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 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 94 95 #ifdef CONFIG_FUNCTION_GRAPH_TRACER 96 97 #ifdef CONFIG_DYNAMIC_FTRACE 98 extern void ftrace_graph_call(void); 99 100 int ftrace_enable_ftrace_graph_caller(void) 101 { 102 unsigned long ip = (unsigned long)(&ftrace_graph_call); 103 u32 old, new; 104 105 old = *(u32 *) &ftrace_graph_call; 106 new = ftrace_call_replace(ip, (unsigned long) &ftrace_graph_caller); 107 return ftrace_modify_code(ip, old, new); 108 } 109 110 int ftrace_disable_ftrace_graph_caller(void) 111 { 112 unsigned long ip = (unsigned long)(&ftrace_graph_call); 113 u32 old, new; 114 115 old = *(u32 *) &ftrace_graph_call; 116 new = ftrace_call_replace(ip, (unsigned long) &ftrace_stub); 117 118 return ftrace_modify_code(ip, old, new); 119 } 120 121 #endif /* !CONFIG_DYNAMIC_FTRACE */ 122 123 /* 124 * Hook the return address and push it in the stack of return addrs 125 * in current thread info. 126 */ 127 unsigned long prepare_ftrace_return(unsigned long parent, 128 unsigned long self_addr, 129 unsigned long frame_pointer) 130 { 131 unsigned long return_hooker = (unsigned long) &return_to_handler; 132 struct ftrace_graph_ent trace; 133 134 if (unlikely(atomic_read(¤t->tracing_graph_pause))) 135 return parent + 8UL; 136 137 if (ftrace_push_return_trace(parent, self_addr, &trace.depth, 138 frame_pointer) == -EBUSY) 139 return parent + 8UL; 140 141 trace.func = self_addr; 142 143 /* Only trace if the calling function expects to */ 144 if (!ftrace_graph_entry(&trace)) { 145 current->curr_ret_stack--; 146 return parent + 8UL; 147 } 148 149 return return_hooker; 150 } 151 #endif /* CONFIG_FUNCTION_GRAPH_TRACER */ 152