctlblk *kcb) +{ + if (kcb->kprobe_status == KPROBE_HIT_SS && + *p->ainsn.insn == BREAKPOINT_INSTRUCTION) { + regs->flags &= ~X86_EFLAGS_TF; + regs->flags |= kcb->kprobe_saved_flags; + return 0; +#ifdef CONFIG_X86_64 + } else if (kcb->kprobe_status == KPROBE_HIT_SSDONE) { + /* TODO: Provide re-entrancy from post_kprobes_handler() and + * avoid exception stack corruption while single-stepping on + * the instruction of the new probe. + */ + arch_disarm_kprobe(p); + regs->ip = (unsigned long)p->addr; + reset_current_kprobe(); + return 1; +#endif + } + save_previous_kprobe(kcb); + set_current_kprobe(p, regs, kcb); + kprobes_inc_nmissed_count(p); + prepare_singlestep(p, regs); + kcb->kprobe_status = KPROBE_REENTER; + return 1; +}
/* * Interrupts are disabled on entry as trap3 is an interrupt gate and they @@ -451,39 +483,9 @@ static int __kprobes kprobe_handler(stru /* Check we're not actually recursing */ if (kprobe_running()) { p = get_kprobe(addr); - if (p) { - if (kcb->kprobe_status == KPROBE_HIT_SS && - *p->ainsn.insn == BREAKPOINT_INSTRUCTION) { - regs->flags &= ~X86_EFLAGS_TF; - regs->flags |= kcb->kprobe_saved_flags; - goto no_kprobe; -#ifdef CONFIG_X86_64 - } else if (kcb->kprobe_status == KPROBE_HIT_SSDONE) { - /* TODO: Provide re-entrancy from - * post_kprobes_handler() and avoid exception - * stack corruption while single-stepping on - * the instruction of the new probe. - */ - arch_disarm_kprobe(p); - regs->ip = (unsigned long)p->addr; - reset_current_kprobe(); - ret = 1; - goto no_kprobe; -#endif - } - /* We have reentered the kprobe_handler(), since - * another probe was hit while within the handler. - * We here save the original kprobes variables and - * just single step on the instruction of the new probe - * without calling any user handlers. - */ - save_previous_kprobe(kcb); - set_current_kprobe(p, regs, kcb); - kprobes_inc_nmissed_count(p); - prepare_singlestep(p, regs); - kcb->kprobe_status = KPROBE_REENTER; - ret = 1; - } else { + if (p) + ret = reenter_kprobe(p, regs, kcb); + else { if (*addr != BREAKPOINT_INSTRUCTION) { /* The breakpoint instruction was removed by * another cpu right after we hit, no further
-- Masami Hiramatsu
Software Engineer Hitachi Computer Products (America) Inc. Software Solutions Division
e-mail: mhiramat@redhat.com, masami.hiramatsu.pt@hitachi.com
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