~ [ source navigation ] ~ [ diff markup ] ~ [ identifier search ] ~

TOMOYO Linux Cross Reference
Linux/arch/arm/kernel/ftrace.c

Version: ~ [ linux-5.6-rc1 ] ~ [ linux-5.5.2 ] ~ [ linux-5.4.17 ] ~ [ linux-5.3.18 ] ~ [ linux-5.2.21 ] ~ [ linux-5.1.21 ] ~ [ linux-5.0.21 ] ~ [ linux-4.20.17 ] ~ [ linux-4.19.102 ] ~ [ linux-4.18.20 ] ~ [ linux-4.17.19 ] ~ [ linux-4.16.18 ] ~ [ linux-4.15.18 ] ~ [ linux-4.14.170 ] ~ [ linux-4.13.16 ] ~ [ linux-4.12.14 ] ~ [ linux-4.11.12 ] ~ [ linux-4.10.17 ] ~ [ linux-4.9.213 ] ~ [ linux-4.8.17 ] ~ [ linux-4.7.10 ] ~ [ linux-4.6.7 ] ~ [ linux-4.5.7 ] ~ [ linux-4.4.213 ] ~ [ linux-4.3.6 ] ~ [ linux-4.2.8 ] ~ [ linux-4.1.52 ] ~ [ linux-4.0.9 ] ~ [ linux-3.19.8 ] ~ [ linux-3.18.140 ] ~ [ linux-3.17.8 ] ~ [ linux-3.16.81 ] ~ [ linux-3.15.10 ] ~ [ linux-3.14.79 ] ~ [ linux-3.13.11 ] ~ [ linux-3.12.74 ] ~ [ linux-3.11.10 ] ~ [ linux-3.10.108 ] ~ [ linux-3.9.11 ] ~ [ linux-3.8.13 ] ~ [ linux-3.7.10 ] ~ [ linux-3.6.11 ] ~ [ linux-3.5.7 ] ~ [ linux-3.4.113 ] ~ [ linux-3.3.8 ] ~ [ linux-3.2.102 ] ~ [ linux-3.1.10 ] ~ [ linux-3.0.101 ] ~ [ linux-2.6.32.71 ] ~ [ linux-2.6.0 ] ~ [ linux-2.4.37.11 ] ~ [ unix-v6-master ] ~ [ ccs-tools-1.8.5 ] ~ [ policy-sample ] ~
Architecture: ~ [ i386 ] ~ [ alpha ] ~ [ m68k ] ~ [ mips ] ~ [ ppc ] ~ [ sparc ] ~ [ sparc64 ] ~

