arch/sparc64/lib/mcount.S

   1 /*
   2  * Copyright (C) 2000 Anton Blanchard (anton@linuxcare.com)
   3  *
   4  * This file implements mcount(), which is used to collect profiling data.
   5  * This can also be tweaked for kernel stack overflow detection.
   6  */
   7
   8 #include <linux/config.h>
   9 #include <linux/linkage.h>
  10
  11 #include <asm/ptrace.h>
  12 #include <asm/thread_info.h>
  13
  14 /*
  15  * This is the main variant and is called by C code.  GCC's -pg option
  16  * automatically instruments every C function with a call to this.
  17  */
  18
  19 #ifdef CONFIG_STACK_DEBUG
  20
  21 #define OVSTACKSIZE     4096            /* lets hope this is enough */
  22
  23         .data
  24         .align          8
  25 panicstring:
  26         .asciz          "Stack overflow\n"
  27         .align          8
  28 ovstack:
  29         .skip           OVSTACKSIZE
  30 #endif
  31         .text
  32         .align 32
  33         .globl mcount, _mcount
  34 mcount:
  35 _mcount:
  36 #ifdef CONFIG_STACK_DEBUG
  37         /*
  38          * Check whether %sp is dangerously low.
  39          */
  40         ldub            [%g6 + TI_FPDEPTH], %g1
  41         srl             %g1, 1, %g3
  42         add             %g3, 1, %g3
  43         sllx            %g3, 8, %g3                     ! each fpregs frame is 256b
  44         add             %g3, 192, %g3
  45         add             %g6, %g3, %g3                   ! where does task_struct+frame end?
  46         sub             %g3, STACK_BIAS, %g3
  47         cmp             %sp, %g3
  48         bg,pt           %xcc, 1f
  49          sethi          %hi(panicstring), %g3
  50         sethi           %hi(ovstack), %g7               ! cant move to panic stack fast enough
  51          or             %g7, %lo(ovstack), %g7
  52         add             %g7, OVSTACKSIZE, %g7
  53         sub             %g7, STACK_BIAS, %g7
  54         mov             %g7, %sp
  55         call            prom_printf
  56          or             %g3, %lo(panicstring), %o0
  57         call            prom_halt
  58          nop
  59 #endif
  60 1:      retl
  61          nop