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
13static const u32 ftrace_nop = 0x01000000;
14
15static 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
26static 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
56int 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
66int 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
76int 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
90extern void ftrace_graph_call(void);
91
92int 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
102int 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 */
119unsigned 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(&current->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

source code of linux/arch/sparc/kernel/ftrace.c