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 static const u32 ftrace_nop = 0x01000000; 11 12 unsigned char *ftrace_nop_replace(void) 13 { 14 return (char *)&ftrace_nop; 15 } 16 17 unsigned char *ftrace_call_replace(unsigned long ip, unsigned long addr) 18 { 19 static u32 call; 20 s32 off; 21 22 off = ((s32)addr - (s32)ip); 23 call = 0x40000000 | ((u32)off >> 2); 24 25 return (unsigned char *) &call; 26 } 27 28 int 29 ftrace_modify_code(unsigned long ip, unsigned char *old_code, 30 unsigned char *new_code) 31 { 32 u32 old = *(u32 *)old_code; 33 u32 new = *(u32 *)new_code; 34 u32 replaced; 35 int faulted; 36 37 __asm__ __volatile__( 38 "1: cas [%[ip]], %[old], %[new]\n" 39 " flush %[ip]\n" 40 " mov 0, %[faulted]\n" 41 "2:\n" 42 " .section .fixup,#alloc,#execinstr\n" 43 " .align 4\n" 44 "3: sethi %%hi(2b), %[faulted]\n" 45 " jmpl %[faulted] + %%lo(2b), %%g0\n" 46 " mov 1, %[faulted]\n" 47 " .previous\n" 48 " .section __ex_table,\"a\"\n" 49 " .align 4\n" 50 " .word 1b, 3b\n" 51 " .previous\n" 52 : "=r" (replaced), [faulted] "=r" (faulted) 53 : [new] "0" (new), [old] "r" (old), [ip] "r" (ip) 54 : "memory"); 55 56 if (replaced != old && replaced != new) 57 faulted = 2; 58 59 return faulted; 60 } 61 62 int ftrace_update_ftrace_func(ftrace_func_t func) 63 { 64 unsigned long ip = (unsigned long)(&ftrace_call); 65 unsigned char old[MCOUNT_INSN_SIZE], *new; 66 67 memcpy(old, &ftrace_call, MCOUNT_INSN_SIZE); 68 new = ftrace_call_replace(ip, (unsigned long)func); 69 return ftrace_modify_code(ip, old, new); 70 } 71 72 int __init ftrace_dyn_arch_init(void *data) 73 { 74 ftrace_mcount_set(data); 75 return 0; 76 } 77