1 | // SPDX-License-Identifier: GPL-2.0 |
2 | #include <linux/spinlock.h> |
3 | #include <linux/hardirq.h> |
4 | #include <linux/ftrace.h> |
5 | #include <linux/percpu.h> |
6 | #include <linux/init.h> |
7 | #include <linux/list.h> |
8 | #include <trace/syscall.h> |
9 | |
10 | #include <asm/ftrace.h> |
11 | |
12 | #ifdef CONFIG_DYNAMIC_FTRACE |
13 | static const u32 ftrace_nop = 0x01000000; |
14 | |
15 | static u32 ftrace_call_replace(unsigned long ip, unsigned long addr) |
16 | { |
17 | u32 call; |
18 | s32 off; |
19 | |
20 | off = ((s32)addr - (s32)ip); |
21 | call = 0x40000000 | ((u32)off >> 2); |
22 | |
23 | return call; |
24 | } |
25 | |
26 | static int ftrace_modify_code(unsigned long ip, u32 old, u32 new) |
27 | { |
28 | u32 replaced; |
29 | int faulted; |
30 | |
31 | __asm__ __volatile__( |
32 | "1: cas [%[ip]], %[old], %[new]\n" |
33 | " flush %[ip]\n" |
34 | " mov 0, %[faulted]\n" |
35 | "2:\n" |
36 | " .section .fixup,#alloc,#execinstr\n" |
37 | " .align 4\n" |
38 | "3: sethi %%hi(2b), %[faulted]\n" |
39 | " jmpl %[faulted] + %%lo(2b), %%g0\n" |
40 | " mov 1, %[faulted]\n" |
41 | " .previous\n" |
42 | " .section __ex_table,\"a\"\n" |
43 | " .align 4\n" |
44 | " .word 1b, 3b\n" |
45 | " .previous\n" |
46 | : "=r" (replaced), [faulted] "=r" (faulted) |
47 | : [new] "0" (new), [old] "r" (old), [ip] "r" (ip) |
48 | : "memory" ); |
49 | |
50 | if (replaced != old && replaced != new) |
51 | faulted = 2; |
52 | |
53 | return faulted; |
54 | } |
55 | |
56 | int ftrace_make_nop(struct module *mod, struct dyn_ftrace *rec, unsigned long addr) |
57 | { |
58 | unsigned long ip = rec->ip; |
59 | u32 old, new; |
60 | |
61 | old = ftrace_call_replace(ip, addr); |
62 | new = ftrace_nop; |
63 | return ftrace_modify_code(ip, old, new); |
64 | } |
65 | |
66 | int ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr) |
67 | { |
68 | unsigned long ip = rec->ip; |
69 | u32 old, new; |
70 | |
71 | old = ftrace_nop; |
72 | new = ftrace_call_replace(ip, addr); |
73 | return ftrace_modify_code(ip, old, new); |
74 | } |
75 | |
76 | int ftrace_update_ftrace_func(ftrace_func_t func) |
77 | { |
78 | unsigned long ip = (unsigned long)(&ftrace_call); |
79 | u32 old, new; |
80 | |
81 | old = *(u32 *) &ftrace_call; |
82 | new = ftrace_call_replace(ip, addr: (unsigned long)func); |
83 | return ftrace_modify_code(ip, old, new); |
84 | } |
85 | #endif |
86 | |
87 | #ifdef CONFIG_FUNCTION_GRAPH_TRACER |
88 | |
89 | #ifdef CONFIG_DYNAMIC_FTRACE |
90 | extern void ftrace_graph_call(void); |
91 | |
92 | int ftrace_enable_ftrace_graph_caller(void) |
93 | { |
94 | unsigned long ip = (unsigned long)(&ftrace_graph_call); |
95 | u32 old, new; |
96 | |
97 | old = *(u32 *) &ftrace_graph_call; |
98 | new = ftrace_call_replace(ip, addr: (unsigned long) &ftrace_graph_caller); |
99 | return ftrace_modify_code(ip, old, new); |
100 | } |
101 | |
102 | int ftrace_disable_ftrace_graph_caller(void) |
103 | { |
104 | unsigned long ip = (unsigned long)(&ftrace_graph_call); |
105 | u32 old, new; |
106 | |
107 | old = *(u32 *) &ftrace_graph_call; |
108 | new = ftrace_call_replace(ip, addr: (unsigned long) &ftrace_stub); |
109 | |
110 | return ftrace_modify_code(ip, old, new); |
111 | } |
112 | |
113 | #endif /* !CONFIG_DYNAMIC_FTRACE */ |
114 | |
115 | /* |
116 | * Hook the return address and push it in the stack of return addrs |
117 | * in current thread info. |
118 | */ |
119 | unsigned long prepare_ftrace_return(unsigned long parent, |
120 | unsigned long self_addr, |
121 | unsigned long frame_pointer) |
122 | { |
123 | unsigned long return_hooker = (unsigned long) &return_to_handler; |
124 | |
125 | if (unlikely(atomic_read(¤t->tracing_graph_pause))) |
126 | return parent + 8UL; |
127 | |
128 | if (function_graph_enter(ret: parent, func: self_addr, frame_pointer, NULL)) |
129 | return parent + 8UL; |
130 | |
131 | return return_hooker; |
132 | } |
133 | #endif /* CONFIG_FUNCTION_GRAPH_TRACER */ |
134 | |