Logo Search packages:      
Sourcecode: linux version File versions

ftrace.c

#include <linux/spinlock.h>
#include <linux/hardirq.h>
#include <linux/ftrace.h>
#include <linux/percpu.h>
#include <linux/init.h>
#include <linux/list.h>

#include <asm/ftrace.h>

static const u32 ftrace_nop = 0x01000000;

notrace unsigned char *ftrace_nop_replace(void)
{
      return (char *)&ftrace_nop;
}

notrace unsigned char *ftrace_call_replace(unsigned long ip, unsigned long addr)
{
      static u32 call;
      s32 off;

      off = ((s32)addr - (s32)ip);
      call = 0x40000000 | ((u32)off >> 2);

      return (unsigned char *) &call;
}

notrace int
ftrace_modify_code(unsigned long ip, unsigned char *old_code,
               unsigned char *new_code)
{
      u32 old = *(u32 *)old_code;
      u32 new = *(u32 *)new_code;
      u32 replaced;
      int faulted;

      __asm__ __volatile__(
      "1:   cas   [%[ip]], %[old], %[new]\n"
      "     flush %[ip]\n"
      "     mov   0, %[faulted]\n"
      "2:\n"
      "     .section .fixup,#alloc,#execinstr\n"
      "     .align      4\n"
      "3:   sethi %%hi(2b), %[faulted]\n"
      "     jmpl  %[faulted] + %%lo(2b), %%g0\n"
      "      mov  1, %[faulted]\n"
      "     .previous\n"
      "     .section __ex_table,\"a\"\n"
      "     .align      4\n"
      "     .word 1b, 3b\n"
      "     .previous\n"
      : "=r" (replaced), [faulted] "=r" (faulted)
      : [new] "0" (new), [old] "r" (old), [ip] "r" (ip)
      : "memory");

      if (replaced != old && replaced != new)
            faulted = 2;

      return faulted;
}

notrace int ftrace_update_ftrace_func(ftrace_func_t func)
{
      unsigned long ip = (unsigned long)(&ftrace_call);
      unsigned char old[MCOUNT_INSN_SIZE], *new;

      memcpy(old, &ftrace_call, MCOUNT_INSN_SIZE);
      new = ftrace_call_replace(ip, (unsigned long)func);
      return ftrace_modify_code(ip, old, new);
}

notrace int ftrace_mcount_set(unsigned long *data)
{
      unsigned long ip = (long)(&mcount_call);
      unsigned long *addr = data;
      unsigned char old[MCOUNT_INSN_SIZE], *new;

      /*
       * Replace the mcount stub with a pointer to the
       * ip recorder function.
       */
      memcpy(old, &mcount_call, MCOUNT_INSN_SIZE);
      new = ftrace_call_replace(ip, *addr);
      *addr = ftrace_modify_code(ip, old, new);

      return 0;
}


int __init ftrace_dyn_arch_init(void *data)
{
      ftrace_mcount_set(data);
      return 0;
}

Generated by  Doxygen 1.6.0   Back to index