  1 /*
  2  * Dynamic function tracing support.
  3  *
  4  * Copyright (C) 2008 Abhishek Sagar <sagar.abhishek@gmail.com>
  5  * Copyright (C) 2010 Rabin Vincent <rabin@rab.in>
  6  *
  7  * For licencing details, see COPYING.
  8  *
  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().
 13  */
 14 
 15 #include <linux/ftrace.h>
 16 #include <linux/uaccess.h>
 17 
 18 #include <asm/cacheflush.h>
 19 #include <asm/opcodes.h>
 20 #include <asm/ftrace.h>
 21 
 22 #include "insn.h"
 23 
 24 #ifdef CONFIG_THUMB2_KERNEL
 25 #define NOP             0xf85deb04      /* pop.w {lr} */
 26 #else
 27 #define NOP             0xe8bd4000      /* pop {lr} */
 28 #endif
 29 
 30 #ifdef CONFIG_DYNAMIC_FTRACE
 31 #ifdef CONFIG_OLD_MCOUNT
 32 #define OLD_MCOUNT_ADDR ((unsigned long) mcount)
 33 #define OLD_FTRACE_ADDR ((unsigned long) ftrace_caller_old)
 34 
 35 #define OLD_NOP         0xe1a00000      /* mov r0, r0 */
 36 
 37 static unsigned long ftrace_nop_replace(struct dyn_ftrace *rec)
 38 {
 39         return rec->arch.old_mcount ? OLD_NOP : NOP;
 40 }
 41 
 42 static unsigned long adjust_address(struct dyn_ftrace *rec, unsigned long addr)
 43 {
 44         if (!rec->arch.old_mcount)
 45                 return addr;
 46 
 47         if (addr == MCOUNT_ADDR)
 48                 addr = OLD_MCOUNT_ADDR;
 49         else if (addr == FTRACE_ADDR)
 50                 addr = OLD_FTRACE_ADDR;
 51 
 52         return addr;
 53 }
 54 #else
 55 static unsigned long ftrace_nop_replace(struct dyn_ftrace *rec)
 56 {
 57         return NOP;
 58 }
 59 
 60 static unsigned long adjust_address(struct dyn_ftrace *rec, unsigned long addr)
 61 {
 62         return addr;
 63 }
 64 #endif
 65 
 66 static unsigned long ftrace_call_replace(unsigned long pc, unsigned long addr)
 67 {
 68         return arm_gen_branch_link(pc, addr);
 69 }
 70 
 71 static int ftrace_modify_code(unsigned long pc, unsigned long old,
 72                               unsigned long new, bool validate)
 73 {
 74         unsigned long replaced;
 75 
 76         if (IS_ENABLED(CONFIG_THUMB2_KERNEL)) {
 77                 old = __opcode_to_mem_thumb32(old);
 78                 new = __opcode_to_mem_thumb32(new);
 79         } else {
 80                 old = __opcode_to_mem_arm(old);
 81                 new = __opcode_to_mem_arm(new);
 82         }
 83 
 84         if (validate) {
 85                 if (probe_kernel_read(&replaced, (void *)pc, MCOUNT_INSN_SIZE))
 86                         return -EFAULT;
 87 
 88                 if (replaced != old)
 89                         return -EINVAL;
 90         }
 91 
 92         if (probe_kernel_write((void *)pc, &new, MCOUNT_INSN_SIZE))
 93                 return -EPERM;
 94 
 95         flush_icache_range(pc, pc + MCOUNT_INSN_SIZE);
 96 
 97         return 0;
 98 }
 99 
100 int ftrace_update_ftrace_func(ftrace_func_t func)
101 {
102         unsigned long pc;
103         unsigned long new;
104         int ret;
105 
106         pc = (unsigned long)&ftrace_call;
107         new = ftrace_call_replace(pc, (unsigned long)func);
108 
109         ret = ftrace_modify_code(pc, 0, new, false);
110 
111 #ifdef CONFIG_OLD_MCOUNT
112         if (!ret) {
113                 pc = (unsigned long)&ftrace_call_old;
114                 new = ftrace_call_replace(pc, (unsigned long)func);
115 
116                 ret = ftrace_modify_code(pc, 0, new, false);
117         }
118 #endif
119 
120         return ret;
121 }
122 
123 int ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr)
124 {
125         unsigned long new, old;
126         unsigned long ip = rec->ip;
127 
128         old = ftrace_nop_replace(rec);
129         new = ftrace_call_replace(ip, adjust_address(rec, addr));
130 
131         return ftrace_modify_code(rec->ip, old, new, true);
132 }
133 
134 int ftrace_make_nop(struct module *mod,
135                     struct dyn_ftrace *rec, unsigned long addr)
136 {
137         unsigned long ip = rec->ip;
138         unsigned long old;
139         unsigned long new;
140         int ret;
141 
142         old = ftrace_call_replace(ip, adjust_address(rec, addr));
143         new = ftrace_nop_replace(rec);
144         ret = ftrace_modify_code(ip, old, new, true);
145 
146 #ifdef CONFIG_OLD_MCOUNT
147         if (ret == -EINVAL && addr == MCOUNT_ADDR) {
148                 rec->arch.old_mcount = true;
149 
150                 old = ftrace_call_replace(ip, adjust_address(rec, addr));
151                 new = ftrace_nop_replace(rec);
152                 ret = ftrace_modify_code(ip, old, new, true);
153         }
154 #endif
155 
156         return ret;
157 }
158 
159 int __init ftrace_dyn_arch_init(void *data)
160 {
161         *(unsigned long *)data = 0;
162 
163         return 0;
164 }
165 #endif /* CONFIG_DYNAMIC_FTRACE */
166 
167 #ifdef CONFIG_FUNCTION_GRAPH_TRACER
168 void prepare_ftrace_return(unsigned long *parent, unsigned long self_addr,
169                            unsigned long frame_pointer)
170 {
171         unsigned long return_hooker = (unsigned long) &return_to_handler;
172         struct ftrace_graph_ent trace;
173         unsigned long old;
174         int err;
175 
176         if (unlikely(atomic_read(&current->tracing_graph_pause)))
177                 return;
178 
179         old = *parent;
180         *parent = return_hooker;
181 
182         trace.func = self_addr;
183         trace.depth = current->curr_ret_stack + 1;
184 
185         /* Only trace if the calling function expects to */
186         if (!ftrace_graph_entry(&trace)) {
187                 *parent = old;
188                 return;
189         }
190 
191         err = ftrace_push_return_trace(old, self_addr, &trace.depth,
192                                        frame_pointer);
193         if (err == -EBUSY) {
194                 *parent = old;
195                 return;
196         }
197 }
198 
199 #ifdef CONFIG_DYNAMIC_FTRACE
200 extern unsigned long ftrace_graph_call;
201 extern unsigned long ftrace_graph_call_old;
202 extern void ftrace_graph_caller_old(void);
203 
204 static int __ftrace_modify_caller(unsigned long *callsite,
205                                   void (*func) (void), bool enable)
206 {
207         unsigned long caller_fn = (unsigned long) func;
208         unsigned long pc = (unsigned long) callsite;
209         unsigned long branch = arm_gen_branch(pc, caller_fn);
210         unsigned long nop = 0xe1a00000; /* mov r0, r0 */
211         unsigned long old = enable ? nop : branch;
212         unsigned long new = enable ? branch : nop;
213 
214         return ftrace_modify_code(pc, old, new, true);
215 }
216 
217 static int ftrace_modify_graph_caller(bool enable)
218 {
219         int ret;
220 
221         ret = __ftrace_modify_caller(&ftrace_graph_call,
222                                      ftrace_graph_caller,
223                                      enable);
224 
225 #ifdef CONFIG_OLD_MCOUNT
226         if (!ret)
227                 ret = __ftrace_modify_caller(&ftrace_graph_call_old,
228                                              ftrace_graph_caller_old,
229                                              enable);
230 #endif
231 
232         return ret;
233 }
234 
235 int ftrace_enable_ftrace_graph_caller(void)
236 {
237         return ftrace_modify_graph_caller(true);
238 }
239 
240 int ftrace_disable_ftrace_graph_caller(void)
241 {
242         return ftrace_modify_graph_caller(false);
243 }
244 #endif /* CONFIG_DYNAMIC_FTRACE */
245 #endif /* CONFIG_FUNCTION_GRAPH_TRACER */
246 

~ [ source navigation ] ~ [ diff markup ] ~ [ identifier search ] ~

kernel.org | git.kernel.org | LWN.net | Project Home | Wiki (Japanese) | Wiki (English) | SVN repository | Mail admin

Linux® is a registered trademark of Linus Torvalds in the United States and other countries.
TOMOYO® is a registered trademark of NTT DATA CORPORATION.

osdn.jp