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