lkml.org 
[lkml]   [2009]   [Dec]   [18]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    Patch in this message
    /
    From
    Subject[PATCH -tip v7 05/11] kprobes/x86: Boost probes when reentering
    Date
    Integrate prepare_singlestep() into setup_singlestep() to boost up reenter
    probes, if possible.

    Signed-off-by: Masami Hiramatsu <mhiramat@redhat.com>
    Cc: Ananth N Mavinakayanahalli <ananth@in.ibm.com>
    Cc: Ingo Molnar <mingo@elte.hu>
    Cc: Jim Keniston <jkenisto@us.ibm.com>
    Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
    Cc: Christoph Hellwig <hch@infradead.org>
    Cc: Steven Rostedt <rostedt@goodmis.org>
    Cc: Frederic Weisbecker <fweisbec@gmail.com>
    Cc: H. Peter Anvin <hpa@zytor.com>
    Cc: Anders Kaseorg <andersk@ksplice.com>
    Cc: Tim Abbott <tabbott@ksplice.com>
    Cc: Andi Kleen <andi@firstfloor.org>
    Cc: Jason Baron <jbaron@redhat.com>
    Cc: Mathieu Desnoyers <compudj@krystal.dyndns.org>
    ---

    arch/x86/kernel/kprobes.c | 48 ++++++++++++++++++++++++---------------------
    1 files changed, 26 insertions(+), 22 deletions(-)

    diff --git a/arch/x86/kernel/kprobes.c b/arch/x86/kernel/kprobes.c
    index 7039e6e..57de6ca 100644
    --- a/arch/x86/kernel/kprobes.c
    +++ b/arch/x86/kernel/kprobes.c
    @@ -403,18 +403,6 @@ static void __kprobes restore_btf(void)
    update_debugctlmsr(current->thread.debugctlmsr);
    }

    -static void __kprobes prepare_singlestep(struct kprobe *p, struct pt_regs *regs)
    -{
    - clear_btf();
    - regs->flags |= X86_EFLAGS_TF;
    - regs->flags &= ~X86_EFLAGS_IF;
    - /* single step inline if the instruction is an int3 */
    - if (p->opcode == BREAKPOINT_INSTRUCTION)
    - regs->ip = (unsigned long)p->addr;
    - else
    - regs->ip = (unsigned long)p->ainsn.insn;
    -}
    -
    void __kprobes arch_prepare_kretprobe(struct kretprobe_instance *ri,
    struct pt_regs *regs)
    {
    @@ -427,19 +415,38 @@ void __kprobes arch_prepare_kretprobe(struct kretprobe_instance *ri,
    }

    static void __kprobes setup_singlestep(struct kprobe *p, struct pt_regs *regs,
    - struct kprobe_ctlblk *kcb)
    + struct kprobe_ctlblk *kcb, int reenter)
    {
    #if !defined(CONFIG_PREEMPT) || defined(CONFIG_FREEZER)
    if (p->ainsn.boostable == 1 && !p->post_handler) {
    /* Boost up -- we can execute copied instructions directly */
    - reset_current_kprobe();
    + if (!reenter)
    + reset_current_kprobe();
    + /*
    + * Reentering boosted probe doesn't reset current_kprobe,
    + * nor set current_kprobe, because it doesn't use single
    + * stepping.
    + */
    regs->ip = (unsigned long)p->ainsn.insn;
    preempt_enable_no_resched();
    return;
    }
    #endif
    - prepare_singlestep(p, regs);
    - kcb->kprobe_status = KPROBE_HIT_SS;
    + if (reenter) {
    + save_previous_kprobe(kcb);
    + set_current_kprobe(p, regs, kcb);
    + kcb->kprobe_status = KPROBE_REENTER;
    + } else
    + kcb->kprobe_status = KPROBE_HIT_SS;
    + /* Prepare real single stepping */
    + clear_btf();
    + regs->flags |= X86_EFLAGS_TF;
    + regs->flags &= ~X86_EFLAGS_IF;
    + /* single step inline if the instruction is an int3 */
    + if (p->opcode == BREAKPOINT_INSTRUCTION)
    + regs->ip = (unsigned long)p->addr;
    + else
    + regs->ip = (unsigned long)p->ainsn.insn;
    }

    /*
    @@ -453,11 +460,8 @@ static int __kprobes reenter_kprobe(struct kprobe *p, struct pt_regs *regs,
    switch (kcb->kprobe_status) {
    case KPROBE_HIT_SSDONE:
    case KPROBE_HIT_ACTIVE:
    - save_previous_kprobe(kcb);
    - set_current_kprobe(p, regs, kcb);
    kprobes_inc_nmissed_count(p);
    - prepare_singlestep(p, regs);
    - kcb->kprobe_status = KPROBE_REENTER;
    + setup_singlestep(p, regs, kcb, 1);
    break;
    case KPROBE_HIT_SS:
    /* A probe has been hit in the codepath leading up to, or just
    @@ -532,13 +536,13 @@ static int __kprobes kprobe_handler(struct pt_regs *regs)
    * more here.
    */
    if (!p->pre_handler || !p->pre_handler(p, regs))
    - setup_singlestep(p, regs, kcb);
    + setup_singlestep(p, regs, kcb, 0);
    return 1;
    }
    } else if (kprobe_running()) {
    p = __get_cpu_var(current_kprobe);
    if (p->break_handler && p->break_handler(p, regs)) {
    - setup_singlestep(p, regs, kcb);
    + setup_singlestep(p, regs, kcb, 0);
    return 1;
    }
    } /* else: not a kprobe fault; let the kernel handle it */

    --
    Masami Hiramatsu

    Software Engineer
    Hitachi Computer Products (America), Inc.
    Software Solutions Division

    e-mail: mhiramat@redhat.com


    \
     
     \ /
      Last update: 2009-12-18 19:17    [W:0.050 / U:0.736 seconds]
    ©2003-2016 Jasper Spaans. hosted at Digital OceanAdvertise on this site