arch/sparc/kernel/ftrace.c

   1 #include <linux/spinlock.h>
   2 #include <linux/hardirq.h>
   3 #include <linux/ftrace.h>
   4 #include <linux/percpu.h>
   5 #include <linux/init.h>
   6 #include <linux/list.h>
   7 #include <trace/syscall.h>
   8
   9 #include <asm/ftrace.h>
  10
  11 #ifdef CONFIG_DYNAMIC_FTRACE
  12 static const u32 ftrace_nop = 0x01000000;
  13
  14 static u32 ftrace_call_replace(unsigned long ip, unsigned long addr)
  15 {
  16         static u32 call;
  17         s32 off;
  18
  19         off = ((s32)addr - (s32)ip);
  20         call = 0x40000000 | ((u32)off >> 2);
  21
  22         return call;
  23 }
  24
  25 static int ftrace_modify_code(unsigned long ip, u32 old, u32 new)
  26 {
  27         u32 replaced;
  28         int faulted;
  29
  30         __asm__ __volatile__(
  31         "1:     cas     [%[ip]], %[old], %[new]\n"
  32         "       flush   %[ip]\n"
  33         "       mov     0, %[faulted]\n"
  34         "2:\n"
  35         "       .section .fixup,#alloc,#execinstr\n"
  36         "       .align  4\n"
  37         "3:     sethi   %%hi(2b), %[faulted]\n"
  38         "       jmpl    %[faulted] + %%lo(2b), %%g0\n"
  39         "        mov    1, %[faulted]\n"
  40         "       .previous\n"
  41         "       .section __ex_table,\"a\"\n"
  42         "       .align  4\n"
  43         "       .word   1b, 3b\n"
  44         "       .previous\n"
  45         : "=r" (replaced), [faulted] "=r" (faulted)
  46         : [new] "0" (new), [old] "r" (old), [ip] "r" (ip)
  47         : "memory");
  48
  49         if (replaced != old && replaced != new)
  50                 faulted = 2;
  51
  52         return faulted;
  53 }
  54
  55 int ftrace_make_nop(struct module *mod, struct dyn_ftrace *rec, unsigned long addr)
  56 {
  57         unsigned long ip = rec->ip;
  58         u32 old, new;
  59
  60         old = ftrace_call_replace(ip, addr);
  61         new = ftrace_nop;
  62         return ftrace_modify_code(ip, old, new);
  63 }
  64
  65 int ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr)
  66 {
  67         unsigned long ip = rec->ip;
  68         u32 old, new;
  69
  70         old = ftrace_nop;
  71         new = ftrace_call_replace(ip, addr);
  72         return ftrace_modify_code(ip, old, new);
  73 }
  74
  75 int ftrace_update_ftrace_func(ftrace_func_t func)
  76 {
  77         unsigned long ip = (unsigned long)(&ftrace_call);
  78         u32 old, new;
  79
  80         old = *(u32 *) &ftrace_call;
  81         new = ftrace_call_replace(ip, (unsigned long)func);
  82         return ftrace_modify_code(ip, old, new);
  83 }
  84
  85 int __init ftrace_dyn_arch_init(void *data)
  86 {
  87         unsigned long *p = data;
  88
  89         *p = 0;
  90
  91         return 0;
  92 }
  93 #endif