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authorSteven Rostedt <rostedt@goodmis.org>2008-05-14 23:49:44 -0400
committerThomas Gleixner <tglx@linutronix.de>2008-05-23 16:43:11 -0400
commit4e491d14f2506b218d678935c25a7027b79178b1 (patch)
treec61c3ca40fe85f8556c579e50e0cb563ffcd06da /arch/powerpc/kernel/ftrace.c
parente0eca07badc023a675a61906020b397da20f07c3 (diff)
ftrace: support for PowerPC
This patch adds full support for ftrace for PowerPC (both 64 and 32 bit). This includes dynamic tracing and function filtering. Signed-off-by: Steven Rostedt <srostedt@redhat.com> Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Diffstat (limited to 'arch/powerpc/kernel/ftrace.c')
-rw-r--r--arch/powerpc/kernel/ftrace.c165
1 files changed, 165 insertions, 0 deletions
diff --git a/arch/powerpc/kernel/ftrace.c b/arch/powerpc/kernel/ftrace.c
new file mode 100644
index 000000000000..5a4993fefa45
--- /dev/null
+++ b/arch/powerpc/kernel/ftrace.c
@@ -0,0 +1,165 @@
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>
18
19#define CALL_BACK 4
20
21static 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
30notrace int ftrace_ip_converted(unsigned long ip)
31{
32 unsigned int save;
33
34 ip -= CALL_BACK;
35 save = *(unsigned int *)ip;
36
37 return save == ftrace_nop;
38}
39
40static unsigned int notrace ftrace_calc_offset(long ip, long addr)
41{
42 return (int)((addr + CALL_BACK) - ip);
43}
44
45notrace unsigned char *ftrace_nop_replace(void)
46{
47 return (char *)&ftrace_nop;
48}
49
50notrace unsigned char *ftrace_call_replace(unsigned long ip, unsigned long addr)
51{
52 static unsigned int op;
53
54 addr = GET_ADDR(addr);
55
56 /* Set to "bl addr" */
57 op = 0x48000001 | (ftrace_calc_offset(ip, addr) & 0x03fffffe);
58
59 /*
60 * No locking needed, this must be called via kstop_machine
61 * which in essence is like running on a uniprocessor machine.
62 */
63 return (unsigned char *)&op;
64}
65
66#ifdef CONFIG_PPC64
67# define _ASM_ALIGN " .align 3 "
68# define _ASM_PTR " .llong "
69#else
70# define _ASM_ALIGN " .align 2 "
71# define _ASM_PTR " .long "
72#endif
73
74notrace int
75ftrace_modify_code(unsigned long ip, unsigned char *old_code,
76 unsigned char *new_code)
77{
78 unsigned replaced;
79 unsigned old = *(unsigned *)old_code;
80 unsigned new = *(unsigned *)new_code;
81 int faulted = 0;
82
83 /* move the IP back to the start of the call */
84 ip -= CALL_BACK;
85
86 /*
87 * Note: Due to modules and __init, code can
88 * disappear and change, we need to protect against faulting
89 * as well as code changing.
90 *
91 * No real locking needed, this code is run through
92 * kstop_machine.
93 */
94 asm volatile (
95 "1: lwz %1, 0(%2)\n"
96 " cmpw %1, %5\n"
97 " bne 2f\n"
98 " stwu %3, 0(%2)\n"
99 "2:\n"
100 ".section .fixup, \"ax\"\n"
101 "3: li %0, 1\n"
102 " b 2b\n"
103 ".previous\n"
104 ".section __ex_table,\"a\"\n"
105 _ASM_ALIGN "\n"
106 _ASM_PTR "1b, 3b\n"
107 ".previous"
108 : "=r"(faulted), "=r"(replaced)
109 : "r"(ip), "r"(new),
110 "0"(faulted), "r"(old)
111 : "memory");
112
113 if (replaced != old && replaced != new)
114 faulted = 2;
115
116 if (!faulted)
117 flush_icache_range(ip, ip + 8);
118
119 return faulted;
120}
121
122notrace int ftrace_update_ftrace_func(ftrace_func_t func)
123{
124 unsigned long ip = (unsigned long)(&ftrace_call);
125 unsigned char old[4], *new;
126 int ret;
127
128 ip += CALL_BACK;
129
130 memcpy(old, &ftrace_call, 4);
131 new = ftrace_call_replace(ip, (unsigned long)func);
132 ret = ftrace_modify_code(ip, old, new);
133
134 return ret;
135}
136
137notrace int ftrace_mcount_set(unsigned long *data)
138{
139 unsigned long ip = (long)(&mcount_call);
140 unsigned long *addr = data;
141 unsigned char old[4], *new;
142
143 /* ip is at the location, but modify code will subtact this */
144 ip += CALL_BACK;
145
146 /*
147 * Replace the mcount stub with a pointer to the
148 * ip recorder function.
149 */
150 memcpy(old, &mcount_call, 4);
151 new = ftrace_call_replace(ip, *addr);
152 *addr = ftrace_modify_code(ip, old, new);
153
154 return 0;
155}
156
157int __init ftrace_dyn_arch_init(void *data)
158{
159 /* This is running in kstop_machine */
160
161 ftrace_mcount_set(data);
162
163 return 0;
164}
165