blob: 60e7e5e45af15135375a0183cca9759ff06442c0 [file] [log] [blame]
Wu Zhangjin538f1952009-11-20 20:34:32 +08001/*
2 * Code for replacing ftrace calls with jumps.
3 *
4 * Copyright (C) 2007-2008 Steven Rostedt <srostedt@redhat.com>
Wu Zhangjine4240542010-05-14 19:08:32 +08005 * Copyright (C) 2009, 2010 DSLab, Lanzhou University, China
Wu Zhangjinf7a904d2010-01-04 17:16:51 +08006 * Author: Wu Zhangjin <wuzhangjin@gmail.com>
Wu Zhangjin538f1952009-11-20 20:34:32 +08007 *
8 * Thanks goes to Steven Rostedt for writing the original x86 version.
9 */
10
11#include <linux/uaccess.h>
12#include <linux/init.h>
13#include <linux/ftrace.h>
Ralf Baechle19e2e172012-07-13 23:38:17 +020014#include <linux/syscalls.h>
Wu Zhangjin538f1952009-11-20 20:34:32 +080015
Wu Zhangjin29c5d342009-11-20 20:34:34 +080016#include <asm/asm.h>
17#include <asm/asm-offsets.h>
Wu Zhangjine4240542010-05-14 19:08:32 +080018#include <asm/cacheflush.h>
Ralf Baechle19e2e172012-07-13 23:38:17 +020019#include <asm/syscall.h>
Wu Zhangjine4240542010-05-14 19:08:32 +080020#include <asm/uasm.h>
Ralf Baechle19e2e172012-07-13 23:38:17 +020021#include <asm/unistd.h>
Wu Zhangjin538f1952009-11-20 20:34:32 +080022
Wu Zhangjind9cdb2f2011-01-20 03:28:29 +080023#include <asm-generic/sections.h>
Wu Zhangjinc9f84872010-05-14 19:08:34 +080024
Thomas Gleixner49de8302011-07-23 12:41:23 +000025#if defined(KBUILD_MCOUNT_RA_ADDRESS) && defined(CONFIG_32BIT)
26#define MCOUNT_OFFSET_INSNS 5
27#else
28#define MCOUNT_OFFSET_INSNS 4
29#endif
30
Markos Chandrascb2f9932013-06-10 10:35:26 +000031#ifdef CONFIG_DYNAMIC_FTRACE
32
Al Cooper58b69402013-01-16 22:43:28 +000033/* Arch override because MIPS doesn't need to run this from stop_machine() */
34void arch_ftrace_update_code(int command)
35{
36 ftrace_modify_all_code(command);
37}
38
Markos Chandrascb2f9932013-06-10 10:35:26 +000039#endif
40
Thomas Gleixner49de8302011-07-23 12:41:23 +000041/*
42 * Check if the address is in kernel space
43 *
44 * Clone core_kernel_text() from kernel/extable.c, but doesn't call
45 * init_kernel_text() for Ftrace doesn't trace functions in init sections.
46 */
47static inline int in_kernel_space(unsigned long ip)
48{
49 if (ip >= (unsigned long)_stext &&
50 ip <= (unsigned long)_etext)
51 return 1;
52 return 0;
53}
54
Wu Zhangjin538f1952009-11-20 20:34:32 +080055#ifdef CONFIG_DYNAMIC_FTRACE
56
57#define JAL 0x0c000000 /* jump & link: ip --> ra, jump to target */
58#define ADDR_MASK 0x03ffffff /* op_code|addr : 31...26|25 ....0 */
David Daneyc54794d2010-12-28 13:21:37 -080059#define JUMP_RANGE_MASK ((1UL << 28) - 1)
Wu Zhangjin538f1952009-11-20 20:34:32 +080060
Wu Zhangjin4d6829f2010-05-14 19:08:31 +080061#define INSN_NOP 0x00000000 /* nop */
Wu Zhangjine4240542010-05-14 19:08:32 +080062#define INSN_JAL(addr) \
63 ((unsigned int)(JAL | (((addr) >> 2) & ADDR_MASK)))
64
65static unsigned int insn_jal_ftrace_caller __read_mostly;
66static unsigned int insn_lui_v1_hi16_mcount __read_mostly;
67static unsigned int insn_j_ftrace_graph_caller __maybe_unused __read_mostly;
68
69static inline void ftrace_dyn_arch_init_insns(void)
70{
71 u32 *buf;
72 unsigned int v1;
73
74 /* lui v1, hi16_mcount */
75 v1 = 3;
76 buf = (u32 *)&insn_lui_v1_hi16_mcount;
77 UASM_i_LA_mostly(&buf, v1, MCOUNT_ADDR);
78
79 /* jal (ftrace_caller + 8), jump over the first two instruction */
80 buf = (u32 *)&insn_jal_ftrace_caller;
