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
  11         .section .kprobes.text, "ax"
  12
  13 ENTRY(ftrace_stub)
  14         br      %r14
  15
  16 ENTRY(_mcount)
  17 #ifdef CONFIG_DYNAMIC_FTRACE
  18         br      %r14
  19
  20 ENTRY(ftrace_caller)
  21 #endif
  22         stm     %r2,%r5,16(%r15)
  23         bras    %r1,2f
  24 0:      .long   ftrace_trace_function
  25 1:      .long   function_trace_stop
  26 2:      l       %r2,1b-0b(%r1)
  27         icm     %r2,0xf,0(%r2)
  28         jnz     3f
  29         st      %r14,56(%r15)
  30         lr      %r0,%r15
  31         ahi     %r15,-96
  32         l       %r3,100(%r15)
  33         la      %r2,0(%r14)
  34         st      %r0,__SF_BACKCHAIN(%r15)
  35         la      %r3,0(%r3)
  36         l       %r14,0b-0b(%r1)
  37         l       %r14,0(%r14)
  38         basr    %r14,%r14
  39 #ifdef CONFIG_FUNCTION_GRAPH_TRACER
  40         l       %r2,100(%r15)
  41         l       %r3,152(%r15)
  42 ENTRY(ftrace_graph_caller)
  43 # The bras instruction gets runtime patched to call prepare_ftrace_return.
  44 # See ftrace_enable_ftrace_graph_caller. The patched instruction is:
  45 #       bras    %r14,prepare_ftrace_return
  46         bras    %r14,0f
  47 0:      st      %r2,100(%r15)
  48 #endif
  49         ahi     %r15,96
  50         l       %r14,56(%r15)
  51 3:      lm      %r2,%r5,16(%r15)
  52         br      %r14
  53
  54 #ifdef CONFIG_FUNCTION_GRAPH_TRACER
  55
  56 ENTRY(return_to_handler)
  57         stm     %r2,%r5,16(%r15)
  58         st      %r14,56(%r15)
  59         lr      %r0,%r15
  60         ahi     %r15,-96
  61         st      %r0,__SF_BACKCHAIN(%r15)
  62         bras    %r1,0f
  63         .long   ftrace_return_to_handler
  64 0:      l       %r2,0b-0b(%r1)
  65         basr    %r14,%r2
  66         lr      %r14,%r2
  67         ahi     %r15,96
  68         lm      %r2,%r5,16(%r15)
  69         br      %r14
  70
  71 #endif