Commit | Line | Data |
---|---|---|
4e491d14 SR |
1 | /* |
2 | * Code for replacing ftrace calls with jumps. | |
3 | * | |
4 | * Copyright (C) 2007-2008 Steven Rostedt <srostedt@redhat.com> | |
5 | * | |
6 | * Thanks goes out to P.A. Semi, Inc for supplying me with a PPC64 box. | |
7 | * | |
8 | */ | |
9 | ||
10 | #include <linux/spinlock.h> | |
11 | #include <linux/hardirq.h> | |
12 | #include <linux/ftrace.h> | |
13 | #include <linux/percpu.h> | |
14 | #include <linux/init.h> | |
15 | #include <linux/list.h> | |
16 | ||
17 | #include <asm/cacheflush.h> | |
395a59d0 | 18 | #include <asm/ftrace.h> |
4e491d14 | 19 | |
4e491d14 SR |
20 | |
21 | static unsigned int ftrace_nop = 0x60000000; | |
22 | ||
23 | #ifdef CONFIG_PPC32 | |
24 | # define GET_ADDR(addr) addr | |
25 | #else | |
26 | /* PowerPC64's functions are data that points to the functions */ | |
27 | # define GET_ADDR(addr) *(unsigned long *)addr | |
28 | #endif | |
29 | ||
395a59d0 | 30 | |
4e491d14 SR |
31 | static unsigned int notrace ftrace_calc_offset(long ip, long addr) |
32 | { | |
395a59d0 | 33 | return (int)(addr - ip); |
4e491d14 SR |
34 | } |
35 | ||
36 | notrace unsigned char *ftrace_nop_replace(void) | |
37 | { | |
38 | return (char *)&ftrace_nop; | |
39 | } | |
40 | ||
41 | notrace unsigned char *ftrace_call_replace(unsigned long ip, unsigned long addr) | |
42 | { | |
43 | static unsigned int op; | |
44 | ||
ccbfac29 SR |
45 | /* |
46 | * It would be nice to just use create_function_call, but that will | |
47 | * update the code itself. Here we need to just return the | |
48 | * instruction that is going to be modified, without modifying the | |
49 | * code. | |
50 | */ | |
4e491d14 SR |
51 | addr = GET_ADDR(addr); |
52 | ||
53 | /* Set to "bl addr" */ | |
ccbfac29 | 54 | op = 0x48000001 | (ftrace_calc_offset(ip, addr) & 0x03fffffc); |
4e491d14 SR |
55 | |
56 | /* | |
57 | * No locking needed, this must be called via kstop_machine | |
58 | * which in essence is like running on a uniprocessor machine. | |
59 | */ | |
60 | return (unsigned char *)&op; | |
61 | } | |
62 | ||
63 | #ifdef CONFIG_PPC64 | |
64 | # define _ASM_ALIGN " .align 3 " | |
65 | # define _ASM_PTR " .llong " | |
66 | #else | |
67 | # define _ASM_ALIGN " .align 2 " | |
68 | # define _ASM_PTR " .long " | |
69 | #endif | |
70 | ||
71 | notrace int | |
72 | ftrace_modify_code(unsigned long ip, unsigned char *old_code, | |
73 | unsigned char *new_code) | |
74 | { | |
75 | unsigned replaced; | |
76 | unsigned old = *(unsigned *)old_code; | |
77 | unsigned new = *(unsigned *)new_code; | |
78 | int faulted = 0; | |
79 | ||
4e491d14 SR |
80 | /* |
81 | * Note: Due to modules and __init, code can | |
82 | * disappear and change, we need to protect against faulting | |
83 | * as well as code changing. | |
84 | * | |
85 | * No real locking needed, this code is run through | |
86 | * kstop_machine. | |
87 | */ | |
88 | asm volatile ( | |
89 | "1: lwz %1, 0(%2)\n" | |
90 | " cmpw %1, %5\n" | |
91 | " bne 2f\n" | |
92 | " stwu %3, 0(%2)\n" | |
93 | "2:\n" | |
94 | ".section .fixup, \"ax\"\n" | |
95 | "3: li %0, 1\n" | |
96 | " b 2b\n" | |
97 | ".previous\n" | |
98 | ".section __ex_table,\"a\"\n" | |
99 | _ASM_ALIGN "\n" | |
100 | _ASM_PTR "1b, 3b\n" | |
101 | ".previous" | |
102 | : "=r"(faulted), "=r"(replaced) | |
103 | : "r"(ip), "r"(new), | |
104 | "0"(faulted), "r"(old) | |
105 | : "memory"); | |
106 | ||
107 | if (replaced != old && replaced != new) | |
108 | faulted = 2; | |
109 | ||
110 | if (!faulted) | |
111 | flush_icache_range(ip, ip + 8); | |
112 | ||
113 | return faulted; | |
114 | } | |
115 | ||
116 | notrace int ftrace_update_ftrace_func(ftrace_func_t func) | |
117 | { | |
118 | unsigned long ip = (unsigned long)(&ftrace_call); | |
395a59d0 | 119 | unsigned char old[MCOUNT_INSN_SIZE], *new; |
4e491d14 SR |
120 | int ret; |
121 | ||
395a59d0 | 122 | memcpy(old, &ftrace_call, MCOUNT_INSN_SIZE); |
4e491d14 SR |
123 | new = ftrace_call_replace(ip, (unsigned long)func); |
124 | ret = ftrace_modify_code(ip, old, new); | |
125 | ||
126 | return ret; | |
127 | } | |
128 | ||
129 | notrace int ftrace_mcount_set(unsigned long *data) | |
130 | { | |
131 | unsigned long ip = (long)(&mcount_call); | |
132 | unsigned long *addr = data; | |
395a59d0 | 133 | unsigned char old[MCOUNT_INSN_SIZE], *new; |
4e491d14 SR |
134 | |
135 | /* | |
136 | * Replace the mcount stub with a pointer to the | |
137 | * ip recorder function. | |
138 | */ | |
395a59d0 | 139 | memcpy(old, &mcount_call, MCOUNT_INSN_SIZE); |
4e491d14 SR |
140 | new = ftrace_call_replace(ip, *addr); |
141 | *addr = ftrace_modify_code(ip, old, new); | |
142 | ||
143 | return 0; | |
144 | } | |
145 | ||
146 | int __init ftrace_dyn_arch_init(void *data) | |
147 | { | |
148 | /* This is running in kstop_machine */ | |
149 | ||
150 | ftrace_mcount_set(data); | |
151 | ||
152 | return 0; | |
153 | } | |
154 |