kprobes: Use text_poke_smp_batch for unoptimizing

Use text_poke_smp_batch() on unoptimization path for reducing
the number of stop_machine() issues. If the number of
unoptimizing probes is more than MAX_OPTIMIZE_PROBES(=256),
kprobes unoptimizes first MAX_OPTIMIZE_PROBES probes and kicks
optimizer for remaining probes.

Signed-off-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ananth N Mavinakayanahalli <ananth@in.ibm.com>
Cc: Jason Baron <jbaron@redhat.com>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: 2nddept-manager@sdl.hitachi.co.jp
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Steven Rostedt <rostedt@goodmis.org>
LKML-Reference: <20101203095434.2961.22657.stgit@ltc236.sdl.hitachi.co.jp>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 40 insertions, 0 deletions

diff --git a/arch/x86/kernel/kprobes.c b/arch/x86/kernel/kprobes.c
index 25a8af76feb..5940282bd2f 100644
--- a/arch/x86/kernel/kprobes.c
+++ b/arch/x86/kernel/kprobes.c
@@ -1457,6 +1457,46 @@ void __kprobes arch_optimize_kprobes(struct list_head *oplist)
         text_poke_smp_batch(jump_poke_params, c);
 }
 
+static void __kprobes setup_unoptimize_kprobe(struct text_poke_param *tprm,
+                                              u8 *insn_buf,
+                                              struct optimized_kprobe *op)
+{
+        /* Set int3 to first byte for kprobes */
+        insn_buf[0] = BREAKPOINT_INSTRUCTION;
+        memcpy(insn_buf + 1, op->optinsn.copied_insn, RELATIVE_ADDR_SIZE);
+
+        tprm->addr = op->kp.addr;
+        tprm->opcode = insn_buf;
+        tprm->len = RELATIVEJUMP_SIZE;
+}
+
+/*
+ * Recover original instructions and breakpoints from relative jumps.
+ * Caller must call with locking kprobe_mutex.
+ */
+extern void arch_unoptimize_kprobes(struct list_head *oplist,
+                                    struct list_head *done_list)
+{
+        struct optimized_kprobe *op, *tmp;
+        int c = 0;
+
+        list_for_each_entry_safe(op, tmp, oplist, list) {
+                /* Setup param */
+                setup_unoptimize_kprobe(&jump_poke_params[c],
+                                        jump_poke_bufs[c].buf, op);
+                list_move(&op->list, done_list);
+                if (++c >= MAX_OPTIMIZE_PROBES)
+                        break;
+        }
+
+        /*
+         * text_poke_smp doesn't support NMI/MCE code modifying.
+         * However, since kprobes itself also doesn't support NMI/MCE
+         * code probing, it's not a problem.
+         */
+        text_poke_smp_batch(jump_poke_params, c);
+}
+
 /* Replace a relative jump with a breakpoint (int3).  */
 void __kprobes arch_unoptimize_kprobe(struct optimized_kprobe *op)
 {