arch/s390/kernel/mcount.S

   1 /*
   2  * Copyright IBM Corp. 2008, 2009
   3  *
   4  *   Author(s): Heiko Carstens <heiko.carstens@de.ibm.com>,
   5  *
   6  */
   7
   8 #include <linux/linkage.h>
   9 #include <asm/asm-offsets.h>
  10 #include <asm/ftrace.h>
  11
  12         .section .kprobes.text, "ax"
  13
  14 ENTRY(ftrace_stub)
  15         br      %r14
  16
  17 ENTRY(_mcount)
  18 #ifdef CONFIG_DYNAMIC_FTRACE
  19         br      %r14
  20
  21 ENTRY(ftrace_caller)
  22 #endif
  23         stm     %r2,%r5,16(%r15)
  24         bras    %r1,2f
  25 0:      .long   ftrace_trace_function
  26 1:      .long   function_trace_stop
  27 2:      l       %r2,1b-0b(%r1)
  28         icm     %r2,0xf,0(%r2)
  29         jnz     3f
  30         st      %r14,56(%r15)
  31         lr      %r0,%r15
  32         ahi     %r15,-96
  33         l       %r3,100(%r15)
  34         la      %r2,0(%r14)
  35         st      %r0,__SF_BACKCHAIN(%r15)
  36         la      %r3,0(%r3)
  37         ahi     %r2,-MCOUNT_INSN_SIZE
  38         l       %r14,0b-0b(%r1)
  39         l       %r14,0(%r14)
  40         basr    %r14,%r14
  41 #ifdef CONFIG_FUNCTION_GRAPH_TRACER
  42         l       %r2,100(%r15)
  43         l       %r3,152(%r15)
  44 ENTRY(ftrace_graph_caller)
  45 # The bras instruction gets runtime patched to call prepare_ftrace_return.
  46 # See ftrace_enable_ftrace_graph_caller. The patched instruction is:
  47 #       bras    %r14,prepare_ftrace_return
  48         bras    %r14,0f
  49 0:      st      %r2,100(%r15)
  50 #endif
  51         ahi     %r15,96
  52         l       %r14,56(%r15)
  53 3:      lm      %r2,%r5,16(%r15)
  54         br      %r14
  55
  56 #ifdef CONFIG_FUNCTION_GRAPH_TRACER
  57
  58 ENTRY(return_to_handler)
  59         stm     %r2,%r5,16(%r15)
  60         st      %r14,56(%r15)
  61         lr      %r0,%r15
  62         ahi     %r15,-96
  63         st      %r0,__SF_BACKCHAIN(%r15)
  64         bras    %r1,0f
  65         .long   ftrace_return_to_handler
  66 0:      l       %r2,0b-0b(%r1)
  67         basr    %r14,%r2
  68         lr      %r14,%r2
  69         ahi     %r15,96
  70         lm      %r2,%r5,16(%r15)
  71         br      %r14
  72
  73 #endif