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    Subject[tip:perf/probes] tracing/kprobes: Fix profiling alignment for perf_counter buffer
    Commit-ID:  74ebb63e7cd25f6fb02a45fc2ea7735bce1217c9
    Gitweb: http://git.kernel.org/tip/74ebb63e7cd25f6fb02a45fc2ea7735bce1217c9
    Author: Masami Hiramatsu <mhiramat@redhat.com>
    AuthorDate: Mon, 14 Sep 2009 16:49:28 -0400
    Committer: Frederic Weisbecker <fweisbec@gmail.com>
    CommitDate: Thu, 17 Sep 2009 04:03:57 +0200

    tracing/kprobes: Fix profiling alignment for perf_counter buffer

    Fix *probe_profile_func() to align buffer size, since perf_counter
    requires its buffer entries to be 8 bytes aligned.

    Signed-off-by: Masami Hiramatsu <mhiramat@redhat.com>
    Acked-by: Steven Rostedt <rostedt@goodmis.org>
    Cc: Jim Keniston <jkenisto@us.ibm.com>
    Cc: Ananth N Mavinakayanahalli <ananth@in.ibm.com>
    Cc: Andi Kleen <ak@linux.intel.com>
    Cc: Christoph Hellwig <hch@infradead.org>
    Cc: Frank Ch. Eigler <fche@redhat.com>
    Cc: H. Peter Anvin <hpa@zytor.com>
    Cc: Ingo Molnar <mingo@elte.hu>
    Cc: Jason Baron <jbaron@redhat.com>
    Cc: K.Prasad <prasad@linux.vnet.ibm.com>
    Cc: Lai Jiangshan <laijs@cn.fujitsu.com>
    Cc: Li Zefan <lizf@cn.fujitsu.com>
    Cc: Peter Zijlstra <peterz@infradead.org>
    Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
    Cc: Tom Zanussi <tzanussi@gmail.com>
    LKML-Reference: <20090914204928.18779.60029.stgit@dhcp-100-2-132.bos.redhat.com>
    Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
    ---
    kernel/trace/trace_kprobe.c | 17 ++++++++++++-----
    1 files changed, 12 insertions(+), 5 deletions(-)

    diff --git a/kernel/trace/trace_kprobe.c b/kernel/trace/trace_kprobe.c
    index 70b632c..d8db935 100644
    --- a/kernel/trace/trace_kprobe.c
    +++ b/kernel/trace/trace_kprobe.c
    @@ -1149,18 +1149,23 @@ static __kprobes int kprobe_profile_func(struct kprobe *kp,
    struct trace_probe *tp = container_of(kp, struct trace_probe, rp.kp);
    struct ftrace_event_call *call = &tp->call;
    struct kprobe_trace_entry *entry;
    - int size, i, pc;
    + int size, __size, i, pc;
    unsigned long irq_flags;

    local_save_flags(irq_flags);
    pc = preempt_count();

    - size = SIZEOF_KPROBE_TRACE_ENTRY(tp->nr_args);
    + __size = SIZEOF_KPROBE_TRACE_ENTRY(tp->nr_args);
    + size = ALIGN(__size + sizeof(u32), sizeof(u64));
    + size -= sizeof(u32);

    do {
    char raw_data[size];
    struct trace_entry *ent;
    -
    + /*
    + * Zero dead bytes from alignment to avoid stack leak
    + * to userspace
    + */
    *(u64 *)(&raw_data[size - sizeof(u64)]) = 0ULL;
    entry = (struct kprobe_trace_entry *)raw_data;
    ent = &entry->ent;
    @@ -1183,13 +1188,15 @@ static __kprobes int kretprobe_profile_func(struct kretprobe_instance *ri,
    struct trace_probe *tp = container_of(ri->rp, struct trace_probe, rp);
    struct ftrace_event_call *call = &tp->call;
    struct kretprobe_trace_entry *entry;
    - int size, i, pc;
    + int size, __size, i, pc;
    unsigned long irq_flags;

    local_save_flags(irq_flags);
    pc = preempt_count();

    - size = SIZEOF_KRETPROBE_TRACE_ENTRY(tp->nr_args);
    + __size = SIZEOF_KRETPROBE_TRACE_ENTRY(tp->nr_args);
    + size = ALIGN(__size + sizeof(u32), sizeof(u64));
    + size -= sizeof(u32);

    do {
    char raw_data[size];

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