David Daneyc54794d2010-12-28 13:21:37 -080081 uasm_i_jal(&buf, (FTRACE_ADDR + 8) & JUMP_RANGE_MASK);
Wu Zhangjine4240542010-05-14 19:08:32 +080082
83#ifdef CONFIG_FUNCTION_GRAPH_TRACER
84 /* j ftrace_graph_caller */
85 buf = (u32 *)&insn_j_ftrace_graph_caller;
David Daneyc54794d2010-12-28 13:21:37 -080086 uasm_i_j(&buf, (unsigned long)ftrace_graph_caller & JUMP_RANGE_MASK);
Wu Zhangjine4240542010-05-14 19:08:32 +080087#endif
88}
Wu Zhangjin538f1952009-11-20 20:34:32 +080089
90static int ftrace_modify_code(unsigned long ip, unsigned int new_code)
91{
Wu Zhangjin046199c2009-11-20 20:34:36 +080092 int faulted;
Leonid Yegoshin6ebda442013-12-16 12:06:55 +000093 mm_segment_t old_fs;
Wu Zhangjin046199c2009-11-20 20:34:36 +080094
95 /* *(unsigned int *)ip = new_code; */
96 safe_store_code(new_code, ip, faulted);
97
98 if (unlikely(faulted))
99 return -EFAULT;
Wu Zhangjin538f1952009-11-20 20:34:32 +0800100
Leonid Yegoshin6ebda442013-12-16 12:06:55 +0000101 old_fs = get_fs();
102 set_fs(get_ds());
Wu Zhangjin538f1952009-11-20 20:34:32 +0800103 flush_icache_range(ip, ip + 8);
Leonid Yegoshin6ebda442013-12-16 12:06:55 +0000104 set_fs(old_fs);
Wu Zhangjin538f1952009-11-20 20:34:32 +0800105
106 return 0;
107}
108
Al Cooper58b69402013-01-16 22:43:28 +0000109#ifndef CONFIG_64BIT
110static int ftrace_modify_code_2(unsigned long ip, unsigned int new_code1,
111 unsigned int new_code2)
112{
113 int faulted;
114
115 safe_store_code(new_code1, ip, faulted);
116 if (unlikely(faulted))
117 return -EFAULT;
Viller Hsiaoa4671092014-02-22 15:46:49 +0800118 safe_store_code(new_code2, ip + 4, faulted);
Al Cooper58b69402013-01-16 22:43:28 +0000119 if (unlikely(faulted))
120 return -EFAULT;
Viller Hsiaoa4671092014-02-22 15:46:49 +0800121 flush_icache_range(ip, ip + 8);
Al Cooper58b69402013-01-16 22:43:28 +0000122 return 0;
123}
124#endif
125
Wu Zhangjin7f21a602011-01-20 03:28:31 +0800126/*
127 * The details about the calling site of mcount on MIPS
128 *
129 * 1. For kernel:
130 *
131 * move at, ra
132 * jal _mcount --> nop
133 *
134 * 2. For modules:
135 *
136 * 2.1 For KBUILD_MCOUNT_RA_ADDRESS and CONFIG_32BIT
137 *
Ralf Baechle70342282013-01-22 12:59:30 +0100138 * lui v1, hi_16bit_of_mcount --> b 1f (0x10000005)
Wu Zhangjin7f21a602011-01-20 03:28:31 +0800139 * addiu v1, v1, low_16bit_of_mcount
140 * move at, ra
141 * move $12, ra_address
142 * jalr v1
143 * sub sp, sp, 8
Ralf Baechle70342282013-01-22 12:59:30 +0100144 * 1: offset = 5 instructions
Wu Zhangjin7f21a602011-01-20 03:28:31 +0800145 * 2.2 For the Other situations
146 *
Ralf Baechle70342282013-01-22 12:59:30 +0100147 * lui v1, hi_16bit_of_mcount --> b 1f (0x10000004)
Wu Zhangjin7f21a602011-01-20 03:28:31 +0800148 * addiu v1, v1, low_16bit_of_mcount
149 * move at, ra
150 * jalr v1
151 * nop | move $12, ra_address | sub sp, sp, 8
Ralf Baechle70342282013-01-22 12:59:30 +0100152 * 1: offset = 4 instructions
Wu Zhangjin7f21a602011-01-20 03:28:31 +0800153 */
154
Wu Zhangjin7f21a602011-01-20 03:28:31 +0800155#define INSN_B_1F (0x10000000 | MCOUNT_OFFSET_INSNS)
156
Wu Zhangjin538f1952009-11-20 20:34:32 +0800157int ftrace_make_nop(struct module *mod,
158 struct dyn_ftrace *rec, unsigned long addr)
159{
160 unsigned int new;
161 unsigned long ip = rec->ip;
162
Wu Zhangjine4240542010-05-14 19:08:32 +0800163 /*
Wu Zhangjind9cdb2f2011-01-20 03:28:29 +0800164 * If ip is in kernel space, no long call, otherwise, long call is
165 * needed.
