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git.proxmox.com Git - mirror_ubuntu-zesty-kernel.git/blob - arch/arm/kernel/ftrace.c
2 * Dynamic function tracing support.
4 * Copyright (C) 2008 Abhishek Sagar <sagar.abhishek@gmail.com>
5 * Copyright (C) 2010 Rabin Vincent <rabin@rab.in>
7 * For licencing details, see COPYING.
9 * Defines low-level handling of mcount calls when the kernel
10 * is compiled with the -pg flag. When using dynamic ftrace, the
11 * mcount call-sites get patched with NOP till they are enabled.
12 * All code mutation routines here are called under stop_machine().
15 #include <linux/ftrace.h>
16 #include <linux/uaccess.h>
17 #include <linux/module.h>
18 #include <linux/stop_machine.h>
20 #include <asm/cacheflush.h>
21 #include <asm/opcodes.h>
22 #include <asm/ftrace.h>
25 #ifdef CONFIG_THUMB2_KERNEL
26 #define NOP 0xf85deb04 /* pop.w {lr} */
28 #define NOP 0xe8bd4000 /* pop {lr} */
31 #ifdef CONFIG_DYNAMIC_FTRACE
32 #ifdef CONFIG_OLD_MCOUNT
33 #define OLD_MCOUNT_ADDR ((unsigned long) mcount)
34 #define OLD_FTRACE_ADDR ((unsigned long) ftrace_caller_old)
36 #define OLD_NOP 0xe1a00000 /* mov r0, r0 */
38 static int __ftrace_modify_code(void *data
)
43 ftrace_modify_all_code(*command
);
49 void arch_ftrace_update_code(int command
)
51 stop_machine(__ftrace_modify_code
, &command
, NULL
);
54 static unsigned long ftrace_nop_replace(struct dyn_ftrace
*rec
)
56 return rec
->arch
.old_mcount
? OLD_NOP
: NOP
;
59 static unsigned long adjust_address(struct dyn_ftrace
*rec
, unsigned long addr
)
61 if (!rec
->arch
.old_mcount
)
64 if (addr
== MCOUNT_ADDR
)
65 addr
= OLD_MCOUNT_ADDR
;
66 else if (addr
== FTRACE_ADDR
)
67 addr
= OLD_FTRACE_ADDR
;
72 static unsigned long ftrace_nop_replace(struct dyn_ftrace
*rec
)
77 static unsigned long adjust_address(struct dyn_ftrace
*rec
, unsigned long addr
)
83 int ftrace_arch_code_modify_prepare(void)
85 set_all_modules_text_rw();
89 int ftrace_arch_code_modify_post_process(void)
91 set_all_modules_text_ro();
92 /* Make sure any TLB misses during machine stop are cleared. */
97 static unsigned long ftrace_call_replace(unsigned long pc
, unsigned long addr
)
99 return arm_gen_branch_link(pc
, addr
);
102 static int ftrace_modify_code(unsigned long pc
, unsigned long old
,
103 unsigned long new, bool validate
)
105 unsigned long replaced
;
107 if (IS_ENABLED(CONFIG_THUMB2_KERNEL
)) {
108 old
= __opcode_to_mem_thumb32(old
);
109 new = __opcode_to_mem_thumb32(new);
111 old
= __opcode_to_mem_arm(old
);
112 new = __opcode_to_mem_arm(new);
116 if (probe_kernel_read(&replaced
, (void *)pc
, MCOUNT_INSN_SIZE
))
123 if (probe_kernel_write((void *)pc
, &new, MCOUNT_INSN_SIZE
))
126 flush_icache_range(pc
, pc
+ MCOUNT_INSN_SIZE
);
131 int ftrace_update_ftrace_func(ftrace_func_t func
)
137 pc
= (unsigned long)&ftrace_call
;
138 new = ftrace_call_replace(pc
, (unsigned long)func
);
140 ret
