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>

diff --git a/kernel/trace/trace_kprobe.c b/kernel/trace/trace_kprobe.c
index 70b632c..d8db935 100644 (file)
--- 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];