Wu Zhangjine4240542010-05-14 19:08:32 +0800166 */
Wu Zhangjin7f21a602011-01-20 03:28:31 +0800167 new = in_kernel_space(ip) ? INSN_NOP : INSN_B_1F;
Al Cooper58b69402013-01-16 22:43:28 +0000168#ifdef CONFIG_64BIT
Wu Zhangjin538f1952009-11-20 20:34:32 +0800169 return ftrace_modify_code(ip, new);
Al Cooper58b69402013-01-16 22:43:28 +0000170#else
171 /*
172 * On 32 bit MIPS platforms, gcc adds a stack adjust
173 * instruction in the delay slot after the branch to
174 * mcount and expects mcount to restore the sp on return.
175 * This is based on a legacy API and does nothing but
176 * waste instructions so it's being removed at runtime.
177 */
178 return ftrace_modify_code_2(ip, new, INSN_NOP);
179#endif
Wu Zhangjin538f1952009-11-20 20:34:32 +0800180}
181
Wu Zhangjin538f1952009-11-20 20:34:32 +0800182int ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr)
183{
184 unsigned int new;
185 unsigned long ip = rec->ip;
186
Wu Zhangjind9cdb2f2011-01-20 03:28:29 +0800187 new = in_kernel_space(ip) ? insn_jal_ftrace_caller :
188 insn_lui_v1_hi16_mcount;
Wu Zhangjin538f1952009-11-20 20:34:32 +0800189
190 return ftrace_modify_code(ip, new);
191}
192
193#define FTRACE_CALL_IP ((unsigned long)(&ftrace_call))
194
195int ftrace_update_ftrace_func(ftrace_func_t func)
196{
197 unsigned int new;
198
Wu Zhangjin4d6829f2010-05-14 19:08:31 +0800199 new = INSN_JAL((unsigned long)func);
Wu Zhangjin538f1952009-11-20 20:34:32 +0800200
201 return ftrace_modify_code(FTRACE_CALL_IP, new);
202}
203
Jiri Slaby3a36cb12014-02-24 19:59:59 +0100204int __init ftrace_dyn_arch_init(void)
Wu Zhangjin538f1952009-11-20 20:34:32 +0800205{
Wu Zhangjine4240542010-05-14 19:08:32 +0800206 /* Encode the instructions when booting */
207 ftrace_dyn_arch_init_insns();
208
209 /* Remove "b ftrace_stub" to ensure ftrace_caller() is executed */
210 ftrace_modify_code(MCOUNT_ADDR, INSN_NOP);
211
Wu Zhangjin538f1952009-11-20 20:34:32 +0800212 return 0;
213}
Wu Zhangjin68ccf752010-05-14 19:08:33 +0800214#endif /* CONFIG_DYNAMIC_FTRACE */
Wu Zhangjin29c5d342009-11-20 20:34:34 +0800215
216#ifdef CONFIG_FUNCTION_GRAPH_TRACER
217
Wu Zhangjine17ff5f2009-11-20 20:34:35 +0800218#ifdef CONFIG_DYNAMIC_FTRACE
219
220extern void ftrace_graph_call(void);
Wu Zhangjine17ff5f2009-11-20 20:34:35 +0800221#define FTRACE_GRAPH_CALL_IP ((unsigned long)(&ftrace_graph_call))
222
223int ftrace_enable_ftrace_graph_caller(void)
224{
225 return ftrace_modify_code(FTRACE_GRAPH_CALL_IP,
Wu Zhangjine4240542010-05-14 19:08:32 +0800226 insn_j_ftrace_graph_caller);
Wu Zhangjine17ff5f2009-11-20 20:34:35 +0800227}
228
229int ftrace_disable_ftrace_graph_caller(void)