= ftrace_modify_code(pc
, 0, new, false);
142 #ifdef CONFIG_OLD_MCOUNT
144 pc
= (unsigned long)&ftrace_call_old
;
145 new = ftrace_call_replace(pc
, (unsigned long)func
);
147 ret
= ftrace_modify_code(pc
, 0, new, false);
154 int ftrace_make_call(struct dyn_ftrace
*rec
, unsigned long addr
)
156 unsigned long new, old
;
157 unsigned long ip
= rec
->ip
;
159 old
= ftrace_nop_replace(rec
);
160 new = ftrace_call_replace(ip
, adjust_address(rec
, addr
));
162 return ftrace_modify_code(rec
->ip
, old
, new, true);
165 int ftrace_make_nop(struct module
*mod
,
166 struct dyn_ftrace
*rec
, unsigned long addr
)
168 unsigned long ip
= rec
->ip
;
173 old
= ftrace_call_replace(ip
, adjust_address(rec
, addr
));
174 new = ftrace_nop_replace(rec
);
175 ret
= ftrace_modify_code(ip
, old
, new, true);
177 #ifdef CONFIG_OLD_MCOUNT
178 if (ret
== -EINVAL
&& addr
== MCOUNT_ADDR
) {
179 rec
->arch
.old_mcount
= true;
181 old
= ftrace_call_replace(ip
, adjust_address(rec
, addr
));
182 new = ftrace_nop_replace(rec
);
183 ret
= ftrace_modify_code(ip
, old
, new, true);
190 int __init
ftrace_dyn_arch_init(void)
194 #endif /* CONFIG_DYNAMIC_FTRACE */
196 #ifdef CONFIG_FUNCTION_GRAPH_TRACER
197 void prepare_ftrace_return(unsigned long *parent
, unsigned long self_addr
,
198 unsigned long frame_pointer
)
200 unsigned long return_hooker
= (unsigned long) &return_to_handler
;
201 struct ftrace_graph_ent trace
;
205 if (unlikely(atomic_read(¤t
->tracing_graph_pause
)))
209 *parent
= return_hooker
;
211 trace
.func
= self_addr
;
212 trace
.depth
= current
->curr_ret_stack
+ 1;
214 /* Only trace if the calling function expects to */
215 if (!ftrace_graph_entry(&trace
)) {
220 err
= ftrace_push_return_trace(old
, self_addr
, &trace
.depth
,
228 #ifdef CONFIG_DYNAMIC_FTRACE
229 extern unsigned long ftrace_graph_call
;
230 extern unsigned long ftrace_graph_call_old
;
231 extern void ftrace_graph_caller_old(void);
233 static int __ftrace_modify_caller(unsigned long *callsite
,
234 void (*func
) (void), bool enable
)
236 unsigned long caller_fn
= (unsigned long) func
;
237 unsigned long pc
= (unsigned long) callsite
;
238 unsigned long branch
= arm_gen_branch(pc
, caller_fn
);
239 unsigned long nop
= 0xe1a00000; /* mov r0, r0 */
240 unsigned long old
= enable
? nop
: branch
;
241 unsigned long new = enable
? branch
: nop
;
243 return ftrace_modify_code(pc
, old
, new, true);
246 static int ftrace_modify_graph_caller(bool enable
)
250 ret
= __ftrace_modify_caller(&ftrace_graph_call
,
254 #ifdef CONFIG_OLD_MCOUNT
256 ret
= __ftrace_modify_caller(&ftrace_graph_call_old
,
257 ftrace_graph_caller_old
,
264 int ftrace_enable_ftrace_graph_caller(void)
266 return ftrace_modify_graph_caller(true);
269 int ftrace_disable_ftrace_graph_caller(void)
271 return ftrace_modify_graph_caller(false);
273 #endif /* CONFIG_DYNAMIC_FTRACE */
274 #endif /* CONFIG_FUNCTION_GRAPH_TRACER */