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    Subject[PATCH] Text Edit Lock - kprobes architecture independent support (v3)
    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.
    Use text_mutex directly instead of a function.
    Remove whitespace modifications.

    (note : kprobes_mutex is always taken outside of text_mutex)

    Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
    Acked-by: Ananth N Mavinakayanahalli <ananth@in.ibm.com>
    Acked-by: Masami Hiramatsu <mhiramat@redhat.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 | 15 +++++++++++++--
    1 file changed, 13 insertions(+), 2 deletions(-)

    Index: linux-2.6-lttng/kernel/kprobes.c
    ===================================================================
    --- linux-2.6-lttng.orig/kernel/kprobes.c 2009-03-02 19:22:51.000000000 -0500
    +++ linux-2.6-lttng/kernel/kprobes.c 2009-03-03 09:11:17.000000000 -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>
    @@ -699,9 +700,10 @@ int __kprobes register_kprobe(struct kpr
    goto out;
    }

    + mutex_lock(&text_mutex);
    ret = arch_prepare_kprobe(p);
    if (ret)
    - goto out;
    + goto out_unlock_text;

    INIT_HLIST_NODE(&p->hlist);
    hlist_add_head_rcu(&p->hlist,
    @@ -710,6 +712,8 @@ int __kprobes register_kprobe(struct kpr
    if (kprobe_enabled)
    arch_arm_kprobe(p);

    +out_unlock_text:
    + mutex_unlock(&text_mutex);
    out:
    mutex_unlock(&kprobe_mutex);

    @@ -746,8 +750,11 @@ valid_p:
    * enabled and not gone - otherwise, the breakpoint would
    * already have been removed. We save on flushing icache.
    */
    - if (kprobe_enabled && !kprobe_gone(old_p))
    + if (kprobe_enabled && !kprobe_gone(old_p)) {
    + mutex_lock(&text_mutex);
    arch_disarm_kprobe(p);
    + mutex_unlock(&text_mutex);
    + }
    hlist_del_rcu(&old_p->hlist);
    } else {
    if (p->break_handler && !kprobe_gone(p))
    @@ -1280,12 +1287,14 @@ static void __kprobes enable_all_kprobes
    if (kprobe_enabled)
    goto already_enabled;

    + mutex_lock(&text_mutex);
    for (i = 0; i < KPROBE_TABLE_SIZE; i++) {
    head = &kprobe_table[i];
    hlist_for_each_entry_rcu(p, node, head, hlist)
    if (!kprobe_gone(p))
    arch_arm_kprobe(p);
    }
    + mutex_unlock(&text_mutex);

    kprobe_enabled = true;
    printk(KERN_INFO "Kprobes globally enabled\n");
    @@ -1310,6 +1319,7 @@ static void __kprobes disable_all_kprobe

    kprobe_enabled = false;
    printk(KERN_INFO "Kprobes globally disabled\n");
    + mutex_lock(&text_mutex);
    for (i = 0; i < KPROBE_TABLE_SIZE; i++) {
    head = &kprobe_table[i];
    hlist_for_each_entry_rcu(p, node, head, hlist) {
    @@ -1318,6 +1328,7 @@ static void __kprobes disable_all_kprobe
    }
    }

    + mutex_unlock(&text_mutex);
    mutex_unlock(&kprobe_mutex);
    /* Allow all currently running kprobes to complete */
    synchronize_sched();
    --
    Mathieu Desnoyers
    OpenPGP key fingerprint: 8CD5 52C3 8E3C 4140 715F BA06 3F25 A8FE 3BAE 9A68


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