230{
Wu Zhangjin4d6829f2010-05-14 19:08:31 +0800231 return ftrace_modify_code(FTRACE_GRAPH_CALL_IP, INSN_NOP);
Wu Zhangjine17ff5f2009-11-20 20:34:35 +0800232}
233
Wu Zhangjin68ccf752010-05-14 19:08:33 +0800234#endif /* CONFIG_DYNAMIC_FTRACE */
Wu Zhangjine17ff5f2009-11-20 20:34:35 +0800235
Wu Zhangjin7326c4e2009-11-20 20:34:38 +0800236#ifndef KBUILD_MCOUNT_RA_ADDRESS
Wu Zhangjin68ccf752010-05-14 19:08:33 +0800237
Ralf Baechle70342282013-01-22 12:59:30 +0100238#define S_RA_SP (0xafbf << 16) /* s{d,w} ra, offset(sp) */
239#define S_R_SP (0xafb0 << 16) /* s{d,w} R, offset(sp) */
Wu Zhangjin29c5d342009-11-20 20:34:34 +0800240#define OFFSET_MASK 0xffff /* stack offset range: 0 ~ PT_SIZE */
241
Wu Zhangjin2816e322011-01-20 03:28:30 +0800242unsigned long ftrace_get_parent_ra_addr(unsigned long self_ra, unsigned long
243 old_parent_ra, unsigned long parent_ra_addr, unsigned long fp)
Wu Zhangjin29c5d342009-11-20 20:34:34 +0800244{
Wu Zhangjin2816e322011-01-20 03:28:30 +0800245 unsigned long sp, ip, tmp;
Wu Zhangjin29c5d342009-11-20 20:34:34 +0800246 unsigned int code;
Wu Zhangjin046199c2009-11-20 20:34:36 +0800247 int faulted;
Wu Zhangjin29c5d342009-11-20 20:34:34 +0800248
Wu Zhangjin68ccf752010-05-14 19:08:33 +0800249 /*
Wu Zhangjin2816e322011-01-20 03:28:30 +0800250 * For module, move the ip from the return address after the
Wu Zhangjin9a620a52011-01-20 03:28:27 +0800251 * instruction "lui v1, hi_16bit_of_mcount"(offset is 24), but for
252 * kernel, move after the instruction "move ra, at"(offset is 16)
Wu Zhangjin68ccf752010-05-14 19:08:33 +0800253 */
Wu Zhangjin2816e322011-01-20 03:28:30 +0800254 ip = self_ra - (in_kernel_space(self_ra) ? 16 : 24);
Wu Zhangjin29c5d342009-11-20 20:34:34 +0800255
Wu Zhangjin68ccf752010-05-14 19:08:33 +0800256 /*
257 * search the text until finding the non-store instruction or "s{d,w}
258 * ra, offset(sp)" instruction
259 */
Wu Zhangjin29c5d342009-11-20 20:34:34 +0800260 do {
Wu Zhangjin046199c2009-11-20 20:34:36 +0800261 /* get the code at "ip": code = *(unsigned int *)ip; */
262 safe_load_code(code, ip, faulted);
263
264 if (unlikely(faulted))
265 return 0;
Wu Zhangjin68ccf752010-05-14 19:08:33 +0800266 /*
267 * If we hit the non-store instruction before finding where the
Wu Zhangjin29c5d342009-11-20 20:34:34 +0800268 * ra is stored, then this is a leaf function and it does not
Wu Zhangjin68ccf752010-05-14 19:08:33 +0800269 * store the ra on the stack
270 */
Wu Zhangjin29c5d342009-11-20 20:34:34 +0800271 if ((code & S_R_SP) != S_R_SP)
Wu Zhangjin2816e322011-01-20 03:28:30 +0800272 return parent_ra_addr;
Wu Zhangjin29c5d342009-11-20 20:34:34 +0800273
