root/arch/xtensa/kernel/mcount.S

   1 /*
   2  * arch/xtensa/kernel/mcount.S
   3  *
   4  * Xtensa specific mcount support
   5  *
   6  * This file is subject to the terms and conditions of the GNU General Public
   7  * License.  See the file "COPYING" in the main directory of this archive
   8  * for more details.
   9  *
  10  * Copyright (C) 2013 Tensilica Inc.
  11  */
  12 
  13 #include <linux/linkage.h>
  14 #include <asm/asmmacro.h>
  15 #include <asm/ftrace.h>
  16 
  17 /*
  18  * Entry condition:
  19  *
  20  *   a2:        a0 of the caller
  21  */
  22 
  23 ENTRY(_mcount)
  24 
  25         abi_entry_default
  26 
  27         movi    a4, ftrace_trace_function
  28         l32i    a4, a4, 0
  29         movi    a3, ftrace_stub
  30         bne     a3, a4, 1f
  31         abi_ret_default
  32 
  33 1:      xor     a7, a2, a1
  34         movi    a3, 0x3fffffff
  35         and     a7, a7, a3
  36         xor     a7, a7, a1
  37 
  38         xor     a6, a0, a1
  39         and     a6, a6, a3
  40         xor     a6, a6, a1
  41         addi    a6, a6, -MCOUNT_INSN_SIZE
  42         callx4  a4
  43 
  44         abi_ret_default
  45 
  46 ENDPROC(_mcount)
  47 
  48 ENTRY(ftrace_stub)
  49         abi_entry_default
  50         abi_ret_default
  51 ENDPROC(ftrace_stub)