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 94