kprobes: indirectly call kprobe_target

Call kprobe_target indirectly.  This prevents gcc to unroll a noinline
function in caller function.

I ported patches which had been discussed on
http://sources.redhat.com/bugzilla/show_bug.cgi?id=3542

Signed-off-by: Masami Hiramatsu <mhiramat@redhat.com>
Acked-by: Ananth N Mavinakayanahalli <ananth@in.ibm.com>
Cc: Jim Keniston <jkenisto@us.ibm.com>
Cc: David Miller <davem@davemloft.net>
Cc: Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 6 insertions, 15 deletions

diff --git a/kernel/test_kprobes.c b/kernel/test_kprobes.c
index 06b6395b45b2..9c0127ead6ab 100644
--- a/kernel/test_kprobes.c
+++ b/kernel/test_kprobes.c
@@ -22,21 +22,10 @@
 
 static u32 rand1, preh_val, posth_val, jph_val;
 static int errors, handler_errors, num_tests;
+static u32 (*target)(u32 value);
 
 static noinline u32 kprobe_target(u32 value)
 {
-        /*
-         * gcc ignores noinline on some architectures unless we stuff
-         * sufficient lard into the function. The get_kprobe() here is
-         * just for that.
-         *
-         * NOTE: We aren't concerned about the correctness of get_kprobe()
-         * here; hence, this call is neither under !preempt nor with the
-         * kprobe_mutex held. This is fine(tm)
-         */
-        if (get_kprobe((void *)0xdeadbeef))
-                printk(KERN_INFO "Kprobe smoke test: probe on 0xdeadbeef!\n");
-
         return (value / div_factor);
 }
 
@@ -74,7 +63,7 @@ static int test_kprobe(void)
                 return ret;
         }
 
-        ret = kprobe_target(rand1);
+        ret = target(rand1);
         unregister_kprobe(&kp);
 
         if (preh_val == 0) {
@@ -121,7 +110,7 @@ static int test_jprobe(void)
                 return ret;
         }
 
-        ret = kprobe_target(rand1);
+        ret = target(rand1);
         unregister_jprobe(&jp);
         if (jph_val == 0) {
                 printk(KERN_ERR "Kprobe smoke test failed: "
@@ -177,7 +166,7 @@ static int test_kretprobe(void)
                 return ret;
         }
 
-        ret = kprobe_target(rand1);
+        ret = target(rand1);
         unregister_kretprobe(&rp);
         if (krph_val != rand1) {
                 printk(KERN_ERR "Kprobe smoke test failed: "
@@ -193,6 +182,8 @@ int init_test_probes(void)
 {
         int ret;
 
+        target = kprobe_target;
+
         do {
                 rand1 = random32();
         } while (rand1 <= div_factor);