Wu Zhangjin9a620a52011-01-20 03:28:27 +0800274 /* Move to the next instruction */
275 ip -= 4;
276 } while ((code & S_RA_SP) != S_RA_SP);
Wu Zhangjin29c5d342009-11-20 20:34:34 +0800277
278 sp = fp + (code & OFFSET_MASK);
Wu Zhangjin046199c2009-11-20 20:34:36 +0800279
Wu Zhangjin2816e322011-01-20 03:28:30 +0800280 /* tmp = *(unsigned long *)sp; */
281 safe_load_stack(tmp, sp, faulted);
Wu Zhangjin046199c2009-11-20 20:34:36 +0800282 if (unlikely(faulted))
283 return 0;
Wu Zhangjin29c5d342009-11-20 20:34:34 +0800284
Wu Zhangjin2816e322011-01-20 03:28:30 +0800285 if (tmp == old_parent_ra)
Wu Zhangjin29c5d342009-11-20 20:34:34 +0800286 return sp;
Wu Zhangjin29c5d342009-11-20 20:34:34 +0800287 return 0;
288}
289
Wu Zhangjin68ccf752010-05-14 19:08:33 +0800290#endif /* !KBUILD_MCOUNT_RA_ADDRESS */
Wu Zhangjin7326c4e2009-11-20 20:34:38 +0800291
Wu Zhangjin29c5d342009-11-20 20:34:34 +0800292/*
293 * Hook the return address and push it in the stack of return addrs
294 * in current thread info.
295 */
Wu Zhangjin2816e322011-01-20 03:28:30 +0800296void prepare_ftrace_return(unsigned long *parent_ra_addr, unsigned long self_ra,
Wu Zhangjin29c5d342009-11-20 20:34:34 +0800297 unsigned long fp)
298{
Wu Zhangjin2816e322011-01-20 03:28:30 +0800299 unsigned long old_parent_ra;
Wu Zhangjin29c5d342009-11-20 20:34:34 +0800300 struct ftrace_graph_ent trace;
301 unsigned long return_hooker = (unsigned long)
302 &return_to_handler;
Wu Zhangjinb9f07eb2011-01-22 02:01:53 +0800303 int faulted, insns;
Wu Zhangjin29c5d342009-11-20 20:34:34 +0800304
305 if (unlikely(atomic_read(&current->tracing_graph_pause)))
306 return;
307
Wu Zhangjin68ccf752010-05-14 19:08:33 +0800308 /*
Wu Zhangjin2816e322011-01-20 03:28:30 +0800309 * "parent_ra_addr" is the stack address saved the return address of
310 * the caller of _mcount.
Wu Zhangjin7326c4e2009-11-20 20:34:38 +0800311 *
312 * if the gcc < 4.5, a leaf function does not save the return address
313 * in the stack address, so, we "emulate" one in _mcount's stack space,
314 * and hijack it directly, but for a non-leaf function, it save the
315 * return address to the its own stack space, we can not hijack it
316 * directly, but need to find the real stack address,
Wu Zhangjin29c5d342009-11-20 20:34:34 +0800317 * ftrace_get_parent_addr() does it!
Wu Zhangjin7326c4e2009-11-20 20:34:38 +0800318 *
319 * if gcc>= 4.5, with the new -mmcount-ra-address option, for a
320 * non-leaf function, the location of the return address will be saved
321 * to $12 for us, and for a leaf function, only put a zero into $12. we
322 * do it in ftrace_graph_caller of mcount.S.
