[IA64] kprobes: kprobe-booster for ia64

Add kprobe-booster support on ia64.

Kprobe-booster improves the performance of kprobes by eliminating single-step,
where possible.  Currently, kprobe-booster is implemented on x86 and x86-64.
This is an ia64 port.

On ia64, kprobe-booster executes a copied bundle directly, instead of single
stepping.  Bundles which have B or X unit and which may cause an exception
(including break) are not executed directly.  And also, to prevent hitting
break exceptions on the copied bundle, only the hindmost kprobe is executed
directly if several kprobes share a bundle and are placed in different slots.
Note: set_brl_inst() is used for preparing an instruction buffer(it does not
modify any active code), so it does not need any atomic operation.

Signed-off-by: Masami Hiramatsu <mhiramat@redhat.com>
Cc: Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com>
Cc: Ananth N Mavinakayanahalli <ananth@in.ibm.com>
Cc: bibo,mao <bibo.mao@intel.com>
Cc: Rusty Lynch <rusty.lynch@intel.com>
Cc: Prasanna S Panchamukhi <prasanna@in.ibm.com>
Cc: Jim Keniston <jkenisto@us.ibm.com>
Cc: Shaohua Li <shaohua.li@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Tony Luck <tony.luck@intel.com>

include/asm-ia64/kprobes.h

@@ -30,8 +30,12 @@
 #include <asm/break.h>
 
 #define __ARCH_WANT_KPROBES_INSN_SLOT
-#define MAX_INSN_SIZE   1
+#define MAX_INSN_SIZE   2	/* last half is for kprobe-booster */
 #define BREAK_INST	(long)(__IA64_BREAK_KPROBE << 6)
+#define NOP_M_INST	(long)(1<<27)
+#define BRL_INST(i1, i2) ((long)((0xcL << 37) |	/* brl */ \
+				(0x1L << 12) |	/* many */ \
+				(((i1) & 1) << 36) | ((i2) << 13))) /* imm */
 
 typedef union cmp_inst {
 	struct {
@@ -112,6 +116,7 @@ struct arch_specific_insn {
  #define INST_FLAG_FIX_RELATIVE_IP_ADDR		1
  #define INST_FLAG_FIX_BRANCH_REG		2
  #define INST_FLAG_BREAK_INST			4
+ #define INST_FLAG_BOOSTABLE			8
  	unsigned long inst_flag;
  	unsigned short target_br_reg;
 	unsigned short slot;