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) 86 { 87 return 0; 88 } 89 #endif 90 91 #ifdef CONFIG_FUNCTION_GRAPH_TRACER 92 93 #ifdef CONFIG_DYNAMIC_FTRACE 94 extern void ftrace_graph_call(void); 95 96 int ftrace_enable_ftrace_graph_caller(void) 97 { 98 unsigned long ip = (unsigned long)(&ftrace_graph_call); 99 u32 old, new; 100 101 old = *(u32 *) &ftrace_graph_call; 102 new = ftrace_call_replace(ip, (unsigned long) &ftrace_graph_caller); 103 return ftrace_modify_code(ip, old, new); 104 } 105 106 int ftrace_disable_ftrace_graph_caller(void) 107 { 108 unsigned long ip = (unsigned long)(&ftrace_graph_call); 109 u32 old, new; 110 111 old = *(u32 *) &ftrace_graph_call; 112 new = ftrace_call_replace(ip, (unsigned long) &ftrace_stub); 113 114 return ftrace_modify_code(ip, old, new); 115 } 116 117 #endif /* !CONFIG_DYNAMIC_FTRACE */ 118 119 /* 120 * Hook the return address and push it in the stack of return addrs 121 * in current thread info. 122 */ 123 unsigned long prepare_ftrace_return(unsigned long parent, 124 unsigned long self_addr, 125 unsigned long frame_pointer) 126 { 127 unsigned long return_hooker = (unsigned long) &return_to_handler; 128 struct ftrace_graph_ent trace; 129 130 if (unlikely(atomic_read(¤t->tracing_graph_pause))) 131 return parent + 8UL; 132 133 if (ftrace_push_return_trace(parent, self_addr, &trace.depth, 134 frame_pointer) == -EBUSY) 135 return parent + 8UL; 136 137 trace.func = self_addr; 138 139 /* Only trace if the calling function expects to */ 140 if (!ftrace_graph_entry(&trace)) { 141 current->curr_ret_stack--; 142 return parent + 8UL; 143 } 144 145 return return_hooker; 146 } 147 #endif /* CONFIG_FUNCTION_GRAPH_TRACER */ 148