Wu Zhangjin29c5d342009-11-20 20:34:34 +0800323 */
324
Wu Zhangjin2816e322011-01-20 03:28:30 +0800325 /* old_parent_ra = *parent_ra_addr; */
326 safe_load_stack(old_parent_ra, parent_ra_addr, faulted);
Wu Zhangjin046199c2009-11-20 20:34:36 +0800327 if (unlikely(faulted))
328 goto out;
Wu Zhangjin7326c4e2009-11-20 20:34:38 +0800329#ifndef KBUILD_MCOUNT_RA_ADDRESS
Wu Zhangjin2816e322011-01-20 03:28:30 +0800330 parent_ra_addr = (unsigned long *)ftrace_get_parent_ra_addr(self_ra,
331 old_parent_ra, (unsigned long)parent_ra_addr, fp);
Wu Zhangjin68ccf752010-05-14 19:08:33 +0800332 /*
333 * If fails when getting the stack address of the non-leaf function's
334 * ra, stop function graph tracer and return
335 */
Wu Zhangjin2816e322011-01-20 03:28:30 +0800336 if (parent_ra_addr == 0)
Wu Zhangjin046199c2009-11-20 20:34:36 +0800337 goto out;
Wu Zhangjin7326c4e2009-11-20 20:34:38 +0800338#endif
Wu Zhangjin2816e322011-01-20 03:28:30 +0800339 /* *parent_ra_addr = return_hooker; */
340 safe_store_stack(return_hooker, parent_ra_addr, faulted);
Wu Zhangjin046199c2009-11-20 20:34:36 +0800341 if (unlikely(faulted))
342 goto out;
Wu Zhangjin29c5d342009-11-20 20:34:34 +0800343
Wu Zhangjin2816e322011-01-20 03:28:30 +0800344 if (ftrace_push_return_trace(old_parent_ra, self_ra, &trace.depth, fp)
345 == -EBUSY) {
346 *parent_ra_addr = old_parent_ra;
Wu Zhangjin29c5d342009-11-20 20:34:34 +0800347 return;
348 }
349
Wu Zhangjinb9f07eb2011-01-22 02:01:53 +0800350 /*
351 * Get the recorded ip of the current mcount calling site in the
352 * __mcount_loc section, which will be used to filter the function
353 * entries configured through the tracing/set_graph_function interface.
354 */
355
356 insns = in_kernel_space(self_ra) ? 2 : MCOUNT_OFFSET_INSNS + 1;
357 trace.func = self_ra - (MCOUNT_INSN_SIZE * insns);
Wu Zhangjin29c5d342009-11-20 20:34:34 +0800358
359 /* Only trace if the calling function expects to */
360 if (!ftrace_graph_entry(&trace)) {
361 current->curr_ret_stack--;
Wu Zhangjin2816e322011-01-20 03:28:30 +0800362 *parent_ra_addr = old_parent_ra;
Wu Zhangjin29c5d342009-11-20 20:34:34 +0800363 }
Wu Zhangjin046199c2009-11-20 20:34:36 +0800364 return;
365out:
366 ftrace_graph_stop();
367 WARN_ON(1);
Wu Zhangjin29c5d342009-11-20 20:34:34 +0800368}
Wu Zhangjin68ccf752010-05-14 19:08:33 +0800369#endif /* CONFIG_FUNCTION_GRAPH_TRACER */
Ralf Baechle19e2e172012-07-13 23:38:17 +0200370
371#ifdef CONFIG_FTRACE_SYSCALLS
372
373#ifdef CONFIG_32BIT
374unsigned long __init arch_syscall_addr(int nr)
375{
376 return (unsigned long)sys_call_table[nr - __NR_O32_Linux];
377}
378#endif
379
380#ifdef CONFIG_64BIT
381
382unsigned long __init arch_syscall_addr(int nr)
383{
384#ifdef CONFIG_MIPS32_N32
385 if (nr >= __NR_N32_Linux && nr <= __NR_N32_Linux + __NR_N32_Linux_syscalls)
Ralf Baechle46e12c02012-07-14 09:22:05 +0200386 return (unsigned long)sysn32_call_table[nr - __NR_N32_Linux];
Ralf Baechle19e2e172012-07-13 23:38:17 +0200387#endif
388 if (nr >= __NR_64_Linux && nr <= __NR_64_Linux + __NR_64_Linux_syscalls)
389 return (unsigned long)sys_call_table[nr - __NR_64_Linux];
390#ifdef CONFIG_MIPS32_O32
391 if (nr >= __NR_O32_Linux && nr <= __NR_O32_Linux + __NR_O32_Linux_syscalls)
392 return (unsigned long)sys32_call_table[nr - __NR_O32_Linux];
393#endif
394
395 return (unsigned long) &sys_ni_syscall;
396}
397#endif
398
399#endif /* CONFIG_FTRACE_SYSCALLS */