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    Subject[patch 07/11] Text Edit Lock - kprobes architecture independent support
    Use the mutual exclusion provided by the text edit lock in the kprobes code. It
    allows coherent manipulation of the kernel code by other subsystems.

    Changelog:

    Move the kernel_text_lock/unlock out of the for loops.

    Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
    Acked-by: Ananth N Mavinakayanahalli <ananth@in.ibm.com>
    CC: prasanna@in.ibm.com
    CC: ananth@in.ibm.com
    CC: anil.s.keshavamurthy@intel.com
    CC: davem@davemloft.net
    CC: Roel Kluin <12o3l@tiscali.nl>
    ---
    kernel/kprobes.c | 19 +++++++++++++------
    1 file changed, 13 insertions(+), 6 deletions(-)

    Index: linux-2.6-lttng/kernel/kprobes.c
    ===================================================================
    --- linux-2.6-lttng.orig/kernel/kprobes.c 2007-11-16 13:40:06.000000000 -0500
    +++ linux-2.6-lttng/kernel/kprobes.c 2007-11-17 10:00:23.000000000 -0500
    @@ -43,6 +43,7 @@
    #include <linux/seq_file.h>
    #include <linux/debugfs.h>
    #include <linux/kdebug.h>
    +#include <linux/memory.h>

    #include <asm-generic/sections.h>
    #include <asm/cacheflush.h>
    @@ -568,9 +569,10 @@ static int __kprobes __register_kprobe(s
    goto out;
    }

    + kernel_text_lock();
    ret = arch_prepare_kprobe(p);
    if (ret)
    - goto out;
    + goto out_unlock_text;

    INIT_HLIST_NODE(&p->hlist);
    hlist_add_head_rcu(&p->hlist,
    @@ -578,7 +580,8 @@ static int __kprobes __register_kprobe(s

    if (kprobe_enabled)
    arch_arm_kprobe(p);
    -
    +out_unlock_text:
    + kernel_text_unlock();
    out:
    mutex_unlock(&kprobe_mutex);

    @@ -621,8 +624,11 @@ valid_p:
    * enabled - otherwise, the breakpoint would already have
    * been removed. We save on flushing icache.
    */
    - if (kprobe_enabled)
    + if (kprobe_enabled) {
    + kernel_text_lock();
    arch_disarm_kprobe(p);
    + kernel_text_unlock();
    + }
    hlist_del_rcu(&old_p->hlist);
    cleanup_p = 1;
    } else {
    @@ -644,9 +650,7 @@ valid_p:
    list_del_rcu(&p->list);
    kfree(old_p);
    }
    - mutex_lock(&kprobe_mutex);
    arch_remove_kprobe(p);
    - mutex_unlock(&kprobe_mutex);
    } else {
    mutex_lock(&kprobe_mutex);
    if (p->break_handler)
    @@ -717,7 +721,6 @@ static int __kprobes pre_handler_kretpro
    ri->rp = rp;
    ri->task = current;
    arch_prepare_kretprobe(ri, regs);
    -
    /* XXX(hch): why is there no hlist_move_head? */
    hlist_del(&ri->uflist);
    hlist_add_head(&ri->uflist, &ri->rp->used_instances);
    @@ -938,11 +941,13 @@ static void __kprobes enable_all_kprobes
    if (kprobe_enabled)
    goto already_enabled;

    + kernel_text_lock();
    for (i = 0; i < KPROBE_TABLE_SIZE; i++) {
    head = &kprobe_table[i];
    hlist_for_each_entry_rcu(p, node, head, hlist)
    arch_arm_kprobe(p);
    }
    + kernel_text_unlock();

    kprobe_enabled = true;
    printk(KERN_INFO "Kprobes globally enabled\n");
    @@ -967,6 +972,7 @@ static void __kprobes disable_all_kprobe

    kprobe_enabled = false;
    printk(KERN_INFO "Kprobes globally disabled\n");
    + kernel_text_lock();
    for (i = 0; i < KPROBE_TABLE_SIZE; i++) {
    head = &kprobe_table[i];
    hlist_for_each_entry_rcu(p, node, head, hlist) {
    @@ -974,6 +980,7 @@ static void __kprobes disable_all_kprobe
    arch_disarm_kprobe(p);
    }
    }
    + kernel_text_unlock();

    mutex_unlock(&kprobe_mutex);
    /* Allow all currently running kprobes to complete */
    --
    Mathieu Desnoyers
    Computer Engineering Ph.D. Student, Ecole Polytechnique de Montreal
    OpenPGP key fingerprint: 8CD5 52C3 8E3C 4140 715F BA06 3F25 A8FE 3BAE